SPECIAL ISSUE Sewer model development under minimum data requirements Frank Blumensaat • Martin Wolfram • Peter Krebs Received: 15 October 2010 / Accepted: 7 June 2011 / Published online: 29 July 2011 Ó Springer-Verlag 2011 Abstract Planning, design and operation of urban drainage systems is often based on hydraulic sewer mod- elling. Sewer models are also increasingly used to quantify pollution loads discharged to aquatic ecosystems (e.g. via combined sewer overflows), which ultimately allows an estimation of the ecological impact emanating from urban drainage systems. The establishment of such network models, however, requires detailed and accurate informa- tion about the sewer network structure and the connected surface area. This infrastructure data is often unavailable, confidential or available in ‘paper’ format only. The pres- ent paper outlines a novel approach to develop a hydraulic sewer model constrained by a minimum amount of data. The approach combines the application of a surface flow accumulation algorithm to a selectively manipulated Dig- ital Elevation Model (DEM) with a routine for hydraulic network dimensioning to generate a close-to-reality sewer network ready to be implemented in a hydraulic modelling platform. The method is tested for three real-life catch- ments of which characteristics vary in scale, topography, state of development and network complexity. For all cases the generated network is implemented on the EPA-SWMM platform to allow hydrodynamic simulations. Model per- formance is assessed by (1) evaluating the spatial match of existing and generated network layout, (2) comparing the estimated hydraulic dimension with real-life infrastructure data and (3) benchmarking simulated runoff with measured data for a defined validation period. The analysis shows that the presented method is capable of reproducing the original network layout, network length and corresponding discharge rates based on little, freely available information. Further research potential is identified to improve the hydraulic dimensioning and the application to complex systems that include control structures. The presented approach is useful to estimate the scope of drainage net- works including layout and design (e.g. for preliminary planning in emerging areas) to screen existing networks and to identify critical spots where more precise informa- tion is required. Keywords Integrated water resources management (IWRM) Á Hydraulic sewer modelling Á Data scarcity Á Rational method Á GIS Á SWMM Introduction Strategic planning and maintenance of urban infrastructure are aspects of increasing relevance, especially against the background of aging assets and increased needs to reduce costs, particularly in the public sector. Reliable functioning of essential services such as storm and wastewater drainage and treatment is particularly relevant to ensure hygienic standards and to prevent urban flooding. Seen in the light of changing climate conditions, such as increasing rain intensities (see Pavlik et al. 2011, this issue) this issue becomes even more significant. Ecological relevance is given due to the risk of receiving water contamination in case of combined sewer overflows and hydraulic overload situations of treatment units (Ellis 1991; Rauch and Har- remoe ¨s 1996). One exceptional example of water pollution induced by urban drainage is given in Ertel et al. (2011, this issue). However, analysis of storm and wastewater drain- age networks represents a great challenge due to the F. Blumensaat (&) Á M. Wolfram Á P. Krebs Urban Drainage Department, Faculty of Forest, Geo and Hydro Sciences, Institute of Urban Water Management, Technische Universita ¨t Dresden, 01062 Dresden, Germany e-mail: frank.blumensaat@tu-dresden.de 123 Environ Earth Sci (2012) 65:1427–1437 DOI 10.1007/s12665-011-1146-1