Impact of land-use on macroinvertebrate communities in the Zwalm river basin.

For determining the impact of land-use on the aquatic ecosystem in a river basin, a Geographic Information System (GIS) has been used to integrate the main impact factors at different scales. The headwaters and streams of the Zwalm River basin (Flanders, Belgium), which is part of the Scheldt river basin, were selected as study site. A river ecological database was developed based on physical-chemical and biological monitoring. The research focussed on three zones within this Zwalm River basin, each characterized by different land-uses and by consequence different types of pollution, mainly of diffuse origin. The impact was measured by means of the biological diversity, the Belgian Biotic Index and a key macroinvertebrate taxon. For measuring, assessing and managing the impact of land-use on biological communities, an integrated and multidisciplinary approach will be necessary.