Hyderabad: Decades of neglect in removing silt and sediment arriving in reservoirs, including freshwater lakes that serve as drinking water sources, has resulted in Telangana’s water bodies losing up to a quarter, and more, of their holding capacity.
In 14 projects, which have been surveyed over the past few years, sand, and other sediments, have slowly grabbed space that could have held 35.15 tmc ft (thousand million cubic feet) of water over the years. This figure represents 35 times the capacity of the Hussainsagar, and is more than the combined storage capacities of the Upper and Lower Manair Dam projects, along with Suddavagu, Mathadivagu, Dindi and Swarna projects to name a few.
Among the affected water bodies is Himayatsagar, that — along with Osmansagar —supplies drinking water to Hyderabad. Incidentally, these two lakes were sought to be scratched off the list of drinking water sources by the previous BRS government.
According to the 2020 ‘Compendium on sedimentation of reservoirs in India’ by the Central Water Commission (CWC), Himayatsagar is among the waterbodies to have lost more than a quarter — 26.56 per cent to be exact — of its storage capacity. Siltation has also affected Osmansagar with official figures putting the lake’s water spread at 6,300 acres, down from its original 10,000 acres.
The worst has occurred at Nizamsagar, with the CWC report putting the loss of storage at this historic reservoir at 60.47 per cent. The Nagarjunasagar reservoir capacity is down by 23.52 per cent and the Srisailam reservoir, 29.96 per cent of its storage due to siltation.
The problem is serious and definitely needs attention, as even at the dead storage levels of several reservoirs is being affected, according to an irrigation department official. For instance, the Singur project on Manjira river which saw its gross storage reduced from its original 29.917 tmc ft to 29.178 tmc ft, the dead storage fell steeply from 0.872 tmc ft to 0.279 tmc ft over the years. Similarly, the dead storage at Komaram Bheem project has halved from 1.785 TMC ft to 0.872 TMC ft.
The department has started an exercise to identify the methods and process to revive at least part of the storages of the reservoirs and other waterbodies. The department official said that preparations are on for calling global tenders for desilting of reservoirs, but cautioned that the process was not a quick fix but would take a few years even to claw back a part of the lost waterholding capacities.
