Khulna Tackles Water Supply Issues Amid Rising Salinity and Population Growth

October 27, 2024

Khulna, Bangladesh’s third largest city, is facing water supply issues due to increasing salinity and population growth. In response, the Khulna Water Supply and Sewerage Authority (KWASA) collaborated with the Asian Development Bank (ADB) and its multi-donor trust fund, CDIA, to prepare the second phase of the Khulna Water Supply Project (KWSP)*.

The ADB-CDIA consulting team recently completed a project preparation study (PPS), which outlined a comprehensive water supply investment program for the city. It also provided an institutional and capacity development roadmap for KWASA, and an assessment of Khulna’s institutional, financial, and governance aspects toward a sustainable water system. The PPS results will inform ADB’s loan preparation leading to implementation.

Population Growth and Increasing Water Demand

The city’s population, currently at 1.26 million in the Khulna City Corporation (KCC) area, is projected to increase to 1.58 million by 2035 and 2.03 million by 2050.

Water usage is currently at 73 liters per person per day, based on ADB-CDIA’s survey of 200 households. Considering this, Khulna will need 220 million liters per day (MLD) by 2035 and 340 MLD by 2050. Meanwhile, water leakage was estimated at 12%, necessitating an intensive non-revenue water program to sustain the current level. Finally, groundwater remains a critical resource, with 100 MLD sourced from the KWASA production wells and private tube wells.

Addressing Water Quality and Quantity Issues

A critical issue for Khulna City is the increasing salinity in its rivers, driven by climate change, upstream river discharge, human activities, and tidal variations.

To address salinity while optimizing Khulna’s water resources, ADB-CDIA assessed three investment options to be included in the KWSP. Option 1 involves a new intake in Madaripur Beel Route Canal while Option 2 proposes an impounding reservoir at or around the Bangabandhu Water Treatment Plant. However, both options were deemed impractical in the immediate term due to data and land acquisition challenges.

Option 3 – found to be the most feasible – involves a composite plan: constructing a small capacity impounding reservoir at the Bangabandhu water treatment plant, building a small intake in the Bhairab River, using groundwater based on a set limit to ensure its sustainability, adopting online monitoring and smart water intake systems, and reducing non-revenue water.

In addition, ADB-CDIA analyzed three options for the clear water transmission main, out of which, they found the looping arrangement integrating new and existing systems to be the most economical and efficient. The managed aquifer recharge (MAR) study further suggested using infiltration ponds and injection wells for recharging aquifers. However, since MAR is still developing in Bangladesh, ADB-CDIA proposed a pilot study for installing injection wells.

Other recommendations included solar power generation, smart water monitoring systems, and a robust district metering area and SCADA systems to enhance water supply efficiency and energy savings. See: Major Project Components

The total cost of the project was estimated at BDT 26.5 billion ($224.6 million).

Augmenting the Proposed Technical Solutions

In May 2024, the ADB-managed Urban Resilience Trust Fund conducted a hydro-geological study to corroborate and supplement the PPS findings with regard to the water source salinity concerns.

The technical study examined alternative surface water sources, groundwater hydrology, land use and land cover, water demand, and private tube wells. Through the use of secondary data, field surveys, and advanced modeling techniques to analyze groundwater scarcity and increasing salinity, the study identified critical issues and proposed comprehensive solutions with a view to applying viable nature-based solutions to be combined with conventional engineering measures.

Khulna’s flat topography makes it vulnerable to seawater intrusion, made worse by ongoing sea level rise. The two main subsidiary rivers feeding the Padma River—the Gorai and Aral Khan Rivers—are the main distributary river systems around the area and are vital in replenishing upstream freshwater supply and pushing out salinity caused by seawater intrusion into the river system, particularly during the dry season.

The study recommended managing the limited groundwater resources sustainably and using them conjunctively with surface water. It also suggested dredging the Gorai River to improve its flow and water quality. A significant finding was the need for coordinated surface and groundwater pumping to prevent over-extraction and maintain adequate river flow and groundwater storage so that seawater intrusion is controlled.

The study advocated for a holistic water management strategy combining natural and engineering measures, including infrastructure upgrades, managed groundwater recharge, as well as regulatory measures to ensure a sustainable water supply. It emphasized the importance of dynamic monitoring systems to adapt to temporal and spatial salinity variations, ensuring Khulna’s water security.

The results were considered in confirming and refining the proposed solutions for KWSP.

Boosting the Impact of the Project Preparation Study

Beyond the investment program, ADB-CDIA developed an institutional and capacity development roadmap for KWASA, outlining short-, medium-, and long-term strategies to enhance its growth and efficiency. Additionally, its social survey provided insights into water consumption, service satisfaction, and willingness to pay for improved services in the target areas.

While the Gender Action Plan was aimed at addressing gender disparities in water access, ADB-CDIA’s assessments of land acquisition impacts, environmental considerations, financial management, and economic aspects further confirmed the project’s viability and long-term sustainability.

The completion of the PPS will mark the start of the next phase of project development activities, which will be undertaken by ADB as part of the loan preparation process.

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* For more details on the Khulna Water Supply Project, pls. contact ADB Project Officer Elma Morsheda (emorsheda@adb.org)