The main aim of this research is to study the hydrological dynamics of Mediterranean mountain basin affected by land use changes, by means of monitoring of soil water. This aim has been reached by measuring and simulating soil water under different soils and vegetation types, considering water and temperature transition regimes. This research was done in a representative forest basin in the Catalunyan Pre-Pyrenees (Ribera Salada catchment) with an area of 222.5 km2, from 1998 through 2005. The vegetation cover in the catchment consists of pasture, tillage and forest. A number of representative plots for each of these land cover types were intensely monitored during the study period. The annual precipitation fluctuates between 516 and 753 mm, while the soil moisture content oscillates between 14 and 26% in the middle and low lying areas of the basin, and between 21 and 48% in shady zones near the river bed, and in the higher parts of the basin. Soil moisture and rainfall are controlled in the first place by altitude, with the existence of two climatic types in the basin (sub-Mediterranean and sub-alpine), and further by the land use. A fully physical process-based hydrologic model (TOPLATS) was found to be able to simulate exactly the soil moisture regimes in the basin in the different combination of local abiotic and biotic factors. The TOPLATS-based results are more precise than the results obtained using another frequently used method, more specifically the Newhall Simulation Model (NSM), which has been developed to simulate soil moisture regimes.