Sensitivity analysis of surface runoff generation for pluvial urban flooding

Abstract

Significant advances have been made in recent times in the domain of integrated hydraulic modelling of urban flooding. Development of a physically based model for dual drainage concept, in which urban surface is treated as a network of open channels and ponds (major system) connected to the sewer network (minor system), has been a step forward (Boonyaaroonnet et al. 2006). However, generation of reasonably realistic surface network is the main concern in this methodology (Djordjevic et al. 2005). This paper presents the results obtained by new developed tools (Boonya-aroonnet et al. 2007) for enhancing the potential of 1D/1D modelling by more accurate GIS-based automatic generation of surface network features. The application of these tools to a real life case study is discussed. Simplification of high resolution of LiDAR Digital Terrain Model (DTM) by re-sampling original 1x1m grid to larger sizes is necessary and sensitivity is analysed. Number of ponds removed and cumulative and discrete volume loss charts were generated and used to determine the suitable threshold values for removal of small ponds. In generating the pathways cross-section geometry, multi-criteria optimization technique was deployed to study the sensitivity of the input parameters on the geometries generated and appropriate parameter selection process.