Many of the world’s rivers are highly fragmented with weirs and dams which alter the flow regime, primarily to provide water for human uses. This affects the flow regime, usually reducing the frequency, volume and duration of flooding which is critical for downstream ecosystems. Also floodplains are affected by structures (e.g. levees) which control and change flood flows, affecting the viability of ecosystems. We investigate potential impacts of dams, diversions and floodplain structures on the ecological condition of rivers and their dependent ecosystems.