ABSTRACT
Flooding, like all natural disasters, is a complex and inherently uncertain phenomenon. In flood forecasting using mathematical models, the sources of uncertainty have been classified as (i) model uncertainty, (ii) input uncertainty, (iii) parameter uncertainty, and (iv) natural and operational uncertainty. In spite of the increasing advancement in the development of flood forecasting models and techniques, uncertainty in flood forecasts remains unavoidable. It is therefore important that the existence of uncertainty be admitted and properly appraised. Hiding uncertainty may create the illusion of certainty, the consequences of which can be very large (Krzysztowicz, 200 I a) . Various benefits of estimating uncertainty in flood forecasting have been identified, which include the rational basis for flood warning (risk-based warnings) and potential economic benefits from flood forecasting and
warning systems. Even with the lack of risk-based flood warning procedures, quantifying uncertainty provides additional information about the forecasts and helps decision makers to use their own judgement more appropriately.
