Abstract
Enhanced management of water systems requires knowledge of the amounts of water availability on time scales of hours to decades. Managers of water systems can use the information from combined hydro-meteorological/hydrologic prediction models to take appropriate actions in a realtime basis and also to plan the development of both structural and non-structural measures. Cooperation between the meteorological and hydrological communities is leading to improved models, from flash floods to climate change scenarios but there is a continuing need for dialogue to understand the needs and capabilities of each community. This paper reviews the role of prediction and discusses different kinds of predictions: deterministic, probabilistic, and scenarios based on external forcing. An important issue is the factoring in of the uncertainties of predictions into a risk management approach to water systems management.