A THEORY OF FLOOD WARNING SYSTEMS

A local flood warning system typically serves a small community situat ed in a headwater area and exposed to flash floods or rapid riverine f loods. Forecasts of such flood events are characterized by short lead times and large uncertainties, A Bayesian theory is formulated for a l ocal flood warning system built of three functional components: monito r, forecaster, and decider. The theory offers a modeling framework and mathematical concepts necessary for (1) developing optimal decision r ules for issuing warnings based on imperfect forecasts, (2) evaluating system performance statistically, and (3) computing the ex ante econo mic benefits from a system.