Understanding efficient seawater intrusion assessment in coastal region of India: a methodological review

India is fortunate to have a long length of coastline. In addition to the numerous villages and industrial communities, many of the country's metropolitan centres are situated along the coastline. Saltwater intrusion is the migration of salty water into freshwater coastal aquifers, resulting in groundwater quality degradation. Land-use changes, climate change, and sea-level rise are the most significant contributing causes to saltwater intrusion in coastal aquifers. Coastal saline water intrusion has a broad range of impacts on the community and financial systems, in addition to the area's overall ecosystem, prompting many studies. According to the research, saline soils cover around 70 thousand square kilometres in India, including about 21,000 square kilometres in coastal regions. It is imperative to understand the extent of seawater intrusion in order to plan and manage mitigation measures towards sustainable development. The objective of this paper is to derive an insightful review of the methods, i.e., hydrogeochemical assessment, geophysical assessment and numerical modelling; used to tackle the pertaining issue of seawater intrusion.