Urban forms and flood resilience: Evaluating the impact of diverse micro-scale configurations on water flow dynamics

Abstract

Urban flooding has become an increasingly critical challenge worldwide, driven by urbanisation-induced changes to natural drainage systems and intensifying climate-driven precipitation extremes. Previous research on water-sensitive urban design has largely focused on stormwater runoff in simplified urban layouts, while giving less attention to the complexity of real urban form and its effect on flood behaviour. This study addresses this gap by systematically evaluating how diverse and complex urban configurations influence flood flow characteristics. Eight representative urban layouts, including four procedurally generated forms and four realistic forms, were developed within a two square kilometre area (1 × 2 km) using UrbanXTool, OpenStreetMap data, and ArcGIS. Two-dimensional hydraulic modelling was conducted under uniform hydraulic conditions to test the influence of six urban morphological parameters: street orientation, street curvature, street length, street width, mean parcel area, and building setbacks. A mild 1% slope, typical of floodplain environments, was selected to isolate the effect of urban form while limiting external hydrological variability. The results indicate that mean parcel area (0.41), building setbacks (inversely associated with building coverage (−0.64), and street length (−0.09) are the parameters most strongly associated with changes in flood dynamics. High-density urban layouts with irregular street networks produced a 35.65% increase in peak water depth and a 24.30% increase in building damage rate compared with other configurations. These findings provide actionable insights for designing flood-resilient urban environments and advance current understanding of how urban morphology influences flood risk.