Spatial and temporal dynamics of soil moisture in a Mediterranean mountain area (Vallcebre, NE Spain)

Abstract

ABSTRACTKnowledge of soil moisture dynamics at reasonable temporal and spatial resolutions is required to improve hydrological understanding and modelling. However, in the Mediterranean area, considered as one of the most vulnerable areas to global change, there is a severe lack of detailed soil moisture data sets. The objective of this study is to investigate the inter‐annual and intra‐annual spatial and temporal distributions of soil moisture in a Mediterranean mountain area, using the detailed hydrological data set gathered in the Vallcebre Research catchments (NE Spain). With the use of time‐domain reflectometry, soil moisture was measured weekly between 1998 and 2003 at eight representative profiles. Time series of soil moisture showed a clear seasonal pattern. Results obtained revealed that soil moisture on hillslopes under forest cover was lower than in downslope areas covered with grasses. However, differences were not persistent through the year but were minimal during the driest and wettest conditions and maximal during the drying and wetting‐up periods. During the wetting‐up and drying‐down periods, the soil moisture distribution depended mainly on local controls. However, during wet conditions, soil moisture patterns were controlled by nonlocal factors that limited the vegetation‐related variability of soil moisture. In this mountain area, forest cover is likely to increase as the climate changes, which will most probably reduce the average soil moisture at the catchment scale as well as its spatial variability. These changes may ultimately be seen as a threat to the future of water resources in this area. Copyright © 2012 John Wiley & Sons, Ltd.