Tasas de erosión, transporte y sedimentación en un medio estuárico: el Río Miñor (Ría de Vigo, Pontevedra)

Abstract

The Miñor river is one o f the 35 minor currents entering the Ría de Vigo (Pontevedra) at Baiona Bay,; close to the SE margin o f the Ría. The present study was carried out over two periods: from May 97 to July 98 and from May 00 to May 01. In this paper we carry out a hydraulic and sedimentologic approach o f the Miñor river, making an estimation of the total fresh-water discharge and sediment input transported as suspended and dissolved loads. The final aim of this study is to calculate erosion rates at the catchment, sediment yield, transport and the nature of the sediments accumulated at the estuarine area. In view of the average discharge for both periods o f time (2.7 m3/s y 6.7 m3/s) and the catchment area (75.6 m2) is possible to estimate suspended and dissolved sediment yields. Mean values for suspended sediments are 25.76 t/km2a for 97/98 and 139.74 t/ km2a for 00/01 and those for dissolved loads of 109 t/km2a y 204 t/km2a, respectively. Finally, considering an average rock density of 2 .7 g/cm3 we can estimate mechanical denudation rates of 9.54 m3/km2a during 97/98 and 51.76 m3/km2a during 00/01. Chemical denudation rates are 40.46 m3/km2a for the first period and 75.56 m3/km2a for the second. Data obtained during 00/01 interval can be considered as maximum values, bearing in mind the very unusually high rainfall conditions.