Sand mining is an environmental hazard as reported in an earlier post titled Control mining of sand dunes in the peninsula! refer to website @ https://northernbreeze.blog/2020/02/21/control-mining-of-sand-dunes-in-the-peninsula/
Whereas, it is a simple rule to follow on sand mining be it along the coastal sand reefs or inland in river sides, it should not exceed the rate of resupply of sand from the sea or from upstream of the river. That can only happen if authorities have proper checks done on a regular basis, but at present, this is not the case in any part of the country; so until proper controls are in place the environment will take is toll.
A simple rule is that sand mining in rivers should not exceed the rate of resupply of sand from upstream.
To read more about the hidden environmental toll occuring due to uncontrolled sand mining that is taking place on large scale visit website@ https://e360.yale.edu/features/the-hidden-environmental-toll-of-mining-the-worlds-sand
Sri Lanka sliding into negative territory in terms of economic development due the three decades long civil-war is facing many more environmental hazards caused by nature such as floods and droughts. Impacts of which could be reduced considerably if authorities control mining and deforestation that is taking place in many parts of the country.