Editorial handling: J. Kuhlemann and A. G. Milnes.

Abstract The current topographic maps of the Rhone Delta — and of Lake Geneva in general — are mainly based on hydrographic data that were acquired during the time of F.-A. Forel at the end of the nineteenth century. In this paper we present results of a new bathymetric survey, based on single- and multi-beam echosounder data. The new data, presented as a digital terrain model, show a well-structured lake bottom morphology, reflecting depositional and erosional processes that shape the lake floor. As a major géomorphologie element, the sub-aquatic Rhone Delta extends from the coastal platform to the depositional fans of the central plain of the lake at 310 m depth. 9 canyons cut the platform edge of the delta. These are sin uous ( “meandering”) channels formed by erosional and depositional processes, as indicated by the steep erosional canyon walls and the depositional levees on the canyo