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Sediment yields and erosion rates in the Napo River basin: An Ecuadorian Andean Amazon tributary

Abstract:

This paper presents the first results obtained by the HYBAM project in the Napo River drainage basin in Ecuador during the period 2001-2002. Three gauging stations were installed in the basin to monitor suspended sediment yields, of which two are located in the Andean foothills and the third station on the Ecuador-Peru border in the Amazonian plain. At the confluence of the Coca and Napo rivers, the suspended sediment yield transported from the Andes Mountains is 13.6 106 t year-1 (766 t km-2 year -1). At the Nuevo Rocafuerte station 210 km downstream, the suspended sediment yield reaches 24.2 106 t year-1 for an annual mean discharge of 2000 m3 s-1. These values indicate intensive erosion processes in the Napo Andean foreland basin between the Andean foothills and the Nuevo Rocafuerte station, estimated to be 900 t km -2 year-1. These high rates of erosion are the result of the geodynamic uplift of the foreland.