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timing of snowmelt peaks in New England ( Hodgkins et al. 2003 ). Key questions addressed by this paper are whether the recent increases in precipitation have also been accompanied by increases in evapotranspiration (ET) due to increasing temperatures ( Fennessey and Kirshen 1994 ) and how the relative changes in precipitation and ET in the future will affect snowfall and groundwater recharge ( Kirshen 2002 ). For example, if increases in evapotranspiration (due to increases in temperature) exceed
timing of snowmelt peaks in New England ( Hodgkins et al. 2003 ). Key questions addressed by this paper are whether the recent increases in precipitation have also been accompanied by increases in evapotranspiration (ET) due to increasing temperatures ( Fennessey and Kirshen 1994 ) and how the relative changes in precipitation and ET in the future will affect snowfall and groundwater recharge ( Kirshen 2002 ). For example, if increases in evapotranspiration (due to increases in temperature) exceed
. 2011 ; Gleeson et al. 2012 ; Feng et al. 2013 ; Döll et al. 2014 ; Richey et al. 2015 ; Jasechko and Perrone 2020 ). These issues have prompted certain nations and U.S. states to consider implementing groundwater management policies, such as California’s Sustainable Groundwater Management Act ( https://ca.water.usgs.gov/sustainable-groundwater-management/ ). To comply with these laws and to develop sustainable groundwater use strategies, water managers need information on recharge including
. 2011 ; Gleeson et al. 2012 ; Feng et al. 2013 ; Döll et al. 2014 ; Richey et al. 2015 ; Jasechko and Perrone 2020 ). These issues have prompted certain nations and U.S. states to consider implementing groundwater management policies, such as California’s Sustainable Groundwater Management Act ( https://ca.water.usgs.gov/sustainable-groundwater-management/ ). To comply with these laws and to develop sustainable groundwater use strategies, water managers need information on recharge including
( Zekster and Loaiciga 1993 ; Allen et al. 2004 ; Green et al. 2007 ; Scibek et al. 2007 ), most of these are limited to impacts on recharge and discharge conditions in moderate/large size catchments. Hansen and Dettinger ( Hansen and Dettinger 2005 ) performed a study focusing on linkage between global-scale climate variations and local groundwater response for a coastal aquifer basin of Southern California. Simulations using multiple ensembles of the ECHAM-3.6 were explored by incorporating the
( Zekster and Loaiciga 1993 ; Allen et al. 2004 ; Green et al. 2007 ; Scibek et al. 2007 ), most of these are limited to impacts on recharge and discharge conditions in moderate/large size catchments. Hansen and Dettinger ( Hansen and Dettinger 2005 ) performed a study focusing on linkage between global-scale climate variations and local groundwater response for a coastal aquifer basin of Southern California. Simulations using multiple ensembles of the ECHAM-3.6 were explored by incorporating the
; Dahm et al. 2003 ; Snyder and Williams 2000 ; Scott et al. 2006 ; Steinwand et al. 2006 ). Sophocleous and Perry (1985) found in Kansas that under shallow water table conditions, 70% of springtime groundwater recharge was lost by evapotranspiration during the subsequent summer and fall. Land surface parameterizations used in regional and global climate models traditionally lack groundwater representation, and therefore they do not allow for upward water flux drawn from below the bottom of a
; Dahm et al. 2003 ; Snyder and Williams 2000 ; Scott et al. 2006 ; Steinwand et al. 2006 ). Sophocleous and Perry (1985) found in Kansas that under shallow water table conditions, 70% of springtime groundwater recharge was lost by evapotranspiration during the subsequent summer and fall. Land surface parameterizations used in regional and global climate models traditionally lack groundwater representation, and therefore they do not allow for upward water flux drawn from below the bottom of a
United States is used. Fig . 5. Spatial distributions of (a) r grd and (b) r srf in percentages at the county scale. b. Effects of irrigation and groundwater withdrawal on terrestrial water and energy budgets Groundwater pumping for irrigation can perturb the surface water and energy balances through changes in ET, groundwater recharge, soil moisture, and other budget terms. Figure 6 shows the spatial distributions of annual mean water table depth [ (m)], potential recharge [PE (mm)], and
United States is used. Fig . 5. Spatial distributions of (a) r grd and (b) r srf in percentages at the county scale. b. Effects of irrigation and groundwater withdrawal on terrestrial water and energy budgets Groundwater pumping for irrigation can perturb the surface water and energy balances through changes in ET, groundwater recharge, soil moisture, and other budget terms. Figure 6 shows the spatial distributions of annual mean water table depth [ (m)], potential recharge [PE (mm)], and
groundwater model of the U.S. Geological Survey, has a modular structure and open environment ( McDonald and Harbaugh 1988 ). It was selected for the model integration in order to link its three packages for simulating water exchanges between aquifer and other hydrological components (i.e., recharge, evapotranspiration, and river) with the soil moisture model and streamflow routing algorithms. The modeling system was calibrated in the Linhuanji catchment of the Huaihe River basin to estimate surface
groundwater model of the U.S. Geological Survey, has a modular structure and open environment ( McDonald and Harbaugh 1988 ). It was selected for the model integration in order to link its three packages for simulating water exchanges between aquifer and other hydrological components (i.e., recharge, evapotranspiration, and river) with the soil moisture model and streamflow routing algorithms. The modeling system was calibrated in the Linhuanji catchment of the Huaihe River basin to estimate surface
the LSXGW model, and how it may impact the macroscale hydrological fluxes. a. The representation of subgrid heterogeneity of WTD in groundwater runoff In Part I , the unconfined aquifer was represented as a lumped reservoir as follows: where S y is the specific yield of the unconfined aquifer, H is the water table level above the datum, I gw is the groundwater recharge flux, and Q gw is the groundwater discharge to streams. Recall that the observations indicate a strong nonlinear
the LSXGW model, and how it may impact the macroscale hydrological fluxes. a. The representation of subgrid heterogeneity of WTD in groundwater runoff In Part I , the unconfined aquifer was represented as a lumped reservoir as follows: where S y is the specific yield of the unconfined aquifer, H is the water table level above the datum, I gw is the groundwater recharge flux, and Q gw is the groundwater discharge to streams. Recall that the observations indicate a strong nonlinear
T 0 /Λ n 2 being the two different constants. b. A new subsurface flow formulation In this section, a new subsurface flow parameterization is proposed that makes use of the dynamic groundwater table depth from either observations or model simulations. The new formulation also accounts for spatial variabilities of topography and recharge. 1) A subsurface flow parameterization incorporating spatial variability Woods et al. (1997) proposed a topographic index for use in regions with rapid
T 0 /Λ n 2 being the two different constants. b. A new subsurface flow formulation In this section, a new subsurface flow parameterization is proposed that makes use of the dynamic groundwater table depth from either observations or model simulations. The new formulation also accounts for spatial variabilities of topography and recharge. 1) A subsurface flow parameterization incorporating spatial variability Woods et al. (1997) proposed a topographic index for use in regions with rapid
spite of this, it is generally accepted that, once water enters the subsurface and is away from evaporative effects, δ 18 O and δD are conservative in their mixing relationships ( Craig 1961 ). By analyzing the natural variations of the oxygen and hydrogen isotope ratios in rainfall (δ 18 O and δD, respectively), researchers have been able to trace the origins of rainfall and groundwater recharge ( Rodriguez-MartĂnez 1997 ; Alyamani 2001 ; Bowen and Wilkinson 2002 ; Jones and Banner 2003 ; Rosen
spite of this, it is generally accepted that, once water enters the subsurface and is away from evaporative effects, δ 18 O and δD are conservative in their mixing relationships ( Craig 1961 ). By analyzing the natural variations of the oxygen and hydrogen isotope ratios in rainfall (δ 18 O and δD, respectively), researchers have been able to trace the origins of rainfall and groundwater recharge ( Rodriguez-MartĂnez 1997 ; Alyamani 2001 ; Bowen and Wilkinson 2002 ; Jones and Banner 2003 ; Rosen
(SIMTOP; Niu et al. 2005 ). The 3.8-m soil depth is divided into 10 hydrologically active layers with varying soil-layer thicknesses. The water table and soil moisture are coupled through net groundwater recharge (gravity drainage–capillary rise); moreover, the representation of groundwater dynamics is a simple extension of a one-dimensional diffusion equation, with a full hydraulic connection between the saturated and unsaturated zone but no horizontal groundwater fluxes between neighboring grid
(SIMTOP; Niu et al. 2005 ). The 3.8-m soil depth is divided into 10 hydrologically active layers with varying soil-layer thicknesses. The water table and soil moisture are coupled through net groundwater recharge (gravity drainage–capillary rise); moreover, the representation of groundwater dynamics is a simple extension of a one-dimensional diffusion equation, with a full hydraulic connection between the saturated and unsaturated zone but no horizontal groundwater fluxes between neighboring grid
