Water and sediment budgets unveiling contrasting hydro-sedimentary patterns in a mountainous Mediterranean catchment

J Tuset; D Vericat; R J Batalla

doi:10.1016/j.scitotenv.2020.140884

Water and sediment budgets unveiling contrasting hydro-sedimentary patterns in a mountainous Mediterranean catchment

Sci Total Environ. 2020 Nov 25:745:140884. doi: 10.1016/j.scitotenv.2020.140884. Epub 2020 Jul 17.

Authors

J Tuset¹, D Vericat², R J Batalla³

Affiliations

¹ Fluvial Dynamics Research Group (RIUS), University of Lleida, E-25198 Lleida, Catalonia, Spain(1); Forest Science and Technology Centre of Catalonia, E-25280 Solsona, Catalonia, Spain. Electronic address: jordi.tuset@ctfc.cat.
² Fluvial Dynamics Research Group (RIUS), University of Lleida, E-25198 Lleida, Catalonia, Spain(1); Forest Science and Technology Centre of Catalonia, E-25280 Solsona, Catalonia, Spain.
³ Fluvial Dynamics Research Group (RIUS), University of Lleida, E-25198 Lleida, Catalonia, Spain(1); Institut Català de Recerca de l'Aigua (ICRA), E-17003 Girona, Catalonia, Spain; Faculty of Forest Sciences and Natural Resources, Universidad Austral de Chile, Valdivia, Chile.

PMID: 32758736
DOI: 10.1016/j.scitotenv.2020.140884

Abstract

Mountain regions have a key role in the generation of runoff, and in the production and transfer of sediments to fluvial networks, especially in Mediterranean catchments where these processes are affected by marked changes in climate and land use (i.e. global change). This paper presents the water and the sediment budgets of the Ribera Salada (224 km²), a meso-scale Mediterranean forested catchment located in the Southern Pyrenees. Field monitoring follows an integrated basins scheme (five nested sub-catchments), where hydrological and sediment transport data were collected continuously over a two-year period (2012-2013). Precipitation was obtained using radar images, which allowed the elaboration of rainfall maps used to characterize the spatial distribution of rainfall across multiple scales. Results indicate that the catchment is hydrologically divided in two areas which show contrasting fluvial regimes: the upper part of the catchment is considered wet and has a constant flow regime, supplying the majority of the water, while the lower part is drier, with ephemeral tributaries and water losses into the alluvial aquifer of the main river channel. In contrast to water yield, most of the suspended sediment load (i.e. 80%) is supplied by the driest part of the catchment where sediment availability was greater and where there is a greater connectivity between sediment sources and the channel network. The sediment yield of the whole catchment and the respective sub-catchments sits in the lower bounds of values reported for the Mediterranean region, indicating the generally low intensity of hydrological and geomorphic processes in the area. Once more the sediment budget approach matched to sound hydrological data proves efficient to characterize sediment dynamics in river basins, with special interest in areas such as the Mediterranean mountain catchments, where the effects of global change appear to be more acute.

Keywords: Ebro basin; Hydrologic cycle; Mediterranean; Rainfall maps; Sediment budgets; Sediment transport.