Introduction

Risk knowledge as a first component, provides the framework for the operation of a flood early warning system. This component should be approached holistically, and includes not only hazard but also exposure and vulnerability factors. Flood forecasting systems are not only required to be robust, adaptive, evolving with experience, timely and sufficiently accurate within pre-determined time horizons but must also provide a usable quantification of the forecasting uncertainty. Flood early warning systems created as the only flood risk management measure can create a false sense of security, thus being counterproductive, increasing rather than mitigating flood risk. Performance assessment techniques are important to ensure effectiveness of flood early warning systems. According to D. Molinari et al. the evaluation of performance should be aimed at identifying its capacity to reduce damage. The chapter also presents an overview of the key concepts discussed in this book.