Sustainability of Groundwater Resources and its Indicators (Proceedings of symposium S3 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 302, 2006, 193-202.

 

Assessment of saline–freshwater interface structure in the Indian coastal delta complexes

 

Indugula Radhakrishna

Integrated Groundwater Resource Systems Development, 12-13-685, Nagarjuna Nagar, Tarnaka, Hyderabad–500 017, Andhra Pradesh, India

iradhakrishna@yahoo.com

 

Abstract The structure of the saline–freshwater interface is important in the context of estimating fresh groundwater reserves and sustainability, saline water intrusion processes and freshwater discharges into adjoining ocean basins. A method of investigating this structure using self potential and resis­tivity logs is presented and tested for the Mahanadi–Brahmini–Baitarni delta systems of Orissa on the Indian coast. The method involves establishing a graphical relationship between Rw (true water resistivity) and Rwe (equivalent water resistivity) and the use of scatter trend diagrams between dissolved solids and other ions to derive and estimate ionic components for unknown zones at different depths. A three-dimensional saline–freshwater interface structure map of the study area has been derived and serves as an important tool for: (i) estimation of freshwater resources and withdrawal strategies for future well field development; (ii) understanding the processes and magnitude of saline water intrusion and developing appropriate mitigation strategies; and (iii) identifying areas with active subsurface fresh groundwater discharge channels into adjoining oceanic basins.

 

Key words  freshwater sustainability; geophysical tool; interface/diffusion boundary; Mahanadi–Brahmini–Baitarni delta systems