Modelling vegetation interactions with channel flow in river valleys of the Mediterranean region

Flooding and erosion an major hazards in semi-arid areas. As a result of cl imate and/or land use changes these hazards could increase. Vulnerable area s include the Mediterranean region of southern Europe. As part of the Europ ean Union (EU)-funded MEDALUS (Mediterranean Desertification and Land Use) research programme on impacts of desertification a model to simulate channe l changes is being developed. This is designed to simulate morphological ch anges in the channels and floodplains of ephemerally flowing streams over t ime scales of a year to decades. It incorporates morphological, sedimentolo gical and vegetation characteristics and simulates the effects of flood eve nts and of climate and human activities for reaches of valley floor. In thi s paper the selection of characteristics and processes in the vegetation co mponent of the model is discussed. The effects of vegetation upon flow, ero sion and deposition processes and the feedback of flow, sediment and moistu re on vegetation are identified. The conceptualisation of the model is outl ined then the problems and strategies for parameterisation are indicated. ( C) 2000 Published by Elsevier Science B.V. All rights reserved.