Flood Management from the Perspective of Integrated Water Resource Management

The Associated Flood Management Programme of the World Meteorological Organisation and Global Water Partnership (2002) has suggested that there are a number of implications for flood management. he first of these is to recognise that the catchment is a system. If we consider the functioning of the catchment; it is a dynamic system in which there are exchanges and movements of sediment, water and pollutants between the land and water bodies that make up the catchment (Figure 1). As a system, it is dynamic across both the spatial and the temporal dimensions as it responses to the various disturbances that affect the system. Because it is a dynamic system, we should be concerned with the catchment’s response under the whole range of conditions and not just to the characteristics of its response under some conditions: those that give rise to a risk of flooding. Just for the moment looking only at the variations of water quantity, we have to avoid arbitrarily partitioning this variation into ‘droughts’, ‘water resources’ and ‘floods’ (Figure 2). In particular, in arid climates, floods are the water resource. Instead, we have to decide how best to manage the overall functioning of the catchment, with the added complication that the response of the catchment in terms of water quantities necessarily also affects the flows of sediment and pollutants. Rather than reacting to perceived local problems, ‘floods’, we will move to looking for opportunities to improve, in the widest sense, the functioning of the catchment.