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| Natural water flows, Interrupted Kota Sriraj | | |
India must recognise
the potential that exists
for modifying the functioning of existing dams to recover many of the environmental benefits of healthy ecosystems that have been compromised by the present mode of operations. The burgeoning human habitat has put immense pressure on available natural resources, especially water. This has been compounded by the disruption in the natural flowing patterns of rivers. Indiscriminate human intervention, in the form of river course diversion, river-bed mining, and damming, has altered the environmental flow of rivers. Environmental flow of a river is the quantity, timing, and quality of water flow that is required to sustain freshwater and estuarine ecosystems in the river, besides supporting the well-being of human habitats that are dependent on these ecosystems. An efficient management of environmental flow in a river helps achieve a flow regime that provides human uses and also maintains the essential process that is required to support healthy river ecosystem, besides assisting in the dilution of pollution load.
Maintaining the environmental flow of a river is crucial, especially given the fact that, of the 177 large rivers of the world, only one-third are free-flowing, and a mere 21 rivers retain a direct connection to the sea.
Ecologically, free-flowing rivers have huge significance. All natural flow levels have a specific ecological function, including drought level flow, that helps in purging exotic species, as well as in concentrating game at a smaller place, for the benefit of predators. Flood flows help in numerous ways like groundwater recharge, nutrient balancing, fish spawning and sediment flushing. At the same time, free-flowing rivers and stretches also provide innumerable community services like fisheries, tourism and water supply.
Dams led the renewable energy revolution but they have played a major role in the disruption of environmental flow. River water management in 1960s focused on flood protection, water supplies, and hydro-power generation. The period witnessed a flurry of dam building activity and, as a result, today more than half of the world's largest rivers are dammed, a figure that continues to increase.
In India alone, approximately 5,100 large dams dot the rivers, making India rank third in the world with regards to the number of large dams. These structures have irretrievably changed the downstream flow patterns, consequently affecting water quality, temperature, sediment movement and deposition.
This detrimental outcome has prompted water management experts and Governments to modify dam operations in order to maintain and preserve river wildlife species and ecosystems without compromising the hydroelectric potential of the water body.
India rapidly develops strategies to resurrect environmental flows on rivers that are dammed. For instance, the World Wildlife Fund project to restore environmental flow releases on the Ramganga river, is an ambitious effort to harness environmental benefits from dammed rivers. The Government must take the cue and recognise the potential that exists for modifying the operations of existing dams to recover many of the environmental and social benefits of healthy ecosystems that have been compromised by present modes of dam operation.
The potential benefits of dam 're-operation' enable recovery of wildlife populations valued commercially and recreationally, including estuarine species. The re-operation process assists in re-activation of the flood storage and water purification benefits that occur when overflows are allowed access into floodplain forests and wetlands. The Government can begin efforts to assess the benefits of dam re-operation by characterising the dam's effects on river flow regime, and by formulating hypotheses about the ecological and social benefits that might be restored by releasing water from the dam in a manner that resembles its natural flow patterns. Many countries are increasingly adopting a legal framework to protect environmental flows. However, legislating environmental flow protection is one thing; determining what those flows should be is quite another. Limits on flow alteration need to be credible, enforceable and linked to ecological health. Many countries whose laws protect environmental flows have yet to quantify flow requirements for most of their water bodies. India must devise an effective water-use permitting system that ensures that the usage of water does not adversely affect the environmental flows. Because the amount of water available is a time-varying quantity subject to competing demands for water, a computerised decision-support-system is needed to link individual and cumulative withdrawals to flow targets. As reform efforts in order to re-operate dams from every continent across the world demonstrate, it is one thing to pass ambitious, high-level laws and policies, and quite another to implement the on-the-ground actions that protect and restore environmental flows. It is at the implementation stage that policy reforms come face-to-face with challenging realities, from political opposition to capacity constraints to institutional barriers. However, a concerted and incremental process over time can deliver meaningful outcomes.
(Courtesy:
@ dailypionner. com) |
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