In:
Geoscientific Model Development, Copernicus GmbH, Vol. 15, No. 18 ( 2022-09-20), p. 7099-7120
Abstract:
Abstract. In the context of changing climate and increasing water
demand, large-scale hydrological models are helpful for understanding and
projecting future water resources across scales. Groundwater is a critical
freshwater resource and strongly controls river flow throughout the year. It
is also essential for ecosystems and contributes to evapotranspiration,
resulting in climate feedback. However, groundwater systems worldwide are
quite diverse, including thick multilayer aquifers and thin heterogeneous
aquifers. Recently, efforts have been made to improve the representation of
groundwater systems in large-scale hydrological models. The evaluation of
the accuracy of these model outputs is challenging because (1) they are
applied at much coarser resolutions than hillslope scale, (2) they simplify
geological structures generally known at local scale, and (3) they do not
adequately include local water management practices (mainly groundwater
pumping). Here, we apply a large-scale hydrological model (CWatM), coupled
with the groundwater flow model MODFLOW, in two different climatic,
geological, and socioeconomic regions: the Seewinkel area (Austria) and the
Bhima basin (India). The coupled model enables simulation of the impact of
the water table on groundwater–soil and groundwater–river exchanges,
groundwater recharge through leaking canals, and groundwater pumping. This
regional-scale analysis enables assessment of the model's ability to
simulate water tables at fine spatial resolutions (1 km for CWatM, 100–250 m for MODFLOW) and when groundwater pumping is well estimated. Evaluating
large-scale models remains challenging, but the results show that the
reproduction of (1) average water table fluctuations and (2) water table
depths without bias can be a benchmark objective of such models. We found
that grid resolution is the main factor that affects water table depth bias
because it smooths river incision, while pumping affects time fluctuations.
Finally, we use the model to assess the impact of groundwater-based
irrigation pumping on evapotranspiration, groundwater recharge, and water
table observations from boreholes.
Type of Medium:
Online Resource
ISSN:
1991-9603
DOI:
10.5194/gmd-15-7099-2022
DOI:
10.5194/gmd-15-7099-2022-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2022
detail.hit.zdb_id:
2456725-5
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