## 10 Bibliometric Analysis of Water-Related Research in Bangladesh
Two clusters are placed in emerging themes, which include 'coastal Bangladesh' and 'GIS', which have low centrality and density and, hence, are weakly developed. Figure 6 illustrates the occurrence network of index keywords in water-related publications in Bangladesh. We selected a minimum number of occurrences of a keyword of 50 times, and 273 keywords met the threshold out of 17,115 keywords. Figure 6 was prepared based on the top 100 out of the 273 keywords. Each keyword is represented by a circle. A bigger circle represents a more frequent occurrence of a keyword, a line shows the connection between keywords, and the color represents the average publication year. As seen in Figure 6, keywords such as 'Banglades', 'arsenic', 'drinking water', and 'water supply' have higher total link strength and greater frequency. Besides, the most cited keywords were 'concentration (parameters)', 'food contamination', 'Eurasia', 'groundwater', and 'health hazard' with 96.74, 89.29, 80.94, 80.60, and 79.21 average citations, respectively. The evolution of interest in the water research field has been changing over time, and the average publication year of keywords allows us to see how research focus is changing over time. For instance, the blue color represents the average publication years before 2010, which were associated with keywords such as 'water supply', 'irrigation', 'water contamination', 'arsenic poisoning', and 'diarrhea'. This finding also supports the most cited articles related to arsenic, water contamination, and health have publishing years before 2010 (see Table 4). On the other hand, we see that the authors' interest has changed to 'procedures','salinity', 'climate change', 'cross-sectional study', 'concentration (composition)', and 'cohort analysis', which were the most common keywords after 2015. Figure 4: Word cloud in terms of keywords plus on Bangladesh water-research-related publications. As a measure of collaborative research on water in Bangladesh, Figure 7 illustrates 530 links between 51 out of 133 countries in seven clusters. Strong collaborations are found among the countries: Bangladesh-USA (link strength = 605), Bangladesh-Australia (link strength = 278), Bangladesh-UK (link strength = 281), and Bangladesh-Japan (link strength = 262). The results show that even though India is in the top five in terms of total link strength, a strong collaboration is not detected between Bangladesh and India (link strength = 98) for joint water research. Figure 5: Thematic map of Bangladesh water-research-related publications. Figure 6: Occurrence network map of index keywords from Bangladesh water-research-related publications. Trending topics in water-related publications in Bangladesh between 1999 and 2021 are presented in Figure 8. Trending topics were generated based on the most frequent author-nominated keywords. The trending topics reveal the most frequent keywords with their occurrence by time. The size of dots represents the frequency of words, whereas the horizontal line depicts the time frame of the frequency of occurrence. As an illustration,'machine learning' and 'northern Bangladesh' are currently (in 2021) trending topics with frequencies of 11 and 6, respectively. Furthermore, it is clear that adaptation and climate change have been trending for the last 5 years: 'adaptation' (\(n=145,2017\)), 'climate change' (\(n=483,2017\)), 'climate change adaptation' (\(n=46,2018\)), and 'adaptation strategies' (\(n=12,2020\)). Similarly, other trending topics allow researchers to interpret how studies have evolved over time and what trends they have. Figure 8: Trending topics in water-research-related publications in Bangladesh. Figure 7: Network map of country co-authorship for Bangladesh water-research-related publications. Countries with a minimum of 10 published and cited articles are included. The map includes 51 countries out of 133 countries in seven clusters. Total link strength of top five countries was as follow: Bangladesh = 2611, USA = 1160, UK = 699, Australia = 583, India = 413.