Sustainability evaluation of the stormwater drainage system in six Indian cities

Abstract

Over the past several decades, urbanisation has spread rapidly over the globe. Research on the viability of urban stormwater drainage systems and the search for solutions to the related problems constitute an important prerequisite for their sustainability evaluation. The Government of India’s sub-committee for the development of “National sustainable habitat parameters on urban stormwater management” has proposed twenty key indices to promote and monitor the sustainable urban stormwater management paradigm. Their evaluation may be taken up at various stages of development, including planning/design, execution, post-operation audits, impact assessment, etc. Eleven of these sustainability indices, including the “Natural drainage system index (NDSI), the Drainage coverage (constructed) index (DCI), the Permeability Index (PI), Water bodies rejuvenation index (WBRI), Water body vulnerability index (WBVI), Water logging index (WLI), Area vulnerability index (AWI), Stormwater discharge quality index (SWDQI), and Rainfall intensity index (RII)” were evaluated for three Tier I cities (Delhi, Mumbai, and Chennai) and three Tier II cities (Varanasi, Chandigarh, and Roorkee) in India based on the available data for 2010 as the datum year and 2020 as the test year. All the considered cities serve as economically and institutionally important urban centres, fall in different climatic zones, and are distributed in two major categories based on the scale of development and population density. All the indices enumerated individually fell within the range of 0 to 1, the two extremities of the sustainability range. Further, ranking of various indices was done employing the Analytical Hierarchy Process, and after deriving the weights for each, aggregation of all these indices was performed to yield an “Overall sustainability index” for each city. Different values were demonstrated along the sustainability scale for all the cities based on performance with regard to various constituent indices in a standalone mode and their interplay in an aggregated mode. The findings are expected to provide important insights to meet the goal of the developing sustainable urban drainage systems (SuDSs).