Volume 15,Issue 6,2017 Table of Contents
2017, 15(6):1-10.
Abstract:
As the potential evapotranspiration (PET) is one of the important factors in the energy cycle and hydrological cycle, the accurate estimation of PET has important practical significance. The FAO56-PM method can give efficient estimation of PET; however, its applicability is constrained as it requires a large amount of data. Different PET estimation methods have been proposed and the applicability of these methods should be tested before they are applied in a typical region. In this study, we attempted to examine the efficiency of 7 PET estimation methods in spatial and temporal dimensions in the upper and middle reaches of Hanjiang River Basin using the daily meteorological data during 1961-2013. The results showed that the radiation-based methods were the optimal choice, followed by the combination method, and the temperature-based methods were the least suitable choice for the PET estimation in the study area. Among these estimation methods, the Makkink method and the Priestley-Taylor method showed the best applicability and highest precision in the study area, while the McCloud method showed the worst applicability and largest error.
As the potential evapotranspiration (PET) is one of the important factors in the energy cycle and hydrological cycle, the accurate estimation of PET has important practical significance. The FAO56-PM method can give efficient estimation of PET; however, its applicability is constrained as it requires a large amount of data. Different PET estimation methods have been proposed and the applicability of these methods should be tested before they are applied in a typical region. In this study, we attempted to examine the efficiency of 7 PET estimation methods in spatial and temporal dimensions in the upper and middle reaches of Hanjiang River Basin using the daily meteorological data during 1961-2013. The results showed that the radiation-based methods were the optimal choice, followed by the combination method, and the temperature-based methods were the least suitable choice for the PET estimation in the study area. Among these estimation methods, the Makkink method and the Priestley-Taylor method showed the best applicability and highest precision in the study area, while the McCloud method showed the worst applicability and largest error.
2 Model evaluation and spatial-temporal variations of potential evapotranspiration in Haihe Catchment
2017, 15(6):11-16.
Abstract:
Based on the observation data of average temperature, sunshine hours, wind speed, and relative humidity at 45 stations in Haihe Catchment during 1960—2012, we compared three potential evapotranspiration models with the Penman—Monteith model. The absolute and relative errors were used as the model evaluation indices. Hargreaves model based on energy balance proved to be the most suitable for potential evapotranspiration estimation in Haihe Catchment. The annual potential evapotranspiration declined at a mean rate of 2.04 mm?a-1 in 1960-2012. The inter-annual variations of potential evapotranspiration in the four seasons all showed a significant decreasing trend, with the largest decline in summer and the smallest decline in winter. Spatially, the average potential evapotranspiration during 1960-2012 tended to increase from the northwest part of the region to the southeast. Moreover, the decrease of potential evapotranspiration occurred in most part of the region, especially in the southeast, which means potential evapotranspiration may be mainly impacted by global dimming. However, potential evapotranspiration in the northwest part of the region showed an increasing trend, probably due to global warming.
Based on the observation data of average temperature, sunshine hours, wind speed, and relative humidity at 45 stations in Haihe Catchment during 1960—2012, we compared three potential evapotranspiration models with the Penman—Monteith model. The absolute and relative errors were used as the model evaluation indices. Hargreaves model based on energy balance proved to be the most suitable for potential evapotranspiration estimation in Haihe Catchment. The annual potential evapotranspiration declined at a mean rate of 2.04 mm?a-1 in 1960-2012. The inter-annual variations of potential evapotranspiration in the four seasons all showed a significant decreasing trend, with the largest decline in summer and the smallest decline in winter. Spatially, the average potential evapotranspiration during 1960-2012 tended to increase from the northwest part of the region to the southeast. Moreover, the decrease of potential evapotranspiration occurred in most part of the region, especially in the southeast, which means potential evapotranspiration may be mainly impacted by global dimming. However, potential evapotranspiration in the northwest part of the region showed an increasing trend, probably due to global warming.
2017, 15(6):17-25.
Abstract:
The 14-day medium-range precipitation forecast is important for drought and flood forecasting and water resources scheduling management. TIGGE (THORPEX Interactive Grand Global Ensemble) provides basic data for regional medium-range ensemble precipitation prediction. Based on the ensemble forecasts of CMA, CMC, ECMWF, JMA and NCEP in the TIGGE datasets in Jiangsu Province, we evaluated their medium-range precipitation forecast results. We mainly used such evaluation methods as the TS, BS, mean absolute deviation, and mean square root error. The results showed that the forecast scores of light and moderate rain during the entire forecast period were all relatively high. The light rain had the highest TS (mostly around 0.5) statistically. However, there were obvious missing reports of precipitations above the moderate level. For the 15-day forecast of daily cumulative rainfall, there was only a 3-day decay period, after which all the error indicators remained stable. The prediction bias in a lead time of over 3 days was mainly overprediction. Meanwhile, the cumulative rainfall forecast of over 5 days was significantly larger than the actual value. The forecast effect was the best in winter and the worst in summer, and the effect in northern Jiangsu was better than that in southern Jiangsu. Across the five representative modes, the ECMWF and JMA modes respectively showed the best performance in rainfall categorical forecast and daily cumulative rainfall forecast.
The 14-day medium-range precipitation forecast is important for drought and flood forecasting and water resources scheduling management. TIGGE (THORPEX Interactive Grand Global Ensemble) provides basic data for regional medium-range ensemble precipitation prediction. Based on the ensemble forecasts of CMA, CMC, ECMWF, JMA and NCEP in the TIGGE datasets in Jiangsu Province, we evaluated their medium-range precipitation forecast results. We mainly used such evaluation methods as the TS, BS, mean absolute deviation, and mean square root error. The results showed that the forecast scores of light and moderate rain during the entire forecast period were all relatively high. The light rain had the highest TS (mostly around 0.5) statistically. However, there were obvious missing reports of precipitations above the moderate level. For the 15-day forecast of daily cumulative rainfall, there was only a 3-day decay period, after which all the error indicators remained stable. The prediction bias in a lead time of over 3 days was mainly overprediction. Meanwhile, the cumulative rainfall forecast of over 5 days was significantly larger than the actual value. The forecast effect was the best in winter and the worst in summer, and the effect in northern Jiangsu was better than that in southern Jiangsu. Across the five representative modes, the ECMWF and JMA modes respectively showed the best performance in rainfall categorical forecast and daily cumulative rainfall forecast.
2017, 15(6):26-32.
Abstract:
In view of the limitations of traditional Markov chain and its improved prediction methods which can only predict the state, in this paper we realized a critical improvement of the Markov chain forecasting method to being able to conduct numerical prediction. We did so by using weighted summation of the average value of each state multiplied by the corresponding predicted probability, on the basis of obtaining the predicted probability of each state with the traditional Markov chain forecasting method according to the characteristics of dependent stochastic variables. The data of this study were collected from Daojieba hydrological station on the Nujiang river, which is a famous international river in southwest China. We used the runoff series from 1957 to 2010 and the suspended sediment series from 1964 to 2010 for analysis, and used the runoff and suspended sediment series from 2011 to 2015 for validation. Results showed that the re-weighted Markov chain forecasting had a high accuracy in numerical prediction and could meet the demand of short-term numerical prediction in stochastic time series.
In view of the limitations of traditional Markov chain and its improved prediction methods which can only predict the state, in this paper we realized a critical improvement of the Markov chain forecasting method to being able to conduct numerical prediction. We did so by using weighted summation of the average value of each state multiplied by the corresponding predicted probability, on the basis of obtaining the predicted probability of each state with the traditional Markov chain forecasting method according to the characteristics of dependent stochastic variables. The data of this study were collected from Daojieba hydrological station on the Nujiang river, which is a famous international river in southwest China. We used the runoff series from 1957 to 2010 and the suspended sediment series from 1964 to 2010 for analysis, and used the runoff and suspended sediment series from 2011 to 2015 for validation. Results showed that the re-weighted Markov chain forecasting had a high accuracy in numerical prediction and could meet the demand of short-term numerical prediction in stochastic time series.
2017, 15(6):33-38.
Abstract:
In order to reveal the spatial-temporal variation characteristics of sunshine duration in the upper and middle reaches of Huaihe River Basin and determine the year of mutation, we adopted such methods as the climate tendency rate, Mann-Kendall trend and mutation test, sliding t-test, and Kriging interpolation, and analyzed the spatial-temporal variation characteristics of sunshine duration based on the data of sunshine duration from 1960 to 2014. The results indicated that the sunshine duration in the past 55 years decreased to a lower level in the 1980s; the annual sunshine duration decreased by about 102.2 h every 10 years; and the climate tendency rates of sunshine duration in the four seasons were as follows: summer (-48.8 h/10a), winter (-29.3 h/10a), autumn (-19.7 h/10a), and spring(-5.4 h/10a). The sunshine duration in a year and in all three seasons except spring showed a significant decreasing trend. Spatially, the decreasing trend of sunshine duration was more obvious and sharp in the middle of the northern basin (near Shangqiu station) and in the northwest (near Zhengzhou and Baofeng stations) (Z<-2), but the decrease was small in the east (except for Xuyi station). The highly significant mutation year of annual and summer sunshine durations was 1980, and the weakly significant mutation year of annual sunshine duration was 1984. The mutation years of autumn and winter were 1999 and 1983 respectively, and the mutation year of spring was in the 1970s. The research results are expected to provide scientific basis for the climate studies and agricultural production in the upper and middle reaches of Huaihe River Basin.
In order to reveal the spatial-temporal variation characteristics of sunshine duration in the upper and middle reaches of Huaihe River Basin and determine the year of mutation, we adopted such methods as the climate tendency rate, Mann-Kendall trend and mutation test, sliding t-test, and Kriging interpolation, and analyzed the spatial-temporal variation characteristics of sunshine duration based on the data of sunshine duration from 1960 to 2014. The results indicated that the sunshine duration in the past 55 years decreased to a lower level in the 1980s; the annual sunshine duration decreased by about 102.2 h every 10 years; and the climate tendency rates of sunshine duration in the four seasons were as follows: summer (-48.8 h/10a), winter (-29.3 h/10a), autumn (-19.7 h/10a), and spring(-5.4 h/10a). The sunshine duration in a year and in all three seasons except spring showed a significant decreasing trend. Spatially, the decreasing trend of sunshine duration was more obvious and sharp in the middle of the northern basin (near Shangqiu station) and in the northwest (near Zhengzhou and Baofeng stations) (Z<-2), but the decrease was small in the east (except for Xuyi station). The highly significant mutation year of annual and summer sunshine durations was 1980, and the weakly significant mutation year of annual sunshine duration was 1984. The mutation years of autumn and winter were 1999 and 1983 respectively, and the mutation year of spring was in the 1970s. The research results are expected to provide scientific basis for the climate studies and agricultural production in the upper and middle reaches of Huaihe River Basin.
2017, 15(6):39-44.
Abstract:
There are too many impact factors of water demand in the urban water demand prediction model and most of the factors are multicollinear. Besides, the BP neural network has slow convergence rate and easily gets into a local optimum. To tackle these problems, we proposed an improved prediction model by combining the principal component analysis (PCA), genetic algorithm (GA), and back propagation neural network (BPNN). Taizhou city was taken as a case for study. We established a water demand prediction model that selects the main impact factors of water demand by principal component analysis and optimizes the connection weights and thresholds of the BP neural network by genetic algorithm. The BP neural network prediction model was set up as the contrast model. The results showed that the average relative error and the maximum relative error of water demand prediction by the improved model in 2003-2014 in Taizhou city were 0.564% and 1.681% respectively. The precision was superior to that of the BP neural network prediction model. The results predicted by the GA-BP model matched with the actual water demand data of Taizhou city, and the model had faster calculation speed and higher precision. It can be used as an effective method for water demand prediction.
There are too many impact factors of water demand in the urban water demand prediction model and most of the factors are multicollinear. Besides, the BP neural network has slow convergence rate and easily gets into a local optimum. To tackle these problems, we proposed an improved prediction model by combining the principal component analysis (PCA), genetic algorithm (GA), and back propagation neural network (BPNN). Taizhou city was taken as a case for study. We established a water demand prediction model that selects the main impact factors of water demand by principal component analysis and optimizes the connection weights and thresholds of the BP neural network by genetic algorithm. The BP neural network prediction model was set up as the contrast model. The results showed that the average relative error and the maximum relative error of water demand prediction by the improved model in 2003-2014 in Taizhou city were 0.564% and 1.681% respectively. The precision was superior to that of the BP neural network prediction model. The results predicted by the GA-BP model matched with the actual water demand data of Taizhou city, and the model had faster calculation speed and higher precision. It can be used as an effective method for water demand prediction.
2017, 15(6):45-50.
Abstract:
Focusing on the sharp decline of the runoff of Fenhe River into the Yellow River, based on the runoff data from 1960 to 2013 of the watershed controlled by the Fenhe reservoir, we analyzed the variation trend of the runoff by using the Mann-Kendall method and sliding T-test to look for the abrupt change points. We also used the double mass curve to calculate the influence of rainfall and human activities on the runoff decline. The results showed that the annual runoffs at Jingle station and Shangjingyou station both showed a trend of decline. The runoff series at Jingle station altered abruptly in 1979, and at Shangjingyou station, it altered abruptly in 1982. The runoff decline in the watershed controlled by Fenhe reservoir was mainly affected by human activities, whose contribution rate was 84.48%. The contribution rates of rainfall and human activities to the runoff at Jingle station were 15.62% and 84.38%, respectively, and those at Shangjingyou station were 14.95% and 85.05%, respectively.
Focusing on the sharp decline of the runoff of Fenhe River into the Yellow River, based on the runoff data from 1960 to 2013 of the watershed controlled by the Fenhe reservoir, we analyzed the variation trend of the runoff by using the Mann-Kendall method and sliding T-test to look for the abrupt change points. We also used the double mass curve to calculate the influence of rainfall and human activities on the runoff decline. The results showed that the annual runoffs at Jingle station and Shangjingyou station both showed a trend of decline. The runoff series at Jingle station altered abruptly in 1979, and at Shangjingyou station, it altered abruptly in 1982. The runoff decline in the watershed controlled by Fenhe reservoir was mainly affected by human activities, whose contribution rate was 84.48%. The contribution rates of rainfall and human activities to the runoff at Jingle station were 15.62% and 84.38%, respectively, and those at Shangjingyou station were 14.95% and 85.05%, respectively.
2017, 15(6):51-58.
Abstract:
In order to understand the temporal and spatial distribution characteristics of annual and main flood season precipitation in the upper and middle reaches of Huaihe River basin, we analyzed the monthly precipitation data in 19 meteorological stations during 1960-2014 by using the climate tendency rate, Mann-Kendall analysis, coefficient of variation, non-uniform coefficient of annual distribution, wavelet analysis, and Kriging method. The results were as follows: (1) The main flood season precipitation accounted for more than 50% of the annual precipitation, and it tended to concentrate in the southwest and southeast. The annual precipitation showed “wet/dry” alternations on the 21-32a, 8-19a, and 3-7a time scales, while the main flood season precipitation showed such alternations on the 24-32a, 8-21a, and 3-7a time scales. The "wet/dry" alternations on the same time scale were basically identical. (2) The coefficient of variation (Cv) of main flood season precipitation was generally greater than that of annual precipitation, yet their spatial distributions were different. The larger Cv values of annual precipitation were mainly distributed in the western and northern basin, while the smaller values were in the east and southeast. The larger Cv values of main flood season precipitation were distributed in the western basin, while the smaller values were in the northeast and Bengbu area. The non-uniformity of annual distribution of precipitation in the north was slightly larger than that in the south. (3) The variation trends of both annual and main flood season precipitation were not significant, failing the 95% confidence test. But the main flood season precipitation showed a slight increasing trend whereas the annual precipitation showed a slight decreasing trend. The annual precipitation tended to decline in the north, west, and southwest, but it tended to increase in the middle, south and southeast. The main flood season precipitation tended to increase in a striped manner from north to south.
In order to understand the temporal and spatial distribution characteristics of annual and main flood season precipitation in the upper and middle reaches of Huaihe River basin, we analyzed the monthly precipitation data in 19 meteorological stations during 1960-2014 by using the climate tendency rate, Mann-Kendall analysis, coefficient of variation, non-uniform coefficient of annual distribution, wavelet analysis, and Kriging method. The results were as follows: (1) The main flood season precipitation accounted for more than 50% of the annual precipitation, and it tended to concentrate in the southwest and southeast. The annual precipitation showed “wet/dry” alternations on the 21-32a, 8-19a, and 3-7a time scales, while the main flood season precipitation showed such alternations on the 24-32a, 8-21a, and 3-7a time scales. The "wet/dry" alternations on the same time scale were basically identical. (2) The coefficient of variation (Cv) of main flood season precipitation was generally greater than that of annual precipitation, yet their spatial distributions were different. The larger Cv values of annual precipitation were mainly distributed in the western and northern basin, while the smaller values were in the east and southeast. The larger Cv values of main flood season precipitation were distributed in the western basin, while the smaller values were in the northeast and Bengbu area. The non-uniformity of annual distribution of precipitation in the north was slightly larger than that in the south. (3) The variation trends of both annual and main flood season precipitation were not significant, failing the 95% confidence test. But the main flood season precipitation showed a slight increasing trend whereas the annual precipitation showed a slight decreasing trend. The annual precipitation tended to decline in the north, west, and southwest, but it tended to increase in the middle, south and southeast. The main flood season precipitation tended to increase in a striped manner from north to south.
2017, 15(6):59-65.
Abstract:
Based on the statistical data of precipitation, runoff coefficient, per-capita water resources, GDP per capita, and population density from 2003 to 2013 in the 5 provinces of Huaihe River Basin, we conducted a comprehensive risk assessment of the water resources shortage in Huaihe River Basin and each province by building a risk assessment system and using the variable fuzzy model and entropy weight method. The results showed that the overall risk of water shortage in the Huaihe River Basin during 2003-2013 was relatively high and showed a trend of slow growth. The risk reached the highest in 2004 when the precipitation was little. During the ten years, the increase of risk in Henan province was the most pronounced, whereas Shandong province was relatively stable with the smallest increase of risk. Henan province had the highest degree of risk among the five regions in the Huaihe River Basin, reaching 3.52. It was followed by Jiangsu province and Shandong province, while Anhui and Hubei provinces had relatively low risks, which were 2.86 and 2.51 respectively. The analysis of the secondary indicators of water shortage risk revealed that Henan province faced the highest threat while Anhui province faced the lowest. Shandong province was the most vulnerable to water shortage while Hubei province was the least vulnerable. Jiangsu province was the most exposed to water shortage while Shandong province was the least exposed. Hubei province had the best restorability from water shortage while Henan province had the worst restorability. Moreover, population density, GDP per capita, and precipitation had a great impact on water shortage risk.
Based on the statistical data of precipitation, runoff coefficient, per-capita water resources, GDP per capita, and population density from 2003 to 2013 in the 5 provinces of Huaihe River Basin, we conducted a comprehensive risk assessment of the water resources shortage in Huaihe River Basin and each province by building a risk assessment system and using the variable fuzzy model and entropy weight method. The results showed that the overall risk of water shortage in the Huaihe River Basin during 2003-2013 was relatively high and showed a trend of slow growth. The risk reached the highest in 2004 when the precipitation was little. During the ten years, the increase of risk in Henan province was the most pronounced, whereas Shandong province was relatively stable with the smallest increase of risk. Henan province had the highest degree of risk among the five regions in the Huaihe River Basin, reaching 3.52. It was followed by Jiangsu province and Shandong province, while Anhui and Hubei provinces had relatively low risks, which were 2.86 and 2.51 respectively. The analysis of the secondary indicators of water shortage risk revealed that Henan province faced the highest threat while Anhui province faced the lowest. Shandong province was the most vulnerable to water shortage while Hubei province was the least vulnerable. Jiangsu province was the most exposed to water shortage while Shandong province was the least exposed. Hubei province had the best restorability from water shortage while Henan province had the worst restorability. Moreover, population density, GDP per capita, and precipitation had a great impact on water shortage risk.
ZHANG Yuan
,
ZHAO Chang-sen
,
,
YANG Sheng-tian
,
ZHANG Hui-tong
,
XIANG Hua
,
SUN Ying
,
YANG Zeng-li
,
DONG Bao-en
,
LIU De-hu
,
ZHANG Chun-bin
,
YU Xin-yi
2017, 15(6):66-73.
Abstract:
Key functional group is of great significance to monitoring aquatic ecosystem health and protecting biodiversity. In this paper, we introduced the Ecopath model to quantitively analyze the structural composition and nutritional relationships in an aquatic ecosystem. After calculating the direction and amount of the substance and energy flow in the ecosystem, we determined the key species in the ecosystem and proposed a method to build the key functional group. The method was then applied to the Xiaoqinghe River Basin. Results showed that the members of the key functional group changed with the season: in spring, there were Oryzias latipes, Carassius auratus, Limnodrilus, Protozoa, and Cryptomonas; in summer, there were Oryzias latipes, Misgurnus anguillicaudatus (including Paramisgurnus dabryanus), Limnodrilus, Protozoa, and Tribonema sp.; in autumn, there were Misgurnus anguillicaudatus (including Paramisgurnus dabryanus), Hemiculter leucisculus, Exopalaemon modestus, Lepadella and Euglena. This approach can provide a simple way to select important species for aquatic ecosystem protection, and provide a basis for the wise management of water resources and construction of aquatic ecological civilization.
Key functional group is of great significance to monitoring aquatic ecosystem health and protecting biodiversity. In this paper, we introduced the Ecopath model to quantitively analyze the structural composition and nutritional relationships in an aquatic ecosystem. After calculating the direction and amount of the substance and energy flow in the ecosystem, we determined the key species in the ecosystem and proposed a method to build the key functional group. The method was then applied to the Xiaoqinghe River Basin. Results showed that the members of the key functional group changed with the season: in spring, there were Oryzias latipes, Carassius auratus, Limnodrilus, Protozoa, and Cryptomonas; in summer, there were Oryzias latipes, Misgurnus anguillicaudatus (including Paramisgurnus dabryanus), Limnodrilus, Protozoa, and Tribonema sp.; in autumn, there were Misgurnus anguillicaudatus (including Paramisgurnus dabryanus), Hemiculter leucisculus, Exopalaemon modestus, Lepadella and Euglena. This approach can provide a simple way to select important species for aquatic ecosystem protection, and provide a basis for the wise management of water resources and construction of aquatic ecological civilization.
11 Assessment on heavy metal pollution of the surface sediments from rivers in Beijing central district
2017, 15(6):74-80.
Abstract:
To investigate the pollution status of heavy metals in the surface sediments from rivers in Beijing Central District, we used the methods of the Geoaccumulation Index, principal component analysis, and Potential Ecological Risk Index to evaluate the pollution level, pollution sources, and potential ecological risks of the heavy metals including Hg, As, Pb, Cr, Cd, Mn, and Cu, respectively. The results showed that the average contents of the heavy metals were as follows: Hg 0.670 mg?kg-1, As 6.01 mg?kg-1, Pb 31.1 mg?kg-1, Cr 63 mg?kg-1, Cd 0.29 mg?kg-1, Mn 277 mg?kg-1, Cu 45 mg?kg-1. The descending order by the average Geoaccumulation Index was Hg(1.49) > Cr(0.34) > Cu(0.24) > Cd(0.14) > Pb(-0.77) > As(-1.41) > Mn(-2.30), showing that the surface sediments were mainly polluted by Hg, Cr, Cu, and Cd elements, with Hg at moderate pollution level and Cr, Cu, Cd at mild to moderate pollution level. The pollution mainly came from three sources: traffic, vehicle repairing, and heating coal combustion. The descending order by the average Potential Ecological Risk Coefficient was Hg(357) > Cd(80) > Cu(13) > As(9) > Pb(7) > Cr(4) > Mn(2), and the average Potential Ecological Risk Index of the sediments was 472, suggesting strong ecological hazard of the sediments in general.
To investigate the pollution status of heavy metals in the surface sediments from rivers in Beijing Central District, we used the methods of the Geoaccumulation Index, principal component analysis, and Potential Ecological Risk Index to evaluate the pollution level, pollution sources, and potential ecological risks of the heavy metals including Hg, As, Pb, Cr, Cd, Mn, and Cu, respectively. The results showed that the average contents of the heavy metals were as follows: Hg 0.670 mg?kg-1, As 6.01 mg?kg-1, Pb 31.1 mg?kg-1, Cr 63 mg?kg-1, Cd 0.29 mg?kg-1, Mn 277 mg?kg-1, Cu 45 mg?kg-1. The descending order by the average Geoaccumulation Index was Hg(1.49) > Cr(0.34) > Cu(0.24) > Cd(0.14) > Pb(-0.77) > As(-1.41) > Mn(-2.30), showing that the surface sediments were mainly polluted by Hg, Cr, Cu, and Cd elements, with Hg at moderate pollution level and Cr, Cu, Cd at mild to moderate pollution level. The pollution mainly came from three sources: traffic, vehicle repairing, and heating coal combustion. The descending order by the average Potential Ecological Risk Coefficient was Hg(357) > Cd(80) > Cu(13) > As(9) > Pb(7) > Cr(4) > Mn(2), and the average Potential Ecological Risk Index of the sediments was 472, suggesting strong ecological hazard of the sediments in general.
2017, 15(6):81-87.
Abstract:
The urban river network in the plain area has various water environment problems such as poor water replenishment effect and deterioration of water quality. In order to solve these problems, we adopted the approach of problem analysis and method optimization to carry out the research on water replenishment scheduling strategies for water quality improvement of urban river networks. The approach included three parts: analyzing and evaluating the present situation, validating the strategies, and proposing implementation schemes. A case study of Tianjin City was carried out. Based on analysis of the current problem, we uncovered the reasons for the substandard water quality of the river network and put forward a set of water replenishment scheduling strategies. Based on the recommended strategies, we proposed an annual overall implementation scheme and an actual implementation scheme. The water demand of the annual overall implementation scheme was 319 million cubic meters. This study showed that the proposed research approach for water replenishment scheduling strategy could increase water utilization efficiency and improve water quality effectively. The approach can be applied to other river networks in plain areas.
The urban river network in the plain area has various water environment problems such as poor water replenishment effect and deterioration of water quality. In order to solve these problems, we adopted the approach of problem analysis and method optimization to carry out the research on water replenishment scheduling strategies for water quality improvement of urban river networks. The approach included three parts: analyzing and evaluating the present situation, validating the strategies, and proposing implementation schemes. A case study of Tianjin City was carried out. Based on analysis of the current problem, we uncovered the reasons for the substandard water quality of the river network and put forward a set of water replenishment scheduling strategies. Based on the recommended strategies, we proposed an annual overall implementation scheme and an actual implementation scheme. The water demand of the annual overall implementation scheme was 319 million cubic meters. This study showed that the proposed research approach for water replenishment scheduling strategy could increase water utilization efficiency and improve water quality effectively. The approach can be applied to other river networks in plain areas.
2017, 15(6):88-95.
Abstract:
In this paper, we established a bargaining model of eco-compensation standards for inter-provincial water source protection under finite and infinite bargaining conditions by applying the Rubinstein & Stahl bargaining model after analyzing the problems in the existing basin eco-compensation calculation methods. The established model was applied to the Yuqiao Reservoir to analyze the eco-compensation standards of Tianjin Municipality for Hebei Province in terms of compensation regions. We discussed the impacts of bidding order variation and discount factor variation on the compensation standards. The results showed that the eco-compensation standards for Yuqiao Reservoir basin, the region around Panjiakou-Daheiting reservoirs and along Luanhe-Tianjin water transfer project, and the main water source region Chengde City were respectively between 167 to 1596 million RMB, 30 to 1149 million RMB, and 849 to 8537 million RMB. The impact factor analysis demonstrated that, in the finite bargaining, the inter-provincial eco-compensation standard was related to the discount factor ?, the duration of the biding stage T, and the last bidder; in the infinite bargaining, the standard was related to the discount factor ? and the first bidder.
In this paper, we established a bargaining model of eco-compensation standards for inter-provincial water source protection under finite and infinite bargaining conditions by applying the Rubinstein & Stahl bargaining model after analyzing the problems in the existing basin eco-compensation calculation methods. The established model was applied to the Yuqiao Reservoir to analyze the eco-compensation standards of Tianjin Municipality for Hebei Province in terms of compensation regions. We discussed the impacts of bidding order variation and discount factor variation on the compensation standards. The results showed that the eco-compensation standards for Yuqiao Reservoir basin, the region around Panjiakou-Daheiting reservoirs and along Luanhe-Tianjin water transfer project, and the main water source region Chengde City were respectively between 167 to 1596 million RMB, 30 to 1149 million RMB, and 849 to 8537 million RMB. The impact factor analysis demonstrated that, in the finite bargaining, the inter-provincial eco-compensation standard was related to the discount factor ?, the duration of the biding stage T, and the last bidder; in the infinite bargaining, the standard was related to the discount factor ? and the first bidder.
2017, 15(6):96-100.
Abstract:
To find out the pollution status of tannery sludge to the soil in the unsaturated zone, we investigated the soil samples at the depth of 0-200 cm in a typical soil profile, and identified the vertical distribution characteristics of the main pollutants, especially the different forms of nitrogen and chromium. High-throughput sequencing was further applied to reveal the bacterial community structures of the soils. The results showed that the tannery sludge contained a variety of high-concentration contaminants, such as high salinity (99000 mg/kg), total nitrogen (30900 mg/kg) and total chromium (30970 mg/kg), which had caused heavy contamination to the surface soil above 20 cm depth. The sludge leachate containing a large amount of organic matter and acid compounds caused a decrease in pH and an increase in TOC of the surface soil. The concentration of pollutants decreased obviously with the increase in soil depth. However, low-concentration organic nitrogen (723 mg/kg) and salinity (7070 mg/kg) were still detected in the soil at the depth of 200 cm. The alkaline soil in the study area had a distinct retardation effect on the transfer of chromium. When the soil depth was deeper than 40 cm, the concentrations of Cr(Ⅲ) and Cr(Ⅵ) decreased to less than 200 mg/kg and 2 mg/kg, respectively. High-salinity and high-chromium contamination can inhibit the growth of some microorganisms in the soil, and Proteobacteria, Firmicutes and Bacteroidetes will become the dominant microbial population in the contaminated soil.
To find out the pollution status of tannery sludge to the soil in the unsaturated zone, we investigated the soil samples at the depth of 0-200 cm in a typical soil profile, and identified the vertical distribution characteristics of the main pollutants, especially the different forms of nitrogen and chromium. High-throughput sequencing was further applied to reveal the bacterial community structures of the soils. The results showed that the tannery sludge contained a variety of high-concentration contaminants, such as high salinity (99000 mg/kg), total nitrogen (30900 mg/kg) and total chromium (30970 mg/kg), which had caused heavy contamination to the surface soil above 20 cm depth. The sludge leachate containing a large amount of organic matter and acid compounds caused a decrease in pH and an increase in TOC of the surface soil. The concentration of pollutants decreased obviously with the increase in soil depth. However, low-concentration organic nitrogen (723 mg/kg) and salinity (7070 mg/kg) were still detected in the soil at the depth of 200 cm. The alkaline soil in the study area had a distinct retardation effect on the transfer of chromium. When the soil depth was deeper than 40 cm, the concentrations of Cr(Ⅲ) and Cr(Ⅵ) decreased to less than 200 mg/kg and 2 mg/kg, respectively. High-salinity and high-chromium contamination can inhibit the growth of some microorganisms in the soil, and Proteobacteria, Firmicutes and Bacteroidetes will become the dominant microbial population in the contaminated soil.
2017, 15(6):101-107.
Abstract:
The prediction of wetland area in the coming years is critical for studying the change trends of the wetland habitat and preserving the wetlands. We developed a grey GM(0, N) model as a simple and convenient method to predict the water surface area of wetlands. First, we used the grey relational analysis model to quantitatively determine the main correlative factors that greatly influenced the wetland area. They were: annual rainfall of Momoge wetland, runoff volume of Nen River, and runoff volume of Taoer River. These three factors were used to establish the GM(0, N) model to predict the area of Momoge wetland. To improve the prediction precision, we modified the GM(0, N) model. Then we conducted the residual test and posterior variance test to evaluate the reliability of the model. The average relative error of the modified GM(0, N) model was 9.1%, and the posterior variance test grade was Grade 1, while the average relative error of the multiple linear regressive model was 15.5%. This suggests that the modified GM(0, N) model has an advantage in a practical application.
The prediction of wetland area in the coming years is critical for studying the change trends of the wetland habitat and preserving the wetlands. We developed a grey GM(0, N) model as a simple and convenient method to predict the water surface area of wetlands. First, we used the grey relational analysis model to quantitatively determine the main correlative factors that greatly influenced the wetland area. They were: annual rainfall of Momoge wetland, runoff volume of Nen River, and runoff volume of Taoer River. These three factors were used to establish the GM(0, N) model to predict the area of Momoge wetland. To improve the prediction precision, we modified the GM(0, N) model. Then we conducted the residual test and posterior variance test to evaluate the reliability of the model. The average relative error of the modified GM(0, N) model was 9.1%, and the posterior variance test grade was Grade 1, while the average relative error of the multiple linear regressive model was 15.5%. This suggests that the modified GM(0, N) model has an advantage in a practical application.
16 Study on the controlled management water level of shallow groundwater in Cangxian area based on GMS
2017, 15(6):108-114.
Abstract:
Due to the over-exploitation of groundwater, a series of environmental and geological problems have been triggered in Cangxian area. This paper was intended to determine the controlled management level of groundwater? as a way to control the exploitation quantity of groundwater and to realize sustainable utilization of the shallow groundwater resources in Cangxian area. Based on the observation data from the shallow water level observation wells in Cangxian area, we analyzed the dynamic characteristics of shallow groundwater level in Cangxian area, and found a periodical change of the groundwater level. Based on a substantial understanding of the hydrogeological conditions in Cangxian area, we developed a groundwater flow model of Cangxian area with the GMS software. On the basis of the current exploitation situation, we predicted the controlled management level of shallow groundwater in Cangxian area under 4 different precipitation frequency scenarios, and determined the threshold value. The threshold values under the 4 scenarios were -6.40–7.00 m, -4.30–7.30 m, -4.70–7.10 m, -4.50–7.00 m respectively. The controlled management water level threshold of the shallow groundwater in Cangxian area was finalized to be -6.40–7.30 m.
Due to the over-exploitation of groundwater, a series of environmental and geological problems have been triggered in Cangxian area. This paper was intended to determine the controlled management level of groundwater? as a way to control the exploitation quantity of groundwater and to realize sustainable utilization of the shallow groundwater resources in Cangxian area. Based on the observation data from the shallow water level observation wells in Cangxian area, we analyzed the dynamic characteristics of shallow groundwater level in Cangxian area, and found a periodical change of the groundwater level. Based on a substantial understanding of the hydrogeological conditions in Cangxian area, we developed a groundwater flow model of Cangxian area with the GMS software. On the basis of the current exploitation situation, we predicted the controlled management level of shallow groundwater in Cangxian area under 4 different precipitation frequency scenarios, and determined the threshold value. The threshold values under the 4 scenarios were -6.40–7.00 m, -4.30–7.30 m, -4.70–7.10 m, -4.50–7.00 m respectively. The controlled management water level threshold of the shallow groundwater in Cangxian area was finalized to be -6.40–7.30 m.
2017, 15(6):115-122.
Abstract:
Many glacier lakes are distributed in Tibet, China. With the passage of time, the temperature gradually raises, and some glacier lakes begin to melt. Their bursts will directly result in disastrous cascade effects and induce secondary disasters such as flood and debris flow. Therefore, it is imperative to timely carry out the study on the mechanism and hazards of glacier lake bursts. In order to better analyze the mechanism and hazard models of glacier lake bursts, we selected the Guangxiecuo glacier lake of Midui Gully in Tibet as the research object, and conducted a series of work including field investigation and sampling, indoor physical experiment, and high-resolution remote-sensing interpretation. The analysis results showed that the burst of Guangxiecuo lake was externally caused by abnormal climate and hydrological conditions and internally caused by the overflow-type and piping-type mechanisms during the burst of the terminal moraine dam. After the burst, the flood gradually transitioned to debris flow. The migration of debris flow seriously threatens the villages, roads, and cultivated land on both sides of the channel. The mechanism research can provide scientific basis for prevention and early warning of glacier lake bursts in the future.
Many glacier lakes are distributed in Tibet, China. With the passage of time, the temperature gradually raises, and some glacier lakes begin to melt. Their bursts will directly result in disastrous cascade effects and induce secondary disasters such as flood and debris flow. Therefore, it is imperative to timely carry out the study on the mechanism and hazards of glacier lake bursts. In order to better analyze the mechanism and hazard models of glacier lake bursts, we selected the Guangxiecuo glacier lake of Midui Gully in Tibet as the research object, and conducted a series of work including field investigation and sampling, indoor physical experiment, and high-resolution remote-sensing interpretation. The analysis results showed that the burst of Guangxiecuo lake was externally caused by abnormal climate and hydrological conditions and internally caused by the overflow-type and piping-type mechanisms during the burst of the terminal moraine dam. After the burst, the flood gradually transitioned to debris flow. The migration of debris flow seriously threatens the villages, roads, and cultivated land on both sides of the channel. The mechanism research can provide scientific basis for prevention and early warning of glacier lake bursts in the future.
2017, 15(6):122-131.
Abstract:
Using the numerical model GMS, in this paper we analyzed the impacts of three reclamation scenarios on groundwater flow field and contaminant transport in the Gulei Peninsula. The three designated reclamation scenarios were sand reclamation (Scenario 1), clay + sand reclamation (Scenario 2), and clay reclamation (Scenario 3). The results showed that (1) There was a regional increase of water table up to 4.78 m after reclamation. The extent of increase from small to large was as follows: Scenario 1, Scenario 2, and Scenario 3. (2) The groundwater flow field difference between different scenarios was the most prominent in the clay region. The maximum difference of water table between Scenario 2 and Scenario 1 was 4.44 m, and that between Scenario 3 and Scenario 1 was 8.20 m. (3) When only the physical interaction was considered, the horizontal contaminant transport was more prominent than the vertical transport in all the three scenarios. (4) Compared with the case of Scenarios 1 and 2, which had basically the same contaminant transport intensity, for the predicted duration of 30a, the contaminant transport area and speed in Scenario 3 respectively decreased by 23.07% and 18.89% in the horizontal direction; in the vertical direction, the contaminant mainly accumulated in the first layer. The concentration of contaminants in the first layer in Scenario 3 was 5.87 times of that in Scenario 1 (or Scenario 2). This indicates that reclamation with low-permeability clay have a certain retardation effect on contaminant transport.
Using the numerical model GMS, in this paper we analyzed the impacts of three reclamation scenarios on groundwater flow field and contaminant transport in the Gulei Peninsula. The three designated reclamation scenarios were sand reclamation (Scenario 1), clay + sand reclamation (Scenario 2), and clay reclamation (Scenario 3). The results showed that (1) There was a regional increase of water table up to 4.78 m after reclamation. The extent of increase from small to large was as follows: Scenario 1, Scenario 2, and Scenario 3. (2) The groundwater flow field difference between different scenarios was the most prominent in the clay region. The maximum difference of water table between Scenario 2 and Scenario 1 was 4.44 m, and that between Scenario 3 and Scenario 1 was 8.20 m. (3) When only the physical interaction was considered, the horizontal contaminant transport was more prominent than the vertical transport in all the three scenarios. (4) Compared with the case of Scenarios 1 and 2, which had basically the same contaminant transport intensity, for the predicted duration of 30a, the contaminant transport area and speed in Scenario 3 respectively decreased by 23.07% and 18.89% in the horizontal direction; in the vertical direction, the contaminant mainly accumulated in the first layer. The concentration of contaminants in the first layer in Scenario 3 was 5.87 times of that in Scenario 1 (or Scenario 2). This indicates that reclamation with low-permeability clay have a certain retardation effect on contaminant transport.
2017, 15(6):132-136.
Abstract:
This study is based on the field investigation and analysis of groundwater samples. It used single-index evaluation and comprehensive evaluation methods to evaluate the groundwater quality of the Nanyang-Xiangyang basin: The Ⅱ-III type shallow groundwater accounted for 26.27% in the Nanyang-Xiangyang basin; the IV type shallow groundwater accounted for 43.22%, and the V type shallow groundwater accounted for 30.51%. The primary indices affected by geological forces and the secondary indices affected by human activities jointly influenced the groundwater quality of Nanyang-Xiangyang basin. Human living and production, oil extraction, and mining activities were the main factors affecting the quality of groundwater in the area. In this study, the main factors influencing the quality of groundwater were identified through the calculation of "single index’s contribution rate to Ⅵ-Ⅴ type groundwater" and "human activities influence degree". The single index with the largest contribution rate to Ⅵ-Ⅴ type groundwater was nitrate, which contributed 56.32%. It was followed by total hardness, iron, and manganese. The human activities influence degree to the shallow groundwater in Nanyang-Xiangyang basin was 54.87%, and the main impact index was the "three nitrogens".
This study is based on the field investigation and analysis of groundwater samples. It used single-index evaluation and comprehensive evaluation methods to evaluate the groundwater quality of the Nanyang-Xiangyang basin: The Ⅱ-III type shallow groundwater accounted for 26.27% in the Nanyang-Xiangyang basin; the IV type shallow groundwater accounted for 43.22%, and the V type shallow groundwater accounted for 30.51%. The primary indices affected by geological forces and the secondary indices affected by human activities jointly influenced the groundwater quality of Nanyang-Xiangyang basin. Human living and production, oil extraction, and mining activities were the main factors affecting the quality of groundwater in the area. In this study, the main factors influencing the quality of groundwater were identified through the calculation of "single index’s contribution rate to Ⅵ-Ⅴ type groundwater" and "human activities influence degree". The single index with the largest contribution rate to Ⅵ-Ⅴ type groundwater was nitrate, which contributed 56.32%. It was followed by total hardness, iron, and manganese. The human activities influence degree to the shallow groundwater in Nanyang-Xiangyang basin was 54.87%, and the main impact index was the "three nitrogens".
2017, 15(6):137-143.
Abstract:
Hanjiang-to-Weihe River Water Transfer Project is a large water conservancy project to ease the water shortage in Guanzhong Plain in Shaanxi province. The Jiaoxihe tunnel crosses a river and faces complicated geographical and geological conditions. We simulated the ventilation in the tunnel with a branch tunnel using CFD numerical simulation, studied the variation of the flow and concentration fields in the tunnel during the construction period under several typical conditions, and analyzed the influence of the vortex on airflow and harmful gas distribution near the working face and in the branch tunnel. When the exhaust passage was hindered, the size and position of vortexes would change periodically near the working face, and their influence range would gradually decline with the ventilation time. In addition, the harmful gas and smoke produced from tunnel blasting would move and diffuse gradually out of the tunnel. After studying the airflow and dissipation of harmful gas in the main tunnel and branch tunnel, we had the following findings: A vortex zone would form after tunnel blasting due to ventilation near the working face and the intersection of the main tunnel and branch tunnel. The production and variation of vortexes would continuously consume the mechanical energy of ventilation, reduce ventilation efficiency, and hinder the dissipation of harmful gas. The dissipation process of the harmful gas in the tunnel included movement and diffusion. The movement process drove the CO out of the tunnel. The diffusion process continuously reduced the peak CO value in the tunnel. We calculated the time needed to reach safety concentration in the tunnel under different conditions and gave relevant suggestions on the construction progress.
Hanjiang-to-Weihe River Water Transfer Project is a large water conservancy project to ease the water shortage in Guanzhong Plain in Shaanxi province. The Jiaoxihe tunnel crosses a river and faces complicated geographical and geological conditions. We simulated the ventilation in the tunnel with a branch tunnel using CFD numerical simulation, studied the variation of the flow and concentration fields in the tunnel during the construction period under several typical conditions, and analyzed the influence of the vortex on airflow and harmful gas distribution near the working face and in the branch tunnel. When the exhaust passage was hindered, the size and position of vortexes would change periodically near the working face, and their influence range would gradually decline with the ventilation time. In addition, the harmful gas and smoke produced from tunnel blasting would move and diffuse gradually out of the tunnel. After studying the airflow and dissipation of harmful gas in the main tunnel and branch tunnel, we had the following findings: A vortex zone would form after tunnel blasting due to ventilation near the working face and the intersection of the main tunnel and branch tunnel. The production and variation of vortexes would continuously consume the mechanical energy of ventilation, reduce ventilation efficiency, and hinder the dissipation of harmful gas. The dissipation process of the harmful gas in the tunnel included movement and diffusion. The movement process drove the CO out of the tunnel. The diffusion process continuously reduced the peak CO value in the tunnel. We calculated the time needed to reach safety concentration in the tunnel under different conditions and gave relevant suggestions on the construction progress.
2017, 15(6):144-150.
Abstract:
This study investigated the influences of initial void ratio, stress, and initial water saturation on the wetting deformation of remolded cohesive soil under constant pressure using the conventional consolidation apparatus. The experimental results showed that the stress and initial void ratio e had significant impact on the wetting deformation. Under low stress, the deformation changed from expansion to shrinkage with the increase of e; while under high stress, all the samples were compressed and the amount of compression would increase with the increase of e. The relationships among wetting deformation, stress, and e were analyzed quantitively. The wetting stability time t0 was affected obviously by the stress and e. The t0 would increase with the increase of stress. Under low stress, t0 would increase with the increase of e; under high stress, t0 would increase first and then decrease with the increase of e. The initial water saturation Sr also had great influences on the wetting deformation. Under low stress, the swelling capacity would decrease first and then increase with the increase of Sr; the "optimum initial water saturation" may exist, which can lead to the smallest deformation. Under high stress, the amount of compression would decrease with the increase of Sr, and their relationship was approximately linear.
This study investigated the influences of initial void ratio, stress, and initial water saturation on the wetting deformation of remolded cohesive soil under constant pressure using the conventional consolidation apparatus. The experimental results showed that the stress and initial void ratio e had significant impact on the wetting deformation. Under low stress, the deformation changed from expansion to shrinkage with the increase of e; while under high stress, all the samples were compressed and the amount of compression would increase with the increase of e. The relationships among wetting deformation, stress, and e were analyzed quantitively. The wetting stability time t0 was affected obviously by the stress and e. The t0 would increase with the increase of stress. Under low stress, t0 would increase with the increase of e; under high stress, t0 would increase first and then decrease with the increase of e. The initial water saturation Sr also had great influences on the wetting deformation. Under low stress, the swelling capacity would decrease first and then increase with the increase of Sr; the "optimum initial water saturation" may exist, which can lead to the smallest deformation. Under high stress, the amount of compression would decrease with the increase of Sr, and their relationship was approximately linear.
2017, 15(6):151-156.
Abstract:
Slope excavation and quality evaluation is the key process in hydraulic engineering. How to evaluate the quality of the excavation work efficiently, comprehensively, and directly is the concern of engineering construction. This research was intended to tackle the problems of inefficient data acquisition and processing and incomplete indicators in the process of slope excavation. We adopted the quality evaluation indicators in technical specifications, utilized the reference design data and the excavated surface point cloud data obtained by 3D laser scanning, and introduced the roughness concept. With these, we established multidimensional quality evaluation indicators including the one-dimensional section line ratio, the two-dimensional variance of over-under-excavation value, and the three-dimensional surface projection ratio. Meanwhile, we developed a quality evaluation system for slope excavation. A case study showed that the above-mentioned multidimensional indicators could comprehensively and directly reflect the excavation quality and provide real-time and comprehensive information support for the quality evaluation and control of slope excavation on site.
Slope excavation and quality evaluation is the key process in hydraulic engineering. How to evaluate the quality of the excavation work efficiently, comprehensively, and directly is the concern of engineering construction. This research was intended to tackle the problems of inefficient data acquisition and processing and incomplete indicators in the process of slope excavation. We adopted the quality evaluation indicators in technical specifications, utilized the reference design data and the excavated surface point cloud data obtained by 3D laser scanning, and introduced the roughness concept. With these, we established multidimensional quality evaluation indicators including the one-dimensional section line ratio, the two-dimensional variance of over-under-excavation value, and the three-dimensional surface projection ratio. Meanwhile, we developed a quality evaluation system for slope excavation. A case study showed that the above-mentioned multidimensional indicators could comprehensively and directly reflect the excavation quality and provide real-time and comprehensive information support for the quality evaluation and control of slope excavation on site.
2017, 15(6):157-164.
Abstract:
The composite supporting structure which consists of two or more kinds of supporting structures has received much attention from researchers and designers, and has been applied in complex soft-soil deep excavation engineering to ensure the safety, economy, and stability of the engineering. Considering there are few studies on the new-type double-row composite supporting structure which consists of diaphragm wall, bored pile, and high pressure jet grouting pile, we took one soft foundation pit engineering as a case study, and designed the new-type double-row composite supporting structure. Using the three-dimensional elastoplastic finite element method, we conducted numerical simulation of the stratified excavation and precipitation of the engineering. Through the analysis of the structural performance of the new-type double-row composite supporting structure and the influence of excavation on the surrounding environment, we verified the validity of the design. This research can provide help to the application and popularization of the new-type composite supporting structure in deep excavation engineering.
The composite supporting structure which consists of two or more kinds of supporting structures has received much attention from researchers and designers, and has been applied in complex soft-soil deep excavation engineering to ensure the safety, economy, and stability of the engineering. Considering there are few studies on the new-type double-row composite supporting structure which consists of diaphragm wall, bored pile, and high pressure jet grouting pile, we took one soft foundation pit engineering as a case study, and designed the new-type double-row composite supporting structure. Using the three-dimensional elastoplastic finite element method, we conducted numerical simulation of the stratified excavation and precipitation of the engineering. Through the analysis of the structural performance of the new-type double-row composite supporting structure and the influence of excavation on the surrounding environment, we verified the validity of the design. This research can provide help to the application and popularization of the new-type composite supporting structure in deep excavation engineering.
2017, 15(6):165-171.
Abstract:
This study focused on the impact of the scheduling and operation of water-related structures on the flood discharge capacity of the river. We constructed a one-dimensional hydrodynamic model based on the Saint-Venant equations and used the Abbott six implicit finite difference method to approximately solve the equations. The measured cross-sectional data were used for equal-interval interpolation of the model. The water-blocking structures were generalized according to the actual attributes of the structure and the calculation requirements of the model. The model was applied to the Guyuan City section of Qingshui river, where the river conditions were complicated. This model could simulate rather accurately the impact of the rubber dam and water-crossing roads on the flood evolution of the river, and reflected the water-blocking effect of water-blocking structures. The simulation results can be used to check the flood control design standards for rivers, and have certain reference value for the relevant departments to make flood control decisions.
This study focused on the impact of the scheduling and operation of water-related structures on the flood discharge capacity of the river. We constructed a one-dimensional hydrodynamic model based on the Saint-Venant equations and used the Abbott six implicit finite difference method to approximately solve the equations. The measured cross-sectional data were used for equal-interval interpolation of the model. The water-blocking structures were generalized according to the actual attributes of the structure and the calculation requirements of the model. The model was applied to the Guyuan City section of Qingshui river, where the river conditions were complicated. This model could simulate rather accurately the impact of the rubber dam and water-crossing roads on the flood evolution of the river, and reflected the water-blocking effect of water-blocking structures. The simulation results can be used to check the flood control design standards for rivers, and have certain reference value for the relevant departments to make flood control decisions.
2017, 15(6):172-178.
Abstract:
In order to study the effect of the modifier (cement and curing agent) on the soil permeability and micro-pore distribution, we studied the permeability of the modified soil and the micro-pores using the permeability test and the mercury intrusion test, with the silty clay in plain reservoirs as the research object. The results showed that the curing agent reduced the pore volume and the permeability coefficient of the modified soil, but the decline was not linear. When the content was 2%, there was an obvious inhibitory effect between the cement and the curing agent. The fast hardening of the curing agent could significantly shorten the construction period. This points out a new direction for engineering repair. In addition, the cement had the greatest influence on the permeability of modified soil. With the increase of cement content, the large pores within the soil would transition to small pores. After 7 days, the soil permeability declined sharply, the amount of large and intermediate pores decreased, and the micro-pores and ultra-micro-pores increased. This study has established a functional relationship between the permeability coefficient and the porosity of large pores and medium-large pores, and can provide a theoretical basis for the stability analysis of the modified soil as impervious material.
In order to study the effect of the modifier (cement and curing agent) on the soil permeability and micro-pore distribution, we studied the permeability of the modified soil and the micro-pores using the permeability test and the mercury intrusion test, with the silty clay in plain reservoirs as the research object. The results showed that the curing agent reduced the pore volume and the permeability coefficient of the modified soil, but the decline was not linear. When the content was 2%, there was an obvious inhibitory effect between the cement and the curing agent. The fast hardening of the curing agent could significantly shorten the construction period. This points out a new direction for engineering repair. In addition, the cement had the greatest influence on the permeability of modified soil. With the increase of cement content, the large pores within the soil would transition to small pores. After 7 days, the soil permeability declined sharply, the amount of large and intermediate pores decreased, and the micro-pores and ultra-micro-pores increased. This study has established a functional relationship between the permeability coefficient and the porosity of large pores and medium-large pores, and can provide a theoretical basis for the stability analysis of the modified soil as impervious material.
2017, 15(6):179-186.
Abstract:
In order to reveal the relationship between the radial growth of Pinus tabuliformis plantations and the drought in the Loess Plateau, we took 30 sample plots of Pinus tabuliformis in Wuqi, Zhidan, and Yanchuan counties as the research object, and obtained the ground meteorological observation data of daily precipitation from 1961 to 2012 from 72 weather stations in and around Loess Plateau. We took the number of consecutive days without effective precipitation as a drought index, analyzed the correlation between drought types and different diameter classes of Pinus tabuliformis plantation, and thus assessed the drought risk of Pinus tabuliformis plantations in the Loess Plateau. Results showed that: (1) The mild drought in the spring and mild drought in the previous summer could inhibit the radial growth of Pinus tabuliformis, and the latter had more influence on the radial growth of Pinus tabuliformis. (2) The greatest drought risk of Pinus tabuliformis plantations in Loess Plateau was near the northwest border of the study area, where the plantations were under the most severe drought stress and therefore was the most unstable. The transition area between the sand area and the loess area to its south had the second highest drought risk assessment index. Most of the other areas had a relatively low drought risk assessment index and relatively stable Pinus tabuliformis plantations.
In order to reveal the relationship between the radial growth of Pinus tabuliformis plantations and the drought in the Loess Plateau, we took 30 sample plots of Pinus tabuliformis in Wuqi, Zhidan, and Yanchuan counties as the research object, and obtained the ground meteorological observation data of daily precipitation from 1961 to 2012 from 72 weather stations in and around Loess Plateau. We took the number of consecutive days without effective precipitation as a drought index, analyzed the correlation between drought types and different diameter classes of Pinus tabuliformis plantation, and thus assessed the drought risk of Pinus tabuliformis plantations in the Loess Plateau. Results showed that: (1) The mild drought in the spring and mild drought in the previous summer could inhibit the radial growth of Pinus tabuliformis, and the latter had more influence on the radial growth of Pinus tabuliformis. (2) The greatest drought risk of Pinus tabuliformis plantations in Loess Plateau was near the northwest border of the study area, where the plantations were under the most severe drought stress and therefore was the most unstable. The transition area between the sand area and the loess area to its south had the second highest drought risk assessment index. Most of the other areas had a relatively low drought risk assessment index and relatively stable Pinus tabuliformis plantations.
2017, 15(6):187-195.
Abstract:
The water receiving areas of the South-to-North Water Transfer Project are suffering the most serious water shortage. We analyzed the water conservation in the water receiving areas in accordance with the requirements of the most stringent water resources management system and the national water security strategy of giving priority to water conservation. Based on the analysis of the existing water-saving evaluation indexes, we constructed evaluation indexes and standards that can comprehensively reflect the regional water consumption structure and the whole-process water utilization efficiency of the whole society. By adopting the single-index evaluation method, we systematically analyzed the comprehensive water-saving situation and water saving trends of different industries in the water-receiving areas before and after the water supply (from 2003 to 2015), and we used a comprehensive evaluation system to evaluate the water utilization efficiency of the water-receiving counties and cities in 2015. The results showed that in recent years, the water-receiving areas made great efforts to save water and improved their water utilization efficiency substantially. However, compared with international advanced water-saving level, the water saving work of these water-receiving areas still needs to be improved and has much potential to be explored.
The water receiving areas of the South-to-North Water Transfer Project are suffering the most serious water shortage. We analyzed the water conservation in the water receiving areas in accordance with the requirements of the most stringent water resources management system and the national water security strategy of giving priority to water conservation. Based on the analysis of the existing water-saving evaluation indexes, we constructed evaluation indexes and standards that can comprehensively reflect the regional water consumption structure and the whole-process water utilization efficiency of the whole society. By adopting the single-index evaluation method, we systematically analyzed the comprehensive water-saving situation and water saving trends of different industries in the water-receiving areas before and after the water supply (from 2003 to 2015), and we used a comprehensive evaluation system to evaluate the water utilization efficiency of the water-receiving counties and cities in 2015. The results showed that in recent years, the water-receiving areas made great efforts to save water and improved their water utilization efficiency substantially. However, compared with international advanced water-saving level, the water saving work of these water-receiving areas still needs to be improved and has much potential to be explored.
2017, 15(6):196-202.
Abstract:
The results of the national investigation and evaluation of mountain flood come in various data types and large data volume, with complicated data structure and high degree of specialization. The national data volume reaches 100T, and the average provincial-level data volume reaches TB scale. It is difficult to manage these data effectively. In this paper, we designed a data model for national investigation and evaluation of mountain flood based on administrative division and small watershed, and established an entity model of the objects and analyzed the relationships of the objects. We used ETL technology to realize multi-level aggregation and integration of massive data. On this basis, we designed and developed a data management platform based on the service-oriented software architecture, and realized various functions such as differentiated information organization of different management levels, multi-dimensional information correlation analysis, and online analysis and summary. The construction of this platform solved some problems in national mountain flood investigation and evaluation such as multi-source massive data management and differentiated demand of different business levels. It can provide reference for management and sharing of mountain flood investigation data at all levels.
The results of the national investigation and evaluation of mountain flood come in various data types and large data volume, with complicated data structure and high degree of specialization. The national data volume reaches 100T, and the average provincial-level data volume reaches TB scale. It is difficult to manage these data effectively. In this paper, we designed a data model for national investigation and evaluation of mountain flood based on administrative division and small watershed, and established an entity model of the objects and analyzed the relationships of the objects. We used ETL technology to realize multi-level aggregation and integration of massive data. On this basis, we designed and developed a data management platform based on the service-oriented software architecture, and realized various functions such as differentiated information organization of different management levels, multi-dimensional information correlation analysis, and online analysis and summary. The construction of this platform solved some problems in national mountain flood investigation and evaluation such as multi-source massive data management and differentiated demand of different business levels. It can provide reference for management and sharing of mountain flood investigation data at all levels.
2017, 15(6):203-208.
Abstract:
The quasi-commercial water project requires tremendous investment. The Public-Private-Partnership (PPP) model can ease the financial pressure of the government effectively. In the process of applying the PPP mode to quasi-commercial water projects, the cooperative relationship and operation mode between governmental departments and social capital, especially the revenue distribution among various stakeholders, are the prerequisites and key factors for the successful implementation of the PPP model. Based on the cooperative game theory, considering the characteristics of quasi-commercial water projects, we built a revenue distribution model for quasi-commercial water projects under the PPP mode, with the 3 core stakeholders (government, social capital, and franchisee) as the objects of distribution. A case study indicated that this model could produce a more reasonable revenue distribution of the quasi-commercial water project under PPP mode and could fully mobilize the enthusiasm of stakeholders.
The quasi-commercial water project requires tremendous investment. The Public-Private-Partnership (PPP) model can ease the financial pressure of the government effectively. In the process of applying the PPP mode to quasi-commercial water projects, the cooperative relationship and operation mode between governmental departments and social capital, especially the revenue distribution among various stakeholders, are the prerequisites and key factors for the successful implementation of the PPP model. Based on the cooperative game theory, considering the characteristics of quasi-commercial water projects, we built a revenue distribution model for quasi-commercial water projects under the PPP mode, with the 3 core stakeholders (government, social capital, and franchisee) as the objects of distribution. A case study indicated that this model could produce a more reasonable revenue distribution of the quasi-commercial water project under PPP mode and could fully mobilize the enthusiasm of stakeholders.
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