Volume 15,Issue 4,2017 Table of Contents
2017, 15(4):1-6.
Abstract:
Water supply and consumption structure reflects the interconnected and interdependent structural relationships between the water supply and consumption types of different industrial sectors in a region. Studying the characteristics and changes of regional water supply and consumption structure has important practical significance in realizing coordinate and harmonious development of regional economy and environment. This paper analyzed the water supply and consumption structural change during 2001-2013 in Tianjin, and analyzed the spatial distribution characteristics of water-use types using Lorenz curve and Gini coefficient. The results showed that the total amount of water supply and consumption tended to rise at an average annual growth rate of 2.31%. The change of water supply and consumption structure was relatively stable. The spatial distribution of agricultural water and domestic water was reasonable, but that of industrial water was greatly unbalanced and exceeded the internationally recognized warning level.
Water supply and consumption structure reflects the interconnected and interdependent structural relationships between the water supply and consumption types of different industrial sectors in a region. Studying the characteristics and changes of regional water supply and consumption structure has important practical significance in realizing coordinate and harmonious development of regional economy and environment. This paper analyzed the water supply and consumption structural change during 2001-2013 in Tianjin, and analyzed the spatial distribution characteristics of water-use types using Lorenz curve and Gini coefficient. The results showed that the total amount of water supply and consumption tended to rise at an average annual growth rate of 2.31%. The change of water supply and consumption structure was relatively stable. The spatial distribution of agricultural water and domestic water was reasonable, but that of industrial water was greatly unbalanced and exceeded the internationally recognized warning level.
2017, 15(4):7-12.
Abstract:
The break-up and freeze-up of the river is under the influence of various natural and human factors, and is an issue of great uncertainty. To further improve the accuracy of break-up and freeze-up forecasts, the key is to consider the combined action of various factors. First, we used the principal component analysis to preliminarily determine the weight of each factor that affects the break-up and freeze-up duration, and used the fuzzy reasoning model to conduct preliminary prediction according to the similarity of the impact factor matrix. Then we identified forecast factors using the TOPSIS-fuzzy comprehensive evaluation model and selected reasonable forecast factors to conduct secondary prediction. The fuzzy reasoning model based on TOPSIS-fuzzy comprehensive evaluation and ice forecast factor identification was tested in a case study and was compared with the fuzzy optimization neural network BP model. The results showed that the fuzzy reasoning model in this paper had high precision and good effects in prediction. It can effectively identify forecast factors, and can well improve the accuracy of freeze-up and break-up duration forecasts. It provides a new approach for ice run prediction.
The break-up and freeze-up of the river is under the influence of various natural and human factors, and is an issue of great uncertainty. To further improve the accuracy of break-up and freeze-up forecasts, the key is to consider the combined action of various factors. First, we used the principal component analysis to preliminarily determine the weight of each factor that affects the break-up and freeze-up duration, and used the fuzzy reasoning model to conduct preliminary prediction according to the similarity of the impact factor matrix. Then we identified forecast factors using the TOPSIS-fuzzy comprehensive evaluation model and selected reasonable forecast factors to conduct secondary prediction. The fuzzy reasoning model based on TOPSIS-fuzzy comprehensive evaluation and ice forecast factor identification was tested in a case study and was compared with the fuzzy optimization neural network BP model. The results showed that the fuzzy reasoning model in this paper had high precision and good effects in prediction. It can effectively identify forecast factors, and can well improve the accuracy of freeze-up and break-up duration forecasts. It provides a new approach for ice run prediction.
2017, 15(4):13-18.
Abstract:
Groundwater is over-exploited in North China Plain, and this brings a series of eco-environmental problems. The sustainability of groundwater carrying capacity in NCP is faced with an unprecedented challenge. The definition of groundwater carrying capacity was put forward in this study and a new evaluation method for groundwater carrying capacity was proposed. The cities were grouped into three regions, i.e. the non-over-exploited and non-overloaded region (NN), the over-exploited but non-overloaded region (ON), and the over-exploited and overloaded region (OO). The results showed that the GDP supported by groundwater was 1560.8 billion RMB in 2003, and it quickly increased to 3758.5 billion RMB in 2011. 33.3% of the cities belong to the NN region. NCP as a whole and 57.2% of the cities belong to the ON region, where groundwater has been over-exploited, but the water use efficiency is relatively low, so there is still room for social and economic development if the water use efficiency is enhanced. 9.5% of the cities belong to the OO region. In the end, we discussed the approaches to enhancing the groundwater carrying capacity, including increasing the available groundwater quantity and enhancing the water use efficiency.
Groundwater is over-exploited in North China Plain, and this brings a series of eco-environmental problems. The sustainability of groundwater carrying capacity in NCP is faced with an unprecedented challenge. The definition of groundwater carrying capacity was put forward in this study and a new evaluation method for groundwater carrying capacity was proposed. The cities were grouped into three regions, i.e. the non-over-exploited and non-overloaded region (NN), the over-exploited but non-overloaded region (ON), and the over-exploited and overloaded region (OO). The results showed that the GDP supported by groundwater was 1560.8 billion RMB in 2003, and it quickly increased to 3758.5 billion RMB in 2011. 33.3% of the cities belong to the NN region. NCP as a whole and 57.2% of the cities belong to the ON region, where groundwater has been over-exploited, but the water use efficiency is relatively low, so there is still room for social and economic development if the water use efficiency is enhanced. 9.5% of the cities belong to the OO region. In the end, we discussed the approaches to enhancing the groundwater carrying capacity, including increasing the available groundwater quantity and enhancing the water use efficiency.
2017, 15(4):19-25.
Abstract:
Based on the daily precipitation data between 1965 and 2009 from 18 rainfall stations in Guangdong Beijiang river basin and the definitions of Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP), this paper studied the intra-annual inhomogeneous distribution characteristics of the precipitation in the basin by analyzing the spatial distribution of the multi-year mean values, variation trend, correlation with annual precipitation, and wet-year and dry-year composite values of PCD and PCP. The results are as follows: 1) PCD generally decreased from south to north; PCP was earlier in most of the north-central basin, but relatively later in the southern basin. 2) Annual precipitation would increase as PCD decreased in most of the basin; as PCP delayed, annual precipitation in the southern basin would decrease but that in the northern basin would increase. 3) As the Mann-Kendall test showed, the PCD and PCP in the basin were mainly on the rise, but not in a significant manner. 4) The spatial distribution of PCD in wet years was similar to that in dry years, but the PCD of dry years was higher. The PCPs in wet years were much more varied than those in dry years. On average, the PCP in wet years lagged about 20 days behind that in dry years.
Based on the daily precipitation data between 1965 and 2009 from 18 rainfall stations in Guangdong Beijiang river basin and the definitions of Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP), this paper studied the intra-annual inhomogeneous distribution characteristics of the precipitation in the basin by analyzing the spatial distribution of the multi-year mean values, variation trend, correlation with annual precipitation, and wet-year and dry-year composite values of PCD and PCP. The results are as follows: 1) PCD generally decreased from south to north; PCP was earlier in most of the north-central basin, but relatively later in the southern basin. 2) Annual precipitation would increase as PCD decreased in most of the basin; as PCP delayed, annual precipitation in the southern basin would decrease but that in the northern basin would increase. 3) As the Mann-Kendall test showed, the PCD and PCP in the basin were mainly on the rise, but not in a significant manner. 4) The spatial distribution of PCD in wet years was similar to that in dry years, but the PCD of dry years was higher. The PCPs in wet years were much more varied than those in dry years. On average, the PCP in wet years lagged about 20 days behind that in dry years.
2017, 15(4):26-33.
Abstract:
Water resource security problem has become one of the important factors which restrict the economic development of Karamay. Based on the investigation into the development and utilization of water resources in Karamay, an evaluation index system for water resource security was established. Considering the space, time, water use, and water sources, we took two steps: ① We selected 12 indexes to build the water resource security evaluation system, and used the analytic hierarchy process (AHP) to build a judgment matrix so as to determine the weight of each factor. ② We combined various types of water demand and water supply schemes to generate various dispatching schemes, and thus form a water resources allocation scheme set. At the same time, we set up water resource security indexes for each scheme, and used AHP to select the optimum results of the WRMM model. Then we evaluated and analyzed the water resource security situation of Karamay in 2011. According to the water resource security index system, the optimal water resources allocation scheme was Scheme 8, whose water supply guarantee rate was up to 100%, water resources exploitation rate was 57%, and irrigation water utilization coefficient was up to 0.75. This research has provided a scientific basis for utilization of water resources and management of water resource security in Karamay.
Water resource security problem has become one of the important factors which restrict the economic development of Karamay. Based on the investigation into the development and utilization of water resources in Karamay, an evaluation index system for water resource security was established. Considering the space, time, water use, and water sources, we took two steps: ① We selected 12 indexes to build the water resource security evaluation system, and used the analytic hierarchy process (AHP) to build a judgment matrix so as to determine the weight of each factor. ② We combined various types of water demand and water supply schemes to generate various dispatching schemes, and thus form a water resources allocation scheme set. At the same time, we set up water resource security indexes for each scheme, and used AHP to select the optimum results of the WRMM model. Then we evaluated and analyzed the water resource security situation of Karamay in 2011. According to the water resource security index system, the optimal water resources allocation scheme was Scheme 8, whose water supply guarantee rate was up to 100%, water resources exploitation rate was 57%, and irrigation water utilization coefficient was up to 0.75. This research has provided a scientific basis for utilization of water resources and management of water resource security in Karamay.
2017, 15(4):34-38.
Abstract:
Study the variation of historical drought and flood has important practical significance for regional comprehensive disaster prevention and mitigation. In this paper, we use the drought and flood records reconstructed the comprehensive index series of regional drought and flood over the past 500 years, and analyed of the variation of flood and drought in Haihe River Basin of 1470-2000. The study found that the drought and flood disasters in Haihe River Basin has obvious fluctuation, showed the periodic phenomenon of “dry - wet - dry”. In 16th Century, the drought disaster became more and more frequent, and reached the peak at the beginning of 17th Century. From last part of 17th to 19th Century, the Haihe River Basin once again moved into the relatively wet period. On 1920s, Haihe river basin moved into dry period, and the disaster intensity increased year by year. At the same time, the Haihe River Basin has obvious periodic process of drought and flood, which is 2.5A, 9.8a, 18.6a, 31.3a, 83.5a, 125.3a and 167.0a, respectively.
Study the variation of historical drought and flood has important practical significance for regional comprehensive disaster prevention and mitigation. In this paper, we use the drought and flood records reconstructed the comprehensive index series of regional drought and flood over the past 500 years, and analyed of the variation of flood and drought in Haihe River Basin of 1470-2000. The study found that the drought and flood disasters in Haihe River Basin has obvious fluctuation, showed the periodic phenomenon of “dry - wet - dry”. In 16th Century, the drought disaster became more and more frequent, and reached the peak at the beginning of 17th Century. From last part of 17th to 19th Century, the Haihe River Basin once again moved into the relatively wet period. On 1920s, Haihe river basin moved into dry period, and the disaster intensity increased year by year. At the same time, the Haihe River Basin has obvious periodic process of drought and flood, which is 2.5A, 9.8a, 18.6a, 31.3a, 83.5a, 125.3a and 167.0a, respectively.
2017, 15(4):39-43.
Abstract:
The urban water logging takes place in the old city area frequently because of its high density of buildings and other characteristics of construction. Responding to this problem, this study used the LID module in SWMM model and chose Infiltration Trench, Permeable Pavement, Rain Barrel, and Bio-Retention Cell for simulation and analysis. We placed different proportions of LID measures (0.1%-15%) on the study area in design storm conditions with different return periods, so as to find the optimal proportions. At last, we combined these proportions to tentatively explore combination optimization. The results showed that the LID measures’ effect on design storms would diminish after their layout reached a certain proportion, which should be the optimal proportion. But the optimal proportions of individual measures cannot be directly applied to the combination scheme because of the interaction between individual measures. The combination optimization still needs further study.
The urban water logging takes place in the old city area frequently because of its high density of buildings and other characteristics of construction. Responding to this problem, this study used the LID module in SWMM model and chose Infiltration Trench, Permeable Pavement, Rain Barrel, and Bio-Retention Cell for simulation and analysis. We placed different proportions of LID measures (0.1%-15%) on the study area in design storm conditions with different return periods, so as to find the optimal proportions. At last, we combined these proportions to tentatively explore combination optimization. The results showed that the LID measures’ effect on design storms would diminish after their layout reached a certain proportion, which should be the optimal proportion. But the optimal proportions of individual measures cannot be directly applied to the combination scheme because of the interaction between individual measures. The combination optimization still needs further study.
2017, 15(4):44-48.
Abstract:
To guide the studies on snowmelt runoff simulation and flood forecast in alpine regions, in this paper, we took the Kashi River basin in Western Tianshan Mountains as the study area, and built a VIC model to conduct runoff simulation study based on the hydro-meteorological data, CFSR reanalysis data, DEM, soil and vegetation data of the study area during 1990 to 2000. It was found that 1) CFSR reanalysis data can be used as a data source in areas lacking meteorological data, but they should be calibrated as they deviate from the real situation. 2) It is feasible to remove CFSR abnormal data by using the precipitation data of an appropriate hydrological station as the basis on which CFSR reanalysis data are calibrated, taking the CFSR reanalysis data grid of the hydrological station as the standard, and establishing its correlations with other CFSR grids. 3) The established VIC model had certain applicability in the study area, and the parameters in this model were reasonable. 4) In the calibration period, the relative errors of model efficiency coefficient and multi-year runoff were 0.80 and 4.7% respectively on the monthly scale, and 0.64 and 3.3% respectively on the daily scale. In the verification period, the relative errors of model efficiency coefficient and multi-year runoff were 0.84 and 14.5% respectively on the monthly scale, and 0.70 and 13.1% respectively on the daily scale.
To guide the studies on snowmelt runoff simulation and flood forecast in alpine regions, in this paper, we took the Kashi River basin in Western Tianshan Mountains as the study area, and built a VIC model to conduct runoff simulation study based on the hydro-meteorological data, CFSR reanalysis data, DEM, soil and vegetation data of the study area during 1990 to 2000. It was found that 1) CFSR reanalysis data can be used as a data source in areas lacking meteorological data, but they should be calibrated as they deviate from the real situation. 2) It is feasible to remove CFSR abnormal data by using the precipitation data of an appropriate hydrological station as the basis on which CFSR reanalysis data are calibrated, taking the CFSR reanalysis data grid of the hydrological station as the standard, and establishing its correlations with other CFSR grids. 3) The established VIC model had certain applicability in the study area, and the parameters in this model were reasonable. 4) In the calibration period, the relative errors of model efficiency coefficient and multi-year runoff were 0.80 and 4.7% respectively on the monthly scale, and 0.64 and 3.3% respectively on the daily scale. In the verification period, the relative errors of model efficiency coefficient and multi-year runoff were 0.84 and 14.5% respectively on the monthly scale, and 0.70 and 13.1% respectively on the daily scale.
2017, 15(4):49-53.
Abstract:
The sensitivity analysis and uncertainty analysis of model parameters are the preconditions for the construction of distributed hydrological model. In this study, a SWAT model was established for the Liao River Basin, and the parameters were calibrated via the SUFI-2 algorithm in SWAT-CUP. On this basis, a more convenient parameter identification method was proposed. The parameters of the main tributaries of Liao River were identified first, and then the best parameters calibrated from SWAT-CUP were applied to the TXINOUT files of each corresponding tributary sub-basin in the SWAT model. Thus a calibrated SWAT model was established with its parameters identified according to the main tributaries. This avoided the complexity of parameter identification in the original procedures of SWAT-CUP tool. The results showed that the average Nash coefficients at main hydrological stations in Zhaosutai River, Qing River, and Chai River were 0.60, 0.65, and 0.68 respectively in the calibration period, and 0.60, 0.72, and 0.77 respectively in the validation period. The results of parameter calibration improved much compared with the global parameter calibration. This parameter identification method can solve the problem that SWAT-CUP global calibration results cannot match both the upstream and downstream sections or the problem of pseudo match. It can avoid complicated parameter settings for land use type, soil texture, and slope of different sub-basins. At the same time, it can reduce the complexity of manual adjustment of SWAT model parameters. The method can be applied well to the process of SWAT model parameter identification.
The sensitivity analysis and uncertainty analysis of model parameters are the preconditions for the construction of distributed hydrological model. In this study, a SWAT model was established for the Liao River Basin, and the parameters were calibrated via the SUFI-2 algorithm in SWAT-CUP. On this basis, a more convenient parameter identification method was proposed. The parameters of the main tributaries of Liao River were identified first, and then the best parameters calibrated from SWAT-CUP were applied to the TXINOUT files of each corresponding tributary sub-basin in the SWAT model. Thus a calibrated SWAT model was established with its parameters identified according to the main tributaries. This avoided the complexity of parameter identification in the original procedures of SWAT-CUP tool. The results showed that the average Nash coefficients at main hydrological stations in Zhaosutai River, Qing River, and Chai River were 0.60, 0.65, and 0.68 respectively in the calibration period, and 0.60, 0.72, and 0.77 respectively in the validation period. The results of parameter calibration improved much compared with the global parameter calibration. This parameter identification method can solve the problem that SWAT-CUP global calibration results cannot match both the upstream and downstream sections or the problem of pseudo match. It can avoid complicated parameter settings for land use type, soil texture, and slope of different sub-basins. At the same time, it can reduce the complexity of manual adjustment of SWAT model parameters. The method can be applied well to the process of SWAT model parameter identification.
2017, 15(4):54-58.
Abstract:
In northern China, where water resources are in long-term shortage, it is common in nearly every city to see serial river-dam-type landscape water bodies built to obstruct rivers and retain water. To calculate the minimum water required to sustain the basic health of such an artificial river ecological system consisting mostly of water landscape, this paper studied the case of a segment of Hutuo River needing remediation of water environment, built an integrated mathematical model that describes the water quality and quantity changes of the “serial dam-type landscape water body”, and proposed a scheme to meet the ecological water demand of river-dam-type landscape water bodies with consideration to both water quality and quantity. The results showed that under the circumstance of 75% frequency of rainfall, the minimum water required by this segment of Hutuo River needing remediation of water environment is 34500 thousand m3/a. This paper also provided the explicit dates and amount of water supply, and provided support for the ecological protection of northern serial river-dam-type landscape water bodies.
In northern China, where water resources are in long-term shortage, it is common in nearly every city to see serial river-dam-type landscape water bodies built to obstruct rivers and retain water. To calculate the minimum water required to sustain the basic health of such an artificial river ecological system consisting mostly of water landscape, this paper studied the case of a segment of Hutuo River needing remediation of water environment, built an integrated mathematical model that describes the water quality and quantity changes of the “serial dam-type landscape water body”, and proposed a scheme to meet the ecological water demand of river-dam-type landscape water bodies with consideration to both water quality and quantity. The results showed that under the circumstance of 75% frequency of rainfall, the minimum water required by this segment of Hutuo River needing remediation of water environment is 34500 thousand m3/a. This paper also provided the explicit dates and amount of water supply, and provided support for the ecological protection of northern serial river-dam-type landscape water bodies.
11 The study of critical flocculation concentration of ammonia nitrogen of colloids in the groundwater
2017, 15(4):59-64.
Abstract:
In order to study the critical flocculation concentrations of ammonia nitrogen in various kinds of colloids in the groundwater, we measured the critical flocculation concentrations of ammonia nitrogen in natural clay colloid, bentonite colloid, kaolin colloid, and natural clay colloids of different particle sizes in a batch test. Results showed that the critical flocculation concentration of ammonia nitrogen varies in different kinds of colloids. The critical flocculation concentrations of ammonia nitrogen in natural clay colloid, bentonite colloid, and kaolin colloid were 1600 mg/L, 24000 mg/L, and 8000 mg/L, respectively. Test results showed that the stability of the bentonite colloid was the strongest and was the least susceptible to ammonia nitrogen. The critical flocculation concentration of ammonia nitrogen also varies in natural clay colloids of different particle sizes. It tended to decrease with the increase of the particle size, indicating that the colloid with bigger particle size has worse stability and thus is more susceptible to ammonia nitrogen. In general, the critical flocculation concentrations of colloids are certainly associated with the type of colloid and the particle size of the colloid.
In order to study the critical flocculation concentrations of ammonia nitrogen in various kinds of colloids in the groundwater, we measured the critical flocculation concentrations of ammonia nitrogen in natural clay colloid, bentonite colloid, kaolin colloid, and natural clay colloids of different particle sizes in a batch test. Results showed that the critical flocculation concentration of ammonia nitrogen varies in different kinds of colloids. The critical flocculation concentrations of ammonia nitrogen in natural clay colloid, bentonite colloid, and kaolin colloid were 1600 mg/L, 24000 mg/L, and 8000 mg/L, respectively. Test results showed that the stability of the bentonite colloid was the strongest and was the least susceptible to ammonia nitrogen. The critical flocculation concentration of ammonia nitrogen also varies in natural clay colloids of different particle sizes. It tended to decrease with the increase of the particle size, indicating that the colloid with bigger particle size has worse stability and thus is more susceptible to ammonia nitrogen. In general, the critical flocculation concentrations of colloids are certainly associated with the type of colloid and the particle size of the colloid.
2017, 15(4):65-70.
Abstract:
Based on the ecological index and the modified press-state-response model, approaching from the two perspectives of environmental quality and ecological security, this paper has successfully constructed a synthetic evaluation index system which can be used to evaluate the eco-environmental situation in regions along the main canal of the Middle Route Project for South-to-North Water Transfer after respectively considering the natural influence and the combined influence of nature, economy, and society. The results indicated that according to the assessment of environmental quality during the entire evaluation period, only Lushan County was "good" and Anyang City was “relatively poor” while all the other regions were “average”. Besides, according to the ecological security assessment, Xichuan County was the only one in a relatively secure state while 97.54 percent of the study area were in an early or moderate warning state, with the moderate-warning regions accounting for 16.28%. Generally speaking, the eco-environmental quality of the study area in 2004 was merely average, and the ecological security situation was worrying; therefore, the government should improve supervision to limit human activities in the study area.
Based on the ecological index and the modified press-state-response model, approaching from the two perspectives of environmental quality and ecological security, this paper has successfully constructed a synthetic evaluation index system which can be used to evaluate the eco-environmental situation in regions along the main canal of the Middle Route Project for South-to-North Water Transfer after respectively considering the natural influence and the combined influence of nature, economy, and society. The results indicated that according to the assessment of environmental quality during the entire evaluation period, only Lushan County was "good" and Anyang City was “relatively poor” while all the other regions were “average”. Besides, according to the ecological security assessment, Xichuan County was the only one in a relatively secure state while 97.54 percent of the study area were in an early or moderate warning state, with the moderate-warning regions accounting for 16.28%. Generally speaking, the eco-environmental quality of the study area in 2004 was merely average, and the ecological security situation was worrying; therefore, the government should improve supervision to limit human activities in the study area.
2017, 15(4):71-78.
Abstract:
Drought disaster was frequently occurred, which seriously restricted agricultural development of Sichuan Province. Selecting of drought index is very important in order to reasonably analyze drought situation of Sichuan Province. Based on daily meteorological data from 1960 to 2013 of 39 meteorological stations of Sichuan Province, Relative Humidity Index, Composite Index of Meteorological Drought , Standardized Precipitation Index and Standardized Precipitation- Evapotranspiration Index were calculated in 1961, 1994, 2006 and 2009～2010. Inverse distance interpolation of Arcgis was used, and spatial distribution was obtained. Application of four drought indexes in Sichuan Province were evaluated which were compared with records of drought disaster in China’s weather disaster. Results showed that: for summer drought in 1961, the moisture index M and comprehensive drought index CI showed no or slight drought,SPI index monitored results were smaller than the actual situation and SPEI index showed the hardest hit which is the best index for monitoring the drought. For the summer drought in summer, M index monitoring results showed smaller, CI index showed vacancy and were smaller in Eastern Sichuan and Western Sichuan, SPEI index showed smaller in Bazhong and Daxian, and SPI index in Chengdu and Mianyang area; For drought in 2006, M index monitoring results weresmall, and CI index werea little better which werestill smaller than actual situation, the monitoring results of SPI and SPEIwereaccordance with actual situation; For the 2009 to 2010 winter and spring drought, SPEI was the best index, M index followed and SPI index was the worst. In a word, SPEI was the best drought index reflecting the spatial distribution of drought in Sichuan Province.
Drought disaster was frequently occurred, which seriously restricted agricultural development of Sichuan Province. Selecting of drought index is very important in order to reasonably analyze drought situation of Sichuan Province. Based on daily meteorological data from 1960 to 2013 of 39 meteorological stations of Sichuan Province, Relative Humidity Index, Composite Index of Meteorological Drought , Standardized Precipitation Index and Standardized Precipitation- Evapotranspiration Index were calculated in 1961, 1994, 2006 and 2009～2010. Inverse distance interpolation of Arcgis was used, and spatial distribution was obtained. Application of four drought indexes in Sichuan Province were evaluated which were compared with records of drought disaster in China’s weather disaster. Results showed that: for summer drought in 1961, the moisture index M and comprehensive drought index CI showed no or slight drought,SPI index monitored results were smaller than the actual situation and SPEI index showed the hardest hit which is the best index for monitoring the drought. For the summer drought in summer, M index monitoring results showed smaller, CI index showed vacancy and were smaller in Eastern Sichuan and Western Sichuan, SPEI index showed smaller in Bazhong and Daxian, and SPI index in Chengdu and Mianyang area; For drought in 2006, M index monitoring results weresmall, and CI index werea little better which werestill smaller than actual situation, the monitoring results of SPI and SPEIwereaccordance with actual situation; For the 2009 to 2010 winter and spring drought, SPEI was the best index, M index followed and SPI index was the worst. In a word, SPEI was the best drought index reflecting the spatial distribution of drought in Sichuan Province.
2017, 15(4):79-86.
Abstract:
Jilin is one of the most important chemical industry cities located in China’s northeastern old industrial base. Heavy metals and polycyclic aromatic hydrocarbons (PAHs) have been detected in the sediments of different regions in China, but little is known about the sewage-received river of Jilin, whose pollution was very severe owing to long-time discharge of industrial and municipal wastewater. The aim of this study was to investigate the pollution of heavy metals and PAHs in sediments and to assess their ecological risks. A total of 35 sediment samples from 12 monitoring sections along this sewage-received river were collected for determination of the concentrations of 8 heavy metals (Hg, Pb, As, Cu, Zn, Cr, Cd, Ni) and 16 USEPA priority pollutant PAHs. Geoaccumulation index, H?kanson potential ecological risk index, and sediment quality guidelines (SQGs) were respectively used to assess the pollution and potential ecological risks of these pollutants in the sediments. The concentrations of heavy metals and PAHs were higher than the background values, especially those of Hg, Pb, Cu, As, NAP, and ANT. The geoaccumulation index indicated that the ecological risks of heavy metals in the sediments from high to low were as follows: Hg＞Pb＞As＞Cu＞Zn＞Cr＞Cd＞Ni. The H?kanson potential ecological risk indexes of heavy metals were ranked as follows: Hg＞As＞Cd＞Pb＞Cu＞Ni＞Zn＞Cr. SQGs indicated that adverse benthic impacts would occur frequently. The sediments were polluted by PAHs and heavy metals, especially Hg.
Jilin is one of the most important chemical industry cities located in China’s northeastern old industrial base. Heavy metals and polycyclic aromatic hydrocarbons (PAHs) have been detected in the sediments of different regions in China, but little is known about the sewage-received river of Jilin, whose pollution was very severe owing to long-time discharge of industrial and municipal wastewater. The aim of this study was to investigate the pollution of heavy metals and PAHs in sediments and to assess their ecological risks. A total of 35 sediment samples from 12 monitoring sections along this sewage-received river were collected for determination of the concentrations of 8 heavy metals (Hg, Pb, As, Cu, Zn, Cr, Cd, Ni) and 16 USEPA priority pollutant PAHs. Geoaccumulation index, H?kanson potential ecological risk index, and sediment quality guidelines (SQGs) were respectively used to assess the pollution and potential ecological risks of these pollutants in the sediments. The concentrations of heavy metals and PAHs were higher than the background values, especially those of Hg, Pb, Cu, As, NAP, and ANT. The geoaccumulation index indicated that the ecological risks of heavy metals in the sediments from high to low were as follows: Hg＞Pb＞As＞Cu＞Zn＞Cr＞Cd＞Ni. The H?kanson potential ecological risk indexes of heavy metals were ranked as follows: Hg＞As＞Cd＞Pb＞Cu＞Ni＞Zn＞Cr. SQGs indicated that adverse benthic impacts would occur frequently. The sediments were polluted by PAHs and heavy metals, especially Hg.
2017, 15(4):87-93.
Abstract:
This study was aimed to analyze the spatial distribution characteristics of soil organic carbon and nitrogen in soils from typical lake littoral wetland of Mu Us Sandland in Shaanxi Province and to provide a scientific basis for studying the way in which wetland ecosystem plays its special function in desertified environment. We collected soil samples from A-F zones along Baxiacaidang Lake and measured the contents of soil organic carbon, total nitrogen, organic nitrogen, nitrate nitrogen, and ammonium nitrogen. Soil organic carbon and nitrogen distribution were analyzed by ANOVA, Spearman correlation coefficients, and principal components analysis. At the depth of 0-10cm, the contents of soil organic carbon and total nitrogen would increase with the increasing water level. Regarding vertical distribution, except for ammonium nitrogen, the contents of soil organic carbon, total nitrogen, organic nitrogen, and nitrate nitrogen would all decrease with the increasing soil depth. The contents of soil organic carbon and total nitrogen were significantly and positively correlated with total phosphorus, volume weight of soil, soil moisture content, and water level. The content of soil ammonium nitrogen was significantly and positively correlated with total phosphorus, soil moisture content, volume weight of soil, total nitrogen, organic carbon, and water level. Between nitrate nitrogen and microbial biomass carbon, the correlation coefficient was 0.637; between nitrate nitrogen and microbial biomass nitrogen, the correlation coefficient was 0.617. The contents of soil organic carbon and nitrogen were not significantly correlated with soil clay content. The cumulative contribution rate of the three principal components was 76.15%. Total phosphorus, soil moisture content, volume weight of soil, and water level were major factors which can affect the spatial distribution of soil organic carbon and nitrogen distribution.
This study was aimed to analyze the spatial distribution characteristics of soil organic carbon and nitrogen in soils from typical lake littoral wetland of Mu Us Sandland in Shaanxi Province and to provide a scientific basis for studying the way in which wetland ecosystem plays its special function in desertified environment. We collected soil samples from A-F zones along Baxiacaidang Lake and measured the contents of soil organic carbon, total nitrogen, organic nitrogen, nitrate nitrogen, and ammonium nitrogen. Soil organic carbon and nitrogen distribution were analyzed by ANOVA, Spearman correlation coefficients, and principal components analysis. At the depth of 0-10cm, the contents of soil organic carbon and total nitrogen would increase with the increasing water level. Regarding vertical distribution, except for ammonium nitrogen, the contents of soil organic carbon, total nitrogen, organic nitrogen, and nitrate nitrogen would all decrease with the increasing soil depth. The contents of soil organic carbon and total nitrogen were significantly and positively correlated with total phosphorus, volume weight of soil, soil moisture content, and water level. The content of soil ammonium nitrogen was significantly and positively correlated with total phosphorus, soil moisture content, volume weight of soil, total nitrogen, organic carbon, and water level. Between nitrate nitrogen and microbial biomass carbon, the correlation coefficient was 0.637; between nitrate nitrogen and microbial biomass nitrogen, the correlation coefficient was 0.617. The contents of soil organic carbon and nitrogen were not significantly correlated with soil clay content. The cumulative contribution rate of the three principal components was 76.15%. Total phosphorus, soil moisture content, volume weight of soil, and water level were major factors which can affect the spatial distribution of soil organic carbon and nitrogen distribution.
2017, 15(4):94-100.
Abstract:
From the point of view of "who protects, who benefits", "who uses, who pays" and "who is responsible for pollution", this paper comprehensively considers the total cost of ecological protection, water resources value and water compensation law. A compensation method for ecological compensation of drinking water source protection area based on water quantity and water quality correction coefficient was established. And taking Yangmu Reservoir as an example, estimated the ecological compensation amount for the location of Yangmu Reservoir's drinking water source protection area: 167.4606 million Yuan / year, that is, the water-use area pays 167.4606 million Yuan per year to the water source protection area as ecological compensation funds. This method avoids the fact that the traditional method only considers the single factor and reflects the actual situation of the ecological compensation of the drinking water source protection area, which has a certain reference function for the establishment of ecological compensation mechanism of the drinking water source protection area.
From the point of view of "who protects, who benefits", "who uses, who pays" and "who is responsible for pollution", this paper comprehensively considers the total cost of ecological protection, water resources value and water compensation law. A compensation method for ecological compensation of drinking water source protection area based on water quantity and water quality correction coefficient was established. And taking Yangmu Reservoir as an example, estimated the ecological compensation amount for the location of Yangmu Reservoir's drinking water source protection area: 167.4606 million Yuan / year, that is, the water-use area pays 167.4606 million Yuan per year to the water source protection area as ecological compensation funds. This method avoids the fact that the traditional method only considers the single factor and reflects the actual situation of the ecological compensation of the drinking water source protection area, which has a certain reference function for the establishment of ecological compensation mechanism of the drinking water source protection area.
2017, 15(4):101-110.
Abstract:
In order to enhance the water ecological carrying capacity of Chengdu city whilst promoting the development of economy and improving the living standards of the people, System Dynamics (SD) method was applied to build a coupled system of water ecology – economy – population – water resources – water environment of the city based on the status quo of water ecology. Four scenario patterns including status-continuing, water-saving, pollution-controlling, and integrated-coordination were simulated by the SD model. Simulation results showed that: in the analog period (2014 to 2020), the status-continuing and pollution-controlling scenario patterns can not effectively reduce the limit coefficient of water ecological carrying capacity, resulting in further deterioration of water ecological problems. However, the water-saving and integrated-coordination scenario patterns can reduce the limit coefficient of water ecological carrying capacity. It should be noted that the water-saving scenario pattern can not significantly reduce the coefficient. The integrated-coordination pattern combining water-saving and pollution-controlling measures can reduce the coefficient more effectively. It is the best pattern to improve the water ecological carrying capacity. With the aforementioned recommended pattern, the limit coefficient of water ecological carrying capacity can be reduced to 0.297 for Chengdu City by 2020, down by 59.4% compared with that of 2010. The research results can provide technical basis for water ecological protection in Chengdu city.
In order to enhance the water ecological carrying capacity of Chengdu city whilst promoting the development of economy and improving the living standards of the people, System Dynamics (SD) method was applied to build a coupled system of water ecology – economy – population – water resources – water environment of the city based on the status quo of water ecology. Four scenario patterns including status-continuing, water-saving, pollution-controlling, and integrated-coordination were simulated by the SD model. Simulation results showed that: in the analog period (2014 to 2020), the status-continuing and pollution-controlling scenario patterns can not effectively reduce the limit coefficient of water ecological carrying capacity, resulting in further deterioration of water ecological problems. However, the water-saving and integrated-coordination scenario patterns can reduce the limit coefficient of water ecological carrying capacity. It should be noted that the water-saving scenario pattern can not significantly reduce the coefficient. The integrated-coordination pattern combining water-saving and pollution-controlling measures can reduce the coefficient more effectively. It is the best pattern to improve the water ecological carrying capacity. With the aforementioned recommended pattern, the limit coefficient of water ecological carrying capacity can be reduced to 0.297 for Chengdu City by 2020, down by 59.4% compared with that of 2010. The research results can provide technical basis for water ecological protection in Chengdu city.
2017, 15(4):111-116.
Abstract:
Using the fissure-conduit media physical model, more groups of experiments are designed to study the change of sinkhole diameter influencing on the storage karst aquifer system and spring flow process. By analyzing data, regulating coefficient increased with the increasing of sinkhole diameter; with low recharge rates, the change of sinkhole diameter had little effect on the attenuation capacity of stage that fissure and sinkhole releasing water simultaneously, however, attenuation capacity obviously reduced with the increasing of sinkhole diameter under high recharge rates ; attenuation coefficient had nothing to do with recharge rates and sink hole diameter, about 0.0017 1/h; the product of regulating coefficient and attenuation coefficient of the first stage is negatively related to the recharge rates and is no related to sinkhole diameter.
Using the fissure-conduit media physical model, more groups of experiments are designed to study the change of sinkhole diameter influencing on the storage karst aquifer system and spring flow process. By analyzing data, regulating coefficient increased with the increasing of sinkhole diameter; with low recharge rates, the change of sinkhole diameter had little effect on the attenuation capacity of stage that fissure and sinkhole releasing water simultaneously, however, attenuation capacity obviously reduced with the increasing of sinkhole diameter under high recharge rates ; attenuation coefficient had nothing to do with recharge rates and sink hole diameter, about 0.0017 1/h; the product of regulating coefficient and attenuation coefficient of the first stage is negatively related to the recharge rates and is no related to sinkhole diameter.
19 Research on the resource types and typical geothermal models of hot dry rock resources of Qinghai
2017, 15(4):117-122.
Abstract:
Since the Cenozoic, affected by the collision and compression of the Indian plate and Eurasian plate, The Tibetan Plateau occurred a strong uplift, and the geological structures of Qinghai changed dramatically. In this special geological, magmatic rocks are widely distributed in the province since the Indo-Yanshanian, and created a pull distribution structure change activity and Qinghai unique geothermal geological conditions since Pull Recent. In this paper, according to the type of geothermal model on HDR resources which has been found at home and abroad, combining geothermal geological background, HDR resource types, distributions and etc, conducted a brief analysis on the different types of HDR resources feature of Qinghai. The discussion focused on the intraplate active tectonic zone type HDR resources and the sedimentary basin type HDR resources. On this basis, research on different geothermal models of HDR resources. The genetic mechanisms of different types of HDR resources are analyzed and compared. Provide the basis for further exploration and development of HDR resources in Qinghai.
Since the Cenozoic, affected by the collision and compression of the Indian plate and Eurasian plate, The Tibetan Plateau occurred a strong uplift, and the geological structures of Qinghai changed dramatically. In this special geological, magmatic rocks are widely distributed in the province since the Indo-Yanshanian, and created a pull distribution structure change activity and Qinghai unique geothermal geological conditions since Pull Recent. In this paper, according to the type of geothermal model on HDR resources which has been found at home and abroad, combining geothermal geological background, HDR resource types, distributions and etc, conducted a brief analysis on the different types of HDR resources feature of Qinghai. The discussion focused on the intraplate active tectonic zone type HDR resources and the sedimentary basin type HDR resources. On this basis, research on different geothermal models of HDR resources. The genetic mechanisms of different types of HDR resources are analyzed and compared. Provide the basis for further exploration and development of HDR resources in Qinghai.
2017, 15(4):123-128.
Abstract:
Based on the three-dimensional stress state and some assumptions of the tapered bucket foundation, we used the limit equilibrium method to obtain the calculation formula of horizontal bearing capacity of tapered bucket foundation, and compared the results with the model test results, and thus validated the reliability of the formula. Through varying different parameters, we analyzed the influence of the obliquity of bucket wall, proportionality coefficient of soil resistance, top diameter of bucket foundation, height-diameter ratio of bucket foundation, and height of acting point on the value of horizontal bearing capacity of tapered bucket foundation. It was found that the horizontal bearing capacity increased rapidly as the obliquity of bucket wall increased. The results of this research are helpful to the optimization design of traditional bucket foundation.
Based on the three-dimensional stress state and some assumptions of the tapered bucket foundation, we used the limit equilibrium method to obtain the calculation formula of horizontal bearing capacity of tapered bucket foundation, and compared the results with the model test results, and thus validated the reliability of the formula. Through varying different parameters, we analyzed the influence of the obliquity of bucket wall, proportionality coefficient of soil resistance, top diameter of bucket foundation, height-diameter ratio of bucket foundation, and height of acting point on the value of horizontal bearing capacity of tapered bucket foundation. It was found that the horizontal bearing capacity increased rapidly as the obliquity of bucket wall increased. The results of this research are helpful to the optimization design of traditional bucket foundation.
2017, 15(4):129-135.
Abstract:
Resistance similarity is an essential requirement in river model experiments. Roughness recheck is affected by the target value, fluctuation amplitude, model material, and research emphasis. A reasonable roughening method will substantially improve the experiment efficiency and accuracy. In order to help researchers quickly choose a reasonable roughening way from the various existing methods, we sorted and reviewed the commonly used roughening methods, which were classified into three types: block-type roughening, strip-type roughening, and patch-type roughening. We introduced the commonly used roughening elements of each method and described in detail the realization means, advantages, drawbacks, and adjustable roughness range of each method. The patch-type roughening methods represented by plastic grass cushions can achieve a roughness value larger than 0.08. The block-type roughening methods represented by cross plates in the form of plum blossom can obtain a peak roughness value of about 0.06. The peak roughness value of strip-type roughening methods is 0.04. Sticking nylon nets or glass film and compact roughening can generally realize a roughness value no larger than 0.02. Digging pits on the model can hardly increase its surface roughness. In addition, this paper presents the methods’ application conditions, roughening ranges, and influence on flow structure, and some roughness calculation methods. It is hoped that with this paper, researchers can determine roughening methods quickly and exactly according to their experiment goals, and improve their research efficiency.
Resistance similarity is an essential requirement in river model experiments. Roughness recheck is affected by the target value, fluctuation amplitude, model material, and research emphasis. A reasonable roughening method will substantially improve the experiment efficiency and accuracy. In order to help researchers quickly choose a reasonable roughening way from the various existing methods, we sorted and reviewed the commonly used roughening methods, which were classified into three types: block-type roughening, strip-type roughening, and patch-type roughening. We introduced the commonly used roughening elements of each method and described in detail the realization means, advantages, drawbacks, and adjustable roughness range of each method. The patch-type roughening methods represented by plastic grass cushions can achieve a roughness value larger than 0.08. The block-type roughening methods represented by cross plates in the form of plum blossom can obtain a peak roughness value of about 0.06. The peak roughness value of strip-type roughening methods is 0.04. Sticking nylon nets or glass film and compact roughening can generally realize a roughness value no larger than 0.02. Digging pits on the model can hardly increase its surface roughness. In addition, this paper presents the methods’ application conditions, roughening ranges, and influence on flow structure, and some roughness calculation methods. It is hoped that with this paper, researchers can determine roughening methods quickly and exactly according to their experiment goals, and improve their research efficiency.
2017, 15(4):136-141.
Abstract:
Using the DEM, based on the bedding rock slope project behind the powerhouse of a hydro-power plant, we studied the seismic responses and anchor reinforcement effect of a bedding stereoplasm rock slope with multiple structural planes, and proposed a seismic reinforcement scheme for the slope. The research showed that the displacement of the unreinforced bedding stereoplasm slope under seismic action showed a stepped increase, and the rock blocks fell apart at the end of the earthquake. After reinforcement, the displacement of the slope diminished significantly, and the slope could remain stable in the earthquake. The shear force response of the anchor elements showed strong correlation with the relative displacement of their nearby structural planes, which means that the relative displacement between the rock planes around the anchor was the main stimulation factor of the anchor reinforcement effect in the earthquake. The relative displacement of the rock planes exposed on the slope surface at a lower elevation was larger; thus, the shear force of the corresponding anchor was larger. On these grounds, we put forward a more reasonable scheme for anchor arrangement.
Using the DEM, based on the bedding rock slope project behind the powerhouse of a hydro-power plant, we studied the seismic responses and anchor reinforcement effect of a bedding stereoplasm rock slope with multiple structural planes, and proposed a seismic reinforcement scheme for the slope. The research showed that the displacement of the unreinforced bedding stereoplasm slope under seismic action showed a stepped increase, and the rock blocks fell apart at the end of the earthquake. After reinforcement, the displacement of the slope diminished significantly, and the slope could remain stable in the earthquake. The shear force response of the anchor elements showed strong correlation with the relative displacement of their nearby structural planes, which means that the relative displacement between the rock planes around the anchor was the main stimulation factor of the anchor reinforcement effect in the earthquake. The relative displacement of the rock planes exposed on the slope surface at a lower elevation was larger; thus, the shear force of the corresponding anchor was larger. On these grounds, we put forward a more reasonable scheme for anchor arrangement.
2017, 15(4):142-147.
Abstract:
This paper introduces the velocity potential analysis method for solving the free bending vibration of an intake tower in water in a hydroelectric power station. It analyzes the basic mechanical characteristics of an intake tower and makes some simplification and hypothesis for the structure in order to introduce the velocity potential analysis method. The frequency equation of the free bending vibration of a standalone intake tower is derived from the distribution parameter beam system. The boundary conditions of the problem are determined according to the Laplace equation of the velocity potential. The bending vibration equation of the intake tower is established via the expression of internal and external water pressure. The frequency equation is derived from the vibration equation. The structural vibration mode and frequency can be obtained through mathematical software programming. The derivation shows that the fluid velocity potential method converts the water into added mass that is associated with the vibration mode of the tower and thus affects the vibration of the structure. This paper then compares this method with the numerical method, analyzes their similarities and differences, and proposes the scope of application of this method. Results show that this method can be used to solve the free bending vibration problem of intake towers with a rectangular cross-section and water on both the inside and the outside, and provides a new way of thinking for further analysis of the seismic response of intake towers.
This paper introduces the velocity potential analysis method for solving the free bending vibration of an intake tower in water in a hydroelectric power station. It analyzes the basic mechanical characteristics of an intake tower and makes some simplification and hypothesis for the structure in order to introduce the velocity potential analysis method. The frequency equation of the free bending vibration of a standalone intake tower is derived from the distribution parameter beam system. The boundary conditions of the problem are determined according to the Laplace equation of the velocity potential. The bending vibration equation of the intake tower is established via the expression of internal and external water pressure. The frequency equation is derived from the vibration equation. The structural vibration mode and frequency can be obtained through mathematical software programming. The derivation shows that the fluid velocity potential method converts the water into added mass that is associated with the vibration mode of the tower and thus affects the vibration of the structure. This paper then compares this method with the numerical method, analyzes their similarities and differences, and proposes the scope of application of this method. Results show that this method can be used to solve the free bending vibration problem of intake towers with a rectangular cross-section and water on both the inside and the outside, and provides a new way of thinking for further analysis of the seismic response of intake towers.
2017, 15(4):148-154.
Abstract:
In order to study the variation of compressive soil pores caused by decrease of pore water pressure, we studied the compressive soil on the two sides of the D7 ground fissure in Xi’an. Using the three-dimensional CT imaging technique, Matlab computing platform and VG Studio Max program, we calculated the porosity and fractal dimension variations caused by the compression deformation of compressive soil during the drop of water level, and discussed the influence factors and variation patterns of the porosity and fractal dimension in the consolidation process. The results showed that the porosity declined from 4.36% to 0.61% with the compression, and that the fractal dimension had a linear correlation with both the porosity and overburden pressure, at a correlation coefficient of 0.9237 and 0.9660 respectively. As an effective supplement of the porosity, fractal dimension could well represent the distribution characteristics of the pores. By analyzing the relationship between porosity and fractal dimension, the study results may provide parameter assignment basis for the fissure-groundwater pumping coupled model.
In order to study the variation of compressive soil pores caused by decrease of pore water pressure, we studied the compressive soil on the two sides of the D7 ground fissure in Xi’an. Using the three-dimensional CT imaging technique, Matlab computing platform and VG Studio Max program, we calculated the porosity and fractal dimension variations caused by the compression deformation of compressive soil during the drop of water level, and discussed the influence factors and variation patterns of the porosity and fractal dimension in the consolidation process. The results showed that the porosity declined from 4.36% to 0.61% with the compression, and that the fractal dimension had a linear correlation with both the porosity and overburden pressure, at a correlation coefficient of 0.9237 and 0.9660 respectively. As an effective supplement of the porosity, fractal dimension could well represent the distribution characteristics of the pores. By analyzing the relationship between porosity and fractal dimension, the study results may provide parameter assignment basis for the fissure-groundwater pumping coupled model.
2017, 15(4):155-160.
Abstract:
RCC gravity dam has a simple structure, can be constructed conveniently, and is widely used nowadays. In practical engineering, foundation anisotropy problems are often encountered. In this paper, we used the finite element analysis software ABAQUS, took the slope dam blocks of a roller compacted concrete gravity dam as the basic computational structure, and established a 3D finite element calculation model of RCC gravity dam. Under the normal storage condition, six different calculation groups were set that have different ratios of horizontal to vertical elastic modulus. Through comparative analysis, we studied the material ratio range within which anisotropy needs not to be considered.
RCC gravity dam has a simple structure, can be constructed conveniently, and is widely used nowadays. In practical engineering, foundation anisotropy problems are often encountered. In this paper, we used the finite element analysis software ABAQUS, took the slope dam blocks of a roller compacted concrete gravity dam as the basic computational structure, and established a 3D finite element calculation model of RCC gravity dam. Under the normal storage condition, six different calculation groups were set that have different ratios of horizontal to vertical elastic modulus. Through comparative analysis, we studied the material ratio range within which anisotropy needs not to be considered.
2017, 15(4):161-167.
Abstract:
Through gas permeability test, water absorption test, and chloride ion erosion test of concrete samples with different mix proportions, this article has analyzed the relationship between the chloride ion diffusion coefficient and permeability, established a concrete durability prediction model based on permeability, and verified the model with a coastal sluice. The results showed that gas permeability coefficient, water absorption coefficient, and chloride ion diffusion coefficient would all increase with the increase of water cement ratio; in different water cement ratio conditions, chloride ion diffusion coefficient would increase with the increase of gas permeability and water absorption coefficient, showing a certain correlation between them. Just by testing the permeability of concrete structures, the established prediction model of concrete durability can predict the service life of the concrete structures. The model was verified and proven feasible with a coastal sluice. It has great significance in predicting the service life of concrete structures in chloride environment directly based on their permeability.
Through gas permeability test, water absorption test, and chloride ion erosion test of concrete samples with different mix proportions, this article has analyzed the relationship between the chloride ion diffusion coefficient and permeability, established a concrete durability prediction model based on permeability, and verified the model with a coastal sluice. The results showed that gas permeability coefficient, water absorption coefficient, and chloride ion diffusion coefficient would all increase with the increase of water cement ratio; in different water cement ratio conditions, chloride ion diffusion coefficient would increase with the increase of gas permeability and water absorption coefficient, showing a certain correlation between them. Just by testing the permeability of concrete structures, the established prediction model of concrete durability can predict the service life of the concrete structures. The model was verified and proven feasible with a coastal sluice. It has great significance in predicting the service life of concrete structures in chloride environment directly based on their permeability.
2017, 15(4):168-174.
Abstract:
The initial impounding speed of a reservoir directly affects the seepage safety of the earth-rock dam. The rise of water level makes the stress field of the dam complicated and fickle, and may affect the seepage state. Ignoring the influence of the stress field in seepage analysis can easily cause some deviation. Based on the saturated-unsaturated seepage theory, with consideration to the initial stress field and seepage field, we analyzed the influence of different impounding speeds on the seepage field using numerical simulation, and then compared and studied the seepage behaviors with or without consideration to the influence of the stress field. The results showed that at a slow impounding speed, the stress had non-significant influence on the hydraulic factors. As the impounding speed increased, there was a large hydraulic gradient in part of the upstream side of the core wall, and the pore water pressure changed abruptly and concentrated, causing harm to the dam. The calculation result leaned towards safe when the influence of seepage-stress coupling was considered. Therefore, it is necessary to consider the influence of the stress field in the seepage analysis of the initial impoundment, and to strictly control the initial water impounding speed.
The initial impounding speed of a reservoir directly affects the seepage safety of the earth-rock dam. The rise of water level makes the stress field of the dam complicated and fickle, and may affect the seepage state. Ignoring the influence of the stress field in seepage analysis can easily cause some deviation. Based on the saturated-unsaturated seepage theory, with consideration to the initial stress field and seepage field, we analyzed the influence of different impounding speeds on the seepage field using numerical simulation, and then compared and studied the seepage behaviors with or without consideration to the influence of the stress field. The results showed that at a slow impounding speed, the stress had non-significant influence on the hydraulic factors. As the impounding speed increased, there was a large hydraulic gradient in part of the upstream side of the core wall, and the pore water pressure changed abruptly and concentrated, causing harm to the dam. The calculation result leaned towards safe when the influence of seepage-stress coupling was considered. Therefore, it is necessary to consider the influence of the stress field in the seepage analysis of the initial impoundment, and to strictly control the initial water impounding speed.
2017, 15(4):175-178.
Abstract:
Based on the fold line distribution function of temperature difference for highway bridges, we derived the calculation formulas for transverse thermal self-restraint stress and framework-restraint stress of inverted siphons. Using the calculation formulas, we calculated the thermal stress of inverted siphons in winter downtime when cold snap invades. Our calculations showed that the total stress of the inner surface of an inverted siphon is a function of the wall thickness and the temperature difference. When wall thickness is constant and temperature difference decreases by 50%, the thermal stress also decreases by 50%. When the temperature difference is constant and the wall thickness decreases by 50%, the thermal stress decreases by 17%. The thermal stress of inverted siphons calculated by the fold line distribution function of temperature difference was larger than that calculated by the exponential distribution function. If the temperature load of inverted siphons is considered on this basis in design, the crack resistance of inverted siphons can be significantly improved.
Based on the fold line distribution function of temperature difference for highway bridges, we derived the calculation formulas for transverse thermal self-restraint stress and framework-restraint stress of inverted siphons. Using the calculation formulas, we calculated the thermal stress of inverted siphons in winter downtime when cold snap invades. Our calculations showed that the total stress of the inner surface of an inverted siphon is a function of the wall thickness and the temperature difference. When wall thickness is constant and temperature difference decreases by 50%, the thermal stress also decreases by 50%. When the temperature difference is constant and the wall thickness decreases by 50%, the thermal stress decreases by 17%. The thermal stress of inverted siphons calculated by the fold line distribution function of temperature difference was larger than that calculated by the exponential distribution function. If the temperature load of inverted siphons is considered on this basis in design, the crack resistance of inverted siphons can be significantly improved.
2017, 15(4):179-185.
Abstract:
The Shandong section of South-to-North Water Transfer Project consists of new water trunk canals, the original rivers, lakes, reservoirs. Almost water transferring line are openly and crossing with roads, Nansihu and liangji canal undertakes shipping missions, traffic accident or shipping accident and many other emergences may effects on the normal work, as a result many potential accidents effects the normal water delivery and construction safety. To be able to take effective emergency control and disposal measures after the accident happens and reduce the losses caused by the emergency, using the checklist method to identify sources of sudden risk, establishing risk assessment system with Fuzzy Suggestion Centralized Decision and Analytic Hierarchy Process to assess the sudden risk in Shandong section of South-to-North water transferred project. The main risks in this project include some sudden risks result from land transportation and shipping, the minor risks include many sudden risks result from human poisoning and natural disasters and machine fault and so on. The risk assessment system provide decision-making basis for emergency control and disposal programs, and provide reference for the risk assessment in the poorly gauged regions.
The Shandong section of South-to-North Water Transfer Project consists of new water trunk canals, the original rivers, lakes, reservoirs. Almost water transferring line are openly and crossing with roads, Nansihu and liangji canal undertakes shipping missions, traffic accident or shipping accident and many other emergences may effects on the normal work, as a result many potential accidents effects the normal water delivery and construction safety. To be able to take effective emergency control and disposal measures after the accident happens and reduce the losses caused by the emergency, using the checklist method to identify sources of sudden risk, establishing risk assessment system with Fuzzy Suggestion Centralized Decision and Analytic Hierarchy Process to assess the sudden risk in Shandong section of South-to-North water transferred project. The main risks in this project include some sudden risks result from land transportation and shipping, the minor risks include many sudden risks result from human poisoning and natural disasters and machine fault and so on. The risk assessment system provide decision-making basis for emergency control and disposal programs, and provide reference for the risk assessment in the poorly gauged regions.
2017, 15(4):186-192.
Abstract:
Based on the water consumption data and economic and social development data of Xi’an City during 2005-2014, the relationship between urban economic development and water consumption structure was analyzed using information entropy and grey correlation method in terms of the time series. The results showed that: the information entropy of Xi’an water structure was growing; the advantage of a single water-consumption type was weakening; and the system balance was improving. The water consumption structure was becoming more reasonable. The correlation coefficients between the economic development and water structure of Xi’an were all above 0.45, suggesting significant correlations. The coupling degrees between urban economy and water structure were between 0.6 and 1, indicating a relatively close interactive coupling between urban economic development and water consumption structure. We suggest taking corresponding measures to control and ensure the balance between water supply and demand in Xi’an, and the key to doing so is to create and promote water-saving technologies.
Based on the water consumption data and economic and social development data of Xi’an City during 2005-2014, the relationship between urban economic development and water consumption structure was analyzed using information entropy and grey correlation method in terms of the time series. The results showed that: the information entropy of Xi’an water structure was growing; the advantage of a single water-consumption type was weakening; and the system balance was improving. The water consumption structure was becoming more reasonable. The correlation coefficients between the economic development and water structure of Xi’an were all above 0.45, suggesting significant correlations. The coupling degrees between urban economy and water structure were between 0.6 and 1, indicating a relatively close interactive coupling between urban economic development and water consumption structure. We suggest taking corresponding measures to control and ensure the balance between water supply and demand in Xi’an, and the key to doing so is to create and promote water-saving technologies.
2017, 15(4):193-197.
Abstract:
Simplex-particle swarm hybrid algorithm (SM-PSO) was applied to analyze the experimental data of water quality of river in two-dimensional transverse dispersion, and to estimate the transverse dispersion coefficient, mean velocity of river, and location of continuous pollutant discharge. The results of numerical experiment show that: 1) SM-PSO algorithm can be effectively employed to analyze the experimental data of water quality and estimate water quality parameters. 2) Under the same condition, the time performance indicator of SM-PSO is less than that of PSO algorithm. 3) The range of initial guess value of water quality parameters has little influence on the convergence speed . 4) c1, c2 and the range of initial guess value have synthetic influences on the search capability in operation. When c1=c2=1.72, the search capability can be kept properly. SM-PSO algorithm can overcome the problem of PSO algorithm where it easily drops into local convergence and premature convergence. The hybrid algorithm was proved to be an effective way to estimate parameters for river water quality models.
Simplex-particle swarm hybrid algorithm (SM-PSO) was applied to analyze the experimental data of water quality of river in two-dimensional transverse dispersion, and to estimate the transverse dispersion coefficient, mean velocity of river, and location of continuous pollutant discharge. The results of numerical experiment show that: 1) SM-PSO algorithm can be effectively employed to analyze the experimental data of water quality and estimate water quality parameters. 2) Under the same condition, the time performance indicator of SM-PSO is less than that of PSO algorithm. 3) The range of initial guess value of water quality parameters has little influence on the convergence speed . 4) c1, c2 and the range of initial guess value have synthetic influences on the search capability in operation. When c1=c2=1.72, the search capability can be kept properly. SM-PSO algorithm can overcome the problem of PSO algorithm where it easily drops into local convergence and premature convergence. The hybrid algorithm was proved to be an effective way to estimate parameters for river water quality models.
2017, 15(4):198-202.
Abstract:
In this paper, we took the middle route of South-to-North Water Diversion Project as an example, and built a one-dimensional emergency dispatch numerical model of the project. On this basis, we selected some typical canal sections as cases for simulation, so as to study the impact of target water level on the canal parameters (such as water level and discharge volume) in the process of emergency dispatch. The results showed that the target water level directly affected the amount of water discharge and the highest water level before the sluice. The higher the target water level, the higher the water level rise, but the smaller the water discharge volume. To improve the safety and economy of emergency dispatch, efforts should be made to increase the target water level before the sluice as much as possible under the premise of ensuring safety. This research can provide some reference for the contingency plans of the S-N project.
In this paper, we took the middle route of South-to-North Water Diversion Project as an example, and built a one-dimensional emergency dispatch numerical model of the project. On this basis, we selected some typical canal sections as cases for simulation, so as to study the impact of target water level on the canal parameters (such as water level and discharge volume) in the process of emergency dispatch. The results showed that the target water level directly affected the amount of water discharge and the highest water level before the sluice. The higher the target water level, the higher the water level rise, but the smaller the water discharge volume. To improve the safety and economy of emergency dispatch, efforts should be made to increase the target water level before the sluice as much as possible under the premise of ensuring safety. This research can provide some reference for the contingency plans of the S-N project.
2017, 15(4):203-208.
Abstract:
To explore the impact of vegetation arrangement and slope gradient on the overland flow Froude number Fr, in order to reveal the inherent law of overland flow Froude number Fr. [Method] Using artificial simulation tests, we systematically studied the relationship between Fr and K value, which is the friction surface area of a unit floor area, under different conditions including six slope gradients and three angles between the vegetation arrangement direction and water flow direction. [Results] In non-submerged flow, with the increase of K , Fr would decrease first and then tend to be steady, and the value of Fr would increase with the increase of slope gradient. Within a certain range of slope gradient, with the same gradient, when Fr>1, with the same K value, the bigger the direction angle, the smaller the Fr; when Fr<1, the situation was the other way around. With the same angle and the same K, the greater the gradient, the greater the corresponding Fr. [Conclusion] At a certain gradient, when the slope vegetation arrangement varies, the Froude number Fr value varies as well. The slope gradient is one of the important factors that influence Fr value range.
To explore the impact of vegetation arrangement and slope gradient on the overland flow Froude number Fr, in order to reveal the inherent law of overland flow Froude number Fr. [Method] Using artificial simulation tests, we systematically studied the relationship between Fr and K value, which is the friction surface area of a unit floor area, under different conditions including six slope gradients and three angles between the vegetation arrangement direction and water flow direction. [Results] In non-submerged flow, with the increase of K , Fr would decrease first and then tend to be steady, and the value of Fr would increase with the increase of slope gradient. Within a certain range of slope gradient, with the same gradient, when Fr>1, with the same K value, the bigger the direction angle, the smaller the Fr; when Fr<1, the situation was the other way around. With the same angle and the same K, the greater the gradient, the greater the corresponding Fr. [Conclusion] At a certain gradient, when the slope vegetation arrangement varies, the Froude number Fr value varies as well. The slope gradient is one of the important factors that influence Fr value range.
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