HESS Opinions "Classification of hydrological models for flood management"

Abstract. Hydrological models for flood management are components of flood risk management, which is the set of actions to be taken to prevent flood disasters. It is a cyclical process: initiated by occurrence of an extreme flood it leads through the reconstruction and rehabilitation phase to risk assessment and project planning and implementation, and finally to operation and preparedness for a next extreme flood when the cycle starts again. We subdivide the tasks of flood management into two consecutive parts: planning and operation, which basically require different kinds of hydrological models. For planning, real time runoff is not needed, one works with design scenarios. For this task models should be used appropriate to the tasks at hand, which reflect characteristics of landscape as well as of hydrological scale. For operation, hydrological forecast models are needed which have to meet a different set of conditions. In this paper, requirements for hydrological models as functions of application, geology and topography, and of area size are surveyed and classified, as a first approach for guiding users to the correct type of model to be used in a given location. It is suggested that one always should start flood modeling with an analysis of local conditions and select or develop task and locality specific models.