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In an attempt to increase the storage capacity of the Krishna river and make sand available, the Water Resources Department (WRD) has undertaken desilting work upstream Prakasam Barrage. A target has been set to remove 50 lakh tonnes of silt from the riverbed, sources say.
The Andhra Pradesh government accorded the administrative approval to ₹102.44 crore for undertaking desilting works on the riverbed upstream Prakasam Barrage in March 2021. The exercise, which was launched September 2021, needs to be taken up half a kilometre away from the Praksam Barrage (from 0.5 km to 13.5 km on the Krishna).
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The Water Resources Department has extracted 8,60,566 cubic metres of silt from the riverbed so far. Of this, 2,02,499 cubic metre has been handed over.
The government has instructed the department that the revenue generated from the sale of the de-silted material should exceed the cost of the end-to-end operation i.e., survey, excavation, transportation, sale among others, and result in a net profit to the government.
Bathymetric survey
As per the bathymetric survey (study and mapping the depth of riverfloor and shapes of underwater terrain) carried out between December 2019 and January 2020, the present storage capacity of Prakasam Barrage is 2.982 tmcft.
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There is a loss in storage capacity of 0.089 tmcft, when compared to the design capacity of 3.071 tmcft, the survey revealed. “The desilting work is expected to increase the water storage capacity by 0.441 tmcft. De-silting is essential to improve the storage capacity, given the growing irrigation and drinking water needs,” says Superintending Engineer Sesham Tirumala Rao.
NGT guidelines
He says the government instructed the Water Resources Department to undertake the desilting operations in conformity with the directions of the National Green Tribunal (NGT). The exercise was divided into 12 projects and awarded to different agencies. The entire cost of desilting operations is met by the Andhra Pradesh Mineral Development Corporation (APMDC) Limited.
The government‘s word of caution comes in the wake of past experiences. During the TDP’s tenure, dredging and excavation of sand were done in upstream Prakasam Barrage in alleged violation of the NGT guidelines.
Following complaints from environmental activists, the NGT had imposed a penalty of ₹100 crore on the government. “The de-silting operations are taken up in strict conformity with the directions of the NGT issued in 2018,” adds Mr. Tirumala Rao.