Management Options for Large Metropolitans on the Verge of a Water Stress

Abstract

Karachi is the largest metropolitan area in Pakistan and houses about 14.91 million people (2017 census). It is the industrial hub and financial capital of Pakistan, but unfortunately, it is facing the worst water crisis in its history. Pakistan is bestowed with extensive water resources, but making use of them requires a paradigm shift in water policy and management. Karachi is facing a water crisis situation over the period of three decades, not due to the shortage of natural resources but to mismanagement on the part of the planners and managers, and the situation is getting worse with no imminent solution in sight. The present additional drinking water demand of Karachi has been estimated to be around 650 MGD (260+390) by the Karachi Water & Sewerage Board (KW&SB). This study accesses the water availability in surface water resources, i.e., the Indus River, in consideration of the requisite water demand of Karachi. There exists a mechanism for water transmission from the Indus River to Karachi at the Kotri Barrage. Being located at the tail of Indus, Kotri Barrage (last barrage before outfall into the sea) faces the two extremes in terms of system water availability: in wet season (monsoon), the system happens to be at the mercy of disastrous floods whereas, there is extreme water shortage during the dry months. In this paper, a sustainable water management plan has been devised for managing the additional water needs of Karachi throughout the year. The proposed plan recommends the diversion of additional flows from the Indus River at Kotri (from the water being wasted into the sea), and these flows have been routed through and stored in already existing infrastructure of the KW&SB, i.e., the Kalri Baghar Feeder Upper (KBFU) canal system and Keenjhar, Haleji, and Hadero Lakes. A further scenario-based integrated reservoir operation study presents the optimal use of available flows and storage capacities. In addition, filling and depletion mechanism of available storages has also been proposed and in all the analysed scenarios due consideration has been given to the environmental flows requirement of downstream Kotri riparian and irrigation indents of KBFU system. Hence, the proposed action plan ensures the availability of requisite flows to meet the drinking water needs of Krachi Metropolitan. Doi: 10.28991/HEF-2022-03-03-06 Full Text: PDF