American Geophysical Union, Water Resources Research, 7(32), p. 2003-2012, 1996
DOI: 10.1029/96wr00897
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The response of a conceptual soil water balance model to storm events is compared to a detailed finite element solution of the one-dimensional Richards equation in order to test the capabilities of the former in calculating the local contributions to infiltration excess runoff in a distributed catchment scale model. Local infiltration excess runoff is computed from ground level precipitation using the time compression approximation and a Philip infiltration capacity curve with Brooks-Corey constitutive equations. The validity of applying the conceptual model for local runoff and soil water balance calculations is investigated by performing numerical experiments over a range of soil types, control volume depths, and initial soil moisture conditions. We find that a good agreement between the conceptual and detailed models is obtained when the gravitational infiltration rate in Philip's formula is set to the saturated hydraulic conductivity, and when percolation from the control volume is updated as a function of the soil moisture content in a stepwise fashion. The comparison between these two models suggests that the simpler (and much less computer-intensive) conceptual water balance technique could be incorporated into distributed models for large scale complex terrains as an efficient means of retaining consideration of spatial variability effects in catchment scale hydrologie simulations. This is illustrated in an application to the Rio Missiaga catchment in the eastern Italian Alps, where the local contributions to surface and subsurface runoff are routed onto a digital elevation model-based conceptual transport network via a simple numerical scheme based on the Muskingum-Cunge method.