Bibliometric and visualisation analysis of global research trends on HYDRUS using Scopus search

HYDRUS is one of the popular software packages used for water, heat and solute transport simulation. Although numerous studies on bibliometric analysis were conducted, the bibliometric research and systematic searching strategy on the HYDRUS are rarely explored by scholars. Therefore, the main focus of this study is to explore existing literature on the global research trends of HYDRUS according to bibliometric methods. The data was filtered and extracted from the Scopus database. Bibliometric analysis was performed in different aspects such as yearly publications trends, countries productivity, leading journals and subject areas. Visualisation analysis was deployed using VOSviewer software for collaboration patterns and content analysis to explore networking and emerging topics in HYDRUS. In total, 1903 literature related to HYDRUS publications from the year 1993 until 2020 were retrieved. The quantity of HYDRUS publications has substantially increased for almost three decades. HYDRUS mainly used in the field of Environmental Science (n=1120, 34.1%), Agricultural and Biological Science (n=871, 26.5%) and Earth and Planetary Sciences (n=424, 12.9%). In addition, Agricultural Water Management Journal (Elsevier, Netherlands) is the leading journal in HYDRUS publications. The top three prolific scholars on subject matters are Šimůnek Jirka (H-Index 71, University of California, United States), Martinus Th. van Genuchten (H-Index 82, Utrecht University, Netherlands) and Harry Vereecken (H-Index 65, Institute of Bio- and Geosciences, Germany). The United States, China and Germany, among the most productive country published papers related to HYDRUS. The HYDRUS study is applied in three clusters; media properties cluster, irrigation cluster and groundwater study cluster, with a primary focus on water flow and solute transport modelling. The keywords analysis revealed that the most active research topics were "model", "water", and "parameter" throughout the study period. This bibliometric technique helps researchers identify and understand the specific knowledge domain on the past, current, and emerging research topics.