DISTRIBUTED NUMERICAL RAINFALL–RUNOFF MODELLING IN AN ARID REGION USING THEMATIC MAPPER DATA AND A GEOGRAPHICAL INFORMATION SYSTEM

The rainfall–runoff process consists of an excess rainfall process and a runoff concentration process. A transient one-dimensional finite difference model describing the partitioning of precipitation between surface runoff, soil moisture storage and deep percolation, through the coupling of saturated–unsaturated zones, has been implemented in a geographical information system including data on vegetation cover derived from the Landsat Thematic Mapper. The model has been used to simulate both the rainfall excess and the resultant outflow hydrographs for a small arid zone drainage basin in the Andean region of Argentina. The overall hydrograph shape, peak discharge, runoff volume and flow duration are predicted within a relative squared error of 13.2%. The spatial input data and the model structure are discussed and suggestions for applications to larger complex basins and for future refinements in the technique are presented.