The Bras-David river is located on Basse-Terre Island (Guadeloupe archipelago, lesser Antilles arc). This volcanic island results from the ongoing subduction of the Atlantic plate under the Caribbean plate. The Bras-David river drains a watershed of 19 km2 on the windward side of the active Soufrière volcano. The catchment is essentially composed of Pleistocene andesitic and dacitic formations, covered by a thick ferralitic soil. The latter consists of highly weathered volcanoclastic debris flows containing rocky clasts at various stages of weathering. Vegetation is mainly dominated by tropical rainforest. The hydrologic regime is torrential: flow rate is characterized by abrupt variations due to tropical rains. Storms and hurricanes are particularly frequent during the rainy season from june to january.

The Capesterre river is located on Basse-Terre Island (Guadeloupe archipelago, lesser Antilles arc). This volcanic island results from the ongoing subduction of the Atlantic plate under the Caribbean plate. Capesterre drains a watershed of 16.4 km2 located on the windward side of the active Soufrière volcano. The Capesterre catchment, mainly composed of lava and pyroclastic flows aged from 600 to 400 ky, is characterized by rather thin soils, typically ranging from 0.5 to 2 meters. Vegetation is dominated by tropical rainforest. The hydrologic regime is torrential: flow rate is characterized by abrupt variations due to tropical rains. Storms and hurricanes are particularly frequent during the rainy season from june to january.