Restoring dammed rivers using artificial floods

An artificial flood on the Spöl River. (Photo: Gabriele Consoli, Eawag) - Naturally, water levels of rivers and streams are variable and fluctuate between drier and wetter periods. Spring snowmelt and the timing and location of rainfall events often drive these fluctuations, especially in alpine areas. Sediment and adsorbed nutrients are mobilised by flowing water and transported through river valleys. This, in turn, helps shape the river, its pools and riffles, and connection with the floodplain. Natural stream systems have healthy riverside vegetation and sources of organic matter that form part of the food web ( Robinson, C.T. et al. Freshwater biology, 2002 ), sustaining aquatic insects, fish and other organisms.