Decision Support for Adaptation Planning of Urban Drainage Systems

Urban drainage networks are under constant pressure caused by a permanently changing environment. For proactive planning, management, and adaptation of urban water infrastructure, a robust and comprehensive knowledge base is needed as decision support. This paper shows an integrated approach for decision support consisting of urban development modeling, climate projections, hydrodynamic sewer modeling, and Web-GIS visualization of interactive risk maps for pluvial flooding. The application on an Alpine case study demonstrates the benefits of such a combined consideration of different drivers. Climate projections of precipitation are based on four climate projections produced specifically for the Alps on a 0.1 degrees grid. In order to obtain precipitation data with an adequate resolution for urban drainage modeling, the projections are downscaled using a statistical downscaling method. The results indicate a trend toward more intense heavy precipitation during summer until 2050. The effect of this trend can either be compensated or amplified by city development. It is shown that population growth on its own does not necessarily lead to a decrease of system performance, but that clever spatial planning can reduce negative effects. The visualization helps to involve stakeholders, politicians, and the public by illustrating model results for strategic planning and in workshops. (C) 2017 American Society of Civil Engineers.