DISTRIBUTED NUMERICAL RAINFALL-RUNOFF MODELING 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 di fference model describing the partitioning of precipitation between su rface runoff, soil moisture storage and deep percolation, through the coupling of saturated-unsaturated zones, has been implemented in a geo graphical information system including data on vegetation cover derive d from the Landsat Thematic Mapper. The model has been used to simulat e 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 dura tion are predicted within a relative squared error of 13.2%. The spati al input data and the model structure are discussed and suggestions fo r applications to larger complex basins and for future refinements in the technique are presented.