Affected by external environmental factors and evolution of dam performance, dam seepage behavior shows nonlinear time-varying characteristics. In this study, to predict and evaluate the long-term development trend an...Affected by external environmental factors and evolution of dam performance, dam seepage behavior shows nonlinear time-varying characteristics. In this study, to predict and evaluate the long-term development trend and short-term fluctuation of the dam seepage behavior, two monitoring models were developed, one for the base flow effect and one for daily variation of dam seepage elements. In the first model, to avoid the influence of the time lag effect on the evaluation of seepage variation with the time effect component of seepage elements, the base values of the seepage element and the reservoir water level were extracted using the wavelet multi-resolution analysis method, and the time effect component was separated by the established base flow effect monitoring model. For the development of the daily variation monitoring model for dam seepage elements, all the previous factors, of which the measured time series prior to the dam seepage element monitoring time may have certain influence on the monitored results, were considered. Those factors that were positively correlated with the analyzed seepage element were initially considered to be the support vector machine(SVM) model input factors, and then the SVM kernel function-based sensitivity analysis was performed to optimize the input factor set and establish the optimized daily variation SVM model. The efficiency and rationality of the two models were verified by case studies of the water level of two piezometric tubes buried under the slope of a concrete gravity dam.Sensitivity analysis of the optimized SVM model shows that the influences of the daily variation of the upstream reservoir water level and rainfall on the daily variation of piezometric tube water level are processes subject to normal distribution.展开更多
Extreme hydrological events induced by typhoons in reservoir areas have presented severe challenges to the safe operation of hydraulic structures. Based on analysis of the seepage characteristics of an earth rock dam,...Extreme hydrological events induced by typhoons in reservoir areas have presented severe challenges to the safe operation of hydraulic structures. Based on analysis of the seepage characteristics of an earth rock dam, a novel seepage safety monitoring model was constructed in this study. The nonlinear influence processes of the antecedent reservoir water level and rainfall were assumed to follow normal distributions. The particle swarm optimization （PSO） algorithm was used to optimize the model parameters so as to raise the fitting accuracy. In addition, a mutation factor was introduced to simulate the sudden increase in the piezometric level induced by short-duration heavy rainfall and the possible historical extreme reservoir water level during a typhoon. In order to verify the efficacy of this model, the earth rock dam of the Siminghu Reservoir was used as an example. The piezometric level at the SW1-2 measuring point during Typhoon Fitow in 2013 was fitted with the present model, and a corresponding theoretical expression was established. Comparison of fitting results of the piezometric level obtained from the present statistical model and traditional statistical model with monitored values during the typhoon shows that the present model has a higher fitting accuracy and can simulate the uprush feature of the seepage pressure during the typhoon perfectly.展开更多
Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. T...Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. This aquifer covers an area of 250 Km2, and represents an essential water resource for Laayoun city and the periphery regions. It is heavily exploited for water supply, agriculture and industry. The freshwater-saltwater interface is affected by groundwater extraction by public supplies, irrigation wells, and domestic wells in the coastal of this aquifer. The position of the interface is controlled by several factors: these include precipitation, recharge rate, dryness, evapotranspiration, hydraulic conductivity and hydraulic head. Landward migration of the interface freshwater-saltwater often results in a significant decrease in the water resources available for coastal communities. The volume pumped by public for irrigation and the domestic usage in 2010-2011 is estimated 2.5 Mm3/year, and in 2015 about 2.91 Mm3/year only for domestic usages. The objectives of this work are to model the groundwater flow and saltwater intrusion in the coastal aquifer of Fum Al Wad, by SEAWAT-2000 program which coupled both the version of MODFLOW-2000 and MT3DMS. They are designed to simulate variable-density groundwater flow and solute transport in three dimensions. The model is calibrated for hydraulic conductivity, specific yield, porosity, and recharge rate as well as dispersivity coefficient. The result of simulation of the hydrodynamic model during the period of 1986-2015 has revealed a piezometric drawdown with 2.3 m approximately at the level of the pumping zone. Furthermore, this piezometric depression is caused by excessive pumping of the various uses of water and its corresponding that has resulted in the migration of the saltwater intrusion into freshwater with 4.3 km approximately. The simulations result for scenarios 2020 and 2030 of Fum Al Wad aquifer showed a vertical decrease of the piezometric head (a展开更多
The Cheria region in Northeastern Algeria has been facing aquifer overexploitation by the agricultural sector and prolonged droughts,resulting in a considerable decline in groundwater levels.This study investigates th...The Cheria region in Northeastern Algeria has been facing aquifer overexploitation by the agricultural sector and prolonged droughts,resulting in a considerable decline in groundwater levels.This study investigates the feasibility of implementing artificial recharge techniques to replenish the Eocene aquifer which serves as the primary water source in the Cheria region.A 3D transient numerical model,based on the finite difference method,was used to simulate groundwater flow from 2021 to 2031 using Visual MODFLOW Flex.During the modelling process,three scenarios were considered:(1)including pumping without a recharge,(2)recharge of the entire area through efficient infiltration without pumping,and(3)artificial recharge using river water infiltration basins at two sites,Draa Douamis sinkholes and Eocene limestone outcrops.The simulation results showed that aquifer exploitation without recharge caused significant drawdowns,which were 3 m to 7 m in the north-eastern part and 8 m to 12 m in the central and southern parts.In contrast,the second scenario,involving recharge without pumping,showed a rise in groundwater levels of 2 m to 2.7 m in the north-eastern part and 3 m to 3.62 m in the central and southern parts.The third scenario,employing artificial recharge,indicated a positive response to artificial recharge,with increased piezometric levels at the proposed sites,signifying a beneficial impact on the aquifer.These findings underline the potential of artificial recharge as a promising approach to address the groundwater depletion and environmental issues in the Cheria Basin.展开更多
The continuous aquifers of the Congolese Cuvette basin constitute the seat of significant water tables reversibly supplying the Congo River basin as well as the water tables they drain. Consisting mainly of sandy-clay...The continuous aquifers of the Congolese Cuvette basin constitute the seat of significant water tables reversibly supplying the Congo River basin as well as the water tables they drain. Consisting mainly of sandy-clayey-sandstone formations, these aquifers contain groundwater which is the main source of drinking water supply for communities in this sector of the departments Cuvette and Cuvette-Ouest. The need for water being more and more acute, these aquifers have been subjected to drilling operations in order to supply drinking water to these populations. The information obtained from these operations is data which made it possible to obtain information relating to the lithology, the hydrogeological parameters of these aquifers and information on the depth and on the lateral variations of the water table. The purpose of this present work is to contribute to the hydrogeological characterization of the aquifer of the Cuvette basin in the departments of Cuvette and Cuvette-Ouest via data from the analysis of the technical sheets of drillings carried out by the ASPERBRAS Company, collected at the Ministry of Major Works and territory planning. This characterization was made using Visual MODFLOW Flex 2015.1 software coupled with Surfer 10 software and Rock Works 17 software. The hydrogeological interpretation of the data shows that this aquifer, whose constitution is essentially made up of sands, clayey sands and clay, is continuous, porous and free. This composition gives the aquifer of Cuvette basin a heterogeneous character. In addition, a piezometric map was produced in order to indicate the direction of the water flows which turned out to be from west to east towards the lowest areas occupied by the valleys of the rivers and rivers. The conceptual model shows that the depth of the aquifer deceases considerably from the Cuvette-Ouest towards the Cuvette.展开更多
Growing water scarcity is one of the major challenges of the 21st century, especially in arid and semi-arid climates such as our study area. The efficient, sustainable and integrated groundwater management plays a key...Growing water scarcity is one of the major challenges of the 21st century, especially in arid and semi-arid climates such as our study area. The efficient, sustainable and integrated groundwater management plays a key role for conserving this vital resource. In order to overcome this issue, the study of aquifer system’s behavior seems necessary. For this purpose, the areal piezometric level map is an essential tool. As piezometric level data are spatially limited in sample points, the?spatial interpolation and geostatistics are the best way to produce the needed map. Several methods exist allowing to approach real values with varying degrees of accuracy. This work aims to compare?and evaluate spatial interpolation methods for groundwater level of Haouz using a dataset of 39 piezometers. The deterministic methods used in this study are Inverse Distance Weighted (IDW) and Radial Basis Functions (RBF) and the probabilistic ones are ordinary kriging (OK), simple kriging (SK) and universal kriging (UK). This study shows the difficulty of having a key role to choose the suitable method for given input dataset. The best model remains the one that, after comparing several methods, offers the best accuracy, which is assessed using Cross-validation and statistical indicators. The results reveals that ordinary kriging with trend removal technique is the optimal method in this case. It indicates the superiority of this technique with a decrease in Root Mean Square Error (RMSE) up to 61.67%. It underestimates groundwater level with an average of 2.8%, which is reliable. The areal piezometric level and associated prediction standard error maps give additional information and recommendations that characterize the studied aquifer system and will ultimately improve sustainable groundwater management.展开更多
This study was completed by an extensive mathematical analysis. New equation to sludge filtration processes has been proposed for use in routine laboratory. The equation has been suggested to replace Ademiluyi’s cake...This study was completed by an extensive mathematical analysis. New equation to sludge filtration processes has been proposed for use in routine laboratory. The equation has been suggested to replace Ademiluyi’s cake filtration equation in view of the limitations of the latter. The new equation can be used for sludges whose compressibility factor is more than one but Ademiluyi’s cake filtration equation can only be used for sludges whose compressibility coefficient is less than one. The new sludge filtration equation was derived using tannθ reduction method. The generalized equation thus obtained resembles Ademiluyi’s equation in the mode of parameter combination except the presence of summation notation in the new equation.展开更多
The Gondo plain lies between Mali and Burkina Faso and it is in interland basin into the West African Craton. Since 2003, this study has been carried out two research projects on the southwest part of the plain, where...The Gondo plain lies between Mali and Burkina Faso and it is in interland basin into the West African Craton. Since 2003, this study has been carried out two research projects on the southwest part of the plain, where the piezometric levels are very low （50 m to 100 m）. It has two main purposes： find water resources to provide drinking water supply to Ouahigouya town and assess the exploitation possibility of the deep aquifer for rural water supply. Combined methods were used to reach the objectives of this study--remote sensing, geology, geophysics （electromagnetism and resistivity methods）, hydrochemistry and isotope chemistry. So, the methodology allows to specify the geology and the tectonic of the eastern border of the basin, identify and characterize the different aquifers and their relationships. Through the implementation of 250 m deep drilled boreholes, this study reveals that the water level of the lower Cambrian limestones can be under pressure below the continental terminal deposits. The study highlights paleo-karstic zones in the Gondo plain and shows that water chemistry and isotope chemistry can be used to differentiate water sheets and evaluate their recharge.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51709021)the Open Foundation of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(Grant No.2016491111)
文摘Affected by external environmental factors and evolution of dam performance, dam seepage behavior shows nonlinear time-varying characteristics. In this study, to predict and evaluate the long-term development trend and short-term fluctuation of the dam seepage behavior, two monitoring models were developed, one for the base flow effect and one for daily variation of dam seepage elements. In the first model, to avoid the influence of the time lag effect on the evaluation of seepage variation with the time effect component of seepage elements, the base values of the seepage element and the reservoir water level were extracted using the wavelet multi-resolution analysis method, and the time effect component was separated by the established base flow effect monitoring model. For the development of the daily variation monitoring model for dam seepage elements, all the previous factors, of which the measured time series prior to the dam seepage element monitoring time may have certain influence on the monitored results, were considered. Those factors that were positively correlated with the analyzed seepage element were initially considered to be the support vector machine(SVM) model input factors, and then the SVM kernel function-based sensitivity analysis was performed to optimize the input factor set and establish the optimized daily variation SVM model. The efficiency and rationality of the two models were verified by case studies of the water level of two piezometric tubes buried under the slope of a concrete gravity dam.Sensitivity analysis of the optimized SVM model shows that the influences of the daily variation of the upstream reservoir water level and rainfall on the daily variation of piezometric tube water level are processes subject to normal distribution.
基金supported by the National Natural Science Foundation of China(Grants No.51179108 and 51679151)the Special Fund for the Public Welfare Industry of the Ministry of Water Resources of China(Grant No.201501033)+1 种基金the National Key Research and Development Program(Grant No.2016YFC0401603)the Program Sponsored for Scientific Innovation Research of College Graduates in Jiangsu Province(Grant No.KYZZ15_0140)
文摘Extreme hydrological events induced by typhoons in reservoir areas have presented severe challenges to the safe operation of hydraulic structures. Based on analysis of the seepage characteristics of an earth rock dam, a novel seepage safety monitoring model was constructed in this study. The nonlinear influence processes of the antecedent reservoir water level and rainfall were assumed to follow normal distributions. The particle swarm optimization （PSO） algorithm was used to optimize the model parameters so as to raise the fitting accuracy. In addition, a mutation factor was introduced to simulate the sudden increase in the piezometric level induced by short-duration heavy rainfall and the possible historical extreme reservoir water level during a typhoon. In order to verify the efficacy of this model, the earth rock dam of the Siminghu Reservoir was used as an example. The piezometric level at the SW1-2 measuring point during Typhoon Fitow in 2013 was fitted with the present model, and a corresponding theoretical expression was established. Comparison of fitting results of the piezometric level obtained from the present statistical model and traditional statistical model with monitored values during the typhoon shows that the present model has a higher fitting accuracy and can simulate the uprush feature of the seepage pressure during the typhoon perfectly.
文摘Saltwater intrusion caused by groundwater over-exploitation from coastal aquifers poses a severe problem in many regions. The Fum Al Wad aquifer is located between Atlantic Ocean in the West and Laayoun in the East. This aquifer covers an area of 250 Km2, and represents an essential water resource for Laayoun city and the periphery regions. It is heavily exploited for water supply, agriculture and industry. The freshwater-saltwater interface is affected by groundwater extraction by public supplies, irrigation wells, and domestic wells in the coastal of this aquifer. The position of the interface is controlled by several factors: these include precipitation, recharge rate, dryness, evapotranspiration, hydraulic conductivity and hydraulic head. Landward migration of the interface freshwater-saltwater often results in a significant decrease in the water resources available for coastal communities. The volume pumped by public for irrigation and the domestic usage in 2010-2011 is estimated 2.5 Mm3/year, and in 2015 about 2.91 Mm3/year only for domestic usages. The objectives of this work are to model the groundwater flow and saltwater intrusion in the coastal aquifer of Fum Al Wad, by SEAWAT-2000 program which coupled both the version of MODFLOW-2000 and MT3DMS. They are designed to simulate variable-density groundwater flow and solute transport in three dimensions. The model is calibrated for hydraulic conductivity, specific yield, porosity, and recharge rate as well as dispersivity coefficient. The result of simulation of the hydrodynamic model during the period of 1986-2015 has revealed a piezometric drawdown with 2.3 m approximately at the level of the pumping zone. Furthermore, this piezometric depression is caused by excessive pumping of the various uses of water and its corresponding that has resulted in the migration of the saltwater intrusion into freshwater with 4.3 km approximately. The simulations result for scenarios 2020 and 2030 of Fum Al Wad aquifer showed a vertical decrease of the piezometric head (a
文摘The Cheria region in Northeastern Algeria has been facing aquifer overexploitation by the agricultural sector and prolonged droughts,resulting in a considerable decline in groundwater levels.This study investigates the feasibility of implementing artificial recharge techniques to replenish the Eocene aquifer which serves as the primary water source in the Cheria region.A 3D transient numerical model,based on the finite difference method,was used to simulate groundwater flow from 2021 to 2031 using Visual MODFLOW Flex.During the modelling process,three scenarios were considered:(1)including pumping without a recharge,(2)recharge of the entire area through efficient infiltration without pumping,and(3)artificial recharge using river water infiltration basins at two sites,Draa Douamis sinkholes and Eocene limestone outcrops.The simulation results showed that aquifer exploitation without recharge caused significant drawdowns,which were 3 m to 7 m in the north-eastern part and 8 m to 12 m in the central and southern parts.In contrast,the second scenario,involving recharge without pumping,showed a rise in groundwater levels of 2 m to 2.7 m in the north-eastern part and 3 m to 3.62 m in the central and southern parts.The third scenario,employing artificial recharge,indicated a positive response to artificial recharge,with increased piezometric levels at the proposed sites,signifying a beneficial impact on the aquifer.These findings underline the potential of artificial recharge as a promising approach to address the groundwater depletion and environmental issues in the Cheria Basin.
文摘The continuous aquifers of the Congolese Cuvette basin constitute the seat of significant water tables reversibly supplying the Congo River basin as well as the water tables they drain. Consisting mainly of sandy-clayey-sandstone formations, these aquifers contain groundwater which is the main source of drinking water supply for communities in this sector of the departments Cuvette and Cuvette-Ouest. The need for water being more and more acute, these aquifers have been subjected to drilling operations in order to supply drinking water to these populations. The information obtained from these operations is data which made it possible to obtain information relating to the lithology, the hydrogeological parameters of these aquifers and information on the depth and on the lateral variations of the water table. The purpose of this present work is to contribute to the hydrogeological characterization of the aquifer of the Cuvette basin in the departments of Cuvette and Cuvette-Ouest via data from the analysis of the technical sheets of drillings carried out by the ASPERBRAS Company, collected at the Ministry of Major Works and territory planning. This characterization was made using Visual MODFLOW Flex 2015.1 software coupled with Surfer 10 software and Rock Works 17 software. The hydrogeological interpretation of the data shows that this aquifer, whose constitution is essentially made up of sands, clayey sands and clay, is continuous, porous and free. This composition gives the aquifer of Cuvette basin a heterogeneous character. In addition, a piezometric map was produced in order to indicate the direction of the water flows which turned out to be from west to east towards the lowest areas occupied by the valleys of the rivers and rivers. The conceptual model shows that the depth of the aquifer deceases considerably from the Cuvette-Ouest towards the Cuvette.
文摘Growing water scarcity is one of the major challenges of the 21st century, especially in arid and semi-arid climates such as our study area. The efficient, sustainable and integrated groundwater management plays a key role for conserving this vital resource. In order to overcome this issue, the study of aquifer system’s behavior seems necessary. For this purpose, the areal piezometric level map is an essential tool. As piezometric level data are spatially limited in sample points, the?spatial interpolation and geostatistics are the best way to produce the needed map. Several methods exist allowing to approach real values with varying degrees of accuracy. This work aims to compare?and evaluate spatial interpolation methods for groundwater level of Haouz using a dataset of 39 piezometers. The deterministic methods used in this study are Inverse Distance Weighted (IDW) and Radial Basis Functions (RBF) and the probabilistic ones are ordinary kriging (OK), simple kriging (SK) and universal kriging (UK). This study shows the difficulty of having a key role to choose the suitable method for given input dataset. The best model remains the one that, after comparing several methods, offers the best accuracy, which is assessed using Cross-validation and statistical indicators. The results reveals that ordinary kriging with trend removal technique is the optimal method in this case. It indicates the superiority of this technique with a decrease in Root Mean Square Error (RMSE) up to 61.67%. It underestimates groundwater level with an average of 2.8%, which is reliable. The areal piezometric level and associated prediction standard error maps give additional information and recommendations that characterize the studied aquifer system and will ultimately improve sustainable groundwater management.
文摘This study was completed by an extensive mathematical analysis. New equation to sludge filtration processes has been proposed for use in routine laboratory. The equation has been suggested to replace Ademiluyi’s cake filtration equation in view of the limitations of the latter. The new equation can be used for sludges whose compressibility factor is more than one but Ademiluyi’s cake filtration equation can only be used for sludges whose compressibility coefficient is less than one. The new sludge filtration equation was derived using tannθ reduction method. The generalized equation thus obtained resembles Ademiluyi’s equation in the mode of parameter combination except the presence of summation notation in the new equation.
文摘The Gondo plain lies between Mali and Burkina Faso and it is in interland basin into the West African Craton. Since 2003, this study has been carried out two research projects on the southwest part of the plain, where the piezometric levels are very low （50 m to 100 m）. It has two main purposes： find water resources to provide drinking water supply to Ouahigouya town and assess the exploitation possibility of the deep aquifer for rural water supply. Combined methods were used to reach the objectives of this study--remote sensing, geology, geophysics （electromagnetism and resistivity methods）, hydrochemistry and isotope chemistry. So, the methodology allows to specify the geology and the tectonic of the eastern border of the basin, identify and characterize the different aquifers and their relationships. Through the implementation of 250 m deep drilled boreholes, this study reveals that the water level of the lower Cambrian limestones can be under pressure below the continental terminal deposits. The study highlights paleo-karstic zones in the Gondo plain and shows that water chemistry and isotope chemistry can be used to differentiate water sheets and evaluate their recharge.
