Latest news with #Mcum
The Hindu
15-05-2025
- Science
- The Hindu
Protests in Goa over NIO hydrologists' report claiming Mahadayi river diversion will have limited impact on the coastal State
A protest has emerged in Goa following the publication of a scientific paper, 'The water budget of the Mahadayi river and its implications for the inter-State dispute', by scientists and researchers from the CSIR- National Institute of Oceanography (NIO), Goa and the Indian National Centre for Ocean Information Services, Ministry of Earth Sciences, Hyderabad. Also Read | Farmers in Karnataka condemn Centre's decision to extend term of Mahadayi tribunal The legal dispute between Karnataka and Goa over the water sharing agreement from the Mahadayi river has lasted over two decades. Despite the Mahadayi Water Disputes Tribunal's (MWDT) order five years ago, the matter remains an emotional subject in both the States. The paper, published in the Journal of Earth System Sciences by scientists and researchers: K. Anilkumar, D. Shankar and K. Suprit — has assessed the water budget of the Mahadayi river, an inter-State basin on India's west coast, by using rainfall mapping and rainfall run-off model to allow them to simulate the discharge at any point along the Mahadayi. The river, called Mahadayi in Karnataka and Mhadei in Goa, arises in the Western Ghats and flows into the eastern Arabian Sea. This river basin is spread over three States — Goa, Karnataka, and Maharashtra. The paper says Karnataka's plans for diversion of the river as approved by the MWDT would not have much impact on Goa. The diversion from the Kalasa tributary could have 'significant impact' but its impact is restricted to the northern part of the Mhadei Wildlife Sanctuary in Goa. Scientists recommend that by creating check dams and storage facilities inside the wildlife sanctuary, the ecological impact of the river diversion could be minimised. The length of the Mahadayi in Karnataka is 36 km and its length in Goa is 74 km. The Mahadayi basin covers an area of 2,032 sq km of which 380 sq km (18%) is in Karnataka, 72 sq km (4%) in Maharashtra, and 1,580 sq km (78%) in Goa. The tribunal has permitted the Karnataka government to utilise 1.72 tmcft of water from Kalasa nala and 2.18 tmcft from Bhandura Nala (two of the main tributaries of Mahadayi). Tillari dam example The researchers suggest a solution in the paper that Goa and Karnataka can 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 tmcft (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 on the Mandovi estuary is less than the natural variability. Similarly, the diversion of 2.18 tmcft (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 paper said. The MWDT was set up in 2010 following the failure of the States to reach an agreement. The tribunal passed the order in August 2018 and in its award granted Karnataka a total of 13.42 tmcft (380 Mcum) of water of which 8.02 tmcft (227 Mcum) was for the proposed Mhadei Hydroelectric project, 1.5 tmcft (42 Mcum) for in basin use and irrigation and allowed the diversion of 1.72 tmcft (48 Mcum) of water from the Kalasa stream and 2.18 tmcft (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. Both the States have challenged the tribunal's verdict before the Supreme Court. '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,' the paper said. Demand explanation Following this report, members of the Mhadei Movement, dressed in blue T-shirt, staged a protest outside the NIO complex near Goa's Dona Paula, with placards displaying a red cross mark on the photographs of the scientists, shaming them, with words such as 'BJP sold Mahadayi', 'Mhadei deal by NIO', 'Anti-Goa NIO'... demanding an explanation from the hydrologists and the institutes for the reason behind publishing the report. Revolutionary Goans Party (RGP) president Manoj Parab said, 'Why are the non-Goan scientists running research on this subject that does not concern them? We are questioning the timing of this report. We spoke to environmentalist Rajendra Kerkar who has done extensive research on Mhadei and he told us that the NIO scientists wrote the report sitting inside their air-conditioned office without having any ground understanding. The three scientists have manufactured this report to favour Karnataka which has gone ahead with the construction of dams on the river, despite the case being heard by the Supreme Court. This is a conspiracy by the BJP.' The party further demanded Goa Chief Minister Pramod Sawant and Congress leaders from the State to come out and speak on the matter and make their stand clear or are they too in favour of the report, Mr. Parab questioned. Viresh Mukesh Borkar, RGP's MLA, said, 'The report was published on September 11, 2024, quietly, and no one knew. It is surprising as the Chief Minister also did not say a word on this for so many months. This looks like a hidden agenda of the BJP government. When the case is already before the Supreme Court, publishing this report means the scientists want to favour the case of the Karnataka government. It is a known fact that Goa's groundwater is depleting, and this river serves the people and flora and fauna of north Goa, if they block its flow from the Western Ghats, Goa will face a man-made disaster.'
Hindustan Times
12-05-2025
- Science
- Hindustan Times
Karnataka's plan for diverting Mahadayi river water won't have much impact on Goa: NIO hydrologists
An analysis of the annual water flow of the disputed Mahadayi river (spelt Mhadei in Goa) by hydrologists at the Goa-headquartered National Institute of Oceanography has suggested that Karnataka's plans for diversion of the water as approved by the tribunal would have less of an impact on Goa and can be mitigated via mitigation measures. In a new paper published in the Journal of Earth System Sciences, the researchers — K Anilkumar, D Shankar and K Suprit — simulated the water budget of the Mahadayi river using a more accurate rainfall mapping and rainfall run-off model which made 'two key improvements compared to the data arrived at by the tribunal' to allow them to simulate the discharge at any point along the Mahadayi. According to the simulation, while the diversion of 1.72 tmc (48.7 Mcum) of water from the Kalasa nala (a northern tributary of the Mahadayi) as permitted by the tribunal will have 'a significant impact of the permitted diversion in the northern part of the Mhadei Wildlife Sanctuary, the impact on the Mahadayi discharge or the Mandovi estuary is less than the natural variability.' Similarly, according to the study, the diversion of 2.18 tmc (61.73 Mcum) from the Bhandura nala (a tributary of the Mahadayi originating not far from its source) as permitted by the tribunal will only have 'a minor impact on the (river's) discharge at the Goa–Karnataka border' according to the paper. The Kalasa and Bhandura are two tributaries of the Mahadayi that Karnataka seeks to divert to the Malaprabha river. Goa and Karnataka are engaged in a two-decade long dispute over water of the Mahadayi river, a river originating in the Western Ghats on the Karnataka side of the border and flowing west before meeting the seat at Panaji. The 2032 km2 basin that covers much of north Goa is crucial for Goa's water needs. Goa primarily opposes Karnataka's plans to divert waters from the Kalasa and Bhandura streams of the Mahadayi basin to the east-flowing Malaprabha river, a tributary of the Krishna that also originates in the Western Ghats not far from the Mahadayi, but flows east but not objecting to Karnataka's in basin use of the water. 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 Mahadayi 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 Malaprabha basin. The dispute is currently before the Supreme Court where both Goa and Karnataka have challenged the tribunals' verdict. The Study According to the authors of the research, they first improved the rainfall distribution data by incorporating the impact of elevation on rainfall in sufficient detail (as small as a 90 m by 90 m quadrants) as opposed to the tribunal's use of the Thiessen polygon method (also known as the weighted average method used to calculate the average rainfall over an area) and assigned a constant value equal to the gauge data to a large area. 'The drawback of using the Thiessen polygon method in an area such as the Western Ghats is that it tends to overestimate or underestimate rainfall in a region where, owing to geographical features, rainfall at two proximate locations can differ widely,' K Suprit who developed the model and who co-authored the paper, said. 'We went on to use a rainfall-mapping method that explicitly prescribes the ridge and mapped the rainfall separately for the windward and leeward sides of the meteorological ridge. The model simulates the sharp reduction in rainfall on the leeward side of the ridge,' he added. 'Hence, the modeling framework used in the study/paper allows the authors This creates a daily discharge time series for the entire basin, which is invaluable for estimating the water resources availability at any point in the entire Mahadayi basin,' he added. The findings At the core of their findings is that at Ganjem in Goa, where waters of the Mhadei transition into the Mandovi estuary and which falls around 40 kms upstream from Panaji, the river receives 2947 Mcum of water per day from June to October (monsoon months) with a standard deviation of 16% or 463 Mcum. Karnataka has been permitted to divert 110.5 Mcum of water. 'The water that will be diverted by Karnataka works out to less than one fourth of one standard deviation. In other words the amount of water that Karnataka is permitted to divert is less than the natural variations in river flow during the monsoon months,' the scientists said. 'The impact of diversion from the Bhandura nala is negligible for the Mahadayi's runoff in Goa,' the paper stated. Goa has consistently argued in its case before the tribunal that Karnataka's plans for water diversion would significantly impact water availability at Ganjem, a barrage whose water is used to supply water to the central parts of the state including the state capital. The researchers also differed with the tribunal's view, as argued by Goa 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 Mahadayi is negligible,' the scientists said. This isn't to suggest that the diversions will have no impact on Goa. According to the paper, 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 impact of the projects permitted by the tribunal is restricted to some distance downstream of the site. Specifically, the impact of diversion from the Kalasa nala is significant in the Mhadei Wildlife Sanctuary,' the paper said but added that Goa's claimed-impacts of the diversion on the ecology of the sanctuary, which were upheld by the tribunal, were overstated because the significant impact of the permitted diversions is limited largely to the northern part of the Mhadei Wildlife Sanctuary. 'The Kalasa diversion does, however, have a significant effect on the flow in the northern part of the Mhadei Wildlife Sanctuary, which covers a stretch of 17 km from the state boundary till the Surla's confluence with the Mahadayi. The diversion of 41.1 Mcum implies a decrease of 35% at the northern end of this stretch covering the sanctuary. This impact, they suggested, could be mitigated by setting up artificial water holes or check dams to help to store a part of the high discharge during rainfall bursts in the sanctuary, as done in the sanctuaries of Goa and also in some other sanctuaries to tide over shortages due to natural seasonal or interannual variability. 'This additional storage will help retain water in the sanctuary, but have a marginal impact on the discharge of the Mahadayi,' the researchers suggested. In summary, the researchers said that their simulation reveals that for the Kalasa nala, there is a significant impact of the permitted diversion 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 Bhandura diversion has a minor impact on the discharge at the Goa–Karnataka border,' the paper also said. The researchers however, noted that the tribunal was right in turning down Karnataka's plea to permit diversion of water from the river feeding the Dudhsagar Falls on the Dudhsagar river, a tributary of the Khandepar (in Goa). 'Permitting this diversion, which would occur just upstream of this iconic waterfall, 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 paper noted. Possible solutions for resolving the dispute The researchers have suggested that it is possible for Goa and Karnataka to reach an agreement in a manner that allows both states to benefit -- a solution that involves Goa and Karnataka reaching an agreement on similar lines to the one Goa has with Karnataka for the Tillari dam -- in which the dam is built upstream on the Karnataka side, since Goa does not have the space not the geography to host a large dam without a huge environmental and people cost -- and both states have a share of the water. A practical solution to the simmering dispute over the Kalasa nala would involve prescribing a floor (minimum) on the downstream runoff and allowing Karnataka to divert more water from the neighbourhood of the Bhandura nala. Prescribing the floor on the downstream runoff in the Kalasa nala or guaranteeing a minimum flow downstream of the Kalasa dam would reduce the effect on the Mhadei Wildlife Sanctuary and ensure downstream runoff even in the driest years. 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 the Surla… Since the contribution of the Bhandura nala to the discharge at the state boundary is small it is possible to permit diversion of the entire runoff of the Bhandura nala to compensate for the lower diversion from the Kalasa nala. The researchers even suggested Karnataka to shift its proposed Bandura dam to a location they call C1, which is lower downstream and located after the confluence of the Bandura stream with the main Mahadayi river, which will allow the setting up of a bigger dam, with less loss of forest cover (since it falls on the leeward side of the Ghats), the waters of which could be shared by Goa and Karnataka. Hence, while Goa needs storages, a fact acknowledged in a meeting of stakeholders in 2015 (India Water Partnership 2016), it is not in a position to construct them in its territory. The leeward region, with its gentler topography), is less densely populated than the coast region and is not as ecologically sensitive as the ridge and foothills, suggesting that it would be easier to impound water there. Hence, a more cooperative approach could help resolve the Mahadayi water dispute. 'Goa and Karnataka will have to agree to a water-sharing formula for the storage at C1. The likely trade-off envisages Goa agreeing to a certain amount of diversion in return for guaranteed supply during the lean season. Prescribing a floor on the discharge downstream, however, is still as essential as the cap on the diversion,' the scientists said. The annual surplus in the Mahadayi basin, when evaluated along with the scarcity towards the end of the lean season, suggests that a viable solution can be found if both Goa and Karnataka work out a cost-sharing and water-sharing formula with storages constructed on the leeward side of the meteorological ridge in the Mahadayi basin. In summary, it should be possible to arrive at a mutually beneficial solution to this dispute by shifting the storages from Goa, where it is difficult to construct them, to the leeward side of the ridge in Karnataka. The gain for Karnataka would be in the permitted diversion and the gain for Goa would be the augmented in-basin storage, from which water could be released during the lean season. Goa has a similar agreement with Maharashtra for the Tillari Irrigation Project, in which the Tillari river, that originates in Maharashtra is dammed in the upper riparian state, but via an agreement, Maharashtra supplies water from the dam to Goa. The scientists however, warn that irrespective of such an agreement being reached the scientists have warned that 'given the difficulty of storing water in this small basin with significant topographic gradients and the fragile ecology of the Sahyadris, both Goa and Karnataka will also have to rethink their cropping patterns.' 'Goa may have to reduce the cultivation of rice during the Rabi season and Karnataka the cultivation of sugarcane,' the researchers suggested. There exists support among the agricultural stakeholders in Goa for rethinking cropping patterns, better management of irrigation, and growing crops that require less water (India Water Partnership 2016), but a similar change is required in Karnataka to preclude groundwater resources reaching a critical state.
