An integrated framework based on the analytical hierarchy process and auto-calibration of the storm water management model for implementing and assessing low impact development practices

Low Impact Development (LID) practices have emerged as promising solutions for mitigating stormwater runoff in urbanized watersheds. However, the constraints of limited space for the large LID units and the absence of a standardized framework for simulating, calibrating, and implementing these practices introduce significant uncertainties. This study proposes a comprehensive framework for the implementation and simulation of three LID practices—rain barrels, cisterns, and drywells—focusing on their runoff reduction potential in a highly urbanized, flood-prone watershed in Istanbul, Turkey. The framework integrates expert knowledge through the Analytical Hierarchy Process to develop site-specific implementation strategies and employs an auto-calibrated Storm Water Management Model for hydrologic simulations. Key findings demonstrate the efficacy of the Optimization Software Tool for Research Involving Computational Heuristics in calibrating sensitive model parameters. Implementation of the proposed LID practices resulted in significant reductions in runoff peak and volume, along with notable improvements in the time to peak during short-duration (2-h) storm events, within geospatial, environmental, and feasibility constraints. However, their effectiveness was comparatively lower under the long-duration storm scenario tested. The employed methodology is transferable to other densely urbanized metropolitan areas, offering valuable insights for decision-makers in designing effective and sustainable urban stormwater management strategies.