Conclusion

This tutorial illustrated how GeoSWMM can be used to evaluate two types of Low Impact Development (LID) alternatives: filter strips and infiltration trenches. The key points demonstrated in this tutorial are:

1. The objective of this hydrologic simulation.
2. Network description and its elements’ (filter strips and infiltration trenches) characteristics
3. Outline of GeoSWMM model development techniques for the study area
4. Review of necessary model input parameters and simulation options
5. Interpretation and comparison of model output results
6. Outline of options for model file export to EPASWMM

Although this tutorial used a series of design storms to evaluate LID performance, a more accurate estimate of their storm water control capabilities would require that a continuous long-term simulation be run for the site. Using several years’ worth of actual rainfall inputs would allow the model to properly account for the variation in antecedent soil conditions between storm events. This factor becomes a critical concern when infiltration-based controls are being considered. Tutorial 10 illustrates how to perform such a continuous simulation.