Analysis of Challenges and Opportunities for Low-Impact Development Techniques in Urbanizing Catchments of the Coastal City of Chennai, India: Case Study

Abstract

Coastal cities of southern peninsular India are characterized by highly seasonal rainfall during a few weeks of a year, a long dry-weather period, flat topography, and shallow groundwater levels. This study investigated the challenges and opportunities prevailing in implementation of low-impact development techniques (LID) as hydrologic restoration measures in catchments of the coastal city of Chennai. Rainfall patterns, which were evaluated with precipitation concentration index (PCI), showed that rainfall in the city is irregularly distributed, with only 3.5–4 months of rainfall occurrence in a year. Catchment-scale numerical modeling of green roof and rainwater harvesting (RWH) structures demonstrated that RWHs are an efficient method of stormwater management in the study area. Vegetation-based LIDs, however, could not be adopted due to their irrigation water demands, which would add to the drinking water demand in the region. Further challenges in the implementation of LIDs because of extreme weather conditions and the shallow ground water table, and potential solutions, were discussed. We concluded that LIDs retrofitted with hydrologic interventions such as managed aquifer recharge and green roofs can provide economic benefits to the low- to middle-income population in the study area.