Troubled waters: Growing climate and population pressures in southern Indian watersheds
Rapid urbanization is squeezing India’s limited water resources. While climate change may compound the problem, research in two southern watersheds points to industrial pollution, unregulated extraction, and changes in land use as the greatest threats to water quality and availability.
The southern city of Bangalore in the state of Karnataka has ridden the tide of India’s transformation in the last half century. Boeing, Samsung, Tata, and Toyota, along with a number of IT juggernauts, are just a few of the corporate giants located in this sprawling city. But its 10 million people, its myriad competing industries, and the farms and suburbs that radiate from its periphery draw on the nearest water source: the Arkavathy river basin.
One of two major reservoirs on the Arkavathy River has dried up entirely; the other supplies only one-fifth of the water it was designed for. The city instead depends heavily on water imported from the Cauvery River more than 100 km away, while rural areas continue to pull from a nearby groundwater aquifer.
These problems are not unique to Bangalore. Across India, urban growth is pushing water demands and pollution on adjacent waterways, diminishing both water quality and quantity. Climate change, meanwhile, may compound the problem. Projections suggest that the subcontinent will experience an average temperature increase of 2-4°C this century. A possible rise in precipitation may be offset by increased evaporation.
While Karnataka state is now investing in rejuvenating the Arkavathy, too little is understood about why water levels are declining, and there is no consensus on how different water users are to be served or regulated. Without understanding these basic issues, adapting to the added pressure from climate change will be a tall order.
Urban growth is pushing water demands and pollution on adjacent waterways, such as this polluted stream in Bangalore City.
Linking human and environmental stressors
Research led by the Ashoka Trust for Research in Ecology and the Environment (ATREE) is shedding light on how India’s precious water resources may withstand the twin challenges of climate change and rapid urban development. The team is exploring both human and environmental changes underway in two southern watersheds—the Arkavathy and the Noyyal sub-basin in Tamil Nadu.
The Noyyal River flows past a number of rapidly growing cities including Coimbatore, a major hub for textiles, information technology, and medical services, and Tiruppur, a hotspot for textile dyeing. Like Bangalore, both cities are increasingly dependent on imported water from other basins. The problem of industrial pollution is far more acute in the heavily industrialized Noyyal basin and the contribution of domestic sewage is rising rapidly.
To address the complex underlying issues, ATREE is applying an integrated “human-environment systems” framework. Researchers are focusing on water users' priorities, integrating data on biophysical changes with an understanding of the many ways in which these users will be affected by climate change. The aim is to fill a number of knowledge gaps, so that rejuvenation efforts will be anchored in solid evidence.
“The primary challenge,” says co-principal investigator Veena Srinivasan, “is to understand how multiple stressors like climate change and urbanization actually interact.” Sharachchandra Lele, the project’s principal investigator adds, “Understanding resilience to climate change is but one of many public policy goals that research should address. Adequacy, equity, and sustainability in water use is equally important.”
Rapid urbanization and growing water demand is leading to increasing stress on groundwater levels in the Arkavathy watershed.
Ground water depletion and pollution pathways
Early findings in the Arkavathy Basin underscore the links between surface and ground water, and between shallow and deep aquifers. Neither climate models nor rainfall data show any significant changes that would explain the sharp decline in flows of the Arkavathy, or the inability of most bodies of water to fill up, even in high rainfall years. The research team speculates that heavy domestic, agricultural, and industrial use of water is having a far greater impact than the onset of climate change.
Most Bangalore residents do not yet feel the pinch of scarcity, offset by imports from the Cauvery River. However, farms and households in the surrounding rural areas, as well as peri-urban households that don’t have access to other water sources are being affected. Groundwater levels in these areas have declined from a depth of 200-300 feet to 800-1,000 feet over the past two decades, and the failure rate of borewells is very high.
Preliminary studies are also pinpointing the pathways and impacts of pollution in the Arkavathy Basin. They show that existing sewage treatment plants are often ineffective in reducing bacterial contamination. And poorly regulated industries are likely sources of the heavy metals that end up in a downstream reservoir used to irrigate vegetables, food, and fodder crops.
Underpinning good governance
While Karnataka hopes to revive the Arkavathy by digging channels, planting trees, and curbing industrial pollution, the competition for scarce water continues unabated. Currently, there is no formal system of water rights, and India’s National Water Policy gives priority to domestic needs without clarifying what agriculture or industry are entitled to.
There are no simple answers, but ATREE hopes to empower people to seek sustainable solutions. “In India, we have strong civil society organizations,” says Srinivasan. “But they are not supported with good scientific data. We are creating the models and collecting the data that can be used by a whole range of stakeholders to advocate for better governance.” Lele adds, “we have initiated a water literacy campaign that will hopefully create the demand for such data.”
Mary O'Neill is an Ottawa-based writer.
The project “Adapting to Climate Change in Urbanizing Watersheds” is funded through the IDRC Research Initiative on Water Resources and Adaptation to Climate Change in Asia, Latin America and the Caribbean with funds from the Government of Canada's fast-start financing.