title: Effects of afforestation on runoff and sediment load in an upland Mediterranean catchment.
abstract: This paper assesses annual and seasonal trends in runoff and sediment load resulting from climate variability and afforestation in an upland Mediterranean basin, the Ribera Salada (NE Iberian Peninsula). We implemented a hydrological and sediment transport distributed model (TETIS) with a daily time-step, using continuous discharge and sediment transport data collected at a monitoring station during the period 2009-2013. Once calibrated and validated, the model was used to simulate the hydrosedimentary response of the basin for the period 1971-2014 using historical climate and land use data. Simulated series were further used to (i) detect sediment transport and hydrologic trends at different temporal scales (annual, seasonal); (ii) assess changes in the contribution of extreme events (i.e. low and high flows) and (ii) assess the relative effect of forest expansion and climate variability on trends observed by applying a scenario of constant land use. The non-parametric Mann-Kendall test indicated upward trends for temperature and decreasing trends (although non-significant) for precipitation. Downward trends occurred for annual runoff, and less significantly for sediment yield. Reductions in runoff were less intense when afforestation was not considered in the model, while trends in sediment yield were reversed. Results also indicated that an increase in the river's torrential behaviour may have occurred throughout the studied period, with low and high flow events gaining importance with respect to the annual contribution, although its magnitude was reduced over time.
authors.affiliation: Catalan Institute for Water Research - ICRA, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003 Girona, Catalonia, Spain; Fluvial Dynamics Research Group - RIUS, University of Lleida, Alcalde Rovira Roure 191, 25198 Lleida, Catalonia, Spain. Electronic address: cbuendia@icra.cat.
authors.forename: C
authors.initials: C
authors.lastname: Buendia
authors.affiliation: School of Geography and the Environment, University of Oxford, South Parks Road, Oxford, OX1 3QY, United Kingdom.
authors.forename: G
authors.initials: G
authors.lastname: Bussi
authors.affiliation: Fluvial Dynamics Research Group - RIUS, University of Lleida, Alcalde Rovira Roure 191, 25198 Lleida, Catalonia, Spain; Forest Sciences Centre of Catalonia, Crta. Sant Llorenç de Morunys km 2, 25280 Solsona, Catalonia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Tuset
authors.affiliation: Fluvial Dynamics Research Group - RIUS, University of Lleida, Alcalde Rovira Roure 191, 25198 Lleida, Catalonia, Spain; Forest Sciences Centre of Catalonia, Crta. Sant Llorenç de Morunys km 2, 25280 Solsona, Catalonia, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Vericat
authors.affiliation: Catalan Institute for Water Research - ICRA, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003 Girona, Catalonia, Spain; Institute of Aquatic Ecology, University of Girona, Campus Montilivi s/n, 17003 Girona, Catalonia, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Sabater
authors.affiliation: Fluvial Dynamics Research Group - RIUS, University of Lleida, Alcalde Rovira Roure 191, 25198 Lleida, Catalonia, Spain; Department of Environment and Climate Change of Spain and Portugal, ENDESA SA, Crta. Tarragona km 89, 25191 Lleida, Catalonia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Palau
authors.affiliation: Catalan Institute for Water Research - ICRA, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003 Girona, Catalonia, Spain; Fluvial Dynamics Research Group - RIUS, University of Lleida, Alcalde Rovira Roure 191, 25198 Lleida, Catalonia, Spain; Forest Sciences Centre of Catalonia, Crta. Sant Llorenç de Morunys km 2, 25280 Solsona, Catalonia, Spain.
authors.forename: R J
authors.initials: RJ
authors.lastname: Batalla
keywords: Afforestation; Climate change; Mediterranean; Ribera Salada; Runoff; Sediment yield; TETIS