The adaptation to climate change, which has been initiated in the German Strategy for Adaptation to Climate Change:(DAS 2008) and the  Adaptation Action Plan (APA 2011), is just being implemented in some municipalities. However, often methods for assessing the performance of existing infrastructure and also for adapting new projects are missing. Within the BMUB funding initiative Klimpass-Aktiv such methods can be developed and put into practice. This article addresses the issue of infiltration ditch systems that are commonly applied for the infiltration of rainwater and to protect against surface runoff on hillsides. These interception and infiltration ditches have to be designed in terms of their volumes for the expected runoff volume. The design is based on location and is largely determined by the expected rainfall. In contrast to the site conditions, the rain intensity cannot be affected or adjusted. Therefore, this represents a particular uncertainty factor in the prognostic analysis. Projections of precipitation are currently only available for daily and in one special application for hourly precipitation totals. Unfortunately, the uncertainties are high and there are no higher-resolution projections that enable design calculations in the classic sense. Therefore, the problem can only be solved qualitatively by, for example, increasing or decreasing intensities which are assumed. For the region of the city of Sangerhausen (Saxony-Anhalt), a considerable increase of the yearly precipitation amounts and increased discharges are assumed (Kropp et al. 2009). However, evidence with regard to the development of precipitation intensities is not clearly available (see chap. 2.4.). In the present study, therefore, the performance of an existing infiltration ditch system in the city of Sangerhausen has been investigated based on a trial-and-error application. Using different scenarios of precipitation intensities, the critical rainfall intensity was determined in which a failure of the system occurs. This is based on the runoff volumes, which are generated by these critical intensities. These are not only helpful in assessment of the infiltration ditches, but also provide a useful basis for decisions regarding the design or redesign of runoff areas and even for the future selection of suitable development areas. Consequentially, information with regard to the required expansion of existing systems can also be derived.
Reinstorf, F; Ohme, J; Scheinert, M; Heilmann, A
Hydrological investigations for the evaluation of the efficiency of infiltration ditches considering predicted climate changes
Hydrologie Und Wasserbewirtschaftung