As the world scrambles to tackle climate change and build resilience to prepare communities for its devastating impacts, nature-based solutions are seen as panaceas. These projects, which use nature and natural processes to help mitigate the effects of climate change and harmful human activities, are growing in number and scale.
In the Philippines and India, mangroves are expanding alongside existing breakwaters on coastlines to protect against storms and flooding. Likewise, in South Africa, wetlands are being restored to replenish groundwater and protect water-scarce cities like Cape Town from drought.
Encourage the global community to scale up and integrate nature-based solutions into modern infrastructure. A 2021 report by the International Institute for Sustainable Development (IISD) concluded that this approach could save the world $248 billion a year in infrastructure costs.
Governments around the world are investing in the research and development of nature-based solutions, and global financial institutions such as the World Bank are actively involved in funding projects utilizing such approaches.
As urban planning scholars studying water resources, urbanization and climate justice in small and medium-sized cities in South Asia, we agree that nature-based solutions have a lot to offer. But we also advise caution. Our work in the Khulna region of southern Bangladesh, which faces multiple ecological crises, provides an example of how integrating nature-based solutions can lead to complex outcomes, helping some communities while harming others.
Khulna’s “Nature-Based Solutions”
In 2011, Bangladesh’s third largest city, Khulna, faced severe water shortages. As groundwater and pollution decrease, so does the intrusion of saltwater into its freshwater sources. Local governments have several options to resolve the crisis.
It could build a desalination plant to treat water from a nearby river. But such devices are known to be ecologically harmful. For example, a paper by the Canadian Institute of Water, Environment and Health states that desalination plants discharge 142 million cubic meters of hypersaline brine per day globally. That’s enough to cover up to 30 centimeters (12 inches) of salt water in the US state of Florida, which can be toxic and extremely harmful to marine life.
Another option for local governments is to impose stricter water-use controls on residents and businesses. That means asking residents to conserve water, asking industry to abandon water-intensive practices and investing in rainwater harvesting systems. Such water-saving policies can be difficult to implement and politically unpopular.
To avoid the negative impact of the desalination plant and possibly unpopular water-saving policies, the local government opted to build a “climate-adapted” water supply system and managed to secure foreign funding from the Asian Development Bank and the Japan International Cooperation Agency (JICA) .
The water system plans to draw water from the Madhumati River in the village of Mollahat, 40 kilometers (25 miles) northeast of Khulna, and deliver it to the city. During the rainy season, the water will be directly treated by the water treatment plant and then provided to consumers. During the dry season, when the salinity in Madhumati is high, the water will be mixed with the low salt water collected in the reservoir during the rainy season to reduce its salinity before being transported to the plant.
Policymakers hope this “nature-based solution” of mixing water will solve future problems as rising sea levels will continue to increase salinity levels in Khulna water. Designing the new water infrastructure as a climate- and nature-friendly framework enabled the local government to justify building this expensive project.
The new water infrastructure completed in 2019 has really benefited the residents of Khulna. It has increased household access to piped water from 23% to 65% and provided water to some informal settlements that previously had no access to water.
The problem caused by the “solution”
The popularity of the new water system in Khulna is evident from our interviews with residents of the city. Instead of queuing for hours to get water from a tube well, they report that women can now get water from a tap at a designated time.
The reports from Morahat, however, were quite different. During our 2018 field trip, one of us spoke to local resident Mohammad Liton, who said he barely slept that year. Liton is concerned about rising salinity and falling water levels in the Madhumati River, which has started to affect his livelihood. Litton argues that the Khulna project has reduced the amount of water available for fishing and rice cultivation in the Morahat area.
In January 2017, Litton and other residents of Mollahat protested the project, which affected the lives of thousands of farmers and fishermen in the village, but authorities did not address their concerns.
An environmental impact report for the project, completed in 2011 as required by the Bangladeshi government and foreign donors, focused only on the water supply location and considered construction as the only impact on Mollahat.
According to representatives of the Bangladesh Environmental Lawyers Association (BELA) we interviewed, the scale of the assessment inaccurately treats the Madhumati River Basin as existing only in Bangladesh. The river is a tributary in the complex Ganges system, which flows from the Ganges in neighboring India.
The Madhumati River has been severely affected by the construction upstream of the controversial Farakka Dam in the Indian state of West Bengal, which has been diverted. The dam has made the river basin more temporally and ecologically sensitive, so the additional burden of pumping water for the Khulna project has severely strained the river’s resources and impacted Mollahat and other communities along the watershed.
Be wary of nature-based solutions
Khulna’s hydro project should serve as a cautionary tale — a lesson for policymakers on what to do and what not to do when implementing nature-based solutions.
In this case, while industries and households in Khulna benefited from the project, residents of Morahat borne the cost. This situation could have been avoided if local authorities had consulted with villagers at the construction site and downstream when assessing the impact of the project. Their feedback can be used to fine-tune the implementation.
Local authorities should also aim to distribute benefits equally between the urban population and nearby rural communities. For example, they could have asked industry to conserve water, which would have relieved the pressure on the Madhumati River and significantly lessened the impact on the Mollahat community.
When green approaches are combined with infrastructure, local authorities must ensure that no harm is done to neighboring communities. Solving urban water supply problems should not come at the expense of rural communities.
As nature-based solutions are promoted, we urge policymakers, donors and communities to be more cautious. Infrastructure projects, such as Khulna’s, must minimize harmful impacts and help address inequalities at the local level and across regions.
The views expressed in this article are the author’s own and do not necessarily reflect the editorial position of Al Jazeera.