Author(s)

M.L. Rodríguez-Blanco, M.M. Taboada-Castro, M.T. Taboada-Castro

Abstract

Suspended solids discharge during consecutive rain episodes was observed in a small rural catchment in northwest Spain during a study of the sources of production and transport of these sediments. At the catchment outlet, discharge was measured and suspended solid samples were taken in the later portion of the rainy season, using an automatic sampler. A multi-interval sampling program was carried out. The results show that in a sequence of discharge peaks, the suspended solid concentrations present an increase and a reduction with flow. The lowest suspended solid concentrations obtained at the last discharge peaks seem to reflect an exhaustion of the sediment source during the succession of events. Clockwise hysteresis loops are described, and the sediment peaks were found to occur either prior to or with the discharge peaks. This type of relation can be explained by the presence of nearby sources and/or sediment exhaustion. Erosion of riverbanks and roads has been observed as important sources of suspended solids in the catchment.

Keywords

hysteresis, northwest Spain, sediment delivery, sequence events