Impact of Climate Change on local use of rainwater: The case of two Indian cities

Abstract

The finite fresh water resource available to cities is under stress and projected to worsen. For Indian cities water available for domestic use is marginalized in the backdrop of its dynamic population growth. It has been well established that current centralized practice of water supply, sanitation and storm water drainage is unsustainable in economic and environmental terms if domestic water security is to be assured. In the 'Soft Path' of water proposed by Peter Gleick, a decentralized, people centric and integrated approach to deliver varying qualities of water for use is emphasized. Herbert Giraldet advocates the cyclic metabolism for utilizing resources to make cities more sustainable. Unlike the current linear metabolism in cities which leads to large quantities of waste, the suggestion is to move towards technologies which will enable cyclic metabolism to ensure a zero waste scenario. In the first part the paper briefly demonstrates the possibility of using grey water, rain water and city supply, in a neighborhood to optimize throughputs without reducing the quantity of water available for each activity. Thereafter the paper examines the issue of rainwater availability for neighborhood cyclic metabolism in coastal Chennai and interior New Delhi. Due to climate change the overall quantum of monsoon rainfall has reduced due to weakening of the Tibetan anticyclone. This has lead to long term rainfall variation with reduced rain in interior cities and increased rain in coastal cities. This paper will examine the implications of long term variation of rainfall on rain water use for the practice of cyclic metabolism.