The offshore areas of Kerala hold enough sand resources to meet the requirements of the construction industry in the State for about 50 years, a study conducted by the Geological Survey of India (GSI) has revealed.
The report of the study, to be presented at a national seminar on ‘Mineral resources of Kerala’ beginning here on Friday under the auspices of the Department of Geology, University of Kerala, states that the impact of marine sand mining on the sea floor could be controlled if it was exploited scientifically.
The authors, including A.C. Dinesh, P. Praveen Kumar, N.M. Shareef and C. Jayaprakash of the Marine and Coastal Survey division, GSI, have identified five sectors in the offshore waters of Kerala, namely Ponnani, Chavakkad, Alappuzha, Kollam North, and Kollam South, with an estimated resource of 2,030 million tonnes of sand suitable for construction industry.
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The study comes in the wake of resistance by fisherfolk to a proposal by the State government to exploit sea sand resources as a substitute for river sand to feed the construction industry.
Routine seabed mapping surveys carried out by GSI had identified sand formations within and beyond the territorial waters (22.2 km from the shoreline) off the west coast. Subsequent sampling surveys using research vessels led to the resource estimation in five sectors.
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The study has also addressed societal concerns about the suitability of marine sand for construction. According to the authors, the dredged marine sand could be stockpiled and exposed to rain to wash the salt content away. “Even a rainfall as low as 9.9 mm can reduce the chloride ion content to levels far below the admissible limit of 0.101 per cent,” the report says.
The paper notes that the amount of shell fragments in fine aggregates of Kerala offshore sand is immaterial and does not affect the strength or durability of structures.
‘No coastal erosion’Pointing out that the marine sand resources in the five sectors were located at a depth of 20 to 25 m at a distance of 10 to 29 km from the coast, the authors argue that there is little chance of slope failure or coastal erosion owing to dredging activities.
The paper asserts that sand-mining will have no greater effect on the sea bottom than that of monsoon waves and daily trawling. The study, however, stresses the need for detailed studies of sand-mining on marine flora and fauna.