Suspended sediment dynamics by event typology and its siltation effects in a semi-arid snowmelt-driven basin

¹ Group of Environmental Fluid Dynamics, Andalusian Institute for Earth System Research (IISTA)-University of Granada, Spain
² Andalusian Regional Government, Spain

^* Corresponding author: mivalag@ugr.es

Abstract

Soil loss and transport processes are key issues to understand erosive and sedimentary dynamics in semi-arid environments. The aim of this work was to characterize the erosive patterns of different types of events and to analyse their effect downstream in a mountainous semi-arid watershed. With that purpose, different events have been typified according to atmospheric and hydrological descriptors from information of 1)historical meteorological data, 2) results of simulations from physically-based and distributed hydrological modeling, which includes the snowmelt dynamics, and 3) available MODIS satellite images. For each event, water samples were taken by an automatic measuring device and analysed to determine the suspended sediment loads. The results allowed to identify three types of events. Among them, the maximum values of the measured suspended solids during rainfall-dominated events, with little snow influence, were an order of magnitude higher than the snowfall-dominated events, with values of 25000 mg/l versus 2500 mg/l respectively. The response of intermediate events, despite of low flow, showed a significant gradient. The results highlight the great dynamic variability of the sediment yield along the basin and the importance of the snow in the lamination of the erosive processes and their consequences on reservoir siltation.