A Prioritization Tool for SUDS Planning in Large Cities by Coupling an Urban Drainage Model with Mixed Integer Linear Programming

Decision making regarding Sustainable Urban Drainage Systems (SUDS) sitting is an analytical complex process, as it involves the evaluation of a high number of environmental, physical and technical considerations. Additionally, as the resources are always limited (e.g. budget and land availability), the prioritization of sub-catchments for SUDS placement would help decision makers to determine where is most beneficial to locate these infrastructures. This study proposes a methodology that couples an urban drainage model and Mixed Integer Linear Programming (MILP) to determine where is more beneficial to locate SUDS to reduce both runoff volumes and combined sewer overflows (CSOs). To achieve this goal, the City Drain model is used to model the runoff generation and the flows among sub-catchments. Three indexes are proposed to quantify the reduction on both CSO and runoff volumes, and a lexicographic multi-objective model is used to find the prioritized sub-catchments within a city. The methodology was applied to sub-catchments of Bogotá (Colombia), comprising an area of 38 km². Preliminary results showed that the prioritized sub-catchments were highly dependent on land availability and the optimal solution did not necessarily involve the selection of the sub-catchments that yield most runoff. This study demonstrates the importance and usefulness of the prioritization tool for SUDS planning, which can be used by other large cities like Bogotá.