Processes and characteristics of hydrogeochemical variations between unconfined and confined aquifer systems: a case study of the Nakdong River Basin in Busan City, Korea

Chung, SY and Rajendran, R and Senapathi, V and Sekar, S and Ranganathan, PC and Oh, YY and Elzain, HE (2020) Processes and characteristics of hydrogeochemical variations between unconfined and confined aquifer systems: a case study of the Nakdong River Basin in Busan City, Korea. In: Environmental Science and Pollution Research, 27 (9). pp. 10087-10102.

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Abstract

This study is to assess the hydrogeochemical characteristics of groundwater at the deltaic region of the Nakdong River Basin in the Busan Metropolitan City of Korea. The study area is covered by the Quaternary sedimentary deposits and the Cretaceous granites associated with unconformity. The thick sedimentary deposits consists of two aquifers, i.e., unconfined and confined aquifers on the basis of clay deposit. Groundwater samples were collected from seven boreholes: two from unconfined aquifer and five from confined aquifer systems during the wet season of 2017 year. ORP and DO indicates that the groundwater of the unconfined aquifer exists in the oxidization condition and that of the confined aquifer pertains in the reduction condition. Piper’s trilinear diagram shows CaSO4 type for groundwater of the unconfined aquifer, and NaCl type for that of the confined aquifer. Ionic concentrations of groundwater increase in the confined aquifer because of direct and reverse ion exchange processes. Carbonate weathering and evaporation are other mechanisms in the water-rock interaction. Saturation indices of dolomite and calcite are observed as oversaturated, while halite reveals undersaturation. Hierarchical cluster analysis (HCA) exhibits that cluster 1 and cluster 2 represents the properties of groundwater in unconfined and confined aquifers, respectively. Factor analysis shows that groundwater of the confined aquifer is much influenced by seawater, and includes heavy metals of iron and aluminum. Groundwater samples in unconfined and confined aquifers are located at the rock weathering and evaporation zones in the Gibbs diagram. Inverse geochemical modeling of PHREEQC code suggests that carbonate dissolution and ion exchange of major ions are the prevailing geochemical processes. This comprehensive research provides the distinguished hydrogeochemical characteristics of groundwater in confined and unconfined aquifer systems of the Nakdong River Basin in Busan City, Korea

Item Type:	Journal Article
Publication:	Environmental Science and Pollution Research
Publisher:	Springer
Additional Information:	The copyright for this article belongs to the Springer.
Keywords:	confined aquifer; Cretaceous; dissolution; dolomite; halite; hydrogeochemistry; ion exchange; ionic composition; unconfined aquifer; weathering rate; wet season, Nakdong Basin; Pusan Pusan (ADS); Pusan South Korea; South Korea, calcium carbonate; ground water, environmental monitoring; river; South Korea; water pollutant, Calcium Carbonate; Environmental Monitoring; Groundwater; Republic of Korea; Rivers; Water Pollutants, Chemical
Department/Centre:	Division of Mechanical Sciences > Civil Engineering
Date Deposited:	02 Feb 2023 04:53
Last Modified:	02 Feb 2023 04:53
URI:	https://eprints.iisc.ac.in/id/eprint/79705

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