Cauvery: Report tells carryover storage of 20tmc

Bangalore, May 15: The Assessors' Report on the availability of water in the Cauvery Basin has suggested a carryover storage of 20 tmc ft of water on normal year yielding 740 tmc ft in the basin.

The report released disputed states for their comments by the Cauvery Water dispute Tribunal on May 10 had apportioned 685.87 tmc ft of water to the four riparian states with Tamil Nadu assigned 394.85 tmc ft (including 10 tmc ft for reservoir losses) to irrigate 24.71 lakh acres, 250.62 tmc ft to Karnataka (including 63.83 tmf ft for minor irrigation covering 3.3 lakh acres and 17.15 tmc reservoir losses), 33.40 tmc ft to Kerala and seven tmc to Pondicherry (including 0.5 tmc ft for drinking water and industrial use).

The assessors, in their report, said though they had adopted dependability of 50 per cent for distribution of available supplies among the party states, it was felt absolutely necessary to provide some safeguards against the delay in the onset of monsoon as also to some extent, shortfall in the availability of water.

Hence it was opined that about 20 tmc of water should be reserved and kept as carryover storage during a normal year in which the availability in the basin would be 740 tmc ft. Water available during that year would be 720 tmc ft after providing for carryover, the report said.

According to the report, the storage pattern of the carryover water would be five tmc each in K R Sagar and Kabini reservoirs, eight tmc in Mettur and two tmc in Bhavani. It suggersted setting up of a mechanism for implementation of the final award of the Tribunal under which there would be a provision for cauvery water regulation commitee and the releases from carryover storage would be controlled by this committee, working under the Cauvery River Authority.

The available carryover storage would be built up progressively ending September, January and 31 May. The total carryover as on January 31 should be 20 tmc plus the likely evaporation losses in the four reservoirs from January to May 31, it said.

The Report said during a good year the extent of carryover storage would also be enhanced by the same quantum and the maximum would be full storage if flood flows were very excessive. During good year, additional storage, depending upon the available river flows shall be made upto to an additional quantity of 50 tmc including Harangi and Hemavathy reservoirs in Karnataka, Banasurasagar in Kerala and Bhavani and Amaravathy in Tamil Nadu.

The quantum of carryover could be decided by the regulation commiteee and would be over and above the 20 tmc which had been mentioned for normal year.

While gradually increasing carryover storage to reach upto a quantum of 50 tmc no additional releases for more irrigation should be made, but only after achieving 50 tmc ft of additional carryover storage the regulation committee might take decision to allow extra releases for irrigation on a year to year basis.

The report stated that it would take some years before Kerala and Karnataka could fully develop and use the irrigation supplies and that the unused water would also be made available for irrigation. It may be clarified that the use of this water by any party State during the intervening period would not give them any right on the use of such water.

It said both Karnataka and Tamil Nadu, during the course of final arguments before the Tribunal, had mentioned about taking up Hydro Power porjects such as Mekedatu and Hogenakkal were proposed in the reach of the river forming common boundary upstream of Mettur Reservoir. Although Karnataka had mentioned about these projects it had contended that these two schemes were mutually incompatible.

The Central Fact Finding Committee had in its report mentioned that the storage of the two reservoirs would be about 250 tmc for generation of Hydro power. However, Tamil Nadu during the course of final argument had brought to the notice of the Tribunal that four hydro power projects in the common boundary reach were proposed by the National Hydro Power Corporation and the capacity of the two reservoirs--Mekedatu and Rasimanal would be 130 tmc, where as the Shivanamudram, the first scheme, would be a run of the river scheme and the Hogenakkal scheme would have a small storage of 0.37 tmc.

As and when these reservoirs were built, there would be large capacity for impounding surplus flow from the Kabini and Cauvery rivers and its tributaries above inter state boundary and these would impound large quantity of surplus flows of good year and help in having considerable reserve quantiy of water to be used in the basin which would greatly improve dependability of utilisible flows.

UNI