AUGMENTATION STRATEGIES FOR SUSTAINABLE WATER SUPPLY TO SHIMLA- A HILL STATION IN INDIA

摘要

Water supply for Shimla, a popular hill station in the northern part of India, was initially planned and executed by the Britishers in the year 1875 for a meager population of 16000. Over the years, the city has grown both geographically and demographically and water demand increased manifold. From 1875 to date, Shimla water supply system has expanded into seven independent water supply schemes originating from Dhalli Catchment, Cherot Nallah, Chair Nallah, Nauti Khad-Ⅰ, Ashwani Khad, Nauti khad-Ⅱ and Giri River. Total water demand (2012) is 64.66 million litres per day (MLD) against source supply of 54.54 MLD. The gap between demand and supply further increases with system inefficiencies, as a result there of consumers are getting water supply only for about 45 minutes in a day. The present deficit of 10.12 MLD (2012) will further amplify to 21.27 MLD in 2021and 42.61 MLD in 2031. Domestic water demand (2012) is 35.17 MLD (12.84 billion litres per annum) whereas if 30% of the rainfall is harvested in built up area (1475.76 hectares), 19.12 MLD (6.98 billion litres) of rainfall can be harvested annually, equivalent to 54% of domestic water demand. The capacity of existing six sewage treatment plants is 35.63 MLD and effluent can partly be reused after treatment for non-potable consumption. To fulfill the growing water demand of Shimla, the available options are (ⅰ) gravitating water from upper reach of River Pabbar, (ⅱ) lifting water from River Satluj and (ⅲ) Rainwater harvesting and reuse of waste water coupled with balance additional water from River Satluj or Pabbar. In this study issues and challenges of water supply in Shimla, reasons of water deficit, in-depth analysis of future demand and supply have been discussed. Further, feasible augmentation strategies, role of rainwater harvesting and reuse of waste water for mitigating the water scarcity have been critically examined for the sustainable water supply to Shimla city.