Abstract

A high resolution multibeam bathymetric survey was carried out in Puerto Montt bay, Chile. Moreover, intensity data derived from acoustic signals reflected by the sea bottom was gathered using the same sonar system; the ratio was calculated between emitted and backscattered energy. The resulting topographic model shows a soft coastal platform and an abrupt slope. There are small submarine channels in the slope zone and a main channel in the central bay zone that could be related to the depression associated with the Tenglo channel. These channels act as conduits for the sediment transport from shallow to deep waters. The backscatter information was used in order to classify seabed sediments, subsequently confirmed by analyzing sediment samples from the respective sites. Coarse sediments feature higher intensities or backscatter signals than fine sediments. Muddy sands generally prevail in the investigation area. However, coarse material tends to concentrate in shallow waters and fine material in deep sectors. Sediment transport in the interior and the mouths of Tenglo channel in strongly influenced by tide currents. This does not hold for material transport occurring on the slope and in the deeper parts of the bay, where other mechanisms, such as turbidity currents, are more important. © 2006 Escuela de Ciencias del Mar Pontificia Universidad Católica de Valparaíso.