Volume 20,Issue 6,2022 Table of Contents
2022, 20(6):1041-1051.
Abstract:
The construction and operation of reservoirs changed the downstream hydrological regime and affected the reproduction of aquatic organisms. The current multi-objective reservoir operation models maximized the economic and ecological comprehensive benefits which only quantify a single ecological flow index. However, downstream river ecology is not only reflected by the magnitude of the streamflow, but also affected by the hydrologic alternation. Hence, it is necessary to explore an optimal operation scheme that can balance the objectives of flood control and economic comprehensive benefits and reduce the negative impact on the downstream ecological environment.Ecological indicators that could reflect the downstream ecological water demand and fluctuation were constructed according to the indicators of hydrologic alteration (IHA). The degree to which the monthly average outflow discharge met the water demand stipulated by the Tennant method was quantified as water quantity level indicator. The daily scale IHAs were filtered and simplified to reflect the flow fluctuation, and the fluctuation deviation between the outflow discharge and the natural flow constituted the hydrological alteration indicator. Water quantity level indicator and hydrological alteration indicator were selected as ecological indicators of hydrologic alteration. The greater the water quantity level indicator with the high flow grade is, the better the ecological benefit. On the other hand, the smaller the hydrological alteration indicator with the less flow fluctuation, the better for reproduction of aquatic organisms.Four objectives, i.e., water supply, power generation, outflow discharge and hydrologic alteration, were used to optimize the operation of Danjiangkou Reservoir, in which the flood control task was taken as constraint. The water transfer volume of the South-to-North Water Transfer and the north Hubei water transfer is collectively referred to as water supply, and the outflow discharge of reservoir include flood discharge and power generation. The Gaussian radial basis functions were used to fit the reservoir operation rules, and the operation model with different combination of the objective functions was optimized. The water supply, power generation and two ecological indexes under different schemes were calculated. Based on the current operation schemes of Danjiangkou Reservoir, the dialectical relationship between each index as well as the pros and cons of each scheme were analyzed and compared to find the best scheme.The application results showed that: water supply benefit was negatively correlated with power generation benefit and ecological indicators; power generation benefit was coordinated with water quantity level indicator, but contradictory with hydrological alteration indicator. In each scheme, the best multi-objective optimal operation scheme considering water supply, power generation, water quantity level and hydrological alteration simultaneously could effectively improve the two ecological indicators on the premise of maintaining the current benefits of water supply and power generation unchanged. Effectively improving the two ecological indicators was conducive to the water ecological protection and the reproduction of aquatic organisms. The outflow discharge of the best scheme was much larger than the ecological baseflow and the minimum ecological flow, and almost reached the optimal ecological flow, which could satisfy the needs of natural reproduction of aquatic organisms in the middle and lower reaches of the Hanjiang River.The water quantity level and hydrological alteration indicators based on IHA were proposed and included in the multi-objective operation model. Compared with the current operation scheme, the proposed reservoir operation model was able to reduce the negative impact on the downstream ecological environment with less data required. This practical approach could provide a reference for the multi-objective ecological operation of Danjiangkou Reservoir.
The construction and operation of reservoirs changed the downstream hydrological regime and affected the reproduction of aquatic organisms. The current multi-objective reservoir operation models maximized the economic and ecological comprehensive benefits which only quantify a single ecological flow index. However, downstream river ecology is not only reflected by the magnitude of the streamflow, but also affected by the hydrologic alternation. Hence, it is necessary to explore an optimal operation scheme that can balance the objectives of flood control and economic comprehensive benefits and reduce the negative impact on the downstream ecological environment.Ecological indicators that could reflect the downstream ecological water demand and fluctuation were constructed according to the indicators of hydrologic alteration (IHA). The degree to which the monthly average outflow discharge met the water demand stipulated by the Tennant method was quantified as water quantity level indicator. The daily scale IHAs were filtered and simplified to reflect the flow fluctuation, and the fluctuation deviation between the outflow discharge and the natural flow constituted the hydrological alteration indicator. Water quantity level indicator and hydrological alteration indicator were selected as ecological indicators of hydrologic alteration. The greater the water quantity level indicator with the high flow grade is, the better the ecological benefit. On the other hand, the smaller the hydrological alteration indicator with the less flow fluctuation, the better for reproduction of aquatic organisms.Four objectives, i.e., water supply, power generation, outflow discharge and hydrologic alteration, were used to optimize the operation of Danjiangkou Reservoir, in which the flood control task was taken as constraint. The water transfer volume of the South-to-North Water Transfer and the north Hubei water transfer is collectively referred to as water supply, and the outflow discharge of reservoir include flood discharge and power generation. The Gaussian radial basis functions were used to fit the reservoir operation rules, and the operation model with different combination of the objective functions was optimized. The water supply, power generation and two ecological indexes under different schemes were calculated. Based on the current operation schemes of Danjiangkou Reservoir, the dialectical relationship between each index as well as the pros and cons of each scheme were analyzed and compared to find the best scheme.The application results showed that: water supply benefit was negatively correlated with power generation benefit and ecological indicators; power generation benefit was coordinated with water quantity level indicator, but contradictory with hydrological alteration indicator. In each scheme, the best multi-objective optimal operation scheme considering water supply, power generation, water quantity level and hydrological alteration simultaneously could effectively improve the two ecological indicators on the premise of maintaining the current benefits of water supply and power generation unchanged. Effectively improving the two ecological indicators was conducive to the water ecological protection and the reproduction of aquatic organisms. The outflow discharge of the best scheme was much larger than the ecological baseflow and the minimum ecological flow, and almost reached the optimal ecological flow, which could satisfy the needs of natural reproduction of aquatic organisms in the middle and lower reaches of the Hanjiang River.The water quantity level and hydrological alteration indicators based on IHA were proposed and included in the multi-objective operation model. Compared with the current operation scheme, the proposed reservoir operation model was able to reduce the negative impact on the downstream ecological environment with less data required. This practical approach could provide a reference for the multi-objective ecological operation of Danjiangkou Reservoir.
2022, 20(6):1052-1064.
Abstract:
Xinjiang Uygur Autonomous Region is one of the most sensitive regions to climate change in the world. Since Shiyafeng pointed out in 2003 that the climate in Xinjiang had changed from "warm-dry" to "warm-wet", many scholars researched climate change in Xinjiang. However, most of these studies mainly focused on the trend of climate change and the impact on runoff, vegetation, glaciers, etc., and rarely combined the environmental change with the social economy. The annual average precipitation in Xinjiang is about 153 mm, and the characteristics of oasis economy and irrigation agriculture make its water resources closely linked with regional development. A comprehensive method for water resources vulnerability is used to evaluate the water resources situation in Xinjiang from 2010 to 2019.The vulnerability of water resources can comprehensively indicate the adverse effects of climate change and human activities on water resources system and the measures taken by human society to maintain the balance of water system. The evaluation index system, which included a target layer, criterion layer, and index layer was established by this model and 25 indexes were selected because the causal relationship between water resources vulnerability elements (exposure, sensitivity, adaptability) and human activities can be accurately expressed with the pressure-state-response model. The vulnerability of water resources was divided into five grades, including non-vulnerability, slight vulnerability, moderate vulnerability, severe vulnerability, and extreme vulnerability. After gaining the indexes’ data, the vulnerability standards of each index were obtained through the equal distance dispersion method, and the index weight was calculated by the entropy weight method. The vulnerability level of water resources in Xinjiang was gained by the set pair analysis, which could deal with the certainty and uncertainty within and between systems, and had been well applied in the field of water resources.The results showed that Xinjiang was severely vulnerable in 2010 and 2014, moderately vulnerable in 2011-2013 and 2015-2016, and slightly vulnerable in 2017-2019, which shows the vulnerability level of water resources in Xinjiang gradually decreased except in 2014. Comparing the vulnerability of the criterion layer and index layer with the comprehensive vulnerability of the system, it can be seen that the vulnerability of pressure layer’s climate change indicators was unstable, while the human activity indicators had obvious vulnerability trends. Among the 10 indicators of pressure layer, the natural growth rate of population was mainly severe-vulnerability, and the vulnerability of GDP growth rate, per capita water consumption, water consumption of 10 000 yuan industrial added value and water consumption of 10 000 yuan GDP was significantly improved. However, fertilizer and energy consumption were increased to severely vulnerable. In the state layer, in addition to water production coefficient and forest coverage, other indicators had a low vulnerability, but attention should be paid to the degree of water resources development. The vulnerability of per capita GDP in the response layer gradually declined from 2010 to 2019. While the vulnerability of irrigation conservation, water conservancy projects and afforestation didn’t decrease until recent years. Nevertheless, wastewater treatment, environmental protection institutions and water consumption in the ecological environment were still inadequate. From 2010 to 2014, the vulnerability level of the criterion layer was mainly moderate vulnerability and severe vulnerability and it began to decline to slightly vulnerable from 2015. The vulnerability change trend of the state layer was the closest to that of the system.On the whole, the vulnerability situation of water resources in Xinjiang has gradually improved, and the vulnerability level of some indicators decreased too. In the future, we should not only strengthen the monitoring and governance of indicators with high and unstable vulnerability but also stabilize indicators with low vulnerability to maintain the vulnerability of regional water resources at a low level.
Xinjiang Uygur Autonomous Region is one of the most sensitive regions to climate change in the world. Since Shiyafeng pointed out in 2003 that the climate in Xinjiang had changed from "warm-dry" to "warm-wet", many scholars researched climate change in Xinjiang. However, most of these studies mainly focused on the trend of climate change and the impact on runoff, vegetation, glaciers, etc., and rarely combined the environmental change with the social economy. The annual average precipitation in Xinjiang is about 153 mm, and the characteristics of oasis economy and irrigation agriculture make its water resources closely linked with regional development. A comprehensive method for water resources vulnerability is used to evaluate the water resources situation in Xinjiang from 2010 to 2019.The vulnerability of water resources can comprehensively indicate the adverse effects of climate change and human activities on water resources system and the measures taken by human society to maintain the balance of water system. The evaluation index system, which included a target layer, criterion layer, and index layer was established by this model and 25 indexes were selected because the causal relationship between water resources vulnerability elements (exposure, sensitivity, adaptability) and human activities can be accurately expressed with the pressure-state-response model. The vulnerability of water resources was divided into five grades, including non-vulnerability, slight vulnerability, moderate vulnerability, severe vulnerability, and extreme vulnerability. After gaining the indexes’ data, the vulnerability standards of each index were obtained through the equal distance dispersion method, and the index weight was calculated by the entropy weight method. The vulnerability level of water resources in Xinjiang was gained by the set pair analysis, which could deal with the certainty and uncertainty within and between systems, and had been well applied in the field of water resources.The results showed that Xinjiang was severely vulnerable in 2010 and 2014, moderately vulnerable in 2011-2013 and 2015-2016, and slightly vulnerable in 2017-2019, which shows the vulnerability level of water resources in Xinjiang gradually decreased except in 2014. Comparing the vulnerability of the criterion layer and index layer with the comprehensive vulnerability of the system, it can be seen that the vulnerability of pressure layer’s climate change indicators was unstable, while the human activity indicators had obvious vulnerability trends. Among the 10 indicators of pressure layer, the natural growth rate of population was mainly severe-vulnerability, and the vulnerability of GDP growth rate, per capita water consumption, water consumption of 10 000 yuan industrial added value and water consumption of 10 000 yuan GDP was significantly improved. However, fertilizer and energy consumption were increased to severely vulnerable. In the state layer, in addition to water production coefficient and forest coverage, other indicators had a low vulnerability, but attention should be paid to the degree of water resources development. The vulnerability of per capita GDP in the response layer gradually declined from 2010 to 2019. While the vulnerability of irrigation conservation, water conservancy projects and afforestation didn’t decrease until recent years. Nevertheless, wastewater treatment, environmental protection institutions and water consumption in the ecological environment were still inadequate. From 2010 to 2014, the vulnerability level of the criterion layer was mainly moderate vulnerability and severe vulnerability and it began to decline to slightly vulnerable from 2015. The vulnerability change trend of the state layer was the closest to that of the system.On the whole, the vulnerability situation of water resources in Xinjiang has gradually improved, and the vulnerability level of some indicators decreased too. In the future, we should not only strengthen the monitoring and governance of indicators with high and unstable vulnerability but also stabilize indicators with low vulnerability to maintain the vulnerability of regional water resources at a low level.
2022, 20(6):1065-1075.
Abstract:
River hydrological rhythm reflects the dynamic changes in natural characteristics of water flow and is the key element of the river ecosystem. Recently, the rapid warming of the Qinghai Tibet Plateau has changed the hydrological rhythm of rivers to a certain extent. There is a national aquatic germplasm reserve in Datong River, and the Qilian Mountain area where it is located has an increase of 2.3 ℃ cumulative temperature. Therefore, exploring the changes in hydrological rhythm in the upper and middle reaches of Datong River under climate change has great significance and can play a supporting role in the ecological protection and water resources management of Datong River.There is evidence of the temperature rise rate on the Qinghai Tibet Plateau in the late 1990s. The data of meteorological stations around the upper and middle reaches of Datong River show that the average annual temperature increase rate after 1997 is 10 times before 1997. With the rapid increase in temperature, the relationship between frozen soil, glaciers, and rainfall runoff in Datong River basin has significantly changed. Based on the IHA-RVA method, the abrupt change time of rapid climate warming in the region in 1997 was selected as the dividing point. A total of 32 indicators were selected to analyze the runoff process in 1960-1996 and 1997-2016 for Gadatan / Qingshizui hydrological station. The principal component analysis method was used to remove redundant indicators, and 8 representative indicators were selected to calculate the overall hydrological change.The results show that: (1) April and October are the months of ice melting and freezing, which are directly affected by climate change. The change degree of median flow is 26.3% and 15.8%, respectively, belonging to slight change. The annual minimum flow of 30 d is representative of the annual minimum flow (1 d, 3 d, 7 d, and 90 d) and the median flow in dry season months. The change is significant, and the change degree reaches 100%. (2) The annual average maximum flow in 7 d is representative of the annual average multi-day maximum flow (1 d, 3 d, 30 d, and 90 d). The median value of the maximum flow in 7 d, and is unchanged, but the probability of falling increases between 25% and 75%, and the degree of change reaches 47%, which is a moderate change. The occurrence time of the annual maximum value, i.e. the occurrence time of the annual extreme flow, is averagely advanced by 7 to 9 d, which is a low change. (3) The number of low pulses is equivalent to the number of flow processes below 75% of the frequency, which is reduced from 2 to 1, and the duration is reduced from 49 d to 7 d. The change degree of the number and duration of low pulses is 29.8% and 50.1%, belonging to low and moderate change. The duration of a high pulse is equivalent to the duration of the flow process which is 25% higher than the frequency, increasing from an average of 5.8 d to 7 d, and the degree of change is 24.1%, which belongs to a low degree of change. The rising rate represents the change rate of flow change. The change rate slows down and low-degree changes occur. (4) The overall hydrological change degree of the upper and middle reaches of Datong River is 43%, indicating that the overall change degree of the upper and middle reaches under the influence of climate change has reached a medium level. With the expansion of the melting area, the transformation of water on the frozen layer and water in the frozen layer intensifies the change in the runoff process.
River hydrological rhythm reflects the dynamic changes in natural characteristics of water flow and is the key element of the river ecosystem. Recently, the rapid warming of the Qinghai Tibet Plateau has changed the hydrological rhythm of rivers to a certain extent. There is a national aquatic germplasm reserve in Datong River, and the Qilian Mountain area where it is located has an increase of 2.3 ℃ cumulative temperature. Therefore, exploring the changes in hydrological rhythm in the upper and middle reaches of Datong River under climate change has great significance and can play a supporting role in the ecological protection and water resources management of Datong River.There is evidence of the temperature rise rate on the Qinghai Tibet Plateau in the late 1990s. The data of meteorological stations around the upper and middle reaches of Datong River show that the average annual temperature increase rate after 1997 is 10 times before 1997. With the rapid increase in temperature, the relationship between frozen soil, glaciers, and rainfall runoff in Datong River basin has significantly changed. Based on the IHA-RVA method, the abrupt change time of rapid climate warming in the region in 1997 was selected as the dividing point. A total of 32 indicators were selected to analyze the runoff process in 1960-1996 and 1997-2016 for Gadatan / Qingshizui hydrological station. The principal component analysis method was used to remove redundant indicators, and 8 representative indicators were selected to calculate the overall hydrological change.The results show that: (1) April and October are the months of ice melting and freezing, which are directly affected by climate change. The change degree of median flow is 26.3% and 15.8%, respectively, belonging to slight change. The annual minimum flow of 30 d is representative of the annual minimum flow (1 d, 3 d, 7 d, and 90 d) and the median flow in dry season months. The change is significant, and the change degree reaches 100%. (2) The annual average maximum flow in 7 d is representative of the annual average multi-day maximum flow (1 d, 3 d, 30 d, and 90 d). The median value of the maximum flow in 7 d, and is unchanged, but the probability of falling increases between 25% and 75%, and the degree of change reaches 47%, which is a moderate change. The occurrence time of the annual maximum value, i.e. the occurrence time of the annual extreme flow, is averagely advanced by 7 to 9 d, which is a low change. (3) The number of low pulses is equivalent to the number of flow processes below 75% of the frequency, which is reduced from 2 to 1, and the duration is reduced from 49 d to 7 d. The change degree of the number and duration of low pulses is 29.8% and 50.1%, belonging to low and moderate change. The duration of a high pulse is equivalent to the duration of the flow process which is 25% higher than the frequency, increasing from an average of 5.8 d to 7 d, and the degree of change is 24.1%, which belongs to a low degree of change. The rising rate represents the change rate of flow change. The change rate slows down and low-degree changes occur. (4) The overall hydrological change degree of the upper and middle reaches of Datong River is 43%, indicating that the overall change degree of the upper and middle reaches under the influence of climate change has reached a medium level. With the expansion of the melting area, the transformation of water on the frozen layer and water in the frozen layer intensifies the change in the runoff process.
2022, 20(6):1076-1083,1127.
Abstract:
To clarify the influence of precipitation and river stage on the variation of groundwater level, the correlation among precipitation, groundwater level, and river stage in the typical area of Sanjiang Plain was quantitatively analyzed, and how the river stage affects the response of nearby groundwater level to precipitation was discussed.The Jianshe street and Haiqing groundwater level observation stations near Songhuajiang River and Wusulijiang River and adjacent Fujin and Haiqing hydrological stations in the typical area of Sanjiang Plain were selected as the research objects. The monthly precipitation, groundwater level, and river stage from 2007 to 2016 were used to study the response of groundwater level to precipitation by the cross-correlation analysis method and cross wavelet transform method, and the partial correlation analysis of groundwater level and river stage was carried out to explain the time lag difference of groundwater level response to precipitation. The results showed that there was a significant correlation between groundwater level and river stage. The partial correlation coefficients of Songhuajiang River and Wusulijiang River were 0.88 and 0.511, respectively, which showed the correlation between the groundwater level of Jianshe street groundwater level observation station and the river stage of Songhuajiang River was closer than that of Haiqing groundwater level observation station and the river stage of Wusulijiang River. There were temporal and spatial differences in the lag level of groundwater level to precipitation near the Songhuajiang River and Wusulijiang River in the study area, and the lag time of groundwater level to precipitation near Songhuajiang River and Wusulijiang River was 21.65 d and 2.17 d, respectively. In addition, the dynamic variations of groundwater level and river stage showed that the river water was generally recharged by groundwater from 2007 to 2016.Combined with the results of partial correlation analysis and the dynamic variations of groundwater level and river stage over the years, the river stage significantly affected the response of groundwater level near the river to precipitation, and the correlation between the river stage of Songhuajiang River and the nearby groundwater level was closer. The interaction between the river water in Songhuajiang River and the nearby groundwater was stronger than that in Wusulijiang River and the nearby groundwater, which showed that the river stage in Songhuajiang River had a greater impact on the response relationship between groundwater level and precipitation, so the lag time of adjacent groundwater level in Songhuajiang River to precipitation was longer. The results show that the conversion among precipitation, groundwater and river water has an important effect on the variation of groundwater level, and the river stage plays an important role in the response of groundwater level to precipitation in this area.
To clarify the influence of precipitation and river stage on the variation of groundwater level, the correlation among precipitation, groundwater level, and river stage in the typical area of Sanjiang Plain was quantitatively analyzed, and how the river stage affects the response of nearby groundwater level to precipitation was discussed.The Jianshe street and Haiqing groundwater level observation stations near Songhuajiang River and Wusulijiang River and adjacent Fujin and Haiqing hydrological stations in the typical area of Sanjiang Plain were selected as the research objects. The monthly precipitation, groundwater level, and river stage from 2007 to 2016 were used to study the response of groundwater level to precipitation by the cross-correlation analysis method and cross wavelet transform method, and the partial correlation analysis of groundwater level and river stage was carried out to explain the time lag difference of groundwater level response to precipitation. The results showed that there was a significant correlation between groundwater level and river stage. The partial correlation coefficients of Songhuajiang River and Wusulijiang River were 0.88 and 0.511, respectively, which showed the correlation between the groundwater level of Jianshe street groundwater level observation station and the river stage of Songhuajiang River was closer than that of Haiqing groundwater level observation station and the river stage of Wusulijiang River. There were temporal and spatial differences in the lag level of groundwater level to precipitation near the Songhuajiang River and Wusulijiang River in the study area, and the lag time of groundwater level to precipitation near Songhuajiang River and Wusulijiang River was 21.65 d and 2.17 d, respectively. In addition, the dynamic variations of groundwater level and river stage showed that the river water was generally recharged by groundwater from 2007 to 2016.Combined with the results of partial correlation analysis and the dynamic variations of groundwater level and river stage over the years, the river stage significantly affected the response of groundwater level near the river to precipitation, and the correlation between the river stage of Songhuajiang River and the nearby groundwater level was closer. The interaction between the river water in Songhuajiang River and the nearby groundwater was stronger than that in Wusulijiang River and the nearby groundwater, which showed that the river stage in Songhuajiang River had a greater impact on the response relationship between groundwater level and precipitation, so the lag time of adjacent groundwater level in Songhuajiang River to precipitation was longer. The results show that the conversion among precipitation, groundwater and river water has an important effect on the variation of groundwater level, and the river stage plays an important role in the response of groundwater level to precipitation in this area.
2022, 20(6):1084-1096.
Abstract:
Evapotranspiration (ET) plays a key role in the surface energy balance and water cycle, and accurate estimation of ET is crucial for agricultural irrigation, climate change prediction, and water resources management and utilization. However, it is still challenging to accurately estimate ET due to its dependence on heterogeneous land surface features, which can rise the complexity of the model parameterization scheme and substantial disagreement between models. Recently, surface flux equilibrium (SFE) method was proposed based on a strong physical mechanism to estimate ET with only standard meteorological station atmospheric observations. Therefore, it has superiority in large-scale and long-time ET estimation for requiring fewer input parameters compared with other methods. Considering the lack of related research work at present, the applicability of SFE method still needs to be validated and evaluated across a broad range of land conditions.CMFD (China Meteorological Forcing Dataset) and GLASS (The Global Land Surface Satellite) net radiation data from 2001 to 2015 were used to estimate daily ET in China based on SFE method. The ET estimations were validated with eddy covariance measurements at 8 ChinaFLUX sites and ET data of water balance at the basin scale, respectively. Moreover, the results were also compared with two types of ET products, including GLEAM (Global Land-surface Evaporation: the Amsterdam Methodology) and CR (Complementary Relationship). Based on the validation of estimation accuracy and the analysis of temporal and spatial variation trends, the applicability evaluation of SFE method was developed for ET estimation in China. The results showed that at a site scale, the daily ET estimated by SFE was in good agreement with the ET observations ( r=0.70, ERMS=1.03 mm/d), which was a little better than the accuracy of GLEAM product ( r=0.62, ERMS=1.19 mm/d). Moreover, SFE method had better performances at the sites covered with forest and grass than those covered with the crop. At the basin scale, the ET estimated by SFE was generally close to the ET of water balance, with a correlation coefficient of 0.96. Specifically, SFE method performed best in the Pearl River basin with a relative deviation of 1.63%. In addition, the accuracy of SFE was better than GLEAM product and CR product in most basins. Based on the spatial and temporal variation trend analysis, it could be found that the interannual variation of SFE and CR products presented a slight decreasing trend from 2001 to 2015 and their variation trend had well consistency on spatial and temporal scales. In contrast, GLEAM product showed a significant increasing trend and the spatial distribution of its variation trend was quite different from the other two ET results. In conclusion, SFE method performed well in the estimation of daily ET in China at the site and basin scale. Based on the verification and trend analysis of SFE results, it could be found that SFE method can achieve the accuracy of existing products. However, SFE method has systematical overestimation when ET is low and underestimation when it is high, especially in the cropland. Apart from the applicability problem in extreme water conditions of SFE method, net radiation data is another source of errors in ET estimation accuracy. Although the estimation accuracy varied across different surface conditions, the prediction errors of SFE method were comparable to errors of ET products. Besides, SFE method has the potential to provide a set of effective alternatives for the accurate estimation of ET because of its few input parameters, strong physical mechanism and simple parameterization scheme.
Evapotranspiration (ET) plays a key role in the surface energy balance and water cycle, and accurate estimation of ET is crucial for agricultural irrigation, climate change prediction, and water resources management and utilization. However, it is still challenging to accurately estimate ET due to its dependence on heterogeneous land surface features, which can rise the complexity of the model parameterization scheme and substantial disagreement between models. Recently, surface flux equilibrium (SFE) method was proposed based on a strong physical mechanism to estimate ET with only standard meteorological station atmospheric observations. Therefore, it has superiority in large-scale and long-time ET estimation for requiring fewer input parameters compared with other methods. Considering the lack of related research work at present, the applicability of SFE method still needs to be validated and evaluated across a broad range of land conditions.CMFD (China Meteorological Forcing Dataset) and GLASS (The Global Land Surface Satellite) net radiation data from 2001 to 2015 were used to estimate daily ET in China based on SFE method. The ET estimations were validated with eddy covariance measurements at 8 ChinaFLUX sites and ET data of water balance at the basin scale, respectively. Moreover, the results were also compared with two types of ET products, including GLEAM (Global Land-surface Evaporation: the Amsterdam Methodology) and CR (Complementary Relationship). Based on the validation of estimation accuracy and the analysis of temporal and spatial variation trends, the applicability evaluation of SFE method was developed for ET estimation in China. The results showed that at a site scale, the daily ET estimated by SFE was in good agreement with the ET observations ( r=0.70, ERMS=1.03 mm/d), which was a little better than the accuracy of GLEAM product ( r=0.62, ERMS=1.19 mm/d). Moreover, SFE method had better performances at the sites covered with forest and grass than those covered with the crop. At the basin scale, the ET estimated by SFE was generally close to the ET of water balance, with a correlation coefficient of 0.96. Specifically, SFE method performed best in the Pearl River basin with a relative deviation of 1.63%. In addition, the accuracy of SFE was better than GLEAM product and CR product in most basins. Based on the spatial and temporal variation trend analysis, it could be found that the interannual variation of SFE and CR products presented a slight decreasing trend from 2001 to 2015 and their variation trend had well consistency on spatial and temporal scales. In contrast, GLEAM product showed a significant increasing trend and the spatial distribution of its variation trend was quite different from the other two ET results. In conclusion, SFE method performed well in the estimation of daily ET in China at the site and basin scale. Based on the verification and trend analysis of SFE results, it could be found that SFE method can achieve the accuracy of existing products. However, SFE method has systematical overestimation when ET is low and underestimation when it is high, especially in the cropland. Apart from the applicability problem in extreme water conditions of SFE method, net radiation data is another source of errors in ET estimation accuracy. Although the estimation accuracy varied across different surface conditions, the prediction errors of SFE method were comparable to errors of ET products. Besides, SFE method has the potential to provide a set of effective alternatives for the accurate estimation of ET because of its few input parameters, strong physical mechanism and simple parameterization scheme.
2022, 20(6):1097-1108.
Abstract:
The analysis of synchronous-asynchronous encounter probability of high-low precipitation between the water source and water receiving area is an important basis for regulation of water resources project and rational water resources allocation. The inter-annual precipitation variation cycles and trends were analyzed by Morlet wavelet analysis of water source and receiving area of the Water Transfer Project in Central Yunnan (WTPCY) from 1960 to 2021. A Copula function was used to construct a joint distribution model of precipitation between the water source and the receiving area of WTPCY based on the historical measured and the shared socio-economic path (SSP1-2.6 and SSP5-8.5) of the International Coupled Model Comparison Program Phase 6 (CMIP 6) precipitation data from 2022 to 2100 . The probability of asynchronous or synchronous precipitation was calculated in the two regions. The results show that: (1) annual precipitation in the water source area of the WTPCY was larger than that in the receiving area, the inter-annual variation of precipitation was relatively small and the intra-annual distribution was more uniform than that in the receiving area. The precipitation sequence from 1960 to 2021 had periodic changes on three time scales of 26 ~39 a, 18~25 a and 4~7 a, respectively, and the precipitation sequence from 2022 to 2100 has periodic changes on three time scales of 38~55 a, 18~30 a and 5~12 a. The precipitation showed a cycle of "more-less-more" alternately. It is expected that the next 10~20 a will continue to be a period of high precipitation. (2) In the past 62 years, the precipitation asynchronous encounter probability between the water source area and the water receiving area was 36.4% and the precipitation synchronous encounter probability of high precipitation years was 25.3%. The precipitation synchronous encounter probability of low precipitation years was less than 30%, and the WTPCY have complementary water transfer conditions. (3) Compared with the baseline, the probability of precipitation synchronous encounters will decrease but asynchronous encounters will increase by different degrees in the SSP1-2.6 and SSP5-8.5 scenarios. Especially, the precipitation synchronous encounter probability of low precipitation years showed a decreasing trend, and the water source area had low precipitation years but the water receiving area had high precipitation years and encounter probability showed a decreasing trend. In summary, the probability conducive to water transfer of synchronous-asynchronous encounter probability about the WTPCY will increase obviously by 3.75%. (4) With the increase in economic development and intensity of human activities, it will lead to climate instability and more uneven spatial and temporal distribution of precipitation. In the near, medium, and long-term projections, the transition from the SSP1-2.6 scenario (sustainable development model) to the SSP5-8.5 scenario (high-intensity development model), the probability of precipitation asynchronous encounter under the SSP5-8.5 scenario may larger than SSP1-2.6 scenario, indicating that the regional differences in precipitation between the water source area and the water receiving area become larger and the spatial and temporal differences in precipitation become more significant. In the future, the precipitation and the probability conducive to water transfer of synchronous-asynchronous encounter probability about the WTPCY will increase obviously. These characteristics are conducive to the operation of the WTPCY. Through comprehensive analysis, quantitative assessment, and simulation prediction of the synchronous-asynchronous encounter probability about the WTPCY under climate change, it provides data support and a reference basis for the synergistic integration of water resources regulation in the WTPCY.
The analysis of synchronous-asynchronous encounter probability of high-low precipitation between the water source and water receiving area is an important basis for regulation of water resources project and rational water resources allocation. The inter-annual precipitation variation cycles and trends were analyzed by Morlet wavelet analysis of water source and receiving area of the Water Transfer Project in Central Yunnan (WTPCY) from 1960 to 2021. A Copula function was used to construct a joint distribution model of precipitation between the water source and the receiving area of WTPCY based on the historical measured and the shared socio-economic path (SSP1-2.6 and SSP5-8.5) of the International Coupled Model Comparison Program Phase 6 (CMIP 6) precipitation data from 2022 to 2100 . The probability of asynchronous or synchronous precipitation was calculated in the two regions. The results show that: (1) annual precipitation in the water source area of the WTPCY was larger than that in the receiving area, the inter-annual variation of precipitation was relatively small and the intra-annual distribution was more uniform than that in the receiving area. The precipitation sequence from 1960 to 2021 had periodic changes on three time scales of 26 ~39 a, 18~25 a and 4~7 a, respectively, and the precipitation sequence from 2022 to 2100 has periodic changes on three time scales of 38~55 a, 18~30 a and 5~12 a. The precipitation showed a cycle of "more-less-more" alternately. It is expected that the next 10~20 a will continue to be a period of high precipitation. (2) In the past 62 years, the precipitation asynchronous encounter probability between the water source area and the water receiving area was 36.4% and the precipitation synchronous encounter probability of high precipitation years was 25.3%. The precipitation synchronous encounter probability of low precipitation years was less than 30%, and the WTPCY have complementary water transfer conditions. (3) Compared with the baseline, the probability of precipitation synchronous encounters will decrease but asynchronous encounters will increase by different degrees in the SSP1-2.6 and SSP5-8.5 scenarios. Especially, the precipitation synchronous encounter probability of low precipitation years showed a decreasing trend, and the water source area had low precipitation years but the water receiving area had high precipitation years and encounter probability showed a decreasing trend. In summary, the probability conducive to water transfer of synchronous-asynchronous encounter probability about the WTPCY will increase obviously by 3.75%. (4) With the increase in economic development and intensity of human activities, it will lead to climate instability and more uneven spatial and temporal distribution of precipitation. In the near, medium, and long-term projections, the transition from the SSP1-2.6 scenario (sustainable development model) to the SSP5-8.5 scenario (high-intensity development model), the probability of precipitation asynchronous encounter under the SSP5-8.5 scenario may larger than SSP1-2.6 scenario, indicating that the regional differences in precipitation between the water source area and the water receiving area become larger and the spatial and temporal differences in precipitation become more significant. In the future, the precipitation and the probability conducive to water transfer of synchronous-asynchronous encounter probability about the WTPCY will increase obviously. These characteristics are conducive to the operation of the WTPCY. Through comprehensive analysis, quantitative assessment, and simulation prediction of the synchronous-asynchronous encounter probability about the WTPCY under climate change, it provides data support and a reference basis for the synergistic integration of water resources regulation in the WTPCY.
2022, 20(6):1109-1116.
Abstract:
The Yangtze-to-Huaihe River Water Transfer Project is a large-scale inter-basin water transfer project which combines a series of gate pump engineering entities and lakes with storage capacity. Water regulation is an important work to guide the operation of project scheduling, which can be divided into annual water regulation, monthly water regulation, and ten-day scale water regulation, according to the scheduling period and time scale. Ten-day scale water regulation determines the daily water transmission and supply process of the water transfer project in the next ten-day period and reduces the operation cost of the water transfer project while meeting the water supply demand. The ten-day scale water regulation is guided by the total ten-day water transfer determined by monthly water regulation, and at the same time provides total daily water transfer for the real-time operation of the pumping station project, which is the key link between water operation scheduling and real-time scheduling of water transfer project. In recent years, a large number of studies have reported the optimal scheduling calculation method of the cascade pumping station system in the water transfer project, but there are few studies on the joint scheduling of the water transfer project and the complex water conveyance system of gate pump lake mixing, especially the optimal scheduling considering the lake regulation-control process. Facing the actual engineering requirements of the Yangtze-to-Huaihe River Water Transfer Project, it is urgent to further study the influence of the lake regulation-control process on the optimal operation mode of cascade pumping stations based on existing research.A study on ten-day scale water volume regulation of inter-basin water transfer project considering the lake storage regulation process was carried out to exploit the potentialities of ensuring water supply and reducing the energy consumption of pumping stations through the regulation and control capacity of the lakes in the project. A multi-objective ten-day scale water volume optimal scheduling model of gate pump series considering lake regulation-control process was constructed, and the genetic algorithm was used to solve the model, to formulate a pumping station-lake joint scheduling scheme that meets the minimum water shortage of water-using units, the minimum energy consumption of pumping stations and the minimum imbalance of lakes in and out. The different typical operating conditions of the dispatching operation of the Yangtze-to-Huaihe River Transfer Project are analyzed, and the advantages of the ten-day scale water volume regulation scheme considering the lake regulation-control process are discussed by taking the free flow transfer condition.The results showed that compared with the scheduling scheme without considering the lake regulation-control process and by considering the lake regulation-control process can reduce the total water shortage rate by 1.2 % and the total energy consumption by 642 kW·h during the scheduling period. The inter-basin water transfer project considering the lake regulation-control process can effectively improve the water supply guarantee rate of the project and reduce the total water transmission energy consumption. The main function of the lake storage capacity is to track the change in water demand by the water storage capacity of the lake, to ensure that the cascade pumping stations are within the efficient operating range as far as possible from the change of water demand. The decision support can be provided for the operation scheduling of the Yangtze-to-Huaihe River Water Transfer Project.
The Yangtze-to-Huaihe River Water Transfer Project is a large-scale inter-basin water transfer project which combines a series of gate pump engineering entities and lakes with storage capacity. Water regulation is an important work to guide the operation of project scheduling, which can be divided into annual water regulation, monthly water regulation, and ten-day scale water regulation, according to the scheduling period and time scale. Ten-day scale water regulation determines the daily water transmission and supply process of the water transfer project in the next ten-day period and reduces the operation cost of the water transfer project while meeting the water supply demand. The ten-day scale water regulation is guided by the total ten-day water transfer determined by monthly water regulation, and at the same time provides total daily water transfer for the real-time operation of the pumping station project, which is the key link between water operation scheduling and real-time scheduling of water transfer project. In recent years, a large number of studies have reported the optimal scheduling calculation method of the cascade pumping station system in the water transfer project, but there are few studies on the joint scheduling of the water transfer project and the complex water conveyance system of gate pump lake mixing, especially the optimal scheduling considering the lake regulation-control process. Facing the actual engineering requirements of the Yangtze-to-Huaihe River Water Transfer Project, it is urgent to further study the influence of the lake regulation-control process on the optimal operation mode of cascade pumping stations based on existing research.A study on ten-day scale water volume regulation of inter-basin water transfer project considering the lake storage regulation process was carried out to exploit the potentialities of ensuring water supply and reducing the energy consumption of pumping stations through the regulation and control capacity of the lakes in the project. A multi-objective ten-day scale water volume optimal scheduling model of gate pump series considering lake regulation-control process was constructed, and the genetic algorithm was used to solve the model, to formulate a pumping station-lake joint scheduling scheme that meets the minimum water shortage of water-using units, the minimum energy consumption of pumping stations and the minimum imbalance of lakes in and out. The different typical operating conditions of the dispatching operation of the Yangtze-to-Huaihe River Transfer Project are analyzed, and the advantages of the ten-day scale water volume regulation scheme considering the lake regulation-control process are discussed by taking the free flow transfer condition.The results showed that compared with the scheduling scheme without considering the lake regulation-control process and by considering the lake regulation-control process can reduce the total water shortage rate by 1.2 % and the total energy consumption by 642 kW·h during the scheduling period. The inter-basin water transfer project considering the lake regulation-control process can effectively improve the water supply guarantee rate of the project and reduce the total water transmission energy consumption. The main function of the lake storage capacity is to track the change in water demand by the water storage capacity of the lake, to ensure that the cascade pumping stations are within the efficient operating range as far as possible from the change of water demand. The decision support can be provided for the operation scheduling of the Yangtze-to-Huaihe River Water Transfer Project.
2022, 20(6):1117-1127.
Abstract:
Wastewater discharged from sewage treatment plants (STPs) may affect the structure and function of microbial communities in the sediment of receiving water body. The response of sediment microbial community in Zao River (Xi′an, China) to STPs discharge was investigated by 16S rRNA sequencing technology and bioinformatic analysis. The results revealed that Proteobacteria , Cyanobacteria , Bacteroides , Firmicutes , Actinobacteria , Chloroflexi and Acidobacteria were the dominant communities in the sediments of Zao River. The obtained sparse curve and species accumulation curve indicated that the sequencing depth and the number of samples were enough to reflect the changes in microbial community richness. The richness and diversity of Zao River community decreased gradually with the inflow of sewage. The difference in microbial community structure between the reaches near the 2nd STP sewage outlet and other river reaches was significant with the marker species being chlamydia . Furthermore, the metabolic pathways enriched in the up-middle-down reaches of the 2nd STP sewage outlet were photosynthesis in energy metabolism (ko00196), bibrio cholerae infection (ko05110), and the biosynthesis of secondary bile acids (ko00121), respectively. In general, nitrite nitrogen and temperature were the most significant environmental factors, accounting for 40.3% of the changes in the whole community. Proteobacteria was positively correlated with salinity, total phosphorus, COD, and pH, and negatively correlated with temperature, total nitrogen and ammonia-nitrogen. Likewise, cyanobacteria was primarily positively correlated with temperature and redox potential, and negatively correlated with pH, nitrate-nitrogen, and total phosphorus. In particular, the microbial communities near 2nd and 9th STP sewage outlets were determined by phosphorus and nitrogen levels, respectively. In conclusion, the altered microbial community structure in the sediments of sewage-receiving rivers can reflect the fluctuation in river water quality and the health of aquatic ecosystems influenced by sewage discharge.
Wastewater discharged from sewage treatment plants (STPs) may affect the structure and function of microbial communities in the sediment of receiving water body. The response of sediment microbial community in Zao River (Xi′an, China) to STPs discharge was investigated by 16S rRNA sequencing technology and bioinformatic analysis. The results revealed that Proteobacteria , Cyanobacteria , Bacteroides , Firmicutes , Actinobacteria , Chloroflexi and Acidobacteria were the dominant communities in the sediments of Zao River. The obtained sparse curve and species accumulation curve indicated that the sequencing depth and the number of samples were enough to reflect the changes in microbial community richness. The richness and diversity of Zao River community decreased gradually with the inflow of sewage. The difference in microbial community structure between the reaches near the 2nd STP sewage outlet and other river reaches was significant with the marker species being chlamydia . Furthermore, the metabolic pathways enriched in the up-middle-down reaches of the 2nd STP sewage outlet were photosynthesis in energy metabolism (ko00196), bibrio cholerae infection (ko05110), and the biosynthesis of secondary bile acids (ko00121), respectively. In general, nitrite nitrogen and temperature were the most significant environmental factors, accounting for 40.3% of the changes in the whole community. Proteobacteria was positively correlated with salinity, total phosphorus, COD, and pH, and negatively correlated with temperature, total nitrogen and ammonia-nitrogen. Likewise, cyanobacteria was primarily positively correlated with temperature and redox potential, and negatively correlated with pH, nitrate-nitrogen, and total phosphorus. In particular, the microbial communities near 2nd and 9th STP sewage outlets were determined by phosphorus and nitrogen levels, respectively. In conclusion, the altered microbial community structure in the sediments of sewage-receiving rivers can reflect the fluctuation in river water quality and the health of aquatic ecosystems influenced by sewage discharge.
2022, 20(6):1128-1138.
Abstract:
In recent years, water bloom occurrence frequency in water sources is increasing gradually. The excessive proliferation of algae not only intensifies the accumulation of toxins in the water body but also leads to a series of chain reactions such as water pollution, which seriously affects human life and health through the food chain. In the long run, the ecosystem will be seriously damaged, attracting the attention of scholars at home and abroad. Therefore, the study of the degree of bloom risk has an important impact on the management and the improvement of water quality.The risk of water bloom in water source areas is affected by many factors, such as internal and external factors. A relatively comprehensive evaluation index system of water bloom risk in water source areas had been constructed from the internal and external levels, which could overcome the limitations caused by only considering external risks. Given the fuzzy characteristics and uncertainties of water quality assessment and impact factors, a variable fuzzy assessment model of water bloom risk in water source areas was constructed by the variable fuzzy set theory. The model could describe the fuzziness of water bloom risk with the help of a relative difference function. Through the transformation of different parameter combinations, the limitation of only a single model was overcome, and the risk of water bloom in lake reservoir-type water source areas was difficult to be quantitatively described because the coupling of multiple factors was solved.The model was applied to the risk assessment of water bloom in Qiaodian Reservoir. The results showed that the characteristic value of the water bloom risk level was 3.19 (grade III risk). The characteristic value of risk level caused by external factors was 2.41 (grade II risk). Among them, the amount of fertilizer per unit area, the impact of upstream water on water bloom and the duration of light were the key indicators that affected the level of exogenous risk. The characteristic value of risk level caused by endogenous factors was 3.54 (grade IV risk), which was closely related to the sedimentation, water temperature and hydraulic retention time of Qiaodian Reservoir.The constructed variable fuzzy evaluation model formed 4 different evaluation models by changing the combination of parameters, which further reflected the nonlinearity of the water bloom risk evaluation system. The multi-dimensional evaluation index system of water bloom risk in the water source area was comprehensively evaluated, which improved the reliability and reliability of the evaluation results. The application results of the example showed that it was consistent with the research conclusion, indicating that the endogenous risk of causing water bloom could not be ignored. The result of the single factor risk grade further showed that the risk fluctuation of water bloom was comprehensively affected by internal and external risks. Therefore, the index system and model can be applied to other similar lake reservoir-type water source areas to provide scientific theoretical support for precise prevention and control of water bloom. In the future, the water source managers should adjust the control direction by giving priority to the treatment of internal pollution, strengthening the control of non-point source pollution, then adjusting the hydraulic cycle, and improving the self-purification capacity of water bodies.
In recent years, water bloom occurrence frequency in water sources is increasing gradually. The excessive proliferation of algae not only intensifies the accumulation of toxins in the water body but also leads to a series of chain reactions such as water pollution, which seriously affects human life and health through the food chain. In the long run, the ecosystem will be seriously damaged, attracting the attention of scholars at home and abroad. Therefore, the study of the degree of bloom risk has an important impact on the management and the improvement of water quality.The risk of water bloom in water source areas is affected by many factors, such as internal and external factors. A relatively comprehensive evaluation index system of water bloom risk in water source areas had been constructed from the internal and external levels, which could overcome the limitations caused by only considering external risks. Given the fuzzy characteristics and uncertainties of water quality assessment and impact factors, a variable fuzzy assessment model of water bloom risk in water source areas was constructed by the variable fuzzy set theory. The model could describe the fuzziness of water bloom risk with the help of a relative difference function. Through the transformation of different parameter combinations, the limitation of only a single model was overcome, and the risk of water bloom in lake reservoir-type water source areas was difficult to be quantitatively described because the coupling of multiple factors was solved.The model was applied to the risk assessment of water bloom in Qiaodian Reservoir. The results showed that the characteristic value of the water bloom risk level was 3.19 (grade III risk). The characteristic value of risk level caused by external factors was 2.41 (grade II risk). Among them, the amount of fertilizer per unit area, the impact of upstream water on water bloom and the duration of light were the key indicators that affected the level of exogenous risk. The characteristic value of risk level caused by endogenous factors was 3.54 (grade IV risk), which was closely related to the sedimentation, water temperature and hydraulic retention time of Qiaodian Reservoir.The constructed variable fuzzy evaluation model formed 4 different evaluation models by changing the combination of parameters, which further reflected the nonlinearity of the water bloom risk evaluation system. The multi-dimensional evaluation index system of water bloom risk in the water source area was comprehensively evaluated, which improved the reliability and reliability of the evaluation results. The application results of the example showed that it was consistent with the research conclusion, indicating that the endogenous risk of causing water bloom could not be ignored. The result of the single factor risk grade further showed that the risk fluctuation of water bloom was comprehensively affected by internal and external risks. Therefore, the index system and model can be applied to other similar lake reservoir-type water source areas to provide scientific theoretical support for precise prevention and control of water bloom. In the future, the water source managers should adjust the control direction by giving priority to the treatment of internal pollution, strengthening the control of non-point source pollution, then adjusting the hydraulic cycle, and improving the self-purification capacity of water bodies.
2022, 20(6):1139-1147.
Abstract:
Groundwater is an important water source for maintaining the health of the ecosystem, and it has an essential service value for ecosystem. There are more studies on the service value assessment of ecosystems such as rivers, wetlands and forests, while the study on service value assessment of groundwater ecosystems is not systematic. The service value of groundwater ecosystem in Tianjin is assessed with a view to providing a technical reference for the sustainable management of groundwater ecosystem. In essence, ecosystem service is the benefit for human beings which is provided by ecosystem. Quantitative assessment of the value of ecosystem service could be beneficial to utilizing land resources, protecting water resources and improving the quality of the ecological environment efficiently, meanwhile, it could be an important tool for the human beings to manage the ecosystem rationally. The service value of groundwater ecosystem could be defined as the benefits generated by groundwater ecosystem and ecological processes that contribute to the environment and quality of life for human beings. At present, there are few studies on the service value of groundwater ecosystem, and its assessment index system and assessment methods are still in the exploration stage; previous studies are mostly focused on static assessments. Based on the classification method of the Millennium Ecosystem Assessment for ecosystem service, the groundwater ecosystem service in Tianjin is classified as four aspects: provisioning service, regulating service, supporting service and cultural service. The roles of the service value of groundwater ecosystem could be defined as six aspects: ① the groundwater could supply water resource to life, industry and agriculture, and it could play as the service value of water supply, ② the groundwater could play as the service value of purifying water quality, ③ the groundwater could react with CO2 to generate calcium carbonate, so it could play as the service value of carbon sequestration, ④ the groundwater could play as the service value of water conservation by supplementing and regulating the rivers, lakes and wetlands, ⑤ the groundwater has the function of keeping the geological environment stable, and it could play as the supporting service value, ⑥ the groundwater also has the service value of scientific research and education. Based on this, a index system of service value assessment of groundwater ecosystem is established. Then, a monetized value assessment model is constructed by the value evaluation method. According to this model, the groundwater ecosystem service value in Tianjin is measured, and the evolution characteristics of groundwater ecosystem service value before and after the water supply of the middle route of South-to-North Water Transfer Project(MRP) are analyzed. The result shows that, during 2008 to 2019, the average annual service value of the groundwater ecosystem in Tianjin is 8.371 billion yuan, including 6.981 billion yuan between 2008 to 2014, and 10.318 billion yuan between 2015 to 2019. After the water supply, the value of groundwater regulating service and supporting service are increased, and the value of provisioning service is decreased. The contribution for the groundwater ecosystem service value via MRP is increasing from 0.264 billion yuan in 2015 to 2.401 billion yuan in 2019.The MRP has effectively increased the amount of available water resources in Tianjin, and effectively curbed the trend of declining of the groundwater, expanding of the groundwater depression cone and increasing of the ground subsidence. As some basic data is difficult to obtain, the methods of data assumptions estimation are used in the process of analysis. The data collection will be strengthened in further research, in order to make the results be more and more accurate.
Groundwater is an important water source for maintaining the health of the ecosystem, and it has an essential service value for ecosystem. There are more studies on the service value assessment of ecosystems such as rivers, wetlands and forests, while the study on service value assessment of groundwater ecosystems is not systematic. The service value of groundwater ecosystem in Tianjin is assessed with a view to providing a technical reference for the sustainable management of groundwater ecosystem. In essence, ecosystem service is the benefit for human beings which is provided by ecosystem. Quantitative assessment of the value of ecosystem service could be beneficial to utilizing land resources, protecting water resources and improving the quality of the ecological environment efficiently, meanwhile, it could be an important tool for the human beings to manage the ecosystem rationally. The service value of groundwater ecosystem could be defined as the benefits generated by groundwater ecosystem and ecological processes that contribute to the environment and quality of life for human beings. At present, there are few studies on the service value of groundwater ecosystem, and its assessment index system and assessment methods are still in the exploration stage; previous studies are mostly focused on static assessments. Based on the classification method of the Millennium Ecosystem Assessment for ecosystem service, the groundwater ecosystem service in Tianjin is classified as four aspects: provisioning service, regulating service, supporting service and cultural service. The roles of the service value of groundwater ecosystem could be defined as six aspects: ① the groundwater could supply water resource to life, industry and agriculture, and it could play as the service value of water supply, ② the groundwater could play as the service value of purifying water quality, ③ the groundwater could react with CO2 to generate calcium carbonate, so it could play as the service value of carbon sequestration, ④ the groundwater could play as the service value of water conservation by supplementing and regulating the rivers, lakes and wetlands, ⑤ the groundwater has the function of keeping the geological environment stable, and it could play as the supporting service value, ⑥ the groundwater also has the service value of scientific research and education. Based on this, a index system of service value assessment of groundwater ecosystem is established. Then, a monetized value assessment model is constructed by the value evaluation method. According to this model, the groundwater ecosystem service value in Tianjin is measured, and the evolution characteristics of groundwater ecosystem service value before and after the water supply of the middle route of South-to-North Water Transfer Project(MRP) are analyzed. The result shows that, during 2008 to 2019, the average annual service value of the groundwater ecosystem in Tianjin is 8.371 billion yuan, including 6.981 billion yuan between 2008 to 2014, and 10.318 billion yuan between 2015 to 2019. After the water supply, the value of groundwater regulating service and supporting service are increased, and the value of provisioning service is decreased. The contribution for the groundwater ecosystem service value via MRP is increasing from 0.264 billion yuan in 2015 to 2.401 billion yuan in 2019.The MRP has effectively increased the amount of available water resources in Tianjin, and effectively curbed the trend of declining of the groundwater, expanding of the groundwater depression cone and increasing of the ground subsidence. As some basic data is difficult to obtain, the methods of data assumptions estimation are used in the process of analysis. The data collection will be strengthened in further research, in order to make the results be more and more accurate.
2022, 20(6):1148-1157.
Abstract:
The South-to-North Water Transfer Project is of great strategic significance for improving the national water network and optimizing the overall pattern of water resource allocation. The drought situation and water quantity changes in the source area of the South-to-North Water Transfer Project affect the stability of the water transfer project and are of great significance to the industrial, agricultural, and residential water use and other aspects of the cities along the route. In recent years, there has been more research on extreme drought monitoring, and a variety of meteorological hydrological drought index models have been widely used, such as the standardized precipitation evapotranspiration index, palmer drought index, standardized precipitation index, and so on. The standardized precipitation evapotranspiration index model is superior to the other two drought index models because it takes into account the evapotranspiration factor. Although some research has been conducted in recent years on climate change in the water source or water-receiving areas of the South-to-North Water Transfer Project, few studies have explored the drought encounters in water source and water-receiving areas in the context of future climate change.By integrating a large number of meteorological observation data and the latest Coupled model Intercomparison Project Phase 6 (CMIP6) climate model data, using standardized precipitation evapotranspiration index, empirical orthogonal function analysis, Copula function, and other methods, the spatial and temporal distribution of drought in the water source area and the water receiving area of the South-to-North Water Transfer Project in the historical period was calculated. The drought encounter problem in the water source area under different climate scenarios in the future was estimated using the CMIP6 meteorological dataset as the driving data and then provided a theoretical basis for water resources planning and management. The empirical orthogonal function was performed using the calculation results of the SPEI and the copula function for the joint probability distribution of drought between the water source and the water receiving area. The mean CMIP6 multi-mode data is used as the input data for future SPEI calculations, and the drought comprehensive evaluation is carried out on the water source area of the South-to-North Water Transfer Project.Results showed that drought events in water-source areas and water-receiving areas were frequent, with more serious drought encounters in 1965-1971 and 1987-2005, and long-term obvious regional differences from the mid-to-late 1970s to around 1985. The combined recurrence periods of drought and severe drought in water-source areas and water-receiving areas were about once in 18 years (5.51%) and once in 123 years (0.81%), respectively, and the recurrence period of extreme drought in both places was about once in 323 years (0.31%).The annual SPEI estimates of future drought events in different climatic scenarios indicate that the number of future drought occurrences under the SSP1-2.6 scenario is relatively small, while the more severe drought encounters in the water source and water-receiving areas may occur in 2034-2036 and 2044-2045 under the SSP2-4.5 scenario and in 2032-2033 and 2068-2070 under the SSP5-8.5 scenario. Multi-modality and multi-scenarios indicate that the risk of drought in the water source area and the water-receiving area of the South-to-North Water Transfer Project may increase in the future. To better play the benefits of the project, it is necessary to strengthen the research on the drought encounter problem in the water source area and the water-receiving area of the middle line of the South-to-North Water Transfer Project.
The South-to-North Water Transfer Project is of great strategic significance for improving the national water network and optimizing the overall pattern of water resource allocation. The drought situation and water quantity changes in the source area of the South-to-North Water Transfer Project affect the stability of the water transfer project and are of great significance to the industrial, agricultural, and residential water use and other aspects of the cities along the route. In recent years, there has been more research on extreme drought monitoring, and a variety of meteorological hydrological drought index models have been widely used, such as the standardized precipitation evapotranspiration index, palmer drought index, standardized precipitation index, and so on. The standardized precipitation evapotranspiration index model is superior to the other two drought index models because it takes into account the evapotranspiration factor. Although some research has been conducted in recent years on climate change in the water source or water-receiving areas of the South-to-North Water Transfer Project, few studies have explored the drought encounters in water source and water-receiving areas in the context of future climate change.By integrating a large number of meteorological observation data and the latest Coupled model Intercomparison Project Phase 6 (CMIP6) climate model data, using standardized precipitation evapotranspiration index, empirical orthogonal function analysis, Copula function, and other methods, the spatial and temporal distribution of drought in the water source area and the water receiving area of the South-to-North Water Transfer Project in the historical period was calculated. The drought encounter problem in the water source area under different climate scenarios in the future was estimated using the CMIP6 meteorological dataset as the driving data and then provided a theoretical basis for water resources planning and management. The empirical orthogonal function was performed using the calculation results of the SPEI and the copula function for the joint probability distribution of drought between the water source and the water receiving area. The mean CMIP6 multi-mode data is used as the input data for future SPEI calculations, and the drought comprehensive evaluation is carried out on the water source area of the South-to-North Water Transfer Project.Results showed that drought events in water-source areas and water-receiving areas were frequent, with more serious drought encounters in 1965-1971 and 1987-2005, and long-term obvious regional differences from the mid-to-late 1970s to around 1985. The combined recurrence periods of drought and severe drought in water-source areas and water-receiving areas were about once in 18 years (5.51%) and once in 123 years (0.81%), respectively, and the recurrence period of extreme drought in both places was about once in 323 years (0.31%).The annual SPEI estimates of future drought events in different climatic scenarios indicate that the number of future drought occurrences under the SSP1-2.6 scenario is relatively small, while the more severe drought encounters in the water source and water-receiving areas may occur in 2034-2036 and 2044-2045 under the SSP2-4.5 scenario and in 2032-2033 and 2068-2070 under the SSP5-8.5 scenario. Multi-modality and multi-scenarios indicate that the risk of drought in the water source area and the water-receiving area of the South-to-North Water Transfer Project may increase in the future. To better play the benefits of the project, it is necessary to strengthen the research on the drought encounter problem in the water source area and the water-receiving area of the middle line of the South-to-North Water Transfer Project.
2022, 20(6):1158-1167.
Abstract:
With the further development of the informatization level of long-distance open channel water transfer projects, the distribution of monitoring stations along the project has become denser and denser, and the monitoring of water regime information and the quality of monitoring data has attracted more attention. The reliability and consistency of the flow monitoring data along the long-distance open channel water transfer project in time and space directly affect the accuracy of the water condition study and hydrodynamic numerical simulation.Taking the middle route project of the South-to-North Water Transfer Project as the research object, aiming at the abnormal phenomenon of the inverted flow of the monitoring station in the dispatching operation, the principle of dynamic balance of water volume and the longest sequence method of interval flow is adopted to construct the inverted data cleaning model of the flow monitoring station. The principle of water dynamic balance is used to calculate the water loss rate of the canal pool along the middle line project, and according to the water loss rate, the theoretical flow value of each control gate along the line is determined. By calculating the deviation of the actual monitoring data of each control gate relative to the theoretical flow data, the relative deviation is selected to be less than 1% for interval division. The interval longest sequence method is used to screen out the data to be modified. The water balance principle is used to modify the modified data. By comparing and analyzing the measured flow data and the theoretical flow data of the control gate, the number of control times of the control gate and the number of control times that occurred in the inverted flow phenomenon are counted, and the causes of the inverted flow phenomenon are summarized. A one-dimensional hydrodynamic model was constructed to verify the impact of data cleaning on the simulation model by taking the flow data before and after cleaning as the upper boundary conditions.A hydrodynamic model is constructed for verification based on the flow data after model cleaning as the upper boundary condition in the Baihe River to Huanghe River section of the middle line project. The results show that the cleaning model eliminates the inverted phenomenon in the flow monitoring data and improves the quality of the flow monitoring data. The mean absolute error of the water level in the front of the gate is reduced by 0.075 7 m and the root mean square error is reduced by 0.089 5 m in the hydrodynamic numerical simulation.Through the analysis of the causes of the inverted data, it is found that the monitoring data deviation of the control gate flow monitoring equipment and the interference of the gate control are the main influencing factors of the phenomenon. By comparing the results of hydrodynamic simulation, it is found that the upper boundary condition of flow data after cleaning can effectively improve the simulation accuracy. The results show that the cleaned flow data is superior to the measured flow data in data space logicality and consistency, which can be popularized and applied in practical engineering.
With the further development of the informatization level of long-distance open channel water transfer projects, the distribution of monitoring stations along the project has become denser and denser, and the monitoring of water regime information and the quality of monitoring data has attracted more attention. The reliability and consistency of the flow monitoring data along the long-distance open channel water transfer project in time and space directly affect the accuracy of the water condition study and hydrodynamic numerical simulation.Taking the middle route project of the South-to-North Water Transfer Project as the research object, aiming at the abnormal phenomenon of the inverted flow of the monitoring station in the dispatching operation, the principle of dynamic balance of water volume and the longest sequence method of interval flow is adopted to construct the inverted data cleaning model of the flow monitoring station. The principle of water dynamic balance is used to calculate the water loss rate of the canal pool along the middle line project, and according to the water loss rate, the theoretical flow value of each control gate along the line is determined. By calculating the deviation of the actual monitoring data of each control gate relative to the theoretical flow data, the relative deviation is selected to be less than 1% for interval division. The interval longest sequence method is used to screen out the data to be modified. The water balance principle is used to modify the modified data. By comparing and analyzing the measured flow data and the theoretical flow data of the control gate, the number of control times of the control gate and the number of control times that occurred in the inverted flow phenomenon are counted, and the causes of the inverted flow phenomenon are summarized. A one-dimensional hydrodynamic model was constructed to verify the impact of data cleaning on the simulation model by taking the flow data before and after cleaning as the upper boundary conditions.A hydrodynamic model is constructed for verification based on the flow data after model cleaning as the upper boundary condition in the Baihe River to Huanghe River section of the middle line project. The results show that the cleaning model eliminates the inverted phenomenon in the flow monitoring data and improves the quality of the flow monitoring data. The mean absolute error of the water level in the front of the gate is reduced by 0.075 7 m and the root mean square error is reduced by 0.089 5 m in the hydrodynamic numerical simulation.Through the analysis of the causes of the inverted data, it is found that the monitoring data deviation of the control gate flow monitoring equipment and the interference of the gate control are the main influencing factors of the phenomenon. By comparing the results of hydrodynamic simulation, it is found that the upper boundary condition of flow data after cleaning can effectively improve the simulation accuracy. The results show that the cleaned flow data is superior to the measured flow data in data space logicality and consistency, which can be popularized and applied in practical engineering.
2022, 20(6):1168-1178.
Abstract:
As the most important basic strategic water resources allocation project in China, the South-to-North Water Transfer Project has completed the construction of the first phase of the east and middle route, and started supplying water from 2013 to 2014. Up to 14/05/2022, the cumulative water transfer of the first phase of the east and middle route has exceeded 53 billion m3.The South-to-North Water Transfer Project is playing an increasingly important supporting role for China's economic and social development and ecological and environmental protection. With the improvement of the strategic position of ecological civilization construction and the significant improvement of the requirements of ecological and environmental protection awareness, it is necessary to study, analyze and reasonably quantify the ecological benefits of the South-to-North Water Transfer Project, so as to provide a reference basis for the planning, construction, operation and management of the South-to-North Water Transfer Project and other inter-basin water transfer projects. Therefore, based on the principle of ecological economics, the ecological benefit evaluation indicators of the built projects of the South-to-North Water Transfer Project were defined, the basic data acquisition and processing methods of the ecological benefit evaluation methods of the built projects of the South-to-North Water Transfer Project were anailzed, Beijing was taken as a typical water receiving area, and the ecological benefits of the phase I project of the middle route of the South-to-North Water Transfer Project to Beijing were discussed, so as to provide technical reference for the ecological benefit evaluation of the built projects of the South-to-North Water Transfer Project. It is assumed that the ecological benefit of the South-to-North Water Transfer Project refers to the full utility of the beneficial effect caused by the change of ecosystem state due to the water supply from the project in the ecosystem and its influence range of the project area after water supply, which can be measured by the change of ecosystem service value. Therefore, the value of ecological services of the first phase of middle route of the South-to-North Water Transfer Project for Beijing City were evaluated by determining the evaluation method in 5 aspects including woodland, city green-land, wetland, groundwater and open water. Based on the statistical data of the capital landscaping government network of Beijing Landscaping Bureau, the basic situation of forest resources and urban green space in Beijing was obtained. The Landsat 8 remote sensing image data and its relevant dataset were used to classify the land use/land cover in Beijing. Through the comparison of the results before and after the year, the changes of land use/land cover before and after the water supply of the South-to-North Water Transfer Project in Beijing were analyzed to supplement the statistical data.The results show that in the first 4 years (2015-2018) in operation of the first phase of middle route of the South-to-North Water Transfer Project, the growth of the value of ecological services of Beijing City is 18.19 billion RMB, of which 6.73 billion RMB is due to the first phase of the middle route of the South-to-North Water Transfer Project. Among them, the ecological service value generated by the new water area are the largest, accounting for 55.02%. The ecological service value generated by pressure mining of groundwater ranks the second, accounting for 34.87%, and the ecological service value generated by the new forest land and the new green land account for 6.90% and 3.21%, respectively. Since the South-to-North Water Transfer did not directly supply wetlands, it is believed that the South-to-North Water Transfer Project had no direct or indirect contribution to the growth of wetland ecosystem service value in Beijing from 2015 to 2018.This research can provide support for the formulation of policies and measures for ecological water use, ecological environment restoration and protection, and efficient utilization of water resources in Beijing and other water reception areas of the South-to-North Water Transfer Project.
As the most important basic strategic water resources allocation project in China, the South-to-North Water Transfer Project has completed the construction of the first phase of the east and middle route, and started supplying water from 2013 to 2014. Up to 14/05/2022, the cumulative water transfer of the first phase of the east and middle route has exceeded 53 billion m3.The South-to-North Water Transfer Project is playing an increasingly important supporting role for China's economic and social development and ecological and environmental protection. With the improvement of the strategic position of ecological civilization construction and the significant improvement of the requirements of ecological and environmental protection awareness, it is necessary to study, analyze and reasonably quantify the ecological benefits of the South-to-North Water Transfer Project, so as to provide a reference basis for the planning, construction, operation and management of the South-to-North Water Transfer Project and other inter-basin water transfer projects. Therefore, based on the principle of ecological economics, the ecological benefit evaluation indicators of the built projects of the South-to-North Water Transfer Project were defined, the basic data acquisition and processing methods of the ecological benefit evaluation methods of the built projects of the South-to-North Water Transfer Project were anailzed, Beijing was taken as a typical water receiving area, and the ecological benefits of the phase I project of the middle route of the South-to-North Water Transfer Project to Beijing were discussed, so as to provide technical reference for the ecological benefit evaluation of the built projects of the South-to-North Water Transfer Project. It is assumed that the ecological benefit of the South-to-North Water Transfer Project refers to the full utility of the beneficial effect caused by the change of ecosystem state due to the water supply from the project in the ecosystem and its influence range of the project area after water supply, which can be measured by the change of ecosystem service value. Therefore, the value of ecological services of the first phase of middle route of the South-to-North Water Transfer Project for Beijing City were evaluated by determining the evaluation method in 5 aspects including woodland, city green-land, wetland, groundwater and open water. Based on the statistical data of the capital landscaping government network of Beijing Landscaping Bureau, the basic situation of forest resources and urban green space in Beijing was obtained. The Landsat 8 remote sensing image data and its relevant dataset were used to classify the land use/land cover in Beijing. Through the comparison of the results before and after the year, the changes of land use/land cover before and after the water supply of the South-to-North Water Transfer Project in Beijing were analyzed to supplement the statistical data.The results show that in the first 4 years (2015-2018) in operation of the first phase of middle route of the South-to-North Water Transfer Project, the growth of the value of ecological services of Beijing City is 18.19 billion RMB, of which 6.73 billion RMB is due to the first phase of the middle route of the South-to-North Water Transfer Project. Among them, the ecological service value generated by the new water area are the largest, accounting for 55.02%. The ecological service value generated by pressure mining of groundwater ranks the second, accounting for 34.87%, and the ecological service value generated by the new forest land and the new green land account for 6.90% and 3.21%, respectively. Since the South-to-North Water Transfer did not directly supply wetlands, it is believed that the South-to-North Water Transfer Project had no direct or indirect contribution to the growth of wetland ecosystem service value in Beijing from 2015 to 2018.This research can provide support for the formulation of policies and measures for ecological water use, ecological environment restoration and protection, and efficient utilization of water resources in Beijing and other water reception areas of the South-to-North Water Transfer Project.
2022, 20(6):1179-1187.
Abstract:
Several local governing bodies are involved in the ecological environmental management of the middle route of the South-to-North Water Transfer Project. As a limited rational economic person, considering their economic benefit, local governments make different action decisions and play games with each other, which have a negative effect on ecological environmental management.The graph model analysis method was used to dynamically describe the strategic interaction among the local governments in the ecological environment governance of water sources in the middle route. First, the main agents in the ecological environment governance in water resources and their respective strategy sets were analyzed. Then, based on the concept of lexicographic preference, the feasible statuses of the conflict were explored. The GMCRⅡ software with five different definitions of equilibrium of NR, GMR, SMR, SEQ, and SIM was used to analyze the equilibriums of the conflict. Finally, considering the actual situation of water resources in the middle route of the South-to-North Water Transfer Project, the dynamic evolution of the ecological environment governance conflict was shown by the diagram.In the process of ecological environment governance, incentive and compensation policies were used by the management institutions of water resources in the middle route to adjust the benefits of local governments, whose strategic choices turned to consider environmental governance. Based on the incentive and compensation policies, industrial support policies were used to adjust local governments’ benefits which resulted in changing their strategic choices to emphasize environmental governance.The result showed that the incentive policies used by management institutions of water resources in the middle route can effectively promote local governments to actively participate in the ecological environment governance, and promote the ecological environment governance conflict to evolve into a state of equilibrium. It is an effective way for the management institutions of water resources in water source of the middle route to guide local governments to cooperate by exploring a variety of incentive models in combination with the development needs.
Several local governing bodies are involved in the ecological environmental management of the middle route of the South-to-North Water Transfer Project. As a limited rational economic person, considering their economic benefit, local governments make different action decisions and play games with each other, which have a negative effect on ecological environmental management.The graph model analysis method was used to dynamically describe the strategic interaction among the local governments in the ecological environment governance of water sources in the middle route. First, the main agents in the ecological environment governance in water resources and their respective strategy sets were analyzed. Then, based on the concept of lexicographic preference, the feasible statuses of the conflict were explored. The GMCRⅡ software with five different definitions of equilibrium of NR, GMR, SMR, SEQ, and SIM was used to analyze the equilibriums of the conflict. Finally, considering the actual situation of water resources in the middle route of the South-to-North Water Transfer Project, the dynamic evolution of the ecological environment governance conflict was shown by the diagram.In the process of ecological environment governance, incentive and compensation policies were used by the management institutions of water resources in the middle route to adjust the benefits of local governments, whose strategic choices turned to consider environmental governance. Based on the incentive and compensation policies, industrial support policies were used to adjust local governments’ benefits which resulted in changing their strategic choices to emphasize environmental governance.The result showed that the incentive policies used by management institutions of water resources in the middle route can effectively promote local governments to actively participate in the ecological environment governance, and promote the ecological environment governance conflict to evolve into a state of equilibrium. It is an effective way for the management institutions of water resources in water source of the middle route to guide local governments to cooperate by exploring a variety of incentive models in combination with the development needs.
2022, 20(6):1188-1196.
Abstract:
The middle route of the South-to-North Water Transfer Project is an important source of water for Henan, Hebei, Tianjin, and Beijing, directly benefiting 60 million people. However, water pollution occur frequently in recent years, which not only bring immeasurable impact on the environment but also threaten social and economic development, causing people to worry about the water safety of the open channel water transfer project.Accorded to the demand for emergency regulation and control of sudden water pollution in an open channel, the emergency regulation and control strategies of the accident section and downstream of the accident section are studied. The decision-making of emergency control includes: analyzing the diffusion process of pollutants by a quantitative method of pollutant characteristic parameters, dividing the accident section and downstream of the accident section, and calculating the duration of the whole emergency incident by quantitative method for the accident section. Given the downstream of the accident section, the method of optimizing partition is adopted to identify the unfavorable channel pool and close the control gate downstream of the unfavorable channel pool, and to extend the water supply time of the whole downstream of the accident section.Taking the Xiaohe River control gate - Guyun River as an example, the research results are as follows: Utilizing quantization of pollutant characteristic parameters, the accident section is identified as the Xiaohe River control gate - Hutuo River control gate, Hutuo River control gate - Gangtou Tunnel control gate downstream of the accident section. The duration of the emergency in the accident section was 7.9 h. Downstream of the accident section, two unfavorable drainage pools were identified by optimizing the zoning method, and the water supply time of unfavorable drainage pools was extended 6.13 d and 5.61 d.
The middle route of the South-to-North Water Transfer Project is an important source of water for Henan, Hebei, Tianjin, and Beijing, directly benefiting 60 million people. However, water pollution occur frequently in recent years, which not only bring immeasurable impact on the environment but also threaten social and economic development, causing people to worry about the water safety of the open channel water transfer project.Accorded to the demand for emergency regulation and control of sudden water pollution in an open channel, the emergency regulation and control strategies of the accident section and downstream of the accident section are studied. The decision-making of emergency control includes: analyzing the diffusion process of pollutants by a quantitative method of pollutant characteristic parameters, dividing the accident section and downstream of the accident section, and calculating the duration of the whole emergency incident by quantitative method for the accident section. Given the downstream of the accident section, the method of optimizing partition is adopted to identify the unfavorable channel pool and close the control gate downstream of the unfavorable channel pool, and to extend the water supply time of the whole downstream of the accident section.Taking the Xiaohe River control gate - Guyun River as an example, the research results are as follows: Utilizing quantization of pollutant characteristic parameters, the accident section is identified as the Xiaohe River control gate - Hutuo River control gate, Hutuo River control gate - Gangtou Tunnel control gate downstream of the accident section. The duration of the emergency in the accident section was 7.9 h. Downstream of the accident section, two unfavorable drainage pools were identified by optimizing the zoning method, and the water supply time of unfavorable drainage pools was extended 6.13 d and 5.61 d.
2022, 20(6):1197-1207.
Abstract:
The specific requirement of the major historical task of building a new socialist countryside is constructing beautiful countryside. However, frequent waterlogging disasters restrict the economic and social development of the small villages and towns in the plain areas in China. Therefore, it is particularly necessary to strengthen the flood control and drainage capacity of the small villages and towns in rural areas. The drainage system inside and around the village is an important measure for flood control and waterlogging removal, which needs to be scientifically evaluated and optimized. However, recently, there are few studies on the drainage system in rural plain areas. The stormwater management model is an open-source model developed by the U.S. Environmental Protection Agency. It has been applied to storm runoff and drainage simulation by researchers for a long time.A typical plain village is chosen as the research object to explore a scientific and convenient method to evaluate and optimize the drainage system of small villages in the plain area. First, the basic situation, drainage system, and historical waterlogging disasters of the village are investigated , and remote sensing images of the region are referenced. This survey considers various situations such as the siltation of peripheral rivers and pipes and canals. 30-year rainfall observation data of the surrounding area is collected. Frequency analysis method is used to calculate the maximum 72-hour rainfall with different frequencies and predict the rainstorm time through the distribution table of rainfall patterns in the basin. A stormwater management model suitable for this village is established based on the investigated data. Most parameters in the stormwater management model are measured to avoid calibration. However, the roughness parameters and the impervious area ratio in the model are very sensitive and need to be calibrated accurately to ensure the accuracy of the model simulation. The historical waterlogging disaster data are used to calibrate and verify the model. This model is used to simulate and evaluate the village waterlogging in different rainstorm return periods. According to the simulation results, some targeted optimization measures are proposed, and the optimization effect is also analyzed.The results show that the village has been affected by the once-in-five-year rainfall. Its maximum ponding time is up to nine hours and the maximum volume is nearly 6 000 cubic meters. Through the analysis, it is revealed that the main drainage channel is overloaded and the detention tank has not been effectively utilized. Given the above problems, some optimization measures, such as digging deep trunk and drainage channels with high drainage pressure and increasing the connectivity of the detention tank are put forward. After optimization, the disaster situation of the village is effectively alleviated. The maximum ponding time is reduced to 0.2 hours and the maximum ponding volume is reduced to 417 cubic meters. Under different rainfall conditions, the optimized ponding time and ponding volume of the village have been effectively improved.Furthermore, taking the typical villages in the plain area of Shandong Province as an example, this study the village waterlogging simulation model is established by SWMM model. The drainage capacity of the village is evaluated, and a practical and effective optimization scheme is put forward. Thus, some conclusions can be put forward. The waterlogging situation of this village can be better reflected by the waterlogging model based on the stormwater management model. There are many weak points in the drainage system of villages, and the ability to prevent waterlogging is low. However, through targeted optimization measures, its ability to prevent waterlogging can be effectively improved.
The specific requirement of the major historical task of building a new socialist countryside is constructing beautiful countryside. However, frequent waterlogging disasters restrict the economic and social development of the small villages and towns in the plain areas in China. Therefore, it is particularly necessary to strengthen the flood control and drainage capacity of the small villages and towns in rural areas. The drainage system inside and around the village is an important measure for flood control and waterlogging removal, which needs to be scientifically evaluated and optimized. However, recently, there are few studies on the drainage system in rural plain areas. The stormwater management model is an open-source model developed by the U.S. Environmental Protection Agency. It has been applied to storm runoff and drainage simulation by researchers for a long time.A typical plain village is chosen as the research object to explore a scientific and convenient method to evaluate and optimize the drainage system of small villages in the plain area. First, the basic situation, drainage system, and historical waterlogging disasters of the village are investigated , and remote sensing images of the region are referenced. This survey considers various situations such as the siltation of peripheral rivers and pipes and canals. 30-year rainfall observation data of the surrounding area is collected. Frequency analysis method is used to calculate the maximum 72-hour rainfall with different frequencies and predict the rainstorm time through the distribution table of rainfall patterns in the basin. A stormwater management model suitable for this village is established based on the investigated data. Most parameters in the stormwater management model are measured to avoid calibration. However, the roughness parameters and the impervious area ratio in the model are very sensitive and need to be calibrated accurately to ensure the accuracy of the model simulation. The historical waterlogging disaster data are used to calibrate and verify the model. This model is used to simulate and evaluate the village waterlogging in different rainstorm return periods. According to the simulation results, some targeted optimization measures are proposed, and the optimization effect is also analyzed.The results show that the village has been affected by the once-in-five-year rainfall. Its maximum ponding time is up to nine hours and the maximum volume is nearly 6 000 cubic meters. Through the analysis, it is revealed that the main drainage channel is overloaded and the detention tank has not been effectively utilized. Given the above problems, some optimization measures, such as digging deep trunk and drainage channels with high drainage pressure and increasing the connectivity of the detention tank are put forward. After optimization, the disaster situation of the village is effectively alleviated. The maximum ponding time is reduced to 0.2 hours and the maximum ponding volume is reduced to 417 cubic meters. Under different rainfall conditions, the optimized ponding time and ponding volume of the village have been effectively improved.Furthermore, taking the typical villages in the plain area of Shandong Province as an example, this study the village waterlogging simulation model is established by SWMM model. The drainage capacity of the village is evaluated, and a practical and effective optimization scheme is put forward. Thus, some conclusions can be put forward. The waterlogging situation of this village can be better reflected by the waterlogging model based on the stormwater management model. There are many weak points in the drainage system of villages, and the ability to prevent waterlogging is low. However, through targeted optimization measures, its ability to prevent waterlogging can be effectively improved.
2022, 20(6):1208-1219.
Abstract:
Rainfall data is one of the main factors that can affect the accuracy of flood simulation in small and medium rivers, and rainfall forecasting is the most direct means of extending the forecast period. At present, there are many precipitation forecast product evaluations and post-processing methods, but the research on the applicability evaluation, accuracy improvement, and forecast of each product is still insufficient in different hydrometeorological subregions. Through the detailed evaluation after applying different correction methods, the numerical forecast products and suitable rainfall correction methods are sought for small and medium basins in different hydrometeorological regions. This research aimed to provide a reliable basis for improving the flood forecasting accuracy and forecast period of medium and small rivers.This research took Tunxi and Suide basins and selected the 2010 to 2015 control forecast data of three products (NCEP, ECMWF, and CMA). The QUANT method and the RQUANT method were used for forecasting rainfall correction, and the multi-classification forecast test, continuous forecast test, and probabilistic forecast test methods were used to compare and analyze the applicability of different forecast products and different correction methods. Taking the measured rainfall in the Tunxi basin as an example, the rainfall was resampled by adding a noise term, and the influence of rainfall uncertainty on the hydrological simulation results was analyzed based on the Xin'anjiang model.The results showed that the selected forecast products had high forecast accuracy for no-rain and light-rain periods. With the increase in rainfall, the forecast ability of each product decreased significantly. The test showed that the rainfall forecast effect in the Suide basin was better, and the overall forecasting accuracy of NCEP and ECMWF was well in the study basin. The forecast accuracy of CMA is slightly worse than that of other products. The prediction accuracy of most of the inspection indicators for each product was improved after the correction. Among them, ECMWF had the highest prediction accuracy in the Suide basin and had good applicability to both correction methods. The prediction accuracy of NCEP and ECMWF after different correct methods was different in the Tunxi basin. CMA's corrected TS score forecast accuracy was superior to other products only in the heavy rains weight level. The uncertainty of rainfall had a negative impact on the hydrological simulation, which led to the uncertainty of the parameters and a decrease in the accuracy of the hydrological simulation.The research provided a reference for selecting suitable numerical forecast products and correction methods for different hydrometeorological regions. Semi-arid areas like Suide basin should use ECMWF revised forecast products, and in humid watersheds like Tunxi basin, NCEP and ECMWF products and correction methods should be selected according to the needs of application indicators, which can reduce rainfall forecast errors in certain procedures and improve the accuracy of flood simulations.
Rainfall data is one of the main factors that can affect the accuracy of flood simulation in small and medium rivers, and rainfall forecasting is the most direct means of extending the forecast period. At present, there are many precipitation forecast product evaluations and post-processing methods, but the research on the applicability evaluation, accuracy improvement, and forecast of each product is still insufficient in different hydrometeorological subregions. Through the detailed evaluation after applying different correction methods, the numerical forecast products and suitable rainfall correction methods are sought for small and medium basins in different hydrometeorological regions. This research aimed to provide a reliable basis for improving the flood forecasting accuracy and forecast period of medium and small rivers.This research took Tunxi and Suide basins and selected the 2010 to 2015 control forecast data of three products (NCEP, ECMWF, and CMA). The QUANT method and the RQUANT method were used for forecasting rainfall correction, and the multi-classification forecast test, continuous forecast test, and probabilistic forecast test methods were used to compare and analyze the applicability of different forecast products and different correction methods. Taking the measured rainfall in the Tunxi basin as an example, the rainfall was resampled by adding a noise term, and the influence of rainfall uncertainty on the hydrological simulation results was analyzed based on the Xin'anjiang model.The results showed that the selected forecast products had high forecast accuracy for no-rain and light-rain periods. With the increase in rainfall, the forecast ability of each product decreased significantly. The test showed that the rainfall forecast effect in the Suide basin was better, and the overall forecasting accuracy of NCEP and ECMWF was well in the study basin. The forecast accuracy of CMA is slightly worse than that of other products. The prediction accuracy of most of the inspection indicators for each product was improved after the correction. Among them, ECMWF had the highest prediction accuracy in the Suide basin and had good applicability to both correction methods. The prediction accuracy of NCEP and ECMWF after different correct methods was different in the Tunxi basin. CMA's corrected TS score forecast accuracy was superior to other products only in the heavy rains weight level. The uncertainty of rainfall had a negative impact on the hydrological simulation, which led to the uncertainty of the parameters and a decrease in the accuracy of the hydrological simulation.The research provided a reference for selecting suitable numerical forecast products and correction methods for different hydrometeorological regions. Semi-arid areas like Suide basin should use ECMWF revised forecast products, and in humid watersheds like Tunxi basin, NCEP and ECMWF products and correction methods should be selected according to the needs of application indicators, which can reduce rainfall forecast errors in certain procedures and improve the accuracy of flood simulations.
2022, 20(6):1220-1230.
Abstract:
The rapid development of urbanization has led to a dramatic increase in the proportion of hardened subsurface, which has had a significant impact on urban water generation and concentration, leading to urban flooding, the urban heat island effect, and the rain island effect. The sponge city is a new type of rainwater management measure. Permeable paving, as a multi-layer infiltration media system, is one of the LID technologies commonly used in sponge city construction, which can effectively absorb rainwater, and achieve the urban water cycle of regulation and storage.To alleviate urban flooding and improve the infiltration, storage, and drainage performance of permeable paving, a sponge permeable paving system filled with porous fibre wool was built as the paving substrate, and a Hydrus-1D numerical simulation model was constructed based on indoor physical experiments to simulate rainfall. Under different rainfall intensities and rainfall intervals, the flow production curves of the permeable pavers were obtained through flow production tests and verified by simulation using Hydrus-1D software. The control characteristics of the fibre wool permeable paving structure on the amount of rainfall runoff were analyzed, the one-dimensional hydrodynamic process of the permeable paving structure was investigated, and the peak flow reduction effect and outflow characteristics under different structural layer ratios were simulated using the numerical model.The results showed that the Hydrus-1D numerical model can simulate the flow production process of sponge permeable paving well. The flow rate and total flow rate curves were well-fitted for intervals of 0 d,1 d, 3 d, 5 d, and 7 d. However, for the flow rate curve at 11 d intervals, the simulated curve was shifted to the right by a larger amount than the measured curve. The model also fitted the storage process well for the rainfall phase, and the simulated curve lagged behind the measured curve to a certain extent when the rainfall stopped. Fibre wool permeable paving could effectively reduce the peak flow rate and had a good outflow delay performance, which had a significant retarding effect on the drainage process. The lower the intensity of rainfall and the longer the interval days, the more significant the effect showed. The maximum water storage performance of the permeable paving was achieved at a rainfall interval of 3 days, and the best peak flow reduction was achieved at a rainfall interval of 9 days. At a rainfall interval of 9 days, the porous fibre wool layer to gravel layer ratio of 1∶3 showed the best effect in terms of smooth water circulation.The experiments showed that sponge permeable paving had a more obvious water control effect at rainfall intensities below heavy rainfall, effectively absorbing rainwater and reducing peak flows. However, the effect of water control under extreme rainfall conditions such as very heavy rainstorms is limited. Sponge permeable pavement flow production curve indicated that it had an obvious slowing effect on the drainage process while reducing runoff, and cutting peak flow so that the drainage process flow remained stable. In practice, the sponge-permeable pavement can reduce the impact on the urban sewage network during heavy rainfall and reduce the pressure on the urban network. The experiments also provided data support for the establishment of numerical simulation methods for urban subsurface runoff water control processes.
The rapid development of urbanization has led to a dramatic increase in the proportion of hardened subsurface, which has had a significant impact on urban water generation and concentration, leading to urban flooding, the urban heat island effect, and the rain island effect. The sponge city is a new type of rainwater management measure. Permeable paving, as a multi-layer infiltration media system, is one of the LID technologies commonly used in sponge city construction, which can effectively absorb rainwater, and achieve the urban water cycle of regulation and storage.To alleviate urban flooding and improve the infiltration, storage, and drainage performance of permeable paving, a sponge permeable paving system filled with porous fibre wool was built as the paving substrate, and a Hydrus-1D numerical simulation model was constructed based on indoor physical experiments to simulate rainfall. Under different rainfall intensities and rainfall intervals, the flow production curves of the permeable pavers were obtained through flow production tests and verified by simulation using Hydrus-1D software. The control characteristics of the fibre wool permeable paving structure on the amount of rainfall runoff were analyzed, the one-dimensional hydrodynamic process of the permeable paving structure was investigated, and the peak flow reduction effect and outflow characteristics under different structural layer ratios were simulated using the numerical model.The results showed that the Hydrus-1D numerical model can simulate the flow production process of sponge permeable paving well. The flow rate and total flow rate curves were well-fitted for intervals of 0 d,1 d, 3 d, 5 d, and 7 d. However, for the flow rate curve at 11 d intervals, the simulated curve was shifted to the right by a larger amount than the measured curve. The model also fitted the storage process well for the rainfall phase, and the simulated curve lagged behind the measured curve to a certain extent when the rainfall stopped. Fibre wool permeable paving could effectively reduce the peak flow rate and had a good outflow delay performance, which had a significant retarding effect on the drainage process. The lower the intensity of rainfall and the longer the interval days, the more significant the effect showed. The maximum water storage performance of the permeable paving was achieved at a rainfall interval of 3 days, and the best peak flow reduction was achieved at a rainfall interval of 9 days. At a rainfall interval of 9 days, the porous fibre wool layer to gravel layer ratio of 1∶3 showed the best effect in terms of smooth water circulation.The experiments showed that sponge permeable paving had a more obvious water control effect at rainfall intensities below heavy rainfall, effectively absorbing rainwater and reducing peak flows. However, the effect of water control under extreme rainfall conditions such as very heavy rainstorms is limited. Sponge permeable pavement flow production curve indicated that it had an obvious slowing effect on the drainage process while reducing runoff, and cutting peak flow so that the drainage process flow remained stable. In practice, the sponge-permeable pavement can reduce the impact on the urban sewage network during heavy rainfall and reduce the pressure on the urban network. The experiments also provided data support for the establishment of numerical simulation methods for urban subsurface runoff water control processes.
2022, 20(6):1231-1239.
Abstract:
The water resources in Gansu province are short and unevenly distributed in time and space, which does not match the economic and social development, population, and cultivated land distribution. The construction of water conservancy project is the key to solving this problem.Taking the water source area of the Bailong River diversion project in Gansu Province as the research area, the development of geological hazards within the influence area of the new reservoir was studied, which could provide support for the safe construction and operation of the reservoir. Based on remote sensing interpretation and field survey, 6 evaluation factors of geological hazard susceptibility were selected, which include elevation, slope, aspect, distance from the fault, the relationship between rock dip and aspect, and distance from the water system.Based on geographical information system (GIS) spatial analysis technology and analytic hierarchy process, the relationship between evaluation factors and geological disasters was analyzed, and the susceptibility of geological disasters was carried out.The historical geological hazards are mainly distributed in the area below 2 300 m elevation, 15° and 30° in slope, within 200 m from the river, and in the south and southeast of the study area. The medium and high-prone areas in the study area accounted for 45.85% of the total area, and geological hazard points accounted for 95.65% of the total geological hazard points.The susceptibility evaluation result is consistent with the distribution of historical geological hazards in the research, which could provide prerequisites for disaster prevention and mitigation work in the reservoir area, and provide technical support for the safe construction and operation of reservoirs.
The water resources in Gansu province are short and unevenly distributed in time and space, which does not match the economic and social development, population, and cultivated land distribution. The construction of water conservancy project is the key to solving this problem.Taking the water source area of the Bailong River diversion project in Gansu Province as the research area, the development of geological hazards within the influence area of the new reservoir was studied, which could provide support for the safe construction and operation of the reservoir. Based on remote sensing interpretation and field survey, 6 evaluation factors of geological hazard susceptibility were selected, which include elevation, slope, aspect, distance from the fault, the relationship between rock dip and aspect, and distance from the water system.Based on geographical information system (GIS) spatial analysis technology and analytic hierarchy process, the relationship between evaluation factors and geological disasters was analyzed, and the susceptibility of geological disasters was carried out.The historical geological hazards are mainly distributed in the area below 2 300 m elevation, 15° and 30° in slope, within 200 m from the river, and in the south and southeast of the study area. The medium and high-prone areas in the study area accounted for 45.85% of the total area, and geological hazard points accounted for 95.65% of the total geological hazard points.The susceptibility evaluation result is consistent with the distribution of historical geological hazards in the research, which could provide prerequisites for disaster prevention and mitigation work in the reservoir area, and provide technical support for the safe construction and operation of reservoirs.
2022, 20(6):1240-1248.
Abstract:
Urban river channel is an important element in city economy and ecology development. Considering soil and water conservation, landscaping or ecological factors, the river bank is usually planted with grass, shrub and other vegetation. The plant coverage has changed the flow surface of the river bank, as well as the flood discharge capacity. Flood control and management is the most crucial factor for the planning of urban rivers, thus, it is quite necessary to study the influence of bank vegetation on river flood discharge.In order to analyze the effect of bank vegetation on river flood discharge, physical model experiments were carried out in laboratory. An experimental platform was built with the length of 40 m, the width of 8 to 12 m, the water depth of 4 to 8 cm and the width depth ratio of 100 to 300. The water levels of no vegetation, sparse vegetation, sparse vegetation + shrub and dense vegetation, were tested under typical flow. Then, the prototype parameters and water level difference corresponding to the tested conditions, were deduced according to the similarity principle. Mathematical analysis was further conducted on basis of the classical composite roughness calculation formulas, including Pavlovskij formula and Einstein-Banks formula. An equation was proposed to determine the increase of composite roughness while the river bank changed from no vegetation state to planted vegetation state. A practical procedure was also given to analyze the influence of bank vegetation on river flood discharge.The results showed that, the water level of the tested channel increased by 0.3 to 1.3 mm due to the dense vegetation, while it increased by 0.1 to 0.4 mm due to the sparse vegetation and sparse vegetation + shrub. The denser the bank vegetation, the higher the water level. For a river with the length of 400 m, the water depth of 0.4 to 0.8 m, and the roughness of 0.026, the water level increased by 2 to 15 mm. For a river with the length of 2200 m, the water depth of 2.2 to 4.4 m, and the roughness of 0.035, the water level increase could be large as 70 mm. When the river bank planted vegetation, the increase of composite roughness was related to two factors, namely, the ratio of the covered wetted perimeter to the total wetted perimeter and the roughness of the covered area. It increased with the growth of the roughness of the vegetation covered area, and decreased with the increase of width-depth ratio. While the width-depth ratio was larger than 60 and 100, the growth of composite roughness due to planted vegetation was no more than 10% and 7%, respectively.Urban river bank is usually planted with grass, shrub, or other vegetation, and the water level increases with the growth of the vegetation density. The water level growth can be large as 70 mm in the river length of 2200 m. The water level increase should be given special consideration. The composite roughness increase is related to the ratio of the planted wetted perimeter to the total and the roughness of the planted area. For the river whose width-depth ratio is larger than 100, the increase of composite roughness is no more than 7%. The formula was proposed to calculate the variation of composite roughness while the river bank vegetation changed. Further, an analysis procedure was given to guide further design.
Urban river channel is an important element in city economy and ecology development. Considering soil and water conservation, landscaping or ecological factors, the river bank is usually planted with grass, shrub and other vegetation. The plant coverage has changed the flow surface of the river bank, as well as the flood discharge capacity. Flood control and management is the most crucial factor for the planning of urban rivers, thus, it is quite necessary to study the influence of bank vegetation on river flood discharge.In order to analyze the effect of bank vegetation on river flood discharge, physical model experiments were carried out in laboratory. An experimental platform was built with the length of 40 m, the width of 8 to 12 m, the water depth of 4 to 8 cm and the width depth ratio of 100 to 300. The water levels of no vegetation, sparse vegetation, sparse vegetation + shrub and dense vegetation, were tested under typical flow. Then, the prototype parameters and water level difference corresponding to the tested conditions, were deduced according to the similarity principle. Mathematical analysis was further conducted on basis of the classical composite roughness calculation formulas, including Pavlovskij formula and Einstein-Banks formula. An equation was proposed to determine the increase of composite roughness while the river bank changed from no vegetation state to planted vegetation state. A practical procedure was also given to analyze the influence of bank vegetation on river flood discharge.The results showed that, the water level of the tested channel increased by 0.3 to 1.3 mm due to the dense vegetation, while it increased by 0.1 to 0.4 mm due to the sparse vegetation and sparse vegetation + shrub. The denser the bank vegetation, the higher the water level. For a river with the length of 400 m, the water depth of 0.4 to 0.8 m, and the roughness of 0.026, the water level increased by 2 to 15 mm. For a river with the length of 2200 m, the water depth of 2.2 to 4.4 m, and the roughness of 0.035, the water level increase could be large as 70 mm. When the river bank planted vegetation, the increase of composite roughness was related to two factors, namely, the ratio of the covered wetted perimeter to the total wetted perimeter and the roughness of the covered area. It increased with the growth of the roughness of the vegetation covered area, and decreased with the increase of width-depth ratio. While the width-depth ratio was larger than 60 and 100, the growth of composite roughness due to planted vegetation was no more than 10% and 7%, respectively.Urban river bank is usually planted with grass, shrub, or other vegetation, and the water level increases with the growth of the vegetation density. The water level growth can be large as 70 mm in the river length of 2200 m. The water level increase should be given special consideration. The composite roughness increase is related to the ratio of the planted wetted perimeter to the total and the roughness of the planted area. For the river whose width-depth ratio is larger than 100, the increase of composite roughness is no more than 7%. The formula was proposed to calculate the variation of composite roughness while the river bank vegetation changed. Further, an analysis procedure was given to guide further design.
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