Journal Sources

Journal sources involved in the publication of articles related to water quality indexing were assessed and visualized. The results of the scientometric analysis involving the journal sources are reported in Fig. 2. 4 and Table 2. 1. A minimum of 15 articles and 30 citations were set for analysis in VOSViewer, which provided a cumulative of 24 out of a total of 493 journals meeting the tolerance level. Fig. 2. 4 exhibits the clusters of journal sources and their inter-relationships through the connected lines. It is important to note that all the relevant journals may not be visible through Fig. 2. 4. Hence, a more detailed quantitative analysis of the journal sources and their influence is provided in Table 2. 1.

Fig. 2. 4. Mapping of mainstream journals in the domain of water quality indexing.

In the network representation of the journal sources, as shown in Fig. 2. 4, the sizes of the fonts and nodes are proportional to the number of publications from that particular journal, i.e., the larger the font and node size, the more is the number of published articles contributed from that journal. Furthermore, the cluster colours, as well as the colours of the connecting lines, indicate the relative closeness among the various journals with respect to mutual cita- tions. Citations are considered to be of high regard in the field of re-search as it is considered as a standard measure to identify the influence of the studies in that particular domain of research (Van Eck & Waltman 2014). From Fig. 2. 4, it was observed that journals like Envi- ronmental Monitoring and Assessment, Indian Journal of Environmental Protection, Environ-

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mental Earth Sciences, Ecological Indicators, and Pollution Research provided a significant con- tribution to the research pertaining to the domain of water quality indexing. Additionally, these journals also have dense networking of the connecting lines, thus indicating their close- ness with respect to the published articles. A more quantitative assessment has been reported in Table 2. 1.

Table 2. 1. Quantitative measurements of journals publishing water quality index research.

Source

Number of docu- ments

Total citations

Average citations^A

Normal- ized cita- tions

Average Normal- ized cita- tions^B Environmental Monitoring

and Assessment 103 2567 25 151.14 1.47

Indian Journal of Environ-

mental Protection 83 481 6 13.11 0.16

Environmental Earth Sci-

ences 73 1188 16 108.44 1.49

Ecological Indicators 48 1854 39 134.11 2.79

Pollution Research 48 215 4 7.75 0.16

Desalination and Water

Treatment 43 250 6 23.94 0.56

Water (Switzerland) 43 269 6 49.83 1.16

Environmental Science and

Pollution Research 40 342 9 42.03 1.05

Arabian Journal of Geosci-

ences 33 506 15 42.21 1.28

Science of the Total Envi-

ronment 31 966 31 121.25 3.91

Nature Environment and

Pollution Technology 29 185 6 16.18 0.56

Water Resources Manage-

ment 23 372 16 35.64 1.55

Water Research 20 1355 68 45.42 2.27

A Average citations are estimated by dividing the total number of citations received by the total number of articles published.

B The Ave. Norm. Citation represents the normalized number of citations of a journal, document, author, or an organization. It corresponds to the total number of citations divided by the average number of citations published in the same year. The normalization concept rectifies the misinterpretation that older documents have more time to receive citations than more recent one (Van Eck & Waltman 2014). The Norm. Citation in Table 2. 1 measures the citation of all the articles within the same journal, while the Ave. Norm. Citation represents the normalized citation per article, it is calculated by dividing the Nor. Citation by the number of articles. All the normalized cita- tion scores presented throughout the thesis are based on this concept.

TH-2896_176104004

Groundwater for Sustaina-

ble Development 18 202 11 33.71 1.87

Environment, Development

and Sustainability 17 72 4 14.87 0.87

Water Science and Tech-

nology 17 208 12 13.61 0.80

Chemosphere 16 284 18 21.29 1.33

International Journal of En- vironmental Research and

Public Health 16 241 15 22.72 1.42

Polish Journal of Environ-

mental Studies 16 108 7 9.49 0.59

Sustainable Water Re-

sources Management 16 124 8 13.98 0.87

Human and Ecological Risk

Assessment 15 287 19 65.22 4.35

International Journal of En- vironmental Science and

Technology 15 166 11 13.11 0.87

International Journal of

River Basin Management 15 89 6 11.53 0.77

Journal of Environmental

Management 15 753 50 34.84 2.32

Five different measuring parameters corresponding to the productivity and influence of journals in the domain of water quality indexing are listed in Table 2. 1; the number of listed documents, total citations, the average citations, normalized citations, and the average nor- malized citations. While the former two parameters are found to be highly correlated to each other in general, the other three parameters are relatively non-aligned with the other two, i.e., the journals governed by a high number of publications or citations may not necessarily display a higher average citation score. It was observed that Fig. 2. 4 and Table 2. 1 showed consistent results, with respect to the most productive journals, i.e., Environmental Monitor- ing and Assessment, Indian Journal of Environmental Protection, Environmental Earth Sciences, Ecological Indicators, Pollution Research, Desalination and Water Treatment, Water (Switzer- land), and Environmental Science and Pollution Research. Out of these, Environmental Moni- toring and Assessment, Environmental Earth Sciences, and Ecological Indicators are the jour- nals receiving a higher range of average citations, thereby indicating stronger influence in terms of both productivity and research significance. However, when it comes to the journals

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having the most influential publications, i.e., in terms of average normalized citations re- ceived, the journal of Human and Ecological Risk Assessment had the highest research signifi- cance, with an average normalized citation score of 4.35. Other journals such as Science of the Total Environment (3.91), Ecological Indicators (2.79), Journal of Environmental Management (2.32) and Water Research (2.27) are among journals with a considerable research signifi- cance in the domain of water quality indexing, with average normalized citation scores of more than 2.00. These journals do not possess a higher quantum of articles in this research domain but significantly contribute to the research.