The basis of basins 1: 50000 is a project carried out by joint order of the Ministry of the Environment (DMA) and the Catalan Water Agency (ACA). The aim of this project is to obtain digital databases and GIS network watershed of Catalonia for scales 1: 50000. It starts from the Terrain Elevation Model (DEM) of Catalonia 15x15 meters generated by interpolation from the altimetric information gathered with the Topographic Map 1: 5000 Catalonia With the new version 1. Elevation Model extracted from the base 1 : 5000 v2 will have a more favorable hydrological behavior, but at the time of starting the generation of watershed only one part of the territory. In this version only shows the basins corresponding to the area of basins of Catalonia.