J. Vandervaere

The development of a physically based model for flow and transport in hillslope transects is presented. In the second paper of this set, Connell et al. [this issue] use this model as the fundamental unit in a catchment application to describe flow within flood-irrigated catchments. The hillslope transect model is based on the assumption that surface and groundwater flow is one-dimensional, flowing down the topographic gradient. This approximation is particularly accurate for flood-irrigated catchments where the land surface is divided into irrigation bays. To maximize the model's utility for catchment modeling, a number of simplifications to the process descriptions are introduced to reduce model complexity and computational overhead. The description of the unsaturated zone makes a distinction between infiltration and capillary rise, allowing infiltration to be a mixture of macropore and matrix flow and capillary rise to be a porous medium process. The capillary rise descriptio...

This article describes measurements made at each site and for each vegetation cover as part of the soils program for the HAPEX-Sahel regional scale experiment. The measurements were based on an initial sampling scheme and included profile soil water content, surface soil water content, soil water potential, infiltration rates, additional measurements on core samples, and grain size analysis. The measurements were used to categorize the state of the surface and profile soil water regimes during the experiment and to derive functional relationships for the soil water characteristic curve, unsaturated hydraulic conductivity function, and infiltration function. Sample results for different supersites and different vegetation covers are presented showing soil water profiles and total soil water storage on days corresponding to the experimental ‘Golden Days’. Sample results are also presented for spatial and temporal distribution of surface moisture content and infiltration tests. The res...