1. Department of Geology, University of Kerala, Thiruvananthapuram, Kerala, India;
2. Department of Geological and Mining Engineering and Sciences, Michigan Technological University, Houghton, MI, USA;
3. Department of Civil Engineering, University of Arkansas, Fayetteville, AR, USA;
4. Centre for Environment and Development, Thiruvananthapuram, Kerala, India;
5. Central Ground Water Board, Thiruvananthapuram, Kerala, India