Streamflow response of Belgian catchments to IPCC climate change scenarios

The IRMB (Integrated Runoff Model-F. Bultot) daily step conceptual model has been applied to eight Belgian catchments with areas ranging from 100 to 1200 km(2). These catchments are characterized by various infiltration rates and ground water storage capacities. The outputs of six GCMs (General Circulation Model) distributed by the IPCC (Intergovernmental Panel on Climate Change) and an earlier scenario have been used to perturb time series of hydrometeorological input data relevant to simulate the water cycle. This paper focuses on the impacts on streamflow and its surface and underground components, as well as on the occurrence of flood days and low flow days. impacts are shown to be catchment and scenario dependent. Due to the scenario diversity, streamflow impacts are found to be either positive or negative. The trends are common to scenarios with the same patterns or to catchments with similar characteristics. For all but two scenarios, all the catchments present an increase of flood frequency. Nevertheless, for all the scenarios, catchments with prevailing surface flow are undergoing an increase in flood frequency during winter months. (C) 1998 Elsevier Science B.V. All rights reserved.