Abstract
People in the southwestern (SW) coastal part of Bangladesh are suffering from a severe freshwater crisis due to saline groundwater at a shallow depth. Fresh groundwater below a 200 m depth is an option, but it is costly to construct deep tubewells for the local inhabitants. The processes of salinization and freshening were previously identified using conventional methods. In this study, we brought new insight into these processes by analyzing existing datasets using multivariate statistics to identify the factors affecting groundwater chemistry. Cluster analysis (CA) revealed three major clusters. Cluster A corresponded to saline (NaCl-type) water. Cluster B was also saline (NaCl-type) water but showed mixing effects. Cluster C was fresh groundwater (NaHCO3-type) and isolated. The hydrochemical characteristics of clusters A, B and C compared remarkably well with the groundwaters from the upper shallow aquifer (USA), lower shallow aquifer (LSA) and deep aquifer (DA), respectively. Factor analysis (FA) showed that 75% of the total variance was influenced by evaporate dissolution, carbonate dissolution/precipitation, cation exchange and anthropogenic pollution to some extent. Therefore, the integrated approach showed the validity of applying multivariate statistical techniques to infer the dominant hydrochemistry and to characterize and understand a complicated hydrogeological system.
Highlights
The sustainability of water resources availability has a major role in the socioeconomic development of each community [1]
Two main types of groundwater were recognized from this diagram: The upper shallow aquifer (USA) was characterized by a sodium chloride (NaCl) water type with a negative cation exchange code, with very few Ca/Mg-HCO3 waters representing mixing with surface water; total dissolved solids (TDS) varied between 423 and 29,616 mg/L
Multivariate statistical analysis is a well-proven method for the grouping of waters and detection of significant factors controlling water quality
Summary
The sustainability of water resources availability has a major role in the socioeconomic development of each community [1]. Salinization due to salt leaching and tidal floodwater mixing with fresh water in the shallow aquifers is well documented in the study area. Multivariate statistics could be an effective tool to verify and differentiate the influencing factors of salinization and freshening, as well as decipher the groundwater composition [11,12,13]. The flow of seawater, as well as the freshwater–saltwater interface, were characterized using water chemistry, borehole logs and geophysical investigation [14] Hydrochemistry of this area signifies a good opportunity to apply multivariate statistics. The present study used these two multivariate statistical techniques to analyze the existing hydrochemical data to categorize groundwaters, identify the major hydrogeochemical processes and explain the main factors affecting the chemistry of groundwater in the coastal aquifers of SW Bangladesh. TFFiiioggnuuarrleeh22is.. tCCorooynnccoeefppthttuueaasllthhuyydddyrraoorggeeeaoo,llmooggoiidccaiaflliemmdooaddfeteellrsshShaoorwwkieinnrggettthhaele.aa[q9q]uu.iiffeerr ttyyppeess wwiitthh tthhee sseeddiimmeenntt ddeeppoossii-tional history of the study area, modified after Sarker et al [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
