Continental contribution of suspended sediment to an estuary: Ria de Vigo

Abstract

Five rivers that flow into the Ria de Vigo were sampled during a period of 2 years from January 1995 to February 1997. Their catchment area approximates 45.3% of the total drainage into the Ria de Vigo. Flow rates and suspended matter (sm) data were recorded to calculate the volume of runoff. The mineralogy was studied using XRD. Three of the five rivers had been previously sampled during a period of one and a half years, from 1987 to 1989, permitting the comparison of data then and now. The results show low contributions of suspended matter from the rivers but that anthropogenic (land use and forest fires) factors have a direct influence on the increase of suspended matter. The mineralogy is very similar in all five rivers without any appreciable seasonal change, although an increase in the amount of gibbsite was found during periods of unusual erosion.