Dinámica erosiva y aplicabilidad de modelos físicos de erosión en una cuenca de montaña mediterránea (Ribera Salada, Cuenca del Segre, Lleida, España)

Abstract

Soil surface hydrology was investigated on hillsides of the Ribera Salada watershed (Segre basin) in order to characterise the runoff/erosion dynamics and the applicability of two erosion models: E2D and EUROSEM. Three soilvegetation units were selected: (1) oak tree and shrub cover, (2) agricidtural terraces, and (3) hillslope shrub cover. Concerning fieldwork, a rain-gauge and fifteen plots with Gerlach traps were controlled during six months to monitor natural events. Six rainfall simulations were made in order to study the role of high-intensity events in runoff and erosion. Furthermore, topographic measurements, samplings and experiments were made so as to evaluate the different plots and to test the applicability of the erosion models. Main conclusions can be drawn as follows: a) low runoff and erosion rates have been registered, suggesting the predominancy of nonhortonian processes in the area, b) the E2D model was not suitable for studying recorded low-magnitude natural events and high-porosity soils, c) direct application of the EUROSEM model generates important errors; a parameter has been calibrated in order to improve the runoff calculation, and d) a great influence of soil moisture variability on runoff dynamics is pointed out for modelling purposes.