Quantifying the efficacy of Low Impact Developments (LIDs) for flood reduction in micro-urban watersheds incorporating climate change

Abstract

Urban floods have become more frequent and devastating in recent decades. Low impact developments (LIDs) have gained wide acceptance as a more sustainable and effective technique for mitigating urban flooding. This study examines the hydrological control effects of LIDs on mitigating runoff depth and peak runoff in the context of climate change for four micro-watersheds (A, B, C and D) in northeast India. In addition, attempts have been made to determine whether redesigning the existing drainage helps reduce runoff in the study area. Results show that redesigning the drainage system has resulted only in 2.5–3.6% reduction in runoff depth for the four micro-watersheds. LIDs were effective in managing the stormwater in all four micro-watersheds. Among the four LIDs considered (green roof, permeable pavements, infiltration trenches, and rain barrels), the green roof showed the highest percentage reduction in runoff characteristics. Climate change analysis has shown a significant increase in the runoff characteristics in all four watersheds. For watersheds A, B, C, and D, the green roof effectively reduced runoff by 30%–38%, 83%, 50%, and 34%, respectively. This study will help the decision-makers to assess and choose the best LIDs to minimize the risk of flooding.