Abstract
Water is a non substitutable resource and a social good, which governments must perforce provide to its citizens in the right quantity and quality. An integrated urban metabolism model is useful in understanding the status quo of an urban water and sanitation system. By defining and measuring the values of relevant hydrological performance indicators—deliverables of the model referred to—a thorough knowledge of the present performance and the gaps, which need to be plugged en route to a sustainable urban water infrastructure, can be obtained, as demonstrated in this paper. This then forms the bedrock for decision-making and policy formulation for change to be introduced top-down as well as advice, which would enable the much needed bottom-up support to policies. The authors have chosen Delhi as the case study city, but would like to point out that this application can be reproduced for any other town/city/region of the world. The water balance within the chosen system boundaries shows that the annual unutilized flows, amounting to 1443 million cubic meters, dominate the metabolic flows of water in Delhi, and the annual groundwater withdrawal, which exceeds 420 million cubic meters, is much greater than the recharge rate, resulting in a rapid depletion of the groundwater level. There is an urgent need thereby to improve the rate of infiltration of stormwater and reduce the rate of runoff by focusing on increasing the share of permeable surfaces in the city, as well as to consider the wastewater streams as potential sources of water, while not forgetting demand side of management measures, as the pressure on the urban water system in the city is likely to intensify with a combination of population growth, economic development, and climate change in the near future. The recommendations provided by the authors towards the end of the article, can, if suitable measures are undertaken and robust policies are implemented, result in Delhi’s enjoying a water surplus in the short term, and progressively attain complete sustainability with regard to the utilization of its water resources.
Highlights
IntroductionA sustainable city is characterized by, inter alia, economic vitality, long-term environmental sustainability (which includes a greater share of green energy in the mix), good healthcare facilities, and energy and water security
A sustainable city is characterized by, inter alia, economic vitality, long-term environmental sustainability, good healthcare facilities, and energy and water security
18% of this demand is met by decentralized groundwater by individual households, ~9% is met through groundwater stock harnessed by the Delhi Jal Board, for centralized supply, another 4% is through groundwater extracted by suppliers in the private water market, and the rest is met through surface water sources through centralized supply
Summary
A sustainable city is characterized by, inter alia, economic vitality, long-term environmental sustainability (which includes a greater share of green energy in the mix), good healthcare facilities, and energy and water security. The authors have demonstrated the usefulness of an urban water metabolism model (used earlier to study urban water systems in other cities by, inter alia, [4,5,6]), which takes a more comprehensive view of the metabolic flows [7] of water and wastewater, and contributes by offering insights into the current performance. These insights enable decision-makers to devise and structure interventions to improve the long-term water security of the region.
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