Swimming Along Reason
— Veena Srinivasan, Sharad Lele, Jagdish Krishnaswamy & Priyanka Jamwal
India’s rivers are dying. The once perennial Kaveri, the lifeline of South India, has been reduced to a 1 km wide dust stretch in places. Drying trends have been reported in the Krishna too and the pollution problem in the Ganga is well recognised. The future of our rivers appears bleak.
So how do we better manage and protect this crucial resource? A nationwide clarion call for action by Isha Foundation’s ‘Rally for Rivers’ campaign has already garnered tremendous public support. But can ‘Rally for Rivers’ really give a new lease of life to our rivers? It can. But only if we get the science right.
The agenda of the Rally for Rivers campaign is simple. It consists of a solution (growing trees for a 1 km buffer zone along rivers) and a strategy (getting a large number of people to ‘vote’ by giving a missed call to a toll free number) to press the government into action. This level of engagement is heartening for researchers and activists who have been raising alarm bells on India’s impending water crisis.
The logic for this campaign: First, forests increase rainfall by transpiring and cycling moisture in the atmosphere locally. Second, trees reduce soil erosion and slow down run-off during heavy rains. So instead of flash floods, water is gradually released, contributing to dry season flows. Third, trees trap sediment and pollutants improving river water quality.
The problem is that the proposed solution will actually contribute little to solving the problem. If done wrong, may do harm. The arguments, though not incorrect, are incomplete, as the major causes for the problem lie elsewhere.
First, there is some evidence that large extents of natural forest can contribute to rainfall and conversely deforestation can decrease rainfall. The science, however, suggests that the link between land cover and climatic change is tenuous. It becomes significant only when changes occur at regional to continental scales. A 1 km of trees along rivers is unlikely to impact local rainfall patterns.
Second, while it is true that forests reduce soil erosion, more trees will help only in flood-prone places. But many river stretches are drying for reasons unrelated to the absence of trees. Sand mining is eroding our rivers’ natural buffers and dams built to divert water for irrigation and cities upstream, leave very little flowing downstream.
The only solution is to release water for ecological needs. To make this possible, upstream farmers and urban users will need to make their practices less water-intensive.
Third, in many parts of India, streams are disappearing because of groundwater over-exploitation. As groundwater levels drop, instead of the aquifer feeding the stream (‘baseflow’), streams are being sucked dry. Till now, the popular solution promoted by governments and NGOs alike has been ‘watershed development’: building check dams, farm bunds, and trenches to slow down the flow of water and boost recharge.
But these structures do not create new water. They merely convert surface run-off into groundwater. By design, groundwater gets recharged, but there is then less water in the stream. Ultimately, there is no way to get around the problem of groundwater depletion except to pump less.
Fourth, it is argued that planting trees will trap pollutants. However, most of the pollution in Indian rivers is not from non-point sources such as run-off from agricultural fields or roads, but raw sewage and industrial effluents released directly into streams. Largescale dredging of rivers for navigation is also degrading water quality.
These types of pollution cannot be stopped by a barrier of trees. They require sustained efforts at building and maintaining effluent treatment plants, monitoring illegal discharges, enforcing existing laws and taking measures to protect aquatic ecosystems.
Finally, even a 1 km-wide tree buffer can have unintended negative social or ecological impacts. Reforesting traditional village commons that serve as grazing lands for the landless (often lower caste), or natural grasslands that have their own unique ecosystems, creates additional problems. Moreover, tree planting is not necessarily benign. Deep-rooted, fast-growing species like eucalyptus have been shown to consume a lot of water and decrease groundwater recharge.
Restoring rivers is a complex problem. The idea of holding the government accountable is commendable. But what should the campaign ask for? We suggest the following: stop rampant sand mining and deforestation in the catchment areas. Restore riparian and flood-plain ecosystems that are not only tree-centric, but include a mix of grasslands, scrub and wetlands.
Tie watershed development funds to measures to reduce groundwater and canal water abstraction by growing less water intensive crops or drip irrigation. Bring big polluters in cities to book. Invest in sewage treatment and solid waste management in urban centres.
Finally, charity begins at home. Let’s change our own diets toward rain-fed coarse cereals like millets and reduce water-intensive rice and sugar.
(The authors are with the Ashoka Trust for Research in Ecology and the Environment, Bengaluru)
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