Volume 17,Issue 6,2019 Table of Contents
2019, 17(6):1-9.
Abstract:
The Long Short-Term Memory ( LSTM ) is suitable for rainfall-runoff modelling and forecasting since it has a strong ability in fitting time series. In this study , the LSTM was employed in predicting runoff in different foresight periods, in order to assess the capability of the LSTM in rainfall-runoff modelling and forecasting . The historical precipitation, meteorological and hydr ological data were used as input data, runoff at after different foresight periods were selected as model output. The calibration period is 14 years and the validation period is 2 years. As expected, the proposed model shows a great ability to predict runoff 0-2 days ahead. With 3 days of foresight period, the LSTM performs relatively poor but still better than the Xinanjiang model. The number o f hidden nodes has a primary impact on the prediction accuracy and training efficiency . While the leng th of input data has an impact on model performance only when the foresight period is 0 day .
The Long Short-Term Memory ( LSTM ) is suitable for rainfall-runoff modelling and forecasting since it has a strong ability in fitting time series. In this study , the LSTM was employed in predicting runoff in different foresight periods, in order to assess the capability of the LSTM in rainfall-runoff modelling and forecasting . The historical precipitation, meteorological and hydr ological data were used as input data, runoff at after different foresight periods were selected as model output. The calibration period is 14 years and the validation period is 2 years. As expected, the proposed model shows a great ability to predict runoff 0-2 days ahead. With 3 days of foresight period, the LSTM performs relatively poor but still better than the Xinanjiang model. The number o f hidden nodes has a primary impact on the prediction accuracy and training efficiency . While the leng th of input data has an impact on model performance only when the foresight period is 0 day .
2019, 17(6):10-19.
Abstract:
As the most important part of runoff,base flow plays a key role in maintaining the river ecosystem stability.In this study,three digital filtering methods (Chapman Maxwell,Lyne Hollick,and Boughton Chapman) were adopted to divide the baseflow series.The daily observed runoff series were obtained from 2001 to 2015 at seven stations in the Huai River and Shaying tributary.Temporal and spatial variations of base flow were further explored at inter annual and seasonal scales using the Mann Kendall trend analysis method and regional impacts of dam regulations were also identified.Results showed that:(1) the Chapman Maxwell digital filtering method was more reasonable for the division of the baseflow process.The baseflow indices of Shaying River were between 0.23 to 0.46,much less than those of the Huai mainstream which were between 0.36 to 0.50;(2) The inter annual base flows in the entire Huai River Basin decreased gradually,particularly those at the Huaidian and Fuyang stations in Shaying river and Wangjiaba station in Huai river,which showed statistically significant decreasing trend.The baseflow series in the flood season at Baiguishan,Huaidian and Fuyang stations in the Shaying River also showed significant decreasing trend.(3) The regulations of dam and sluice decreased the downstream runoff and baseflow,and the regulation effects in the Shaying River were more serious,especially in the flood season (i.e.,August).The mainstream of the Huaihe River was weakly regulated by the dam,and the reduction was not significant.The study is expected to provide technical support for understanding the characteristics of water cycle and its transformation relationship in the upper and middle reaches of the Huai River Basin,and also provide a basis for sustainable utilization of groundwater resources and impact assessment of human activities.
As the most important part of runoff,base flow plays a key role in maintaining the river ecosystem stability.In this study,three digital filtering methods (Chapman Maxwell,Lyne Hollick,and Boughton Chapman) were adopted to divide the baseflow series.The daily observed runoff series were obtained from 2001 to 2015 at seven stations in the Huai River and Shaying tributary.Temporal and spatial variations of base flow were further explored at inter annual and seasonal scales using the Mann Kendall trend analysis method and regional impacts of dam regulations were also identified.Results showed that:(1) the Chapman Maxwell digital filtering method was more reasonable for the division of the baseflow process.The baseflow indices of Shaying River were between 0.23 to 0.46,much less than those of the Huai mainstream which were between 0.36 to 0.50;(2) The inter annual base flows in the entire Huai River Basin decreased gradually,particularly those at the Huaidian and Fuyang stations in Shaying river and Wangjiaba station in Huai river,which showed statistically significant decreasing trend.The baseflow series in the flood season at Baiguishan,Huaidian and Fuyang stations in the Shaying River also showed significant decreasing trend.(3) The regulations of dam and sluice decreased the downstream runoff and baseflow,and the regulation effects in the Shaying River were more serious,especially in the flood season (i.e.,August).The mainstream of the Huaihe River was weakly regulated by the dam,and the reduction was not significant.The study is expected to provide technical support for understanding the characteristics of water cycle and its transformation relationship in the upper and middle reaches of the Huai River Basin,and also provide a basis for sustainable utilization of groundwater resources and impact assessment of human activities.
2019, 17(6):20-27.
Abstract:
In this paper, the Pearson correlation, overlapping averages method, and inverse distance weighting ( IDW ) were used to make a corresponding analysis based on the SM data from SMOS ( Soil Moisture and Ocean Salinity ) satellite and in-situ GNSS-MET ( Global Navigation Satellite System-Meteorology) . We evaluated the applicability of SMOS SM data and analyzed the variety of SM and its influencing factors. The results showed that: ( 1) the general dynamic trend of soil water movement in the study area ( April to October) could be demonstrated by the SMOS SM data, how ever the SM from SMOS was slightly lower than that from the in-situ measured; ( 2) The SM from SMOS satellite in the ascending orbit were higher than those in the descending orbit. The SM from SMOS during the period from June to August were higher than those in the other months. The seasonal variation in soil water was obvious, and the SM in summer was significantly higher than that in spring; ( 3) T he spatial SM was greatly different in the Three-River Headwater s region. Generally , the soil was relatively wet in the source area of Lantsang River, while it was relatively dry in the source area of the Yangtze River .
In this paper, the Pearson correlation, overlapping averages method, and inverse distance weighting ( IDW ) were used to make a corresponding analysis based on the SM data from SMOS ( Soil Moisture and Ocean Salinity ) satellite and in-situ GNSS-MET ( Global Navigation Satellite System-Meteorology) . We evaluated the applicability of SMOS SM data and analyzed the variety of SM and its influencing factors. The results showed that: ( 1) the general dynamic trend of soil water movement in the study area ( April to October) could be demonstrated by the SMOS SM data, how ever the SM from SMOS was slightly lower than that from the in-situ measured; ( 2) The SM from SMOS satellite in the ascending orbit were higher than those in the descending orbit. The SM from SMOS during the period from June to August were higher than those in the other months. The seasonal variation in soil water was obvious, and the SM in summer was significantly higher than that in spring; ( 3) T he spatial SM was greatly different in the Three-River Headwater s region. Generally , the soil was relatively wet in the source area of Lantsang River, while it was relatively dry in the source area of the Yangtze River .
2019, 17(6):28-36.
Abstract:
Mountainous area is the main producing area of river runoff. Systematically grasping the spatial and temporal distribution patter n of precipitation in mountainous area can provide important basic support for precise analysis of water circulation system and scientific formulation of water resources development and utilization strategy. Aimingt he lack of observation data in mountainous ar eas, this study developed a downscaling correction model for TRMM satellite precipitation data product in Guizhou and Guang xi karst mountainous region by using geographic weighted reg ression method and multiple linear regr ession met hod. The accuracy of dow nscaling correction results and their effects at different elevation intervals were analyzed, and summarized the temporal and spatial distribution of precipitation in the mountains. The results showed that : ( 1) the correction accuracy of the geographic weighted regression method was better than the multiple linear regr essionmethod, and the geographic weighted regr essionmethod performed better in the high altitude area at a significance level of A= 01 01; ( 2) the annual average precipitation in the study area showed high in the south, low in the north, high in the East and low in the west, characteristics and the annual distribution was uneven. Summer ( June2 August) precipitation was 74018 mm, accounting for 52% of the whole year ; ( 3) the spatial distribution of precipitation in the study area was closely related to the to pography. The elevation of lo w2altitude areas had a greater impact on precipitation, and the slope of high-altitude areas had a greater impact on precipitation.
Mountainous area is the main producing area of river runoff. Systematically grasping the spatial and temporal distribution patter n of precipitation in mountainous area can provide important basic support for precise analysis of water circulation system and scientific formulation of water resources development and utilization strategy. Aimingt he lack of observation data in mountainous ar eas, this study developed a downscaling correction model for TRMM satellite precipitation data product in Guizhou and Guang xi karst mountainous region by using geographic weighted reg ression method and multiple linear regr ession met hod. The accuracy of dow nscaling correction results and their effects at different elevation intervals were analyzed, and summarized the temporal and spatial distribution of precipitation in the mountains. The results showed that : ( 1) the correction accuracy of the geographic weighted regression method was better than the multiple linear regr essionmethod, and the geographic weighted regr essionmethod performed better in the high altitude area at a significance level of A= 01 01; ( 2) the annual average precipitation in the study area showed high in the south, low in the north, high in the East and low in the west, characteristics and the annual distribution was uneven. Summer ( June2 August) precipitation was 74018 mm, accounting for 52% of the whole year ; ( 3) the spatial distribution of precipitation in the study area was closely related to the to pography. The elevation of lo w2altitude areas had a greater impact on precipitation, and the slope of high-altitude areas had a greater impact on precipitation.
2019, 17(6):37-44.
Abstract:
Flood risk assessment is one of the important means to study flood disasters and can provide a basis for the planning of reg ional flood disaster monitoring and prediction, flood control and disaster mitigation measures. In this study, Wu' an City of Hebei P rovince was taken as study area, based on the theory of disaster risk system and the local actual situation, hazard, sensitivity , and prevention capability ability o f flood disaster were selected as assessment aspects. There were nine evaluation indicators of social economic factors such as population density and economic level. The GIS weighted comprehensive evaluation method and spatial analysis super position functions were used to obtain flood risk assessment results. The results indicated that the overall risk distribution o f flood disaster s in W ucan City was characterized by the gradual decline of the high2risk areas in the central and southwestern areas. Specifically, t he river valley had a high2r isk level, and the risk along the Ming River w as higher than other areas. The risk level of the plain was obvious, and the sensitivity was strong; the risk level o f farming area was higher than that in the forest and gr ass area. Through the historical disaster data to verify the evaluation results, the Wu' an flood disaster assessment results presented in this paper are consistent with the actual situation.
Flood risk assessment is one of the important means to study flood disasters and can provide a basis for the planning of reg ional flood disaster monitoring and prediction, flood control and disaster mitigation measures. In this study, Wu' an City of Hebei P rovince was taken as study area, based on the theory of disaster risk system and the local actual situation, hazard, sensitivity , and prevention capability ability o f flood disaster were selected as assessment aspects. There were nine evaluation indicators of social economic factors such as population density and economic level. The GIS weighted comprehensive evaluation method and spatial analysis super position functions were used to obtain flood risk assessment results. The results indicated that the overall risk distribution o f flood disaster s in W ucan City was characterized by the gradual decline of the high2risk areas in the central and southwestern areas. Specifically, t he river valley had a high2r isk level, and the risk along the Ming River w as higher than other areas. The risk level of the plain was obvious, and the sensitivity was strong; the risk level o f farming area was higher than that in the forest and gr ass area. Through the historical disaster data to verify the evaluation results, the Wu' an flood disaster assessment results presented in this paper are consistent with the actual situation.
2019, 17(6):45-53.
Abstract:
In view of the flood control demand of the East Route of South-to-North Water Diversion Project in Shandong area, the flood risk zoning model was established based on the fundamental principles of hazard, sensitivity and vulnerability of flood disasters. Nine influencing indices such as rainstorm days in the flood season, rainstorm intensity , elevation, standard deviation of elevation, river network density, and buffer zone of lakes, gross domestic product, population density, and land use type were comprehensively considered. The weights of indices were determined by means of the analytic hierarchy process ( AHP) with the auxiliary of Monte Carlo method. The cartographic algebra function in ArcGIS was adopted to perform the normalization processing of the various indicator layers. After calculating and mapping process, the risk zoning map of flood disasters of the study area was obtained. The results showed that the high2risk areas of south, north and east Shandong were located in the surrounding regions of Nansi Lake and so me local areas in Zaozhuang City, L iao cheng City and the north side o f the Yellow River, the vicinity of Jinan City and part of regions of the east peninsula. Compared with the historical data o f flood disaster s, the above zoning results proved t o accord with the actual situation of the study area, which show ed that the results have important referencing values for flood prevention and decision management in Shandong section of the East Route of South-to-NorthWater Transfer Project.
In view of the flood control demand of the East Route of South-to-North Water Diversion Project in Shandong area, the flood risk zoning model was established based on the fundamental principles of hazard, sensitivity and vulnerability of flood disasters. Nine influencing indices such as rainstorm days in the flood season, rainstorm intensity , elevation, standard deviation of elevation, river network density, and buffer zone of lakes, gross domestic product, population density, and land use type were comprehensively considered. The weights of indices were determined by means of the analytic hierarchy process ( AHP) with the auxiliary of Monte Carlo method. The cartographic algebra function in ArcGIS was adopted to perform the normalization processing of the various indicator layers. After calculating and mapping process, the risk zoning map of flood disasters of the study area was obtained. The results showed that the high2risk areas of south, north and east Shandong were located in the surrounding regions of Nansi Lake and so me local areas in Zaozhuang City, L iao cheng City and the north side o f the Yellow River, the vicinity of Jinan City and part of regions of the east peninsula. Compared with the historical data o f flood disaster s, the above zoning results proved t o accord with the actual situation of the study area, which show ed that the results have important referencing values for flood prevention and decision management in Shandong section of the East Route of South-to-NorthWater Transfer Project.
2019, 17(6):54-61.
Abstract:
Policymakers should balance the cost and profit contradiction of water supply when made decisions reg arding simulation and optimization o f multi-reservoir operation in an inter-basin water transfer system. Considering obvious differences between the cost of local and diverted water, we established an optimization and multi-scenario model for water resources management based on cost of water-supply sources. In this paper , we analyzed the conditions and harmony of multi-water resources through the above model with minimum water supply shortage as an objective function, restricted diverted water as a constraint condition. In this study, Hongze Lake, Luoma Lake and the east route of So uth-to-North Water Diversion Project was selected as resea rch object. The results indicated that: ( 1) local water from Hong ze Lake and Luoma Lake can meet the water demand in normal and high flow years. ( 2) we could reduce the water short ages of HongZe Lake and comunity by diver ting water from Hongze Lake to Luo ma Lake, while the inflow of Hong ze Lake was normal or high and inflow of the Luoma Lake was high. ( 3) The water shortage problem in low flow year could be solved through an effective agreed amount of annual diverted water from Yangtze River ( 4) under the multi-year av erage condition, 0. 6 times of the agreed diversion volume was a compromise scheme which can balance the consideration of reducing the w ater shortage and diversion cost of the system. Through the above research, we can get some references for optimization operation in an inter-basin water transfer system.
Policymakers should balance the cost and profit contradiction of water supply when made decisions reg arding simulation and optimization o f multi-reservoir operation in an inter-basin water transfer system. Considering obvious differences between the cost of local and diverted water, we established an optimization and multi-scenario model for water resources management based on cost of water-supply sources. In this paper , we analyzed the conditions and harmony of multi-water resources through the above model with minimum water supply shortage as an objective function, restricted diverted water as a constraint condition. In this study, Hongze Lake, Luoma Lake and the east route of So uth-to-North Water Diversion Project was selected as resea rch object. The results indicated that: ( 1) local water from Hong ze Lake and Luoma Lake can meet the water demand in normal and high flow years. ( 2) we could reduce the water short ages of HongZe Lake and comunity by diver ting water from Hongze Lake to Luo ma Lake, while the inflow of Hong ze Lake was normal or high and inflow of the Luoma Lake was high. ( 3) The water shortage problem in low flow year could be solved through an effective agreed amount of annual diverted water from Yangtze River ( 4) under the multi-year av erage condition, 0. 6 times of the agreed diversion volume was a compromise scheme which can balance the consideration of reducing the w ater shortage and diversion cost of the system. Through the above research, we can get some references for optimization operation in an inter-basin water transfer system.
2019, 17(6):62-68.
Abstract:
In view of the shortcomings of the traditional Grey Model ( 1, 1) ( GM ) ( 1, 1) in the data prepr ocessing stage, a new data preprocessing method was proposed by analyzing the causes of model errors. Based on the annual precipitation data of Xiajiang County from 1958 to 2018, drought year time series was obtained by calculating SPI index ( standardized precipitation index ) . The classical gray model GM0 , the translational conversion preprocessing gray model GM 1 , and the average weakening buffer operator pr eprocessing gray model GM 2 based on translation transformation were compared on the real-time series data set. The results showed that the translational conversion combined with the average weakening buffer operator compensated the shortcomings of the prepr ocessing stage and effectively reduced the error of the traditional model. The average prediction error of the improved GM 2 model w as 3.32% , which was 44.16 and 16.24 percentage points lower than the other two models. It is proved that the model has better prediction accuracy . It can be applied to the prediction of dry years, providing a theoretical basis for regional drought pr ediction and drought control.
In view of the shortcomings of the traditional Grey Model ( 1, 1) ( GM ) ( 1, 1) in the data prepr ocessing stage, a new data preprocessing method was proposed by analyzing the causes of model errors. Based on the annual precipitation data of Xiajiang County from 1958 to 2018, drought year time series was obtained by calculating SPI index ( standardized precipitation index ) . The classical gray model GM0 , the translational conversion preprocessing gray model GM 1 , and the average weakening buffer operator pr eprocessing gray model GM 2 based on translation transformation were compared on the real-time series data set. The results showed that the translational conversion combined with the average weakening buffer operator compensated the shortcomings of the prepr ocessing stage and effectively reduced the error of the traditional model. The average prediction error of the improved GM 2 model w as 3.32% , which was 44.16 and 16.24 percentage points lower than the other two models. It is proved that the model has better prediction accuracy . It can be applied to the prediction of dry years, providing a theoretical basis for regional drought pr ediction and drought control.
2019, 17(6):69-74.
Abstract:
Precipitation data is one of the important input data in the hydrological model. Spatial interpolation of rainfall is an effective method to obtain surface rainfall data. Therefore, it is very important to improve the existing rainfall interpolation met ho ds to obtain more accurate continuous time series and surface precipitation data. MIKE SHE hydrological model was used to simulate the daily runoff using improved interpolated precipitation data to analyze the accuracy of the model in the Yuan Jiang Basin . Results exhibited that the precipitation data obtained by the improved method ( IDW-Thiessen interpolation method) was better than Thiessen polygon in the process of runoff simulation. Therefore, daily runoff process was carried out by using the precipitation data obtained by IDW-Thiessen interpolation method in the Bu Yuan Jiang Basin. The Nash coefficients were higher than 0.7 during the calibratio n and validation periods compared to the Nash coefficients of the runoff simulation results
Precipitation data is one of the important input data in the hydrological model. Spatial interpolation of rainfall is an effective method to obtain surface rainfall data. Therefore, it is very important to improve the existing rainfall interpolation met ho ds to obtain more accurate continuous time series and surface precipitation data. MIKE SHE hydrological model was used to simulate the daily runoff using improved interpolated precipitation data to analyze the accuracy of the model in the Yuan Jiang Basin . Results exhibited that the precipitation data obtained by the improved method ( IDW-Thiessen interpolation method) was better than Thiessen polygon in the process of runoff simulation. Therefore, daily runoff process was carried out by using the precipitation data obtained by IDW-Thiessen interpolation method in the Bu Yuan Jiang Basin. The Nash coefficients were higher than 0.7 during the calibratio n and validation periods compared to the Nash coefficients of the runoff simulation results
2019, 17(6):75-85.
Abstract:
Standardized Precipitation Evapotranspiration Index ( SPEI ) was used to quantitatively characterize the drought conditions based on monthly precipitation and mean temperature data obtained from 17 meteorological stations from 196022018 in Guizhou Province. The M2K tr end test and R/ S analysis were used to analyze the drought trend in Guizhou Province in the past 59 years. The continuous wavelet transform and cross wavelet transform were used to analyze the characteristics of oscillation period of SPEI and four circulation factors ( M EI, N AO , AO , PDO ) , their common char acteristics and correlation in time and frequency domain. The results showed that the monthly, spring, autumn and annual SPEI series showed a significant downward trend and the decline - 0. 108/ ( 10a) fo r autumn SPEI compared to other series, which indicated that spring and autumn drought gradually intensify in Guizhou Province. The spring and autumn drought may upward in future and the intensity may become more severe, while the intensity of summer and winter drought expressed a weakened possibility . The SPEI had 16-48 months inter-annual oscillation period, and there was a common patterns of 24-110 month at inter-annual and 128-250 month at inter-decadal oscillation circles between SPEI and M EI, N A O, AO , P DO, while a lag positive correlation existed between SPEI and N AO , A O . O verall, M EI mainly affect ed the int er-annual cycle variation o f drought, while PDO and AO mainly affected the longer inter-decadal cycle variation of drought.
Standardized Precipitation Evapotranspiration Index ( SPEI ) was used to quantitatively characterize the drought conditions based on monthly precipitation and mean temperature data obtained from 17 meteorological stations from 196022018 in Guizhou Province. The M2K tr end test and R/ S analysis were used to analyze the drought trend in Guizhou Province in the past 59 years. The continuous wavelet transform and cross wavelet transform were used to analyze the characteristics of oscillation period of SPEI and four circulation factors ( M EI, N AO , AO , PDO ) , their common char acteristics and correlation in time and frequency domain. The results showed that the monthly, spring, autumn and annual SPEI series showed a significant downward trend and the decline - 0. 108/ ( 10a) fo r autumn SPEI compared to other series, which indicated that spring and autumn drought gradually intensify in Guizhou Province. The spring and autumn drought may upward in future and the intensity may become more severe, while the intensity of summer and winter drought expressed a weakened possibility . The SPEI had 16-48 months inter-annual oscillation period, and there was a common patterns of 24-110 month at inter-annual and 128-250 month at inter-decadal oscillation circles between SPEI and M EI, N A O, AO , P DO, while a lag positive correlation existed between SPEI and N AO , A O . O verall, M EI mainly affect ed the int er-annual cycle variation o f drought, while PDO and AO mainly affected the longer inter-decadal cycle variation of drought.
2019, 17(6):86-94.
Abstract:
The chemical characteristics and water level of shallow groundwater is an important indicator of groundwater environment change in the arid area. Under standing its temporal and spatial variations are of key significance for the sustainable development in arid ecosystems. The Ejina Oasis in the lower reaches of Heihe River of the second largest inland river basin of northwestern China was selected as the study area. Based on the shallow groundwater sampling and water chemical composition analysis data of August 2017, the historical hydro-geochemistry data ( September 2001 and August 2009) and groundwater table depth automatic monitoring data, the tempo-spatial variations of shallow groundwatercs hydro-geochemistry in Ejina Oasis and the response to groundwater depth were analy zed using the Inverse Distance Weight ( IDW ) inter polation method and the Piper graphic method. The results showed that the shallow groundwater level in the Ejina Oasis gradually decreased from southwest to northeast; however, groundwatercs TDS, in contrast, gradually increased in this direction. There was no obvious change in groundwater chemical types in 2001, 2009 and 2017, and the type of water chemistry in 2001, 2009 and 2017 were SO 4 · Cl-M g · N a, SO4 · Cl-Na · M g , SO 4 · Cl-N a · M g, respectively. The change o f TDS in groundwater was more obvious, and the highest TDS was observed in 2001, followed by 2017, while the lowest was detected in 2009. A nonlinear relationship between TDS and groundwater table depth was detected. The water table depth ranged 1.5-3 m and below 6 m, TDS did not change much with a value of approximately 2 000 mg / L ; however , at 326 m, TDS increased when the groundwater table depth was getting larger.
The chemical characteristics and water level of shallow groundwater is an important indicator of groundwater environment change in the arid area. Under standing its temporal and spatial variations are of key significance for the sustainable development in arid ecosystems. The Ejina Oasis in the lower reaches of Heihe River of the second largest inland river basin of northwestern China was selected as the study area. Based on the shallow groundwater sampling and water chemical composition analysis data of August 2017, the historical hydro-geochemistry data ( September 2001 and August 2009) and groundwater table depth automatic monitoring data, the tempo-spatial variations of shallow groundwatercs hydro-geochemistry in Ejina Oasis and the response to groundwater depth were analy zed using the Inverse Distance Weight ( IDW ) inter polation method and the Piper graphic method. The results showed that the shallow groundwater level in the Ejina Oasis gradually decreased from southwest to northeast; however, groundwatercs TDS, in contrast, gradually increased in this direction. There was no obvious change in groundwater chemical types in 2001, 2009 and 2017, and the type of water chemistry in 2001, 2009 and 2017 were SO 4 · Cl-M g · N a, SO4 · Cl-Na · M g , SO 4 · Cl-N a · M g, respectively. The change o f TDS in groundwater was more obvious, and the highest TDS was observed in 2001, followed by 2017, while the lowest was detected in 2009. A nonlinear relationship between TDS and groundwater table depth was detected. The water table depth ranged 1.5-3 m and below 6 m, TDS did not change much with a value of approximately 2 000 mg / L ; however , at 326 m, TDS increased when the groundwater table depth was getting larger.
2019, 17(6):95-101.
Abstract:
Comprehensive pollution index and principal component analysis ( PCA ) method were used to perform water safety evaluation based on drinking water sources obtained from 18 villages of Lang County in Nyingchi City. In order to avoid the influence of weight assignment on single evaluat ion method, two methods were used by combining the evaluation method based on Fuzzy Borda. The results sho wed that the combined evaluation method based on Fuzzy Borda had higher discrimination comparedto comprehensive pollution index and principal component analysis method. Results revealed that comprehensive pollution index assessment, PCA , combined evaluation method based on Fuzzy Borda had similar trend. The higherSpearman coefficient and Kendall correlation coefficient had also proven that the fuzzy Borda method was a feasible option for rural drinking water safety assessment. The results of drinking water safety evaluation assessment in 18 villages showed that the drinking source of villages such as Bangma, Tomai, Chongkang, Dui, Zhuo, Laiyi, Lie, Xiu, Zhaxitang, Jie, Niang , Kangma, Gagong, Dongxiong , Dorong, Remi, Lado and Sangmuin was turned decreasing gradually.
Comprehensive pollution index and principal component analysis ( PCA ) method were used to perform water safety evaluation based on drinking water sources obtained from 18 villages of Lang County in Nyingchi City. In order to avoid the influence of weight assignment on single evaluat ion method, two methods were used by combining the evaluation method based on Fuzzy Borda. The results sho wed that the combined evaluation method based on Fuzzy Borda had higher discrimination comparedto comprehensive pollution index and principal component analysis method. Results revealed that comprehensive pollution index assessment, PCA , combined evaluation method based on Fuzzy Borda had similar trend. The higherSpearman coefficient and Kendall correlation coefficient had also proven that the fuzzy Borda method was a feasible option for rural drinking water safety assessment. The results of drinking water safety evaluation assessment in 18 villages showed that the drinking source of villages such as Bangma, Tomai, Chongkang, Dui, Zhuo, Laiyi, Lie, Xiu, Zhaxitang, Jie, Niang , Kangma, Gagong, Dongxiong , Dorong, Remi, Lado and Sangmuin was turned decreasing gradually.
2019, 17(6):102-112.
Abstract:
In order to objectively and scientifically reflect the water quality of the main channel of the middle route of the South-to-North Water Diversion Project ( MRSNWDP ) , the monthly water quality monitoring data of 8 routine monitoring sections along the main channel from January 2015 to May 2018 was selected for comprehensive water quality assessment. The results of the single-factor evaluation indicated that the water quality of the MRSNWDP main channel was class ó . The evaluation result was class ?2 ò ( based on mean and median) and class ?2 ? ( based on maximum) , If the total nitrogen was not taken into account. The comprehensive pollution index evaluation results showed that all sections of the main channel were between 01 16 and 01 30, and the evaluation results of all sections were qualified. The proportion of total nitrogen to pollution index of most sections was mo re than 50% . T he fuzzy evaluation results showed that the membership degree of class ? water quality standard was more than 01 7 class ò water quality standard was between 01 14 and 01 17, respectively. The membership degree of ó2 ? water quality standard was very low. T he final evaluation results of water quality were all class ? . Based on the three evaluation results, the water quality of the MRSNWDP main channel was generally good and can meet the water supply quality reqirements.
In order to objectively and scientifically reflect the water quality of the main channel of the middle route of the South-to-North Water Diversion Project ( MRSNWDP ) , the monthly water quality monitoring data of 8 routine monitoring sections along the main channel from January 2015 to May 2018 was selected for comprehensive water quality assessment. The results of the single-factor evaluation indicated that the water quality of the MRSNWDP main channel was class ó . The evaluation result was class ?2 ò ( based on mean and median) and class ?2 ? ( based on maximum) , If the total nitrogen was not taken into account. The comprehensive pollution index evaluation results showed that all sections of the main channel were between 01 16 and 01 30, and the evaluation results of all sections were qualified. The proportion of total nitrogen to pollution index of most sections was mo re than 50% . T he fuzzy evaluation results showed that the membership degree of class ? water quality standard was more than 01 7 class ò water quality standard was between 01 14 and 01 17, respectively. The membership degree of ó2 ? water quality standard was very low. T he final evaluation results of water quality were all class ? . Based on the three evaluation results, the water quality of the MRSNWDP main channel was generally good and can meet the water supply quality reqirements.
JIA Wenjuan
,
WANG Fen
,
WANG Ming ming
,
WANG Dayang
,
ZHENG Lei
,
DING Aizhong
,
LIU Bao yun
,
LIANG Xin
,
HU Yu
2019, 17(6):113-120.
Abstract:
The use of ozone for advanced treatment of secondary effluent is of great significance for alleviating river pollution problems in the northern region.In order to investigate the oxidation characteristics of ozone to dissolved organic matter in the secondary effluent,different concentrations of ozone were continuously used in water samples taken from the secondary effluent of the Shahe Wastewater Treatment Plant in Beijing,and dissolved in each water sample within 60 minutes.The change of dissolved organic carbon (DOC),ultraviolet absorption spectrum,fluorescence spectrum and molecular weight distribution of water samples along with time were detected after ozone treatment.The experiment results showed that the removal efficiency of DOC increased with the increase of ozone dosage and ozone treatment time.The maximum removal efficiency was achieved up to 70% when the concentration of ozone was 1.31 mg / L and the reaction time was up to 60 minutes.After reaction of ozone for 5 minutes,the fluorescence of organic matter in the water was almost eliminated,while the UV absorbance value was partially reduced.The organic matter with the molecular weights of 5-6 kDa,1-3 kDa,and 400 Da was significantly reduced and partially converted into the organic matter with the molecular weight of 60 Da.The results indicated that after ozone oxidation treatment,the quantity of organic matter in the secondary effluent significantly reduced and the organic matter with large molecular weight in the secondary effluent almost completely degraded.
The use of ozone for advanced treatment of secondary effluent is of great significance for alleviating river pollution problems in the northern region.In order to investigate the oxidation characteristics of ozone to dissolved organic matter in the secondary effluent,different concentrations of ozone were continuously used in water samples taken from the secondary effluent of the Shahe Wastewater Treatment Plant in Beijing,and dissolved in each water sample within 60 minutes.The change of dissolved organic carbon (DOC),ultraviolet absorption spectrum,fluorescence spectrum and molecular weight distribution of water samples along with time were detected after ozone treatment.The experiment results showed that the removal efficiency of DOC increased with the increase of ozone dosage and ozone treatment time.The maximum removal efficiency was achieved up to 70% when the concentration of ozone was 1.31 mg / L and the reaction time was up to 60 minutes.After reaction of ozone for 5 minutes,the fluorescence of organic matter in the water was almost eliminated,while the UV absorbance value was partially reduced.The organic matter with the molecular weights of 5-6 kDa,1-3 kDa,and 400 Da was significantly reduced and partially converted into the organic matter with the molecular weight of 60 Da.The results indicated that after ozone oxidation treatment,the quantity of organic matter in the secondary effluent significantly reduced and the organic matter with large molecular weight in the secondary effluent almost completely degraded.
2019, 17(6):121-126.
Abstract:
Based on the spatial variability of hydrogeological parameters of a contaminated site and the change of concentration with time,a dynamic evaluation model of health risk assessment was constructed.Through a sensitivity analysis,stochastic parameters that had great influence on numerical simulations by spatial variability were selected.Two percentiles (50% and 95%) were selected to represent normal and most unfavorable condition,respectively,to predict the variation in duration of the health risk at the sensitive spot.A chromium-contaminated site in Gaocheng City,China,was selected as a case study.The results showed that the initial health risk value of sensitive spot was 0.81,while removing the contaminant plume after one year,under the normal and the most unfavorable conditions the risk values were 1.28 and 1.52,respectively.Accordingly,there was a gradually increasing non-carcinogenic risk.Under normal conditions,the risk value was not reach to acceptable level until 13th year,indicating the sensitive point.
Based on the spatial variability of hydrogeological parameters of a contaminated site and the change of concentration with time,a dynamic evaluation model of health risk assessment was constructed.Through a sensitivity analysis,stochastic parameters that had great influence on numerical simulations by spatial variability were selected.Two percentiles (50% and 95%) were selected to represent normal and most unfavorable condition,respectively,to predict the variation in duration of the health risk at the sensitive spot.A chromium-contaminated site in Gaocheng City,China,was selected as a case study.The results showed that the initial health risk value of sensitive spot was 0.81,while removing the contaminant plume after one year,under the normal and the most unfavorable conditions the risk values were 1.28 and 1.52,respectively.Accordingly,there was a gradually increasing non-carcinogenic risk.Under normal conditions,the risk value was not reach to acceptable level until 13th year,indicating the sensitive point.
YANG Yulin
,
LI Junfeng
,
,
LIU Weiwei
,
SONG Dongbao
,
YANG Jie
,
TAO Junhong
,
TENG Xiaolei
2019, 17(6):127-137.
Abstract:
The Moguhu reservoir is a typical piedmont alluvial fan plain reservoir situated in the arid area of Northwest China.The water quality of Moguhu reservoir has been seriously polluted for a long time.Based on the pollution source survey and estimation of pollution load,the water quality of Moguhu reservoir was simulated by using SMS water quality model in different planning years.The water environmental capacity of the reservoir was analyzed through the distribution characteristics and evolution trends of various pollutant concentrations.The prevention and control plan for the total amount of pollution load reduction was proposed in a targeted manner.The results showed that water quality of the Moguhu reservoir continued to deteriorate into a worse than Grade V.To ensure the improvement of the water quality of the Moguhu reservoir in the future,it is necessary to reduce the discharge of pollutants in the watershed.The simulation results of the pollutant concentration field showed that controlling the upstream inlet port of the south was the key to the main pollution load reduction of the Moguhu reservoir.According to the prediction of the pollutant distribution concentration field after reduction,the water quality was obviously improved which indicated that the pollution control scheme was effective.
The Moguhu reservoir is a typical piedmont alluvial fan plain reservoir situated in the arid area of Northwest China.The water quality of Moguhu reservoir has been seriously polluted for a long time.Based on the pollution source survey and estimation of pollution load,the water quality of Moguhu reservoir was simulated by using SMS water quality model in different planning years.The water environmental capacity of the reservoir was analyzed through the distribution characteristics and evolution trends of various pollutant concentrations.The prevention and control plan for the total amount of pollution load reduction was proposed in a targeted manner.The results showed that water quality of the Moguhu reservoir continued to deteriorate into a worse than Grade V.To ensure the improvement of the water quality of the Moguhu reservoir in the future,it is necessary to reduce the discharge of pollutants in the watershed.The simulation results of the pollutant concentration field showed that controlling the upstream inlet port of the south was the key to the main pollution load reduction of the Moguhu reservoir.According to the prediction of the pollutant distribution concentration field after reduction,the water quality was obviously improved which indicated that the pollution control scheme was effective.
2019, 17(6):138-147.
Abstract:
The water surface area ratio is an important indicator of ecological construction.In general,the larger the water area in a region,the better the ecological environment.The water area is affected by both climate change and human activities.The law and cause of water surface area change in China are key scientific issues.In this study,nationwide 9 research areas were selected based on climatic conditions and economic development levels.Based on the Google Earth Engine cloud computing platform,the Landsat image was used to extract water surface area from 1986 to 2018 using the method of combining multiple spectral indices.The dynamic variation of water surface area was analyzed by Mann Kendall test.The contribution of climate change and human activities to water surface area changes were further calculated by double mass analysis and a distributed hydrological model.The results showed that semi arid and semi humid areas were strongly affected by human activities,and there was a significant change was observed in water surface area.Humid areas were affected by climate change,and the water area was also significantly increased.Human activities such as excessive use of water resources,water transfer projects and reservoir construction directly determined changes in water surface area in most areas.This research can provide scientific support for ecological construction.
The water surface area ratio is an important indicator of ecological construction.In general,the larger the water area in a region,the better the ecological environment.The water area is affected by both climate change and human activities.The law and cause of water surface area change in China are key scientific issues.In this study,nationwide 9 research areas were selected based on climatic conditions and economic development levels.Based on the Google Earth Engine cloud computing platform,the Landsat image was used to extract water surface area from 1986 to 2018 using the method of combining multiple spectral indices.The dynamic variation of water surface area was analyzed by Mann Kendall test.The contribution of climate change and human activities to water surface area changes were further calculated by double mass analysis and a distributed hydrological model.The results showed that semi arid and semi humid areas were strongly affected by human activities,and there was a significant change was observed in water surface area.Humid areas were affected by climate change,and the water area was also significantly increased.Human activities such as excessive use of water resources,water transfer projects and reservoir construction directly determined changes in water surface area in most areas.This research can provide scientific support for ecological construction.
YANG Xi
,
CHEN Xingwei
,
,
FANG Yihui
,
KANG Huiping，LI Xiaocheng，DENG Haijun
,
,
LIN Bingqin
2019, 17(6):148-155.
Abstract:
In order to study the health evaluation of the tidal river,12 specific aspects including river morphology,hydrology,water quality,saltwater invasion,biological and social service functions were constructed based on the hydrological,water environment and water ecological characteristics of tidal channel.A segmentedcomprehensive evaluation method was proposed to solve the special difference between the natural characteristics and social function of the long river channel.For health[JP] evaluation,the lower reaches of the Minjiang River were taken as an example in this study.The lower reaches of the Minjiang River can be divided into 5 segments,i.e., the dam of Shuikou power stationBifurcated segment,BifurcatedHongshan Bridge (North channel) segment,Hongshan BridgeConfluence (North channel segment BifurcatedConfluence (South channel) segment and ConfluenceMingjiang River mouth segment,respectively.The results revealed that health state of the BifurcatedConfluence (South channel) segment was categorized in subhealth,while the other 4 segments channels and the overall health status of the lower reaches of the Minjiang River were in general grade.Based on the segmentedintegrated river health evaluation model,the grade criteria of river health and the health status of each river segment can be obtained.The use of game theory to optimize the combined weights of indicators can reduce the subjective impact of weight on the evaluation results,which is worthy of further promotion and application.
In order to study the health evaluation of the tidal river,12 specific aspects including river morphology,hydrology,water quality,saltwater invasion,biological and social service functions were constructed based on the hydrological,water environment and water ecological characteristics of tidal channel.A segmentedcomprehensive evaluation method was proposed to solve the special difference between the natural characteristics and social function of the long river channel.For health[JP] evaluation,the lower reaches of the Minjiang River were taken as an example in this study.The lower reaches of the Minjiang River can be divided into 5 segments,i.e., the dam of Shuikou power stationBifurcated segment,BifurcatedHongshan Bridge (North channel) segment,Hongshan BridgeConfluence (North channel segment BifurcatedConfluence (South channel) segment and ConfluenceMingjiang River mouth segment,respectively.The results revealed that health state of the BifurcatedConfluence (South channel) segment was categorized in subhealth,while the other 4 segments channels and the overall health status of the lower reaches of the Minjiang River were in general grade.Based on the segmentedintegrated river health evaluation model,the grade criteria of river health and the health status of each river segment can be obtained.The use of game theory to optimize the combined weights of indicators can reduce the subjective impact of weight on the evaluation results,which is worthy of further promotion and application.
2019, 17(6):156-162.
Abstract:
Water temperature is a key environmental factor in the aquatic ecosystem,and it plays an important role in the survival and reproduction of aquatic organisms as well as the ecological balance of the aquatic environmental system.The building of large reservoirs will change the original water temperature structure of the river,and the water temperature stratification will appear in the vertical direction.Due to the limitation of observation conditions and methods,the stratified observation of water temperature in reservoirs with water depth over 200 m is seldom carried out both in China and overseas.In this study,Xiaowan Hydropower Plant on Lancang River was taken as research object,and the uninterrupted high density water temperature data of 1-200 m depth in front of the dam was obtained to examine the vertical water temperature distribution characteristics in front of the dam of Xiaowan Hydropower Plant.The results showed that Xiaowan Reservoir was a typical stratified reservoir with annual water temperature stratification in front of the dam,which appeared most obvious in summer and most subtly in winter.The annual average temperature difference of surface and bottom water was 8.14 ℃ and the annual change rate of water temperature relative to water depth was 0.04 ℃/m.There was a positive correlation between surface water temperature and air temperature in front of the dam,and the maximum water temperature appeared lags behind the air temperature.The changing trend of thermocline thickness was opposite to the depth and the depth of thermocline decreased in spring,increased in winter while remained stable in summer and autumn,respectively.
Water temperature is a key environmental factor in the aquatic ecosystem,and it plays an important role in the survival and reproduction of aquatic organisms as well as the ecological balance of the aquatic environmental system.The building of large reservoirs will change the original water temperature structure of the river,and the water temperature stratification will appear in the vertical direction.Due to the limitation of observation conditions and methods,the stratified observation of water temperature in reservoirs with water depth over 200 m is seldom carried out both in China and overseas.In this study,Xiaowan Hydropower Plant on Lancang River was taken as research object,and the uninterrupted high density water temperature data of 1-200 m depth in front of the dam was obtained to examine the vertical water temperature distribution characteristics in front of the dam of Xiaowan Hydropower Plant.The results showed that Xiaowan Reservoir was a typical stratified reservoir with annual water temperature stratification in front of the dam,which appeared most obvious in summer and most subtly in winter.The annual average temperature difference of surface and bottom water was 8.14 ℃ and the annual change rate of water temperature relative to water depth was 0.04 ℃/m.There was a positive correlation between surface water temperature and air temperature in front of the dam,and the maximum water temperature appeared lags behind the air temperature.The changing trend of thermocline thickness was opposite to the depth and the depth of thermocline decreased in spring,increased in winter while remained stable in summer and autumn,respectively.
2019, 17(6):163-169.
Abstract:
It is of great significance to determine permeability and influence radius of pumping test from a single complete submersible well in arid area,which was roughly calculated from Kuzagin formula with Hydrogeologic data at the Shunping County in this study.Characteristics of α readings and spontaneous potential of the well were investigated,and then well observations were used to verify the relationship among α readings,spontaneous potential and the influence radius.The results showed that there was a close relationship among α readins,spontaneous potential and influence radius.The maximum value of α readings and spontaneous potential appeared at the spot of pumping well.These two parameters decreased gradually from the spot of pumping well to the edge of influence radius,and at last these two values approached background level of original water table.The accuracy of Kusagin formula, which is commonly used in steady pumping test of complete submersible well was poor.The α readings and spontaneous potential were then used to obtain the influence radius, and the result was reliable.It was a representative example in middle and fine sand aquifers with similar conditions.
It is of great significance to determine permeability and influence radius of pumping test from a single complete submersible well in arid area,which was roughly calculated from Kuzagin formula with Hydrogeologic data at the Shunping County in this study.Characteristics of α readings and spontaneous potential of the well were investigated,and then well observations were used to verify the relationship among α readings,spontaneous potential and the influence radius.The results showed that there was a close relationship among α readins,spontaneous potential and influence radius.The maximum value of α readings and spontaneous potential appeared at the spot of pumping well.These two parameters decreased gradually from the spot of pumping well to the edge of influence radius,and at last these two values approached background level of original water table.The accuracy of Kusagin formula, which is commonly used in steady pumping test of complete submersible well was poor.The α readings and spontaneous potential were then used to obtain the influence radius, and the result was reliable.It was a representative example in middle and fine sand aquifers with similar conditions.
2019, 17(6):170-177.
Abstract:
The Archean metamorphic rock in Fuping County has undergone multiple stages of metamorphosed deep melting,mainly composed of plutonium rich gneiss.The stratum is dense and flexible,and it is very difficult to find water because it contains a small amount of groundwater.Based on the combination of geological survey,geophysical exploration and drilling verification, this work systematically analyzed the regularity and electrical characteristics of the four types of groundwater,including structural fissure water in the metamorphic rock area,fissures in the weathering crust,pore water,layered fissure water,and contact type bedrock fissure water.The results show that the structural fissure water was mainly distributed in the structural fracture zone.The fissure porosity water in the weathering crust was widely distributed but the water volume was small.The water richness of the weathered crust and fracture zone in the valley was generally larger,the layered fissure water and the contact bedrock Fracture water was predominantly present on the contact zone of a hard brittle-soft rock combination.In the apparent resistivity section,the structural fissure water presented a steep reduction stopband,and the composite weathercock fissureporosity water presented a concave lowresistance curve.Layered fissure water surface distribution showing a horizontal low resistance curve.Bedrock fissure water contacted with the veins presented as strip-shaped high resistance+type fault low resistance reflection.
The Archean metamorphic rock in Fuping County has undergone multiple stages of metamorphosed deep melting,mainly composed of plutonium rich gneiss.The stratum is dense and flexible,and it is very difficult to find water because it contains a small amount of groundwater.Based on the combination of geological survey,geophysical exploration and drilling verification, this work systematically analyzed the regularity and electrical characteristics of the four types of groundwater,including structural fissure water in the metamorphic rock area,fissures in the weathering crust,pore water,layered fissure water,and contact type bedrock fissure water.The results show that the structural fissure water was mainly distributed in the structural fracture zone.The fissure porosity water in the weathering crust was widely distributed but the water volume was small.The water richness of the weathered crust and fracture zone in the valley was generally larger,the layered fissure water and the contact bedrock Fracture water was predominantly present on the contact zone of a hard brittle-soft rock combination.In the apparent resistivity section,the structural fissure water presented a steep reduction stopband,and the composite weathercock fissureporosity water presented a concave lowresistance curve.Layered fissure water surface distribution showing a horizontal low resistance curve.Bedrock fissure water contacted with the veins presented as strip-shaped high resistance+type fault low resistance reflection.
2019, 17(6):178-186.
Abstract:
The inlet vortex of the pumping station can endanger the operation of the pump and reduce the performance of the pumping station.The occurrence and development of the intake vortex is related to the submerged depth of the intake.In this paper,five different submerged depths were selected based on the actual operation of the pumping station,and therefore,the numerical simulation was carried out by using fluent software.The flow field structure of the intake of different submerged depths were analyzed,and then the vortex value and the distribution law of vortex were obtained.The results showed that submerged depth at 0.09D (intake height of passage) to 0.2D and constant flow rate,the vortex strength become smaller with the increase of submerged depth..The vortex intensity of the 0.09D submerged depth was the largest,and there was no obvious vortex at the submerged depth of 0D and 0.05D.The results also revealed that when the submerged depth was 0.09D,0.14D and 0.2D,respectively,the vortex was terminated near 0.3 m below the top plate.The research results can provide a reference for the design of the inlet submerged depth of the pumping station.
The inlet vortex of the pumping station can endanger the operation of the pump and reduce the performance of the pumping station.The occurrence and development of the intake vortex is related to the submerged depth of the intake.In this paper,five different submerged depths were selected based on the actual operation of the pumping station,and therefore,the numerical simulation was carried out by using fluent software.The flow field structure of the intake of different submerged depths were analyzed,and then the vortex value and the distribution law of vortex were obtained.The results showed that submerged depth at 0.09D (intake height of passage) to 0.2D and constant flow rate,the vortex strength become smaller with the increase of submerged depth..The vortex intensity of the 0.09D submerged depth was the largest,and there was no obvious vortex at the submerged depth of 0D and 0.05D.The results also revealed that when the submerged depth was 0.09D,0.14D and 0.2D,respectively,the vortex was terminated near 0.3 m below the top plate.The research results can provide a reference for the design of the inlet submerged depth of the pumping station.
23 Analysis of the effect of valve characteristics on hydraulic transition process of pumping station
2019, 17(6):187-192.
Abstract:
The control valve is used to protect water pump from falling back when pump is stopped accidentally.But it is inventible to cause water hammer which is unfavorable to the water pipe line.Therefore,valve characteristic which can not only effectively prevent the pump from runaway but is also valid for controlling the valve closure water hammer should become the research priorities .Firstly,an ideal relationship model between the nondimensional flow coefficient of pump outlet valve and relative valve opening was theoretically derived.Then,through the hydraulic transient simulations of practical engineering,several typical valve characteristics were compared,and the proposed water hammer control effect of ideal valve characteristic was evaluated.The results showed that the control valve characteristic was an important factor affecting the hydraulic transient of pump station,and the ideal characteristic should be concave.The pump outlet valve with convex characteristic should not be selected because the maximum outlet pressure was large.When the pump outlet valve had ideal concave characteristic,the maximum pressure at the valve outlet decreased significantly under the same valve closing condition.In addition,the ideal valve was also beneficial for improving the minimum pressure along the pipeline and prevents the form of negative pressure.The ideal characteristic model of control valve can provide important theoretical support for the selection of pump outlet control valve in water diversion project.
The control valve is used to protect water pump from falling back when pump is stopped accidentally.But it is inventible to cause water hammer which is unfavorable to the water pipe line.Therefore,valve characteristic which can not only effectively prevent the pump from runaway but is also valid for controlling the valve closure water hammer should become the research priorities .Firstly,an ideal relationship model between the nondimensional flow coefficient of pump outlet valve and relative valve opening was theoretically derived.Then,through the hydraulic transient simulations of practical engineering,several typical valve characteristics were compared,and the proposed water hammer control effect of ideal valve characteristic was evaluated.The results showed that the control valve characteristic was an important factor affecting the hydraulic transient of pump station,and the ideal characteristic should be concave.The pump outlet valve with convex characteristic should not be selected because the maximum outlet pressure was large.When the pump outlet valve had ideal concave characteristic,the maximum pressure at the valve outlet decreased significantly under the same valve closing condition.In addition,the ideal valve was also beneficial for improving the minimum pressure along the pipeline and prevents the form of negative pressure.The ideal characteristic model of control valve can provide important theoretical support for the selection of pump outlet control valve in water diversion project.
2019, 17(6):193-200.
Abstract:
In the detection of dam anti seepage treatment effect,the geophysical method can achieve rapid and non-destructive detection.However,it is difficult to make an accurate judgment on the quality of anti-seepage treatment because of the multi-solution of single geophysical method.In order to analyze the anti-seepage effect of concrete seepage presentation wall and curtain grouting of a reservoir dam, different geophysical methods such as ground penetrating radar and high density electrical method of detection were carried.The detection test showed that the continuity of the dam cut off wall was generally good,and there were no obvious discontinuities,holes and other abnormal defects.There were intermittent areas of low resistance on the downstream side of the dam,some of which had high water content.There were contact and leakage between the water pipeline and the dam body.The dam body downstream of the K0+200 to K0+300 section had poor filling quality,loose body,and high water content.The karst was developed with high water content between the foot of right dam and the mountain.The geophysical exploration technology can be applied to the detection of seepage prevention effect of concrete impermeable wall and dam foundation curtain grouting.
In the detection of dam anti seepage treatment effect,the geophysical method can achieve rapid and non-destructive detection.However,it is difficult to make an accurate judgment on the quality of anti-seepage treatment because of the multi-solution of single geophysical method.In order to analyze the anti-seepage effect of concrete seepage presentation wall and curtain grouting of a reservoir dam, different geophysical methods such as ground penetrating radar and high density electrical method of detection were carried.The detection test showed that the continuity of the dam cut off wall was generally good,and there were no obvious discontinuities,holes and other abnormal defects.There were intermittent areas of low resistance on the downstream side of the dam,some of which had high water content.There were contact and leakage between the water pipeline and the dam body.The dam body downstream of the K0+200 to K0+300 section had poor filling quality,loose body,and high water content.The karst was developed with high water content between the foot of right dam and the mountain.The geophysical exploration technology can be applied to the detection of seepage prevention effect of concrete impermeable wall and dam foundation curtain grouting.
25 Study on the hydraulic characteristics of dustpan shaped inlet of an axial flow pump based on PANS
2019, 17(6):201-208.
Abstract:
A three dimensional numerical simulation was carried out using CFD model and a modified secondary development PANS turbulence model,to study the turbulence model applicability for simulation of dustpan shaped inlet axial flow pump.The results showed that the modified PANS turbulence model can capture the vortices of various turbulence scales,and can reflect the detail characteristics of internal flows.Four scheme were proposed to study the influence of isolation pier,length of isolation pier and rear wall distance on the internal hydraulic characteristics of inlet passage.The results showed that the pulsation value of point pressure near the outer wall of inlet passage bell mouth was the smallest in scheme 3,and the pulsation value of the point J3 and J4 was about 77% and 62% of the original scheme.In scheme 4,the internal flow characteristics of inlet passage were the best and the hydraulic loss was the least,which was about 25% of the original scheme.
A three dimensional numerical simulation was carried out using CFD model and a modified secondary development PANS turbulence model,to study the turbulence model applicability for simulation of dustpan shaped inlet axial flow pump.The results showed that the modified PANS turbulence model can capture the vortices of various turbulence scales,and can reflect the detail characteristics of internal flows.Four scheme were proposed to study the influence of isolation pier,length of isolation pier and rear wall distance on the internal hydraulic characteristics of inlet passage.The results showed that the pulsation value of point pressure near the outer wall of inlet passage bell mouth was the smallest in scheme 3,and the pulsation value of the point J3 and J4 was about 77% and 62% of the original scheme.In scheme 4,the internal flow characteristics of inlet passage were the best and the hydraulic loss was the least,which was about 25% of the original scheme.
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