Automated Urban Rainfall–Runoff Model Generation with Detailed Land Cover and Flow Routing

Constructing hydrological models for large urban areas is time consuming and laborious due to the requirements for high-resolution data and fine model detail. An open-source algorithm using adaptive subcatchments is proposed to automate Storm Water Management Model (SWMM) construction. The algorithm merges areas with homogeneous land cover and a common outlet into larger subcatchments, while retaining small-scale details where land cover or topography is more heterogeneous. The method was tested on an 85-ha urban catchment in Helsinki, Finland. A model with adaptive subcatchments reproduced the observed discharge at the catchment outlet with high model-performance indices emphasizing the strength of the proposed method. Computation times of the adaptive model were substantially lower than those of a corresponding model with uniformly sized high-resolution subcatchments. Given that high-resolution land cover and topography data are available, the proposed algorithm provides an advanced method for implementing SWMM models automatically even for large urban catchments without a substantial manual workload. Simultaneously, the high-resolution land cover details of the catchments can be maintained where they matter the most.