Hydrologycal responses of a small Mediterranean agricultural catchment

Abstract

[eng] Field studies have recently shown that quickflow may be produced in Mediterranean environments as the result of saturation mechanisms, considering that the dominant runoff processes may change throughout the year due to the significant seasonality. One of the most representative agriculture elements of Mediterranean- climate regions is rainfed herbaceous crops. The aim of this study is to achieve a better understanding of hydrological responses and the role played by under-drained systems in runoff variations under such climatic and land use conditions. Field measurements were conducted in Can Revull, a small catchment (1.03 km2) in the island of Mallorca. The mean annual precipitation and potential evapotranspiration are 517 mm and 1010 mm, respectively. The hydrological regime is intermittent with a mean annual discharge of 4 l s 1. Based on 3 years of field data (July 2004-June 2007), this study presents a soil water balance of the catchment and an evaluation of the variability of runoff and its components on an annual and seasonal time scale. In addition, the response of runoff components at event-scale was analysed. At the annual and seasonal time scales, it was only possible to observe a succession of three different hydrological periods throughout the year conditioned by the evapotranspiration which also plays an important role in the baseflow response. Precisely, baseflow was predominant, presumably enhanced by the under-drained system. Furthermore, quickflow response was dominated by saturation mechanisms, whereas rainfall excess mechanisms were limited during study period to dry seasons when baseflow was not present and discharge values therefore were lower.