Introduction

Recent flood events have shown the devastating impact that flooding can have on people and property. Flood warning and forecasting systems can help to reduce the effects of flooding by allowing people to be evacuated from areas at risk, and to move vehicles and personal possessions to safety. With sufficient warning, temporary defences can also be installed, and river and tidal control structures operated to mitigate the effects of flooding. Many countries and local authorities now operate some form of flood warning system, and the underlying technology requires knowledge across a range of technical areas, including rainfall and tidal detection systems, river and coastal flood forecasting models, flood warning dissemination systems, and emergency response procedures. This introductory chapter provides a general overview of the flood warning process, approaches to flood forecasting and emergency response, and the nature of flood risk.