Augmentation Strategies for Sustainable Water Supply to Shimla - A Hill Station in India

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 16,000. Over the years, the city has grown both geographically and demographically, and water demand increased manyfold. From 1875 to date, the 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 liters 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 are consumers who 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 liters per annum) whereas if 30% of the rainfall is harvested in built-up areas (1475.76 hectares), 19.12 MLD (6.98 billion liters) of rainfall can be harvested annually, equivalent to 54% of domestic water demand. The capacity of six existingsewage treatment plants is 35.63 MLD, and effluent can partly be reused after treatment for nonpotable 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 for water deficit, and in-depth analysis of future demand and supply are 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.