A community based flood early warning system (CBFEWS) is a system of tools and plans to detect and respond to flood risks by the communities. The CBFEWS, developed by ICIMOD, is based on a simple instrument installed upstream to detect flood automatically, and provides the real time flood warning to the vulnerable communities downstream. In Nepal, CBFEWS is jointly implemented by the Department of Hydrology and Meteorology / Community Based Flood and Glacial Lake Outburst Risk Reduction Project and ICIMOD.