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Dredging the Ganga will upset its ecosystem

ht view Updated: Sep 11, 2014 22:46 IST

The NDA government has planned to dredge sections of the Ganga from Allahabad to Haldia (some 1,600 km) to deepen its bed and to turn it navigable for cargo-laden ships. The substantial amounts of sand and silt recovered from the river bed is expected to be used in the construction sector.

Prima facie this is an attractive plan. But dig deep and it becomes clear why the plan is wrong. Dredging is like disemboweling and it can impact the natural functioning of the river ecosystem. It is also not a one-off event. Most nations that have dredged their rivers keep spending a fortune to maintain them. Countries like the Netherlands, Britain and the US have dredged their rivers for varying reasons, like navigation, removing pollutants and flood control.

Monsoonal rivers like the Ganga are distinctive in their load, the morphology and biodiversity and hence should not be considered automatically suitable for dredging purposes. Originating from the fragile Himalayas and discharging high to very high sediment-laden flows the Ganga annually carries a great load of water and sediments, and hence it would require almost annual dredging to ensure its continued navigability, making it cost intensive.

The Ganga, when compared to other rivers, has a unique biodiversity with animals like the Gangetic dolphins, the crocodiles or a wide variety of turtles. Dredging would put these species at risk. This, coupled with hardly any scientific data available to assess the adverse impact of large-scale dredging, could prove catastrophic.

Rivers, when used for commercial navigation, are at a risk of different kinds of pollutions. The Ganga — already struggling from very high levels of domestic and industrial pollutants — can certainly do without an additional source of pollution.

For a river to be navigable it requires a constant level of water at all times. This is doubtful in the case of the Ganga, especially during the lean non-monsoon season.

Given this, the least our decision-makers must do is to ensure that a credible risk impact assessment of its dredging plan is done before starting the project.
If the idea is to dredge for sand and silt, the focus should be on the reservoirs of dams and barrages where the sand and silt has compromised the productivity of the said structures.

Manoj Misra is convener, Yamuna Jiye Abhiyaan
The views expressed by the author are personal