Details
| Original language | English |
|---|---|
| Article number | e2022WR032430 |
| Journal | Water resources research |
| Volume | 59 |
| Issue number | 3 |
| Early online date | 6 Mar 2023 |
| Publication status | Published - 15 Mar 2023 |
Abstract
Groundwater recharge is the main forcing of regional groundwater flow. In traditional partial-differential-equation (pde)-based models that treat aquifers as separate compartments, groundwater recharge needs to be defined as a boundary condition or it is a coupling condition to other compartments. Integrated models that treat the vadose and phreatic zones as a continuum allow for a more sophisticated calculation of subsurface fluxes, as feedbacks between both zones are captured. However, they do not contain an explicit groundwater-recharge term so it needs to be estimated by post-processing. Groundwater recharge consists of changes in groundwater storage and of the flux crossing the water table, which can be calculated based on hydraulic gradients. We introduce a method to evaluate the change of groundwater storage by a time-cumulative water balance over the depth section of water table fluctuations, avoiding the use of a specific yield. We demonstrate the approach first by a simple 1-D vertical model that does not allow for lateral outflow and illustrates the ambiguity of computing groundwater recharge by different methods. We then apply the approach to a 3-D model with a complex topography and subsurface structure. The latter example shows that groundwater recharge is highly variable in space and time with notable differences between regional and local estimates. Local heterogeneity of topography or subsurface properties results in complex redistribution patterns of groundwater. In fully integrated models, river-groundwater exchange flow may severely bias the estimate of groundwater recharge. We, therefore, advise masking out groundwater recharge at river locations.
Keywords
- fully integrated hydrological models, groundwater recharge, parflow-CLM, river-aquifer interactions, surface-subsurface flow, water table fluctuations
ASJC Scopus subject areas
- Environmental Science(all)
- Water Science and Technology
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In: Water resources research, Vol. 59, No. 3, e2022WR032430, 15.03.2023.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Estimating Groundwater Recharge in Fully Integrated pde-Based Hydrological Models
AU - Waldowski, Bastian
AU - Sánchez-León, Emilio
AU - Cirpka, Olaf A.
AU - Brandhorst, Natascha
AU - Hendricks Franssen, Harrie Jan
AU - Neuweiler, Insa
N1 - Funding Information: This research was performed in the Research Unit FOR2131 “Data Assimilation for Improved Characterisation of Fluxes across Compartmental Interfaces”, funded by Deutsche Forschungsgemeinschaft (grants: NE 824/12‐2, Ci 26/13‐2, and HE 6239/4‐2). Open Access funding enabled and organized by Projekt DEAL.
PY - 2023/3/15
Y1 - 2023/3/15
N2 - Groundwater recharge is the main forcing of regional groundwater flow. In traditional partial-differential-equation (pde)-based models that treat aquifers as separate compartments, groundwater recharge needs to be defined as a boundary condition or it is a coupling condition to other compartments. Integrated models that treat the vadose and phreatic zones as a continuum allow for a more sophisticated calculation of subsurface fluxes, as feedbacks between both zones are captured. However, they do not contain an explicit groundwater-recharge term so it needs to be estimated by post-processing. Groundwater recharge consists of changes in groundwater storage and of the flux crossing the water table, which can be calculated based on hydraulic gradients. We introduce a method to evaluate the change of groundwater storage by a time-cumulative water balance over the depth section of water table fluctuations, avoiding the use of a specific yield. We demonstrate the approach first by a simple 1-D vertical model that does not allow for lateral outflow and illustrates the ambiguity of computing groundwater recharge by different methods. We then apply the approach to a 3-D model with a complex topography and subsurface structure. The latter example shows that groundwater recharge is highly variable in space and time with notable differences between regional and local estimates. Local heterogeneity of topography or subsurface properties results in complex redistribution patterns of groundwater. In fully integrated models, river-groundwater exchange flow may severely bias the estimate of groundwater recharge. We, therefore, advise masking out groundwater recharge at river locations.
AB - Groundwater recharge is the main forcing of regional groundwater flow. In traditional partial-differential-equation (pde)-based models that treat aquifers as separate compartments, groundwater recharge needs to be defined as a boundary condition or it is a coupling condition to other compartments. Integrated models that treat the vadose and phreatic zones as a continuum allow for a more sophisticated calculation of subsurface fluxes, as feedbacks between both zones are captured. However, they do not contain an explicit groundwater-recharge term so it needs to be estimated by post-processing. Groundwater recharge consists of changes in groundwater storage and of the flux crossing the water table, which can be calculated based on hydraulic gradients. We introduce a method to evaluate the change of groundwater storage by a time-cumulative water balance over the depth section of water table fluctuations, avoiding the use of a specific yield. We demonstrate the approach first by a simple 1-D vertical model that does not allow for lateral outflow and illustrates the ambiguity of computing groundwater recharge by different methods. We then apply the approach to a 3-D model with a complex topography and subsurface structure. The latter example shows that groundwater recharge is highly variable in space and time with notable differences between regional and local estimates. Local heterogeneity of topography or subsurface properties results in complex redistribution patterns of groundwater. In fully integrated models, river-groundwater exchange flow may severely bias the estimate of groundwater recharge. We, therefore, advise masking out groundwater recharge at river locations.
KW - fully integrated hydrological models
KW - groundwater recharge
KW - parflow-CLM
KW - river-aquifer interactions
KW - surface-subsurface flow
KW - water table fluctuations
UR - http://www.scopus.com/inward/record.url?scp=85152562458&partnerID=8YFLogxK
U2 - 10.1029/2022WR032430
DO - 10.1029/2022WR032430
M3 - Article
AN - SCOPUS:85152562458
VL - 59
JO - Water resources research
JF - Water resources research
SN - 0043-1397
IS - 3
M1 - e2022WR032430
ER -