Development and application of an automated subcatchment generator for SWMM using open data

Abstract

An open source subcatchment generator program was developed for the Stormwater Management Model (SWMM) to automate tedious stages in the model construction process. The generator divides the investigated area into subcatchments using a uniform computation grid and connects the grid cells together and to the underlying stormwater network. The system was tested by applying it to two small urban catchments with different fractions of impervious surfaces in Helsinki, Finland, using mostly openly available data. The simulated discharge results were compared to measured data and to results obtained from manually built models. The proposed system significantly accelerated the setup of a SWMM modelling project, as the routing between the subcatchments as well as the subcatchment slopes and flow widths were directly derived from the computation grid. Automatically generated and manually constructed SWMM models produced discharge results that differed only slightly from each other.

Keywords:

• SWMM
• automatization
• open data

Acknowledgements

This study is part of ‘The Quality and Quantity of Runoff Water in relation to Land Use in Urbanised Catchments’ project (URCA). GisToSWMM5 can be downloaded from GitHub (https://github.com/AaltoUrbanWater/). The DEMs were provided by the National Land Survey of Finland (through https://avoindata.fi), the stormwater network geometry by the Helsinki Region Environmental Services Authority HSY, and the land use data by the City of Helsinki (http://kartta.hel.fi/). The Kumpula rainfall data and the temperature data by the Finnish Meteorological Institute are available at https://en.ilmatieteenlaitos.fi/open-data/. CSC – IT Center for Science Ltd. is acknowledged for the allocation of computational resources. Luode Consulting Oy and Labkotec Oy are acknowledged for providing instrumentation and support for the discharge measurement systems. Finally, we are grateful to the three anonymous reviewers and the editors for the constructive comments and criticism that improved the quality of the manuscript.