Says effect will be felt more on Mhadei Wildlife Sanctuary
PANAJI
Karnataka’s plans for diversion of the water from the disputed Mhadei river will have less of an impact on Goa as a whole, but a significant impact of the permitted diversion by the Tribunal will be seen on the Mhadei Wildlife Sanctuary, reveals a latest study by hydrologists.
“The water budget of the Mahadayi river and its implications for the inter-state dispute”, a joint study undertaken by the hydrologists from the National Institute of Oceanography (NIO) and Indian National Centre for Ocean Information Services, explains that the diversion from the Kalasa tributary could have “significant impact” but its impact is restricted to the northern part of the Mhadei Wildlife Sanctuary.
The researchers – K Anilkumar, D Shankar and K Suprit – have suggested that it is possible for Goa and Karnataka to reach an agreement on similar lines to the one Goa has with Maharashtra for the Tillari dam, in which the dam is built upstream on the Maharashtra side, since Goa does not have the space nor the geography to host a large dam without a huge environmental and people cost – and both states have a share of the water.
“For the Kalasa nala, there is a significant impact of the permitted diversion – 1.72 tmc (48.7 Mcum) by the Mhadei Water Dispute Tribunal in the northern part of the Mhadei Wildlife Sanctuary, but the impact on the Mahadayi discharge or the Mandovi estuary is less than the natural variability,” the researchers said in their report published in the Journals of Earth Sciences.
Similarly, according to the study, the diversion of 2.18 tmc (61.73 Mcum) from the Bhandura nala as permitted by the tribunal will only have “a minor impact on the (river’s) discharge at the Goa–Karnataka border.
The tribunal in its award passed in August 2018 had granted Karnataka a total of 13.42 tmc (380 Mcum) of water of which 8.02 tmc (227 Mcum) was for the proposed Mhadei Hydroelectric project, 1.5 tmc (42 Mcum) for in basin use and irrigation and allowed the diversion of 1.72 tmc (48 Mcum) of water from the Kalasa stream and 2.18 tmc (61 Mcum) at the proposed Bandura dam. In all, the tribunal permitted Karnataka to divert 110 Mcum of water from the Mhadei basin to the east flowing into Malaprabha basin.
According to the researchers, Goa’s claimed impacts of the diversion on ecology, which were upheld by the tribunal, are overstated because the significant impact of the permitted diversions is limited largely to the northern part of the Mhadei Wildlife Sanctuary, but does extend further downstream to the rest of the sanctuary in low-rainfall years.
“Though the tribunal upheld Goa’s contention that the projects would jeopardise navigation in the Mandovi estuary, available information is sufficient to show that these projects have no impact on navigation in the Mandovi estuary or the Cumbarjua Canal. Indeed, navigation in the Mandovi, which is made possible by the tides, is possible even during the lean season, when the natural flow of the Mhadei is negligible,” it said.
The researchers have argued in favour of Goa’s contention that a significant part of the Mhadei basin is subject to saline intrusion owing to the tides and that this estuary-affected area should be excluded from the estimate of water availability. It is difficult to store water in this coastal plain owing to its Cat terrain and high population density.
The researchers, however, claimed that if Tribunal had to accept Karnataka’s plea to permit diversion of water from the river feeding the Dudhsagar Falls on the Dudhsagar River, a tributary of the Khandepar; would have reduced its flow to a trickle and also affected the Bhagwan Mahavir Wildlife Sanctuary and Mollem National Park. This diversion to the Supa reservoir would have also had a significant impact on the Opa Water Works.
The researchers opined that since the Kalasa diversion canal is already constructed (Karnataka Neeravari Nigam Limited 2022b), a practical solution is to restrict the diversion to the proposed 30 Mcum from the Kalasa nala and avoid diverting water from Surla… Since the contribution of the Bhandura nala to the discharge at the State boundary is small and it is possible to permit diversion of the entire runoff of the Bhandura nala to compensate for the lower diversion from the Kalasa nala.
