Restoration of Minor Irrigation Tanks in Telangana State

The Government of Telangana is proposing to invest a huge sum of about Rs 22,500 Cr for repairs to tanks with a view to restore Irrigation under them. Before taking up such massive programme, the Government should have had undertaken detailed study of tanks and invited suggestions from the Experts, Engineers, Social Scientists, General Public, Farmers etc.

The silting of tanks depends on many factors like size, shape, slope of the catchment, vegetation, land use, soils in the catchment etc. Each of the above factors influences the rate and quantum of silting. Normally, for M.I tank, 15% of total capacity will be provided for siltation in a period of 50 years.

The tanks whose catchment consists of rocky and morum soils do not get silted up except a thin layer of silt consisting of sand will be formed in the bed of tank which will not be useful for fields. Further, there is a danger of deepening of the tank in the name of desilting and to utilize the soils for road works and other construction activities apart from receiving payment for excavation. This will also cause in increase in dead storage and decrease in live capacity which ultimately affects irrigation under the tank.

There is another danger that if the virgin soils are removed there will be percolation into underground and ultimately the tank may not hold water permanently.

However, desilting will be useful in the tanks having catchment with B.C soils which are prone for silting rapidly. Such desilted soils are useful for the fields and helps in restoring the capacity of the tank. Therefore, it is essential to conduct surveys before taking up desilting of tanks.

Regarding repairs to tanks, it is to be mentioned that repairs have been taken up under various programmes namely plan, non plan, world bank, JICA, Nabard etc. If we study the history of repairs carried out to the tanks, we will notice that no tank was left unattended and the same tank was repaired repeatedly spending huge sums of money. Normally, a tank does not require repairs except for clearing jungle growth on the bund, near weir and sluice. However, there may be some tanks which have the past history of breaches which require detailed investigation for strengthening. The investigation shall include testing of bund soils, adequacy of spillway, approach and tail channels, condition of weir and sluice.

To sum up the above observations, it is suggested that:

1. Tanks requiring desilting and repairs only to be taken up.

2. Jungle clearance of tanks to be taken up on continuous basis.

In addition to the above, repairs to feeder channels may be taken up after detailed surveys to restore supply to the chain of tanks. New feeder channels may also be taken up where ever feasible.

By KSN Reddy, Retd. Engineer in Chief (I&CAD). He can be reached at [email protected]