Relationships between spatial-scale and runoff in a small semi-arid catchment under contrasting soil humidity conditions (Extremadura, Southwest Spain)

Abstract

The present paper studies the hydrological processes (surface runoff) at different spatial scales in the dehesa ecosystem: pedon scale with a rainfall simulator, slope scale with surface runoff measurements in open plots and, finally, catchment scale of order 1 and 2. The hydrological behaviour at the different levels is analized under two contrasting conditions: dry and humid environment. The results show that at the microplot and at the hillslope scale the dominating factors of runoff production are easier to explain than at the catchment scale, where heterogeneity increases, with discontinuous fluxes due to reinfiltration in the sediment-filled valley bottoms. The influence of soil moisture on the processes has been defined as well.