A methodology for evaluation of flood forecast‐response systems: 1. Analyses and concepts

Determination of the value of flood forecasts at a microeconomic level necessitates the consideration of numerous hydrologic, organizational, behavioral, and economic factors. These factors and their interactions are captured in a concept of a flood forecast‐response (FFR) system. The forecast system extends from the collection of data through the forecasting of floods to the dissemination of warnings. The response system encompasses decision making by the floodplain dweller and the protective actions he takes. A methodology for evaluation of the performance of FFR systems is presented. It concerns specifically the economic evaluation of the effectiveness of riverine flood forecasts as a means of reducing property damage. The methodology is built of (1) a model of the FFR process and (2) a performance theory. The first element provides a comprehensive mathematical description of the physical FFR process which takes place during floodings; it outputs the expected annual losses (cost of protective action plus flood damage) incurred by the floodplain dweller under several scenarios. The second element establishes the performance measures and expresses them in terms of the outputs of the FFR model; the measures consist of values (expected annual reductions of the loss), efficiencies, and expected opportunity losses. This part presents a system analysis of the FFR process, describes the general structure of the methodology, and introduces the performance theory. The second part details the theory, and the third part reports three case studies.