Overbank deposition during a flood in a reach of the middle Ebro River

Abstract

This work reports on the sediment budget of a 106-km reach of the Ebro River, between Monzalbarba and Sástago during the 7.5-year flood occurred in late February 2003. The budget has been constructed from hydrological data, water and suspended sediment discrete samples obtained at five control sections, and official data on flooded areas during the event. Results indicate that the study reach behaved as a sink of sediments, with a negative budget of around 90,000 t (i.e., 845 t/km) that were deposited within the system during the flood. This value represents 19% of the solid load estimated at the entrance of the fluvial system and indicates a mean sedimentation rate of 12 mm on the river’s floodplain. Values in the same range have reported for other large rivers during flood events of similar magnitude.