Modelling the hydrological response of a Mediterranean medium-sized headwater basin subject to land cover change: The Cardener River basin (NE Spain)

SummaryAbandonment of old agricultural fields is one of the main land cover changes over the second half of the XX century in Pyrenean headwater catchments, resulting in a natural succession from old crop fields and meadows towards shrub and forested covers, as well as an increase in forest canopy densities. In this situation, important changes in hydrological processes, water balance and, in consequence, water resources have been identified in the records and are expected for the future. The HYLUC model [Calder, I.R., 2003. Assessing the water use of short vegetation and forests: development of the Hydrological Land Use Change (HYLUC) model. Water Resources Research, 39(11), 1318] was tested for simulating the daily flows and water balance of the River Cardener (NE Spain) as well as for estimating the hydrological consequences of changes in land cover under operational conditions, i.e., with limited input data and parameter requirements. HYLUC successfully simulated the historical daily flows, flow duration curve and annual water balances in the catchment. It had several advantages over the hydrological model currently used for operational purposes in this catchment, although a snow cover sub-model should be added if it is to be applied to the main headwater catchments in the same Pyrenean region. When the model was used to simulate the consequences of land cover changes, the differences in water balance were larger than those predicted with an annual water balance equation. However, similar results were obtained from the analysis of historical data from headwater catchments of the Ebro River basin, and the decrease in low flows simulated under forest cover was comparable to that observed under Mediterranean climate elsewhere.