[Commentary] Restoring urban wetlands for a brighter future

The World Bank estimates that 34.4 percent of India’s population is urban, marking a steady rise in city-dwellers over the past six decades. As the demand for land for housing and commercial use grows, green and blue spaces in cities are declining steadily. Among other natural spaces, urban wetlands often find themselves on the losing end of an endless tug-of-war between development and conservation.

Take Bengaluru for instance. India’s IT hub, also known as the City of Lakes or the Garden City, has seen a population boom in recent decades thanks to the growth of the technology sector. Alongside this unprecedented growth, however, it has also seen a serious decline in urban wetlands. Wetlands in Bengaluru comprise lakes, tanks, ponds, reservoirs, and vegetated waterbodies, mostly existing in isolated patches. Borewells supplement the existing tank-lake system, providing water for sanitation, household use, and irrigation. However, in the recent past, excessive groundwater use and increasing water pollution has drained Bengaluru’s existing water supply. Wetland surface area declined from 64.3 sq. km. (1965) to 54.8 sq. km. (2018), with losses attributed to draining for construction and eutrophication due to pollution influx. Indeed, during the same period, satellite imagery highlighted an increase in built-up area from 52.0 sq. km (1965) to 592.2 sq. km (2018). Similarly, the water table around certain lakes in the city has dropped from 28 m below the surface to 300 m below the surface in 20 years, creating an acute groundwater shortage in parts of Bengaluru. The same study recorded encroachment of 54% of the city’s lakes for illegal development.

Caught in urban expansion, India’s wetlands are often sidelined for large-scale development projects. While the inner-city limits of Bengaluru are well-established, the majority of new infrastructure and wetland loss has occurred on the periphery of the main city. A study by Wetlands International South Asia (WISA) found that Mumbai has lost 71% of its wetlands, followed by Ahmedabad (57%), Bengaluru (56%), and Delhi-NCR (38%). Disruptions to underlying hydrology have contributed to the drying of wetlands and other waterbodies on the periphery and within these cities. Encroachment, drainage and landfilling, discharge of industrial and domestic effluents into waterbodies, and over-exploitation are key causes of wetland loss today. However, the major cause of wetland loss is not the physical draining or pollution of these waterbodies; a lack of awareness and knowledge of wetlands and their ecosystem services can be blamed for this widespread loss.

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Healthy wetlands, healthy cities

The Ramsar Convention of 1971 establishes guidelines for wetland conservation and responsible use and provides a classification key for major wetlands across the world. India, among other nations, is a signatory to this Convention and thereby charged with creating a competent wetland conservation plan, something that has often been brushed aside in the face of progress. Yet in a country with over 757,000 wetlands accounting for almost 4.7 percent of its geographic area, India has only extended Ramsar protected status to 42 wetlands, eight percent of which are found in and around urban centres. Yet it is time for India to look beyond protected areas and protected wetlands and extend conservation measures to lesser-studied waterbodies, including those within city limits.

Wetlands are incredibly productive ecosystems and range from mangrove swamps to lakes and reservoirs, and all these can co-exist with urban spaces with proper location and zoning. They are characterised by waterlogged soils, the presence of aquatic vegetation, and a high water table through most of the year. They also provide a range of ecosystem services – goods and services provided by natural and man-made ecosystems to benefit humankind. Urban wetlands offer a variety of oft-undervalued goods and services to city dwellers when protected and restored in city landscapes.

As the urban population continues to grow, the need for water is expected to rise. Competition between agriculture, domestic water use, and industrial use will likely increase the demand for available water, making wetland restoration and conservation critical in the coming years. Additionally, wetlands play a major role in reducing urban flooding. Alterations in natural topography and removal of vegetation cover have increased flood frequency even during years of normal rainfall. Floods occur increasingly quickly, sometimes in a matter of minutes, posing severe risk to urban populations especially those in impoverished neighbourhoods. Drainage systems are unable to cope with increased surface water runoff, as seen in Mumbai during the 2005 floods which killed hundreds of people. This unprecedented flooding was attributed to an antiquated drainage system that was unable to hold more than 25 mm water per hour (rainfall was recorded at 950 mm in 24 hours), poor urban planning in suburban Mumbai where development projects did not require an Environmental Impact Assessment prior to construction, and the widespread loss of mangroves in the city. Mumbai lost 40% of its mangroves between 1995 and 2005 to both builders and slum encroachment. As the city expands northwards, mangrove loss along the Mithi River and Mahim Creek continues to pose a threat to the city’s waterbird populations, the livelihoods of fisherfolk along these waterbodies, and residents who face flood risk during the monsoons. Coastal cities depend heavily upon mangroves for protection against storms and resultant inland flooding.

Read more: Navi Mumbai couple fights to save a bird haven from becoming a golf course

Healthy wetlands also provide food and livelihoods for countless citizens. The East Kolkata Wetlands provide a living for over 50,000 fisherfolk and small-scale cultivators. The primary source of income is from rearing 10,000 tonnes of wastewater-reared fish each year. These fish are also made available on the city markets for a cheaper price than in other cities due to the cost-effective rearing practices utilised in the East Kolkata Wetlands. These man-made wetlands also serve as sewage-treatment ponds, where water from Kolkata’s Hooghly River is flushed into holding ponds and held until the waste settles to the bottom of the wetlands. However, the waste assimilation and recycling functions of wetlands can be overwhelmed by excessive effluents, especially if urban effluents have toxins and contaminants.

Wetland vegetation is a key player in filtering agricultural and industrial runoff and holding pollutants on the wetland floor. Then, the clean surface water is released downstream, creating a natural sewage treatment system. Only 24% of Kolkata’s daily wastewater is treated within the city’s treatment plants; the remaining water is treated in these wetlands, offering a major service to the city’s people. Such multi-use wetlands hold great potential for cities such as Bengaluru and Mumbai, where the demand for multiple benefits from waterbodies far exceeds the number of wetlands.

Restoring and conserving urban wetlands

City wetlands may be declining in quantity and quality, but cities around the world are taking measures to ensure their revival. The 2018 Ramsar Conference of the Parties (COP13) instituted a Wetland City Accreditation scheme that gives global recognition to cities that voluntarily take steps towards protecting their wetlands. Eighteen cities were recognised in 2018 as pioneers in urban wetland conservation, including six cities in China and Colombo, Sri Lanka, among others. Methods of meeting Accreditation goals include increasing public awareness of wetland use and importance, stakeholder participation in municipal planning and infrastructure development, and restoring degraded wetlands.

“Urban wetlands could become hotspots of multiple ecosystem services, linked livelihoods and biodiversity but this requires that our definition of so-called “Smart Cities” is tweaked, we set up long-term and short-term goals and we encourage partnerships between residents, stakeholders and government agencies.  There are encouraging signs from some of our cities, but we have a long way to go,” says Jagdish Krishnaswamy, Convenor and Senior Fellow at the Ashoka Trust for Research in Ecology and the Environment (ATREE).

India must turn its focus inwards and work towards restoring urban wetlands in order to balance ecosystem services and development in a growing nation. A far-sighted approach incorporating multiple stakeholders and considering multiple benefits of wetland conservation is imperative if we are to create liveable, healthy cities of the future.

CITATION:

Brinkmann, K., Hoffmann, E., & Buerkert, A. (2020). Spatial and temporal dynamics of Urban Wetlands in an Indian Megacity over the past 50 years. Remote Sensing, 12(4), 662.

Ramachandra, T. V., Aithal, B. H., & Kumar, U. (2012). Conservation of wetlands to mitigate urban floods. Journal of Resources, Energy and Development, 9(1), 1-22.

Gupta, K. (2007). Urban flood resilience planning and management and lessons for the future: a case study of Mumbai, India. Urban Water Journal, 4(3).

The author is a wetland ecologist and geologist working on inland wetlands of the Western Ghats. She is also an avid science communicator and has launched a children’s environmental e-magazine.

Banner image: Domestic sewage from the surrounding areas prevents Singapura lake from drying up completely. Photo by Shashank Palur.