Erosion and fluvial sedimentation in the River Segura basin (Spain)

Abstract This paper reports a study of hydric erosion and fluvial sedimentation of the River Segura basin which is situated in the SE of the Iberian Peninsula, and which has one of the highest erosion rates in Spain. The aims of the study are: To quantify the soil losses in the drainage area of the most important reservoirs in the Segura basin; to determine the volume of sediment yields; to determine the amount of sediment that has been retained in the reservoirs; and to evaluate the effects that sediment accumulation has on the hydraulic systems. The Universal Soil Loss Equation (USLE) was applied to the drainage basin and the depth of water in the reservoir was measured, with the aim of establishing significant statistical relationships between the sediment delivery ratio and the geomorphological parameters of the basins. The results obtained showed that gross erosion in the study area, according to the USLE has an average value of about 30 tons per hectare per year. Annual decrease of available storage volume in the observed reservoirs is 3.6 hm 3 , which is equivalent to 0.5% of the total volume every year. A total of 4 millions tons of sediment were retained in the reservoirs every year.