Best Management Practices for stormwater-runoff with alternative methods in a large urban catchment in Berlin, Germany

Because of multiple constraints, e.g. existing drainage systems, little ava ilable space and higher costs, Best Management Practices (BMP) for stormwat er-runoff in existing urban areas is more difficult to apply than for new u rban developments. For a large urban catchment (about 22 km(2)) with a sepa rate drainage system in Berlin, Germany a combination of decentral (non-str uctural) and semi-central stormwater-management measures proved to be the b est solution. It offers a high effectiveness concerning stormwater treatmen t at relatively low costs. Modern planning tools such as Geographic Informa tion Systems (GIS) were used to investigate the possibilities of implementi ng decentral measures in larger areas. Correlations between field surveys a nd data from the 'Environmental Information System' of Berlin shows that ev en in highly urbanised areas a disconnection of 30% of the impervious area can easily be achieved. The resulting reduction of the discharge makes it p ossible to convert existing retention tanks to soil filter tanks. The purif ication efficiency of this combined measures is higher than of a central st ormwater settling tank which has been simulated with a pollution load model . (C) 1998 published by Elsevier Science Ltd. All rights reserved.