Monitorizacion de los cambios de uso del suelo en la cabecera de cuenca de la ribera salada mediante fotografía aérea y S.I.G. (El Solsonès, Lleida, España)

Abstract

During the last 50 years an abandonment of the traditional crops and rural settlements has taken place in the catalan Prepyrenées.- In this study the land use changes observed from the fifties to the present day have been monitored in a 6577 ha-watershed located in the headiuaters of the Ribera Salada (El Solsonès). In order to do that aerial photographs from the years 1957 and 1993 have been compared, using 1993-ortophotomaps as cartographic base. The analysis of the land use changes according to different variables (aspect and slope) and different approaches (change intensity and final land use) has been performed using ARC/INFO®. Several trends have been established in the land use evolution according to aspect and slope. The results show that the crops are the land use with the maximum decrease in surface, which has taken place mostly on steep slopes, giving place to meadows. On the other side, the surface occupied by dense forests has considerably increased (845 ha).