Effects of post-abandonment management on surface runoff in a Mediterranean mid-mountain basin

Abstract

Mid-mountain catchments across the Mediterranean basin undergone a decrease in runoff and sediment yield during the second half of the 20th century mainly due to forest cover increase following rural abandonment together with a transition to drier climatic conditions. During last decades, land use and land cover (LULC) management of these areas has become a target of environmental policy makers and stakeholders to ensure the sustainability of ecosystem services. In some areas, an active management through the reduction of vegetation density or by human afforestation has been applied, while others undergone a natural process of revegetation. In this context, assessing the contribution of different LULC management on runoff is fundamental for addressing water management and soil loss at the catchment and regional scales. Within this background, the aim of this work is to analyse the relative effects of LULC management techniques on hydrological connectivity and water yield in a Mediterranean mid-mountain basin. To pursue this objective, we applied hydrological connectivity (IC index) and ecohydrological (RHESSys) models to different sub-basins of the Leza River catchment (Iberian System, Spain), representative of three different scenarios: (i) natural revegetation; (ii) human afforestation; and (iii) shrub clearing. Results shows how hydrological connectivity tends to decrease when vegetation cover increases (i.e., natural revegetation and human afforestation) while tend to increase when shrub clearing take place. Runoff coefficient followed a similar pattern, decreasing in basins where vegetation increases and decreasing where there was vegetation clearing. Important differences were observed in terms of the distribution of connectivity changes, their location in relation to the outlet and the effects on surface runoff. Studies of this type are necessary to know the response of the Mediterranean basins to different types of management with the aim of adopting sustainable management measures to guarantee surface water resources in a context of Global Change.