Tamil Nadu Dam Storage Status with half the Monsoon gone

Weather Update

All of us know majority of Tamil Nadu is a rain shadow region as far as Southwest Monsoon goes. But when one looks at the catchment areas of all major irrigation dams of the state they are dependant on Southwest Monsoon for inflows. This is one of the key reason why most weather bloggers track Southwest Monsoon status religiously.

With half the Monsoon season gone its time to run a check on the current storage of key irrigation dams of the state. With regard to Cauvery Basin in addition to the three major dams in the state we have also added the status of the dams in Karnataka as the inflows into Tamil Nadu is closely linked to the storage levels of the Upper Riparian state.

As of yesterday the gross storage in Cauvery Basin overall is less than 1/3rd of the available capacity. Crucially it is nearly 175 TMC down on last year at the same time. We had given through our earlier post a few days back indicating how Cauvery needs to get more than 50% excess inflows during the remaining months to reach its normal inflow for the Southwest Monsoon season. The avg inflow during Aug. & Sept is about 125 TMC into Karnataka reservoirs, with the current shortfall at 175 TMC over last year, a gap of nearly 50 TMC needs to be bridged.

The rest of the Key irrigation dams across TN are also not faring well with the overall storage at just 15% of the overall capacity. Except for Papanasam rest of all the other dams depend on Southwest Monsoon heavily for inflows. Overall scenario is not very assuring for Tamil Nadu as things stand. The cumulative storage of all major dams of the state stands at 17% nearly 1/5th of the storage at the same time last year. It is advisable for Delta Farmers to plan their irrigation with ” No Help Fr om Mettur” scenario. In case Mettur storage improves drastically then we can enjoy the bonus.

Though some may say its July end, August is still left, looking at the weather models it appears August indeed will provide a window of about a week to ten days of active monsoon conditions over Peninsular India. Taking this into account Optimistic COMK estimates are for an overall storage of about 50% by the end of Southwest Monsoon season in Tamil Nadu. Hence it may be prudent for the government to start thinking of Deficit Plans at least on paper.