Insight into the Coastal Brackish Water Intrusion: A State-of-the-Art Review

Brackish water intrusion (BWI) is the major concerning processes that degrades the groundwater quality and jeopardises the availability of freshwater in coastal aquifers. Massive extraction of groundwater resources as a result of population hike, urban sprawl, and sea-level rise have resulted in salinization of many coastal aquifer systems around the globe. BWI results in major fluctuations in the biogeochemistry of the disturbed aquifer system and influences the drinking, irrigation, and industrial water qualities and as a consequence, on wellbeing of the people in coastal areas in terms of their economic and socio-cultural conditions. BWI leads to drastic change in their economic and socio-cultural activities which have impelled an extensive array of studies and research. Therefore, the purpose of the this chapter is to demonstrate a complete overview of the methods that regulate BWI, the present worldwide distribution scenario of brackish water, numerous investigative techniques to detect BWI and finally advanced mitigation methods, in brief. BWI generally occurs in coastal aquifer systems known as subterranean estuaries, which are dynamic in nature. These estuaries get both freshwater from the terrestrial surface and saline water from the sea, exposing this fluid combination to intensive biogeochemical dynamics since they are loaded with the aquifer and aquicludes materials. Therefore, to preserve valuable resources of coastal ecosystem from degradation, BWI and other pollutants, it is necessary to take practical steps. Recently, experts’ interest in brackish water desalination technologies has expanded worldwide. Due to its low salt concentration compared to that of saline water, brackish water, may be served as an excellent substitute for freshwater conversion and is commonly employed in several water-stressed nations. However, it is essential that freshwater generated by partial or entire desalination of brackish water should meet the standard of productivity and living. Since the last decades, usage of green technologies, particularly use of renewable energy (RE) in desalination has turned the unusable brackish water into a valuable and usable natural resource.