What This Tutorial Covers

This tutorial serves as a hands-on guide for professionals using GeoSWMM, with a focus on the practical application of detention pond design for post-development stormwater management. It is intended for users who already have a working knowledge of hydrology, hydraulics, stormwater management modeling, model input data in ArcGIS Pro and the use of EPA SWMM elements and flow routing methods for representing drainage systems. 

The tutorial walks users through the process of mitigating increased post-development runoff by introducing a detention pond at the outlet of the catchment. It emphasizes key tasks such as defining pond properties, representing storage behavior within the model, and designing and evaluating the detention system using a storage unit, three orifices, and a transverse weir. As in the previous tutorials, the system is analyzed under three 2-hour synthetic storm events with return periods of 2- years, 10- years, and 100- years. These skills are especially relevant for engineers and planners seeking to manage increased runoff caused by development and to control peak discharge from urban catchments. 

Users will learn how to use detention storage to reduce runoff impacts, detain the Water Quality Capture Volume (WQCV), and limit peak post-development runoff rates to their pre-development levels. This tutorial complements the GeoSWMM User’s Manual by offering a structured, example-driven walkthrough of real-world modeling scenarios. 

The following section begins a step-by-step demonstration of the worked example project, guiding users through each stage of designing, and evaluating a GeoSWMM detention pond model for post-development runoff control.