In this paper spatial analysis tools are presented which allow the simulation and prediction of flash flooding in semiarid basins. Real-time data from automatic hydrological information systems, the SAIH system, in Spain are integrated in a Geographical Information System (GIS) environment. Making intensive use of the Digital Elevation Model (DEM), the parameters of the developed distributed hydrological models are estimated. The proposed operational environment, Shyska, is applied to the management of flash floods in real time in the basins of the southeast of Spain. This system constitutes a support tool for decision taking, based on spatial analysis, when a flood event occurs.