Assessing the effects of land surface representation on recharge simulated by models of varying complexity

Sorensen, James; Finch, Jon; Ireson, Andrew; Jackson, Christopher. 2012 Assessing the effects of land surface representation on recharge simulated by models of varying complexity. [Lecture] In: 39th IAH Congress, Niagara, Canada, 16-21 Sept 2012. (Unpublished)

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Numerical models are frequently used for the quantification of groundwater recharge at the catchment scale. However, there is uncertainty as to the necessary level of detail with which the land surface needs to be represented. We compared four models that simulate recharge and represent the land surface with varying degrees of complexity. These models were: Penman-Grindley (PG), UN Food and Agricultural Organisation (FAO), SPAtial Distributed Evaporation (SPADE) and Joint UK Land Environment Simulator (JULES). The models were setup at four intensively monitored sites with different vegetation and soil types in two adjacent catchments. Standard parameter values were used to reflect how the models might be used by practitioners. The models were validated against soil moisture observations at all sites, as well as observed transpiration and interception over a year at a woodland site. The components of the simulated water balances were also compared at each site. Significant differences were noted in potential recharge between models at both grassland sites, although simulated average annual potential recharge varied by only 15 % at the grassland site on permeable soil. At the woodland sites, soil moisture contents were reproduced least accurately and there were large differences in potential recharge at both woodland sites. This predominantly resulted from varied and inaccurate simulation of evaporation, particularly in the form of interception losses where this was explicitly represented in models. Differences in model structure, such as runoff representation, and parameter selection also influenced the results.

Item Type: Publication - Conference Item (Lecture)
Programmes: BGS Programmes 2010 > Groundwater Science
Additional Keywords: GroundwaterBGS, Groundwater, Groundwater modelling
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Date made live: 02 Oct 2012 10:50 +0 (UTC)

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