Geochemical variations due to salinization in groundwater along the southeast coast of India

Abstract

In recent years, the extraction of groundwater (GW) in coastal aquifers has rendered the fragile aquifers more saline due to the sea water intrusion. Groundwater from the coastal aquifers of the Pudhucherry region were sampled to study the process of salinization. An integrated approach was adopted to identify the salinization process, by coordinating the results of borehole geophysics, rainfall pattern, water level variation, hydrochemical characters and multivariate statistical analysis. A total of 136 groundwater samples were collected during two different seasons, southwest monsoon (SWM) and northeast monsoon (NEM). The major cations and anions were analyzed adopting standard procedures. Resistivity and litholog indicate that the southeastern (SE) part of the study region has lower resistivity than in north. Based on electrical conductivity (EC) and total dissolved solids (TDS) values, most of the samples are potable, except for few samples from southeastern region. The study results indicated that higher values of Na, EC, K, SO4, Mg and Cl were observed during NEM, indicating leaching of salt into the aquifer and ion exchange process. The predominant hydrochemical facies of groundwater was Na-Cl and Ca–Mg–Cl type reflecting the saline water and the mixing process of saltwater and fresh groundwater, respectively. Though more number of samples with higher EC was noted in NEM, the results of PCA and correlation analysis indicate the predominance of leaching of salts and intense agricultural activities. The process of sea water intrusion was observed to be dominant during SWM.

Aquifer salinization: A groundwater appraisal of northeast coast of Odisha using water quality index (WQI) and geospatial interpretation

“…5 and 6) as well as increase of TDS in seaward direction indicates the effect of seawater intrusion in the study area. excess of Na/Cl ratio over seawater (0.88) in 41 out of 60 cases, further supports seawater intrusion in study area (Rajendiran et al, 2021). The Stiff diagram also shows that the water type along the coast is sodium-chloride, which suggests the intrusion of saline water into the deeper aquifer from adjacent seawater.…”

Characteristics and genesis of groundwater salinization in coastal areas of the Lower Reaches of Oujiang Basin

“…Groundwater serves as a critical resource for sustaining human activities, economic development, and maintaining the stability of coastal ecosystem and water resource security (Wang, 2019;Alhassan et al 2018). However, due to the impacts of global climate change, sea level rise, and human activities, groundwater related environmental issues in coastal areas have escalated, with groundwater salinization emerging as a significant ecological and geological concern worldwide (Trabelsi and Zouari, 2019;Bahir and Ouhamdouc, 2020;Thilagavathi et al 2021). Elevated salt levels in groundwater not only impede industrial development and escalate operational expenses but also lead to land salinization and adversely affect agricultural production.…”

Assessment of Hydrogeochemical Characteristics and Seawater Intrusion in Coastal Aquifers by Integrating Statistical and Graphical Techniques: Quaternary Aquifer, West Nile Delta, Egypt

“…Due to extreme use of the groundwater in coastal aquifers for industrial, agricultural, and urban expansion, seawater intrusion has come to be a global problem [8][9][10][11]. Climate change has raised atmospheric surface temperatures and melted ice caps, mountain glaciers, and polar ice sheets, which raises ocean and sea water levels, compounding the problem [12].…”