Internal evaluation of a physically-based distributed model using data from a Mediterranean mountain catchment

Abstract

An evaluation of the performance of a physically-based distributed model of a small Mediterranean mountain catchment is presented. This was carried out using hydrological response data, including measurements of runoff, soil moisture, phreatic surface level and actual evapotranspiration. A-priori model parameterisation was based as far as possible on property data measured in the catchment. Limited model calibration was required to identify an appropriate value for terms controlling water loss to a deeper regional aquifer. The model provided good results for an initial calibration period, when judged in terms of catchment discharge. However, model performance for runoff declined substantially when evaluated against a consecutive, rather drier, period of data. Evaluation against other catchment responses allowed identification of the problems responsible for the observed lack of model robustness in flow simulation. In particular, it was shown that an incorrect parameterisation of the soil water model was preventing adequate representation of drainage from soils during hydrograph recessions. This excess moisture was then being removed via an overestimation of evapotranspiration. It also appeared that the model underestimated canopy interception. The results presented here suggest that model evaluation against catchment scale variables summarising its water balance can be of great use in identifying problems with model parameterisation, even for distributed models. Evaluation using spatially distributed data yielded less useful information on model performance, owing to the relative sparseness of data points, and problems of mismatch of scale between the measurement and the model grid.

Spatio-temporal patterns in land use and management affecting surface runoff response of agricultural catchments—A review

“…This is partly a result of a lack of detailed data on location and temporal behaviour, and partly because of the difficulties of adequately representing such small structures by commonly used fixed raster cell sizes (Anderton et al, 2002). The second problem at least might be partly solved using nested approaches to representing topography, where areas of concentrated flow are represented in higher spatial resolution (Heathwaite et al, 2005), or in triangulated irregular networks (TINs) that explicitly account for linear features in the landscape (Vivoni et al, 2005).…”

Multi-criteria assessment of the Representative Elementary Watershed approach on the Donga catchment (Benin) using a downward approach of model complexity

“…In order to assess the model structure, the evaluation of a distributed model representing various processes should be done on each hydrological compartment it represents and at various scales (Refsgaard, 1997;Michaud and Sorooshian;1994;Bergström et al, 2002;Fortin et al 2001, Anderton et al 2002. As a single and integrative variable (i.e.…”

Hydrological processes and their seasonal controls in a small Mediterranean mountain catchment in the Pyrenees

“…The deep seasonal changes in antecedent conditions represent a problem for precipitation-runoff models (Gan et al, 1997;Piñol et al, 1997;Gallart et al, 2000;Anderton et al, 2002b). The flow record is compared below with the record of the depth to the water table, to illustrate the seasonal changes in the runoff generation mechanisms.…”