Performance Assessment of LID Techniques to Control Urban Floods Under Historical and Future Rainfall and Land Cover Scenarios

The expansion of urbanization and city development is a leading cause of land use change from natural to artificial surfaces, increasing the risk of flooding with numerous social and economic consequences. As an urban flood management technique, Low-Impact Development (LID) mitigates social and economic damages by restoring or maintaining a catchment’s natural hydrological conditions. This paper aims to examine how LID techniques help control urban floods in the Garmsar urban area, Iran, under both historical rainfall and land cover conditions as well as future scenarios. To achieve this, two historical precipitation events were modeled using SWMM software. Then, by implementing a combination of permeable pavement, infiltration trenches, and green roofs, the effectiveness of LIDs in controlling total flood volume was assessed. Using the CA-Markov method and the RCP 4.5 climate change scenario, future land cover and rainfall depth were projected and applied to the SWMM model to evaluate the performance of LIDs under future conditions. The results indicate that the existing drainage system is inadequate to manage urban runoff, leading to flooding. However, integrating the existing system with LID techniques proved highly effective, reducing total runoff volume by up to 100% in some sub-catchments under both historical and future scenarios. This study confirms the adverse effects of land use and climate change in exacerbating floods and underscores the need for urban planners to incorporate LID strategies in city development.