Drainage disaster
DRAINAGE and the ultimate disposal of agricultural effluent are complex problems. Sindh has faced the catastrophic consequences of flawed design and substandard execution of mega drainage projects — mainly the Left Bank Outfall Drain and the Right Bank Outfall Drain. Wapda has designed, executed, and monitored these poorly conceived projects. The LBOD system has become a flooding menace in the districts of lower Sindh, while the RBOD has devastated the once-pristine Manchhar Lake.
At the tail end of the Indus Basin Irrigation System, Sindh is unfairly seen as a sink for effluent from the basin’s irrigation network. The World Bank-financed National Drainage Programme, initiated in 1997, proposed a national surface drainage system to transport the Indus Basin Irrigation System’s saline effluent to the sea, using Sindh as a conduit. This prescription collapsed when the multi-donor-funded LBOD project failed miserably to handle the agricultural effluent of just three districts.
A critical component of the Cholri weir on the drain suffered severe scouring soon after becoming operational and eventually collapsed. This debacle forced proponents of the national surface drainage system to retreat from the scheme, as ultimate disposal into the sea became a nightmare. Since then, the LBOD is seen as a blot on Wapda’s engineering credentials. The RBOD experience proved worse, as the project inflicted an ecological disaster on Manchhar Lake, once Pakistan’s largest freshwater body. Wapda’s design allowed drainage effluent to flow from the right-bank districts into Manchhar Lake. Within a few years, this drain devastated the lake by turning it into a vast pond of effluent. Hundreds of self-sufficient families living on the bank or nearby lost their livelihoods in fishing and agriculture. The disaster compelled them to migrate from the area. Wapda’s serious lack of capacity to design, execute, and manage mega drainage projects thus stood exposed.
Despite this history of failure, Wapda has proposed another scheme — the Ghotki drainage project — as a solution to waterlogging and salinity in the area. The proposed project is estimated to cost a whopping Rs156.217 billion and would cover the construction of a 1,067-kilometre drainage network across Ubauro, Daharki, Khangarh, and Mirpur Mathelo in Ghotki District.
Four drainage systems — the Karo Naro, Raitee, Rainee, and Thar — will carry an effluent discharge of 3,183 cusecs. Clearly, no lessons have been learnt from the Manchhar disaster. The project proposes two major outfalls into the Nara Canal.
No lessons have been learned from the Manchhar Lake fiasco.
The project’s environmental and social impact assessment recognises that unplanned disposal of such water will create environmental issues in other areas and at disposal sites. However, surprisingly, the assessment provides no data on dilution. It also does not mention the expected impact on the water quality of Nara Canal when a substantial quantity of saline effluent is discharged during the low-flow season. This serious omission raises concerns about the quality and credibility of the ESIA.
Nara is Sindh’s longest irrigation canal. It passes through Khairpur, Sanghar, Mirpurkhas, Umerkot, and Tharparkar, irrigating 2.2 million acres of land. According to the Sindh Irrigation and Drainage Authority, the canal is the primary source of freshwater for irrigation, drinking, and domestic use for a population of 6.6m, which is served by 127 drinking-water schemes, along with numerous authorised and unauthorised connections. Releasing large quantities of untreated effluent can pollute canal water to harmful levels, potentially causing a public health disaster, especially during low flows. Moreover, the proposed effluent disposal mechanism violates the recommendations of a commission of inquiry constituted by the Supreme Court in 2016. The commission advised against disposing of untreated wastewater into irrigation canals.
Although the project scope does not explicitly mention extending the drain to the neighbouring district of Rahim Yar Khan in Punjab, the possibility cannot be ruled out once the new drain is operational. Under the Salinity Control and Reclamation Project, an unquantified volume of effluent from Rahim Yar Khan is presently being discharged in the desert of the dehs of Poh and Sutiaro in Ghotki.
A vast area remains inundated by drainage effluent and has been rendered infertile due to unabated effluent flows from Punjab into Ghotki. Drainage projects have already wreaked havoc in Sindh. The province cannot afford a new ecological menace.
The writer is a water governance expert.
Published in Dawn, October 21st, 2026
