A row has once again broken out in Karnataka and Tamil Nadu over sharing Cauvery waters. It occurs every six years or so when the monsoon fails in the Cauvery’s catchment regions in Karnataka and northern Kerala. Since June, Tamil Nadu has received about a third of its water entitlement as per the Cauvery tribunal award, which spells out the schedule of monthly releases from Karnataka’s reservoirs in a normal year.

Tamil Nadu is of the view that Karnataka could have released more despite being rain-hit to irrigate its summer paddy crop (kuruvai), while Karnataka cites its poor reservoir levels and drinking water scarcity to suggest that it is struggling to abide by the orders of the Cauvery Water Regulation Committee (CWRC). In the absence of clear information on water availability, thanks to the way in which it is measured, it would be wrong to judge either side. The CWRC has said that Karnataka should release 3,000 cusecs (cubic feet per second) of water between September 28 and October 15; it had been instructed to release 5,000 cusecs in the preceding 15-day period. As per the award, Karnataka would have been required to release about 14,000 cusecs in September, while Tamil Nadu would like 12,500 cusecs.

The Karnataka government seems reasonably satisfied with the ruling. This could be revised if the Cauvery watershed receives rain, even as Tamil Nadu has its own catchment area. The root problem is that the Cauvery tribunal award does not spell out a formula for sharing water in deficit years. Besides, the award does not define deficit clearly. Nor are there comprehensive ways to measure water availability. Normal water availability should consider not just reservoir levels, but groundwater levels, soil moisture and river velocity, depth and volume. It is against this benchmark that deficits should be assessed across the river basin.

The lack of coordination between State agriculture departments, the water resources bureaucracy and the IMD leads to poor preparedness. While the IMD does not come up with localised or basin-specific forecasts, it is also true that reservoir and crop management authorities tend to discount its forecasts. Dam authorities are unable to accurately assess how localised rain or its absence will impact reservoir levels. But apart from these techno-managerial issues, the biggest problem is the assumption that demand cannot be curtailed even in a deficit year. Prior knowledge of a rain deficit should translate into a Plan B in cropping, substituting sugarcane and paddy with pulses or millets. These efforts should be marked by procurement support. The river basin authority should persuade the two States to come up with a demand management plan. The water demand of cities such as Bengaluru is unsustainable. Bengaluru has no worthwhile storage or conservation plan. The States must conserve water through rainwater harvesting and tanks, especially in monsoon-surplus years such as 2022. Such planning is, sadly, not in evidence.