Karnataka

Bathymetry survey to be conducted to assess sand availability in CRZ areas

With the last date of the sand extraction season nearing, workers unloading sand from a boat on the Netravathi in Mangaluru on Friday.

With the last date of the sand extraction season nearing, workers unloading sand from a boat on the Netravathi in Mangaluru on Friday.   | Photo Credit: H.S. MANJUNATH

Permits for sand extraction to be issued only if excess sand is found to be available, says Senthil

Unbridled sand extraction from rivers in Coastal Regulation Zone (CRZ) in Dakshina Kannada, which got reduced to some extent recently, is set to get further reduced following the district administration’s decision to go for accurate assessment of sand available for extraction.

The administration has decided to go for a bathymetry survey of riverbeds in CRZ areas to assess the quantum of excess sand that may be extracted ‘to facilitate smooth movement of fishing boats.’

Through bathymetry, one can measure the depth of a water body and map underwater features through different methods. This survey is widely used for research including flood inundation, water contour, leakage etc.

Dakshina Kannada Deputy Commissioner S. Sasikanth Senthil, who is also the Chairman of the District Sand Monitoring Committee, told The Hindu that the administration would get a baseline survey done immediately after the present sand extraction gets over, that is, by June 15. Bathymetry survey will be conducted before issuing permits for the next season in August to assess sand deposition in riverbeds post-monsoon.

Only if it was found that sand was available in excess in identified areas, then permits would be issued to extract the same, Mr. Senthil said.

The committee had limited the number of permits within one hundred this season, as against over 400 issued a couple of years ago as the first step to prevent excess exploitation of riverbeds.

Asked whether the number of permits would further get reduced, Mr. Senthil said it was likely.

Environmentalists have been raising concerns that riverbeds of Netravati and the Phalguni (Gurupura) were razed to the bottom-extent possible in the last five years while demanding complete ban on sand extraction in CRZ areas till the sand gets replenished to healthy levels.

B.K. Murthy, geologist with the Mines and Geology Department, said bathemetry survey was already done to identify sand bars for concreting National Highway 75 between B.C. Road and Addahole in the district.

Unlike the present GPS-cum-satellite imagery-based survey, bathymetry provides accurate data about excess sand availability. The survey would be conducted only in identified zones and not across the river-length since it is costly, he added.

While the CRZ norms prohibit sand extraction in CRZ areas for commercial exploitation, authorities and sand mafia circumvented this through an exception which allowed extraction only to facilitate smooth movement of fishing boats.

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Printable version | Aug 4, 2020 2:35:44 PM | https://www.thehindu.com/news/national/karnataka/bathymetry-survey-to-be-conducted-to-assess-sand-availability-in-crz-areas/article24117258.ece

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