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| Titel |
A critical assessment of simple recharge models: application to the UK Chalk |
| VerfasserIn |
A. M. Ireson, A. P. Butler |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 17, no. 6 ; Nr. 17, no. 6 (2013-06-03), S.2083-2096 |
| Datensatznummer |
250018890
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| Publikation (Nr.) |
 copernicus.org/hess-17-2083-2013.pdf |
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| Zusammenfassung |
| Quantification of the timing and magnitude of point-scale groundwater
recharge is challenging, but possible at specific sites given sufficient high
spatial and temporal resolution field observations, and a suitable physically
based model. Such models are generally too computationally intensive and have
too many unknown parameters to be practically applicable within distributed,
larger-scale hydrological or groundwater models. This motivates the need for
simpler recharge models, which are widely used within groundwater models.
However, it is important that these models are able to capture adequately the
unsaturated zone flow processes. We perform an inter-comparison of recharge
simulated by a detailed physically based model and a simple recharge model,
with both models applied to a field site in the fractured porous Chalk in the
UK. Flow processes are simulated convincingly using a dual permeability,
equivalent continuum, vertically heterogeneous, Richards' equation model,
applied to a 2-D hillslope transect. A simple conventional recharge model was
then calibrated to reproduce the water table response simulated by the
physically based model. The performance in reproducing the water table was
surprisingly good, given the known discrepancies between the actual processes
and the model representation. However, comparisons of recharge fluxes
simulated by each model highlighted problems with the process representations
in the simple model. Specifically, bypass flow events during the summer were
compensating for recharge that should have come from slow, continual drainage
of the unsaturated zone. Such a model may still be useful for assessment of
groundwater resources on a monthly basis, under non-extreme climatic
conditions. However, under extreme wet or dry conditions, or under a changed
climate the predictive capacity of such models is likely to be inadequate. |
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