Spatiotemporal variability in groundwater chemistry of a mountainous catchment with complex geologic and climate gradients in south west India

Abstract

Mountainous catchments are one of the world's important water sources that sustains a major portion of global population and a rich biodiversity. The groundwater quantity and quality of mountainous watersheds are depended generally on the geologic characteristics and climate gradients. Although many groundwater studies have been carried out in the midlands and lowlands of many river basins, not enough focus has been paid to the mountainous catchments of tropics. Here we report a case study on groundwater quality and controlling factors of a mountainous catchments of the Western Ghats mountain ranges of peninsular India -the Bhavani river basin, which is identi ed as a testbed for longterm monitoring of the Critical Zone process. A total of 88 water samples were collected seasonally for assessing various physico-chemical parameters, solute contents and scaling properties. The results of the study revealed that the hydrochemistry of groundwater is in uenced by both silicate and carbonate weathering. Mineral stability indices computed for the groundwater reveal that about 52 % of the samples are supersaturated with carbonate minerals and often exhibit scaling due to solute overloading. Among the contributing factors that determine water quality of groundwaters, chemical weathering and anthropogenic activities play a signi cant role.

Hydrochemical characterization of groundwater for consumption and agriculture: A case study from Phulpur Upazila, Bangladesh

“…Nevertheless, there were a few points on the equiline, suggesting the weathering of both carbonate and silicate minerals. Our results were juxtaposed with those from a previous study (Gayathri et al, 2021), and there was a consistency in the findings.…”

“…Bicarbonate levels, however, spanned 73.2-359.9 mg/l with a 164.09 mg/l average (Table 2). The elevated carbonate and bicarbonate levels are attributed to carbonate minerals in recharge zones and silicate weathering (Gayathri et al, 2021). Chloride concentrations varied between 8.9-59.9 mg/l (average: 26.2 mg/l).…”

Tracing the Sources of River Waters Using Stable Isotopes (δ18O and δ2H) in Two Mountainous Watersheds, Southern Western Ghats, India

“…The groundwater data collected from the Upper Bhavani River Basin O value of −4.60±0.83‰ for the Open well and −5.61±0.72‰ for the Bore well (Table 4). The groundwater samples displayed an average dexcess value of 14.31±2.25‰, similar to the value of the river water (14.00±3.14‰) (Gayathri , 2023). This indicates that during PRM, the rivers are fed essentially by the local groundwater sources that are generally lighter in isotopic composition, compared to the Water et al et al et al during the PRM season showed an average δ 18 precipitation received from the moisture sources.…”

Rock–water interaction, chemical weathering and solute transport of two rivers draining contrasting climate gradients in Western Ghats, India

“…The seasonal variation of EC and TDS in the Bhavani river showed an increase during the post-monsoon and pre-monsoon seasons, which is probably due to excessive evaporation and/or due to base flow contributions from groundwater sources rich in solute contents (Gayathri et al, 2021). The lower concentration of dissolved ions during the monsoon season in both the Thuthapuzha and the Upper Bhavani river basins can be attributed to the higher precipitation and subsequent streamflow during the southwest monsoon season (Figure 2).…”

“…These enclaves occur as small streaks, lenses and thick linear and lensoidal bands and vary in thickness from a centimetre to a few tens of meters (Suthanandam, Muthu, & Radhakrishnan, 1996). The occurrence of kankar (an evaporite form of CaCO 3 ) in the soil profile of the Bhavani river basin indicates the chemical weathering and redeposition of calcium carbonates from the calcium-rich enclaves in the host rocks (Gayathri et al, 2021).…”