Title: Developing an urban runof management model by using satellite precipitation datasets to allocate LIDs under climate change conditions

Abstract

Flood control and management are becoming increasingly important to many cities due to urban development and significant changes in the natural climate pattern. The objective of this study is to evaluate the effect of climate change on hydrological conditions and runoff management for low impact development (LID) systems in the Tehran municipality area. The TRMM satellite precipitation data (3B42) were first analyzed for the study area by using the eleven models recommended by the IPCC. The MIROC model was identified as the best climate model among several models according to its best performance for R2, RMSE and MAE for providing future precipitation data. Then, the precipitation simulated by the MIROC model was downscaled by the LARS-WG model under two scenarios, RCP 4.5 and University of TehranRCP 8.5. Furthermore, runoff was calculated by the Storm Water Management Model (SWMM) for different storms. The results showed an increase in the intensity of the 25-year storm in the time horizon of 2021- 2040, while the average annual precipitation showed a decrease of 30%. In this study, two LID options (permeable pavement and bio-retention cell) were selected and optimized with two objectives: (1) minimizing the produced runoff and (2) minimizing the costs of LID construction and maintenance under climate change conditions. The results indicated that the running costs increased by 30% and 55% for the scenarios of RCP 4.5 and RCP 8.5, respectively. These costs tended to prevent changes of up to 250×103 m3 in the first scenario and 328×103 m3 in the second scenario in the volume of floodwater produced under climate change conditions.