Modeling of the Hydrologic Performance of Distributed LID Stormwater under a Changing Climate: Municipal-Scale Performance Improvements

AbstractResults are presented from a large-scale Monte Carlo–style simulation of the use of low-impact development (LID) technologies to reduce runoff from severe storms. Simulations were run to model the hydrologic behavior of a municipal-scale storm sewer network that included porous pavements and green-blue roof systems as part of a distributed stormwater management system. Simulations were run for a variety of land-use types (residential, commercial, and mixed use), design approaches (traditional, LID, and traditional designs with a single LID technology), and pipe networks. The land-use and design approaches for a given location in the municipal network were allocated randomly and run for a broad range of design rainfall depths resulting in over 200,000 individual hydrologic simulations. The results indicate that green-blue roof systems can significantly reduce the peak discharge compared with impervious roof systems, and porous pavements can significantly reduce the total discharge over the municipality compared with impervious pavement systems. This study can inform municipalities about how to achieve current discharge performance with a significantly larger storm volume. Results show that the same peak discharge can be achieved for a 10% deeper storm with the adoption of LID technologies over 30% of the municipality drainage area. This in turn will ensure that the storm system is able to manage the increased storm depths that will result from climate change over the coming decades.