A NEW METHOD FOR CREATING MAPS OF ARTIFICIALLY DRAINED AREAS IN LARGE RIVER BASINS BASED ON AERIAL PHOTOGRAPHS AND GEODATA

With regard to the creation of river basin plans and programmes of measures according to the EU Water Framework Directive, the importance of model-supported analyses of nutrient inputs into aquatic systems and the localization of source areas is increasing. Especially in lowland regions artificial drainage installations play a major role, but little information exists concerning their location within larger river basins. Therefore, artificially drained lands were identified by interpreting aerial photographs and typical site conditions of the drained plots were derived. A GIS-based approach was then developed, which allows the delineation of artificially drained lands by combining various site conditions like soil properties and land use type. After checking the validity of a derived map for the River Ems basin (12 940 km(2)) With small-scale drainage installation maps, the approach was applied to northwestern Germany (98 000 km(2)). This was followed by a discussion of results and uncertainties. Copyright (C) 2008 John Wiley & Sons, Ltd.