Incorporating External Green Infrastructure Models into Storm Water Management Model (SWMM) Simulations Using Interface Files

Abstract

The United States Environmental Protection Agency's Storm Water Management Model (SWMM) is widely used to predict the quantity and quality of stormwater runoff and runoffs from other drainage systems in urban catchments. However, it can be useful to replace the green infrastructure (GI) model in SWMM for certain applications. This paper explains why and how GIs can be modeled using models of choice and proposes a method to systematically incorporate external GI models into SWMM when using it to model the other elements of the catchment. A file-based coupling method is presented that uses a GI model of choice to compute the output hydrographs of selected contributing drainage areas. These GI outputs are then used as input flows to SWMM in the form of routing interface or rainfall data files. This study also presents a toolbox that contains functions to create the external files and to modify the SWMM input files to accommodate the external modeling of a part of the catchment using a GI model of choice. Finally, the use of the coupling method and the toolbox is illustrated using two case studies investigating the effectiveness of different GI models and the parameter estimation of subcatchments after implementing GIs. In summary, the proposed method and toolbox enable the use of different GI models in SWMM catchment-scale studies.