Simulations were conducted with the regional climate model RegCM incorporating water table dynamics from 1 September 1982 to 28 August 2002 to detect precipitation and temperature extremes. Compared with observed r10(...Simulations were conducted with the regional climate model RegCM incorporating water table dynamics from 1 September 1982 to 28 August 2002 to detect precipitation and temperature extremes. Compared with observed r10(number of days with precipitation ≥ 10 mm d–1), RegCM3_Hydro(the regional climate model with water table dynamics considered) simulated rain belts, including those in southern China and the middle and lower reaches of the Yangtze River, and provided data for arid to semi-arid areas such as the Heihe River Basin in northwestern China. RegCM3_Hydro indicated a significant increasing trend of r95p(days with daily precipitation greater than the 95th percentile of daily amounts) for the Yangtze, Yellow, and Pearl River basins, consistent with r95p observations. The Haihe River Basin was also chosen as a specific case to detect the effect of groundwater on extreme precipitation using peaks over threshold(POT)-based generalized Pareto distribution(GPD) with parameters estimated by the L-moment method. Quantile plots showed that all but a few of the plotted points were distributed near diagonal lines and the modeled data fitted well with the samples. Finally, the effects of water table dynamics on temperature extremes were also evaluated. In the Yellow River Basin and Songhuajiang River Basin, the trends of the number of warm days(TX95n) from RegCM3_Hydro matched observed values more closely when water table dynamics were considered, and clearly increasing numbers of warm days from 1983 to 2001 were detected.展开更多
Hydro-chemical characteristics of groundwater and their changes as affected by human activities were studied in the Ejin Sub-Basin of the Inner Mongolia Autonomous Region, China, to understand the groundwater evolutio...Hydro-chemical characteristics of groundwater and their changes as affected by human activities were studied in the Ejin Sub-Basin of the Inner Mongolia Autonomous Region, China, to understand the groundwater evolution, to identify the predominant geochemical processes taking place along the horizontal groundwater flow path, and to characterize anthropogenic factors affecting the groundwater environment based on previous data. The concentrations of major ions and total dissolved solids (TDS) in the groundwater showed a great variation, with 62.5% of the samples being brackish (TDS ≥ 1 000 mg L^-l). The groundwater system showed a gradual hydro-chemical zonation composed of Na^+ -HCO3^-, Na^+ -Mg^2+ -SO4 ^2 -Cl^-, and Na^+ -Cl^-. The relationships among the dissolved species allowed identification of the origin of solutes and the processes that generated the observed water compositions. The dissolution of halite, dolomite, and 2- gypsum explained, in part, the presence of Na^+, K^+, Cl^-, SO^4 , and Ca^2+, but other processes, such as mixing, Na^+ exchange for Ca^2+ and Mg^2+, and calcite precipitation also contributed to the composition of water. Human activity, in particular large-scale water resources development associated with dramatic population growth in the last 50 years, has led to tremendous changes in the groundwater regime, which reflected in surface water runoff change, decline of groundwater table and degeneration of surface water and groundwater quality. Solving these largely anthropogenic problems requires concerted, massive and long-term efforts.展开更多
Interactions between surface water and groundwater are dynamic and complex in large endorheic river watersheds in Northwest China due to the influence of both irrigation practices and the local terrain. These interact...Interactions between surface water and groundwater are dynamic and complex in large endorheic river watersheds in Northwest China due to the influence of both irrigation practices and the local terrain. These interactions interchange numerous times throughout the middle reaches, making streamflow simulation a challenge in endorheic river watersheds. In this study, we modified the linear-reservoir groundwater module in SWAT(Soil and Water Assessment Tools, a widely used hydrological model) with a new nonlinear relationship to better represent groundwater processes; we then applied the original SWAT and modified SWAT to the Heihe River Watershed, the second largest endorheic river watershed in Northwest China, to simulate streamflow. After calibrating both the original SWAT model and the modified SWAT model, we analyzed model performance during two periods: an irrigation period and a non-irrigation period. Our results show that the modified SWAT model with the nonlinear groundwater module performed significantly better during both the irrigation and non-irrigation periods. Moreover, after comparing different runoff components simulated by the two models, the results show that, after the implementation of the new nonlinear groundwater module in SWAT, proportions of runoff components changed-and the groundwater flow had significantly increased, dominating the discharge season. Therefore, SWAT coupled with the non-linear groundwater module represents the complex hydrological process in the study area more realistically. Moreover, the results for various runoff components simulated by the modified SWAT models can be used to describe the hydrological characteristics of lowland areas. This indicates that the modified SWAT model is applicable to simulate complex hydrological process of arid endorheic rivers.展开更多
The variation characteristics of aquifer parameters,induced by groundwater source heat pump(GWSHP) operation under variable flow,were theoretically analyzed through a case study,in which the characteristics of buildin...The variation characteristics of aquifer parameters,induced by groundwater source heat pump(GWSHP) operation under variable flow,were theoretically analyzed through a case study,in which the characteristics of building air conditioning load were considered.The results,compared with the constant flow operation,indicate that the influence on the variations of porosity,hydraulic conductivity and confined water head is decreased by 48%,51% and 71%,respectively,under variable flow operation.The security of variable flow operation is superior to that of constant flow.It is also concluded that the climate region and function of the buildings are primary factors which affect the suitability of variable flow operation in GWSHP.展开更多
The groundwater flow characteristics of the Galma River Basin were simulated numerically by using the finite element method. The two-dimensional partial differential equation governing transient flow in an unconfined ...The groundwater flow characteristics of the Galma River Basin were simulated numerically by using the finite element method. The two-dimensional partial differential equation governing transient flow in an unconfined aquifer was modified to incorporate the effect of precipitation as a measurable source as it affects groundwater flow, such that for a given amount of precipitation over the basin, the flow of groundwater can be predicted at any point in the basin. With appropriate initial and boundary conditions, the modified equation was solved and the solution programmed for computer run. After calibration and verification, the borehole hydraulic data for the basin was used to predict flow due to groundwater hydraulic heads for 20 years. Findings revealed that there is a direct correlation of 0.79 and a strong linear relationship between simulated and observed hydraulic heads, and that data availability and choice of appropriate initial and boundary conditions are significant for good numerical modelling results. The contour plot of the hydraulic heads showed variation of heads from higher values at the upstream to lower values downstream, and groundwater flow follows the natural topography of the land from the upstream end of the basin towards the main streams and Galma River.展开更多
Assessment report of the Intergovernmental Panel on Climate Change (IPCC) highlighted the complex linkages between climate change and water. The likely warmer climate induced by the climate change is set to alter hy...Assessment report of the Intergovernmental Panel on Climate Change (IPCC) highlighted the complex linkages between climate change and water. The likely warmer climate induced by the climate change is set to alter hydrological cycle and the shifting pattern of the rainfall would affect the spatial and temporal distribution of runoff, soil moisture, and surface and groundwater reserves. Therefore, there is an urgent need to assess the impacts of climate change on water and devise adaptation measures including management structures and processes by which one can deal with this challenge. The paper highlights with the global overview of climate change impacts on water in the arid region, supported and substantiated through scientific evidence drawn from IPCC reports and other relevant documents. This paper provides an overview of water resource management challenges including transboundary geopolitical concerns documented across the world and emphasizes the importance of an integrated framework for adaptive policy making. Further, it examines the viable water resource management options for various sectors and regions and showcases some of the international best practices in adaptation and mitigation. The paper also explains the complementary role of traditional knowledge in coping with climate change risks and uncertainties and the need for a balanced view in designing adaptation and mitigation strategies.展开更多
基金supported by the National Basic Research Program of China (Grant Nos. 2010CB428403 and 2009CB421407)the National Natural Science Foundation of China (Grant No. 91125016)Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA05110102)
文摘Simulations were conducted with the regional climate model RegCM incorporating water table dynamics from 1 September 1982 to 28 August 2002 to detect precipitation and temperature extremes. Compared with observed r10(number of days with precipitation ≥ 10 mm d–1), RegCM3_Hydro(the regional climate model with water table dynamics considered) simulated rain belts, including those in southern China and the middle and lower reaches of the Yangtze River, and provided data for arid to semi-arid areas such as the Heihe River Basin in northwestern China. RegCM3_Hydro indicated a significant increasing trend of r95p(days with daily precipitation greater than the 95th percentile of daily amounts) for the Yangtze, Yellow, and Pearl River basins, consistent with r95p observations. The Haihe River Basin was also chosen as a specific case to detect the effect of groundwater on extreme precipitation using peaks over threshold(POT)-based generalized Pareto distribution(GPD) with parameters estimated by the L-moment method. Quantile plots showed that all but a few of the plotted points were distributed near diagonal lines and the modeled data fitted well with the samples. Finally, the effects of water table dynamics on temperature extremes were also evaluated. In the Yellow River Basin and Songhuajiang River Basin, the trends of the number of warm days(TX95n) from RegCM3_Hydro matched observed values more closely when water table dynamics were considered, and clearly increasing numbers of warm days from 1983 to 2001 were detected.
基金Project supported by the National Natural Science Foundation of China (Nos. 40671010 and 40501012).
文摘Hydro-chemical characteristics of groundwater and their changes as affected by human activities were studied in the Ejin Sub-Basin of the Inner Mongolia Autonomous Region, China, to understand the groundwater evolution, to identify the predominant geochemical processes taking place along the horizontal groundwater flow path, and to characterize anthropogenic factors affecting the groundwater environment based on previous data. The concentrations of major ions and total dissolved solids (TDS) in the groundwater showed a great variation, with 62.5% of the samples being brackish (TDS ≥ 1 000 mg L^-l). The groundwater system showed a gradual hydro-chemical zonation composed of Na^+ -HCO3^-, Na^+ -Mg^2+ -SO4 ^2 -Cl^-, and Na^+ -Cl^-. The relationships among the dissolved species allowed identification of the origin of solutes and the processes that generated the observed water compositions. The dissolution of halite, dolomite, and 2- gypsum explained, in part, the presence of Na^+, K^+, Cl^-, SO^4 , and Ca^2+, but other processes, such as mixing, Na^+ exchange for Ca^2+ and Mg^2+, and calcite precipitation also contributed to the composition of water. Human activity, in particular large-scale water resources development associated with dramatic population growth in the last 50 years, has led to tremendous changes in the groundwater regime, which reflected in surface water runoff change, decline of groundwater table and degeneration of surface water and groundwater quality. Solving these largely anthropogenic problems requires concerted, massive and long-term efforts.
基金Under the auspices of Natural Science Foundation of Qinghai Province(No.2017-ZJ-961Q)National Natural Science Foundation of China(No.91125010,41530752)Scherer Endowment Fund of Department of Geography,Western Michigan University
文摘Interactions between surface water and groundwater are dynamic and complex in large endorheic river watersheds in Northwest China due to the influence of both irrigation practices and the local terrain. These interactions interchange numerous times throughout the middle reaches, making streamflow simulation a challenge in endorheic river watersheds. In this study, we modified the linear-reservoir groundwater module in SWAT(Soil and Water Assessment Tools, a widely used hydrological model) with a new nonlinear relationship to better represent groundwater processes; we then applied the original SWAT and modified SWAT to the Heihe River Watershed, the second largest endorheic river watershed in Northwest China, to simulate streamflow. After calibrating both the original SWAT model and the modified SWAT model, we analyzed model performance during two periods: an irrigation period and a non-irrigation period. Our results show that the modified SWAT model with the nonlinear groundwater module performed significantly better during both the irrigation and non-irrigation periods. Moreover, after comparing different runoff components simulated by the two models, the results show that, after the implementation of the new nonlinear groundwater module in SWAT, proportions of runoff components changed-and the groundwater flow had significantly increased, dominating the discharge season. Therefore, SWAT coupled with the non-linear groundwater module represents the complex hydrological process in the study area more realistically. Moreover, the results for various runoff components simulated by the modified SWAT models can be used to describe the hydrological characteristics of lowland areas. This indicates that the modified SWAT model is applicable to simulate complex hydrological process of arid endorheic rivers.
基金Project(2006BAJ01B05) supported by the National Science and Technology Pillar Program during the 11th Five-Year Plane Period
文摘The variation characteristics of aquifer parameters,induced by groundwater source heat pump(GWSHP) operation under variable flow,were theoretically analyzed through a case study,in which the characteristics of building air conditioning load were considered.The results,compared with the constant flow operation,indicate that the influence on the variations of porosity,hydraulic conductivity and confined water head is decreased by 48%,51% and 71%,respectively,under variable flow operation.The security of variable flow operation is superior to that of constant flow.It is also concluded that the climate region and function of the buildings are primary factors which affect the suitability of variable flow operation in GWSHP.
文摘The groundwater flow characteristics of the Galma River Basin were simulated numerically by using the finite element method. The two-dimensional partial differential equation governing transient flow in an unconfined aquifer was modified to incorporate the effect of precipitation as a measurable source as it affects groundwater flow, such that for a given amount of precipitation over the basin, the flow of groundwater can be predicted at any point in the basin. With appropriate initial and boundary conditions, the modified equation was solved and the solution programmed for computer run. After calibration and verification, the borehole hydraulic data for the basin was used to predict flow due to groundwater hydraulic heads for 20 years. Findings revealed that there is a direct correlation of 0.79 and a strong linear relationship between simulated and observed hydraulic heads, and that data availability and choice of appropriate initial and boundary conditions are significant for good numerical modelling results. The contour plot of the hydraulic heads showed variation of heads from higher values at the upstream to lower values downstream, and groundwater flow follows the natural topography of the land from the upstream end of the basin towards the main streams and Galma River.
文摘Assessment report of the Intergovernmental Panel on Climate Change (IPCC) highlighted the complex linkages between climate change and water. The likely warmer climate induced by the climate change is set to alter hydrological cycle and the shifting pattern of the rainfall would affect the spatial and temporal distribution of runoff, soil moisture, and surface and groundwater reserves. Therefore, there is an urgent need to assess the impacts of climate change on water and devise adaptation measures including management structures and processes by which one can deal with this challenge. The paper highlights with the global overview of climate change impacts on water in the arid region, supported and substantiated through scientific evidence drawn from IPCC reports and other relevant documents. This paper provides an overview of water resource management challenges including transboundary geopolitical concerns documented across the world and emphasizes the importance of an integrated framework for adaptive policy making. Further, it examines the viable water resource management options for various sectors and regions and showcases some of the international best practices in adaptation and mitigation. The paper also explains the complementary role of traditional knowledge in coping with climate change risks and uncertainties and the need for a balanced view in designing adaptation and mitigation strategies.