Hydrogeochemistry of the Koyna River basin, India

Abstract

Hydrogeochemistry of the Koyna River basin, famous for the Koyna earthquake (magnitude 7) of 1967, has been studied. Basalt is the primary aquifer; laterites, alluvium, and talus deposits form aquifers of secondary importance. Groundwater generally occurs under water table conditions in shallow aquifers. Deeper aquifers are associated only with basalts. One hundred and 87 water samples were collected from various sources, such as dugwells, borewells, springs, and surface water, including 40 samples for analysis of iron. Only major constituents were analyzed. Analyses show that the concentrations of Ca 2? exceed that of Mg 2? in almost all water samples; the concentrations of Na ? are generally next to Ca 2? and are always higher than that of K ? ; and CO 3 2and SO 4 2are very low and are often negligible. Groundwater in borewells tapping deeper aquifers has higher mineralization compared to that in dugwells representing shallow aquifers. Majority of the water samples are dominated by alkaline earths (Ca 2? , Mg 2? ) and weak acids (HCO 3 -, CO 3 2-). Groundwater from shallow aquifers is generally calciumbicarbonate type (53%) and calcium-magnesium-bicarbonate type (27%). In case of deeper aquifer, it is mostly calcium-magnesium-bicarbonate type (29%), sodiumbicarbonate type (24%), calcium-bicarbonate type (19%), calcium-magnesium-sodium-bicarbonate type (19%) and sodium-calcium-bicarbonate type (9%). Groundwater water is generally fit for drinking and irrigation purposes, except in the lower reaches of the Koyna River basin, which is affected by near water logging conditions.

Assessment of groundwater quality for drinking and irrigation use in shallow hard rock aquifer of Pudunagaram, Palakkad District Kerala

“…Naik et al (2009) carried out the groundwater study in Koyna river basin and conclude that the groundwater samples are dominated by alkaline earth elements, the shallow aquifers groundwater samples are generally Ca-HCO 3 and Ca-Mg-HCO 3 type, whereas deeper aquifer groundwater samples are Ca-Mg-HOC 3 and Na-HCO 3 type. Most of the groundwater sample is generally fit for drinking and irrigation purposes.…”

Search for hydraulic connectivity between surface reservoirs and surrounding aquifers in the reservoir-triggered seismic environment (Koyna region, India) using hydrochemical and isotopic signatures

“…4 and 5) were observed. Naik et al (2009) carried out hydrochemical investigations in the Koyna River Basin covering either dug wells or shallow bore wells mainly in the plain area. Their findings indicated that Ca was the dominating cation followed by Na and Mg.…”

Hydro-geochemical evaluation of groundwater for irrigation in the Ganges river basin areas of Bangladesh

“…Groundwater interaction with aquifer rocks signi cantly affects the groundwater chemistry, and this mechanism varies with season and place (Kumar et al 2014;Ahmed et al 2018). Different geochemical facies also foremost the chemical features of groundwater and well recognized by many researchers i.e., Park et al (2005); Naik et al (2009); Rajendiran et al (2012); Xiao et al (2012); Sivasubramanian et al (2013); Kumar et al (2014); Bhuiyan et al (2016); and Islam et al (2017cIslam et al ( , 2018. Some studies in Bangladesh (e.g., Bhuiyan et al 2010;Mirza et al 2012;Islam et al 2016Islam et al , 2017aAhmed et al 2018) have been carried out, exclusively in the coastal zone where salinity is a big problem.…”