Variability of sediment yield from a high mountain catchment, Central Spanish Pyrenees

Abstract

The Izas experimental catchment is located in the high Gállego Valley, Central Spanish Pyrenees, in an environment strongly affected by the presence of snow during at least six months of the year. Discharge and sediment transport variability are closely linked to snowmelt and to intense autumn rainfalls. Following 11 yr of data collection, the seasonal and interannual variability of sediment transport has been estimated, as well as the relative importance of bedload, suspended sediment and solutes. The results obtained show that the total sediment yield is relatively low (between 200 and 320 t km^-2 yr^-1) and that solutes represent more than 60% of the sediment exported. Bedload, which in other mountain catchments reaches a great quantity, represents here, in general, less than 30% of the total sediment yield. Seasonal and interannual sediment transport variability is very high, mainly depending on the intensity of autumnal rainfalls.