Sindh Chief Minister Syed Murad Ali Shah has emphasised the necessity of establishing an urban flooding control system in the city for which low-lying hotspot areas vulnerable to flooding needed to be identified, enabling the design of sewer tunnels leading to the main interceptor tunnels at Lyari and Malir River. First, hotspots of low-lying prone to urban flooding areas need to be identified, the sewer tunnels would be designed including their alignment and outfall points so that the tunnels bring water to the main interceptor tunnels at Lyari and Malir River, Murad Shah said and added to achieve the objective rejuvenation of Lyari and Malir Rivers by making them free from all sewer outfall structures into both rivers may also be undertaken.
He said this in a meeting held here at CM House on Saturday. Minister Local Govt Saeed Ghani, Mayor Karachi Murtaza Ahab, Chief Secretary Asif Hyder Shah, PSCM Agha Wasif, Secretary LG Khalid Hyder Shah, CEO Salahuddin, Municipal Commissioner KMC Afzal Zaidi and others attended the meeting. During the discussion, it was observed that some of the leading causes of urban flooding were clogging of drains with solid waste, obstruction of flow in the drains, lack of outfall infrastructures, growing squatter settlements and encroachments.
The CM said that efforts were made to tackle this problem by removing unauthorized settlements or cleaning drains and developing watershed plans but these actions remained ineffective in the long run. We can construct new sewage tunnels in flood-prone areas which would carry a load of sewage from internal trunk sewers in the city and bring wastewater to treatment plants, the CM said. CM said that his government was building treatment plants according to the wastewater generated in the city and its by-products may be used for agriculture and horticulture. Murad Shah said that there was some proposal for a rapid large urban tunnelling system through most modern earth pressure balance machines which did not cause problems for surface settlement.
He added that the tunnelling system with pipe jacking would collect urban floods and in return, all natural streams of the Lyari River and Malir River would be restored. He directed the KW&SC to propose that Karachi should have a combined sewerage system or otherwise. It is also pertinent that effluent discharge from the industry is accommodated in the treatment eventually at the treatment plants making it a combined effluent treatment including that of domestic or municipal wastewater.
The CM said that there was a need for a masterplan study may be conducted to control urban flooding in Karachi. He added that the study should include a tunnelling option and be completed within six months. Once the study is conducted financial model would be developed, he said. KW&SC suggested having a pilot study done in terms of wastewater generated till 2047 as KW&SC was already undertaking its Master Plan of water and sewerage services and infrastructure till 2047. Mayor Karachi Murtaza Wahab said that old areas of the city may be taken as pilot projects for urban flooding control systems.
