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Water quality has always remained paramount when it comes to sustainable development. The most convenient method of determining the health of a particular water body is through water quality indexing. Based on the filtered 2049 articles published, the present review-based study was conducted for a science-based mapping to evaluate the research in the domain of water quality indexing until 2020. A three-stage sequential process; bibliometric examination, scientometric investigation, and qualitative valuation resulted in the identification of the most influential and productive journals, researchers, articles, and countries dynamic in the research field. Keyword analysis further revealed that groundwater quality assessment for drinking water has been the key focus of research among scholars. The scientometric analysis was followed by a qualitative discussion on the current topics of research; mainly categorized into four classes, i.e., specific indices, human intervention, performance assessment and emerging technologies, and also highlighting some of the significant research gaps. This was followed by presenting a research framework wherein, plausible future directives were proposed. This study thus provides a more comprehensive picture on the existing researches carried out in the domain of water quality indexing, identifying the primary gaps and thereby providing multi-disciplinary guidance for various researchers and practitioners linked to the current research to the future.

The present study has been conducted for three objectives for the assessment of sediment pollution loadings and their ecological risk. Firstly, the hierarchical clustering of the raw sediment dataset was carried out, which categorized the sampling locations into three statistically significant clusters, depending on their similarities in behaviours. Clusters 1, 2, and 3 corresponded to high, moderate, and low pollution sites, respectively. The principal component analysis was then carried out on the dataset for three different seasons; pre-monsoon, monsoon and post-monsoon respectively, which showed significant temporal changes in the pollution sources. Various indices such as contamination factor, pollution load index, enrichment factor, and the geo-accumulation index showed that the wetland is most affected in the post-monsoon season as compared to other seasons. At the same time, monsoon remains the best. This was attributed to the significant increase in the wetland's water depth during the monsoon, coupled with the rise in precipitation capacity during the post-monsoon. Secondly, the potential ecological risk due to the contaminants displayed that the post-monsoon period has the greatest number of sites under the moderate risk category. In contrast, all the sites during the monsoon attributed to low risk. Also, Cd was found to be the primary contributor to ecological risk. Finally, chemical speciation analyses of all the heavy metals were conducted to determine their available forms in the sediment column. Cr, Mn, and Mg were observed to have a profoundly negative impact on aquatic ecology (available in F1 fraction in higher percentages). While Fe was predominant in reducible (F3) form, Cd was found to have equal contributions in reducible and oxidizable (F3 and F4, respectively) forms. Cu and Pb displayed typical complex characteristics of all the fractions in almost equal proportions. The results of the study indicated that although the anthropogenic interventions to the wetland have not been significant till yet, as far as the sediment contamination is concerned, it would be too late if swift and appropriate measures are not taken for restricting future probable contaminations.