Land use management effects on water yield and hydrological connectivity after rural abandonment in a mid-mountain basin: Leza Valley (Iberian System, Spain)

During the second half of the 20^th century the mountain areas of the Mediterranean region undergone an intense process of rural abandonment. This process together with a transition to warmer and drier climatic conditions caused a decrease in runoff and sediment yield, which have several consequences from hydrological, geomorphological and ecological points of view. Land use management of these areas has become a target of environmental authorities and stakeholders to ensure the sustainability of ecosystem services. An active management has been applied in some areas through the reduction of vegetation density or by human afforestation, while other areas have not been managed, undergoing a natural process of revegetation. In this context, assessing the contribution of different land use management on runoff is fundamental for addressing water management at the catchment and regional scales, especially in a context of climate change. The main objective of this work is to analyse the relative effects of land use management techniques to 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-catchments of the Leza Valley (Iberian System, Spain), representative of three different scenarios: (i) natural revegetation, (ii) human afforestation, and (iii) shrub clearing. Results show how hydrological connectivity tends to decrease when vegetation cover increases (i.e., natural revegetation and human afforestation) while tends to increase when shrub clearing takes place. Runoff coefficient followed a similar pattern, decreasing in basins where vegetation increases and decreasing where there is 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.

This research project was supported by the MANMOUNT (PID2019-105983RB-100/AEI/ 10.13039/501100011033) project funded by the MICINN-FEDER and the PRX21/00375 project funded by the Ministry of Universities of Spain from the “Salvador de Madariaga” programme. Manel Llena has a “Juan de la Cierva Formación” postdoctoral contract (FJC2020-043890-I/AEI/ 10.13039/501100011033) from the Spanish Ministry of Science and Innovation, while Melani Cortijos-López is working with an FPI contract (PRE2020-094509) from the Spanish Ministry of Economy and Competitiveness associated to the MANMOUNT project.