Abstract
Scientific research into isotope hydrograph separation (IHS) has rapidly increased in recent years. However, there is a lack of systematic and quantitative research to explore how this field has evolved over time. In this study, the methods of text mining and bibliometric analysis were combined to address this shortcoming. The results showed that there were clear periodical characteristics in IHS studies between 1986 and 2019. High-frequency words, e.g., catchment, stable isotope, runoff, groundwater, precipitation, runoff generation, and soil, were the basic topics in IHS studies. Forest and glacier/snow were the main landscapes in this research field. ‘Variation’, ‘spatial’, and ‘uncertainty’ are hot issues for future research. Today, studies involving the geographical source, flow path, and transit/residence time of streamflow components have enhanced our understanding of the hydrological processes by using hydrometeorological measurements, water chemistry, and stable isotope approaches. In the future, new methods, such as path analysis and ensemble hydrograph separation, should be verified and used in more regions, especially in remote and mountainous areas. Additionally, the understanding of the role of surface water in streamflow components remains limited and should be deeply studied in the future.
Highlights
Published: 15 September 2021In 1969, Hubert et al [1] published their pioneering paper on hydrograph separation using stable isotope tracers
Since 2013, there has been a rapid increase in scientific output in the field, which provides an unprecedented opportunity to explore the dynamics of isotope hydrograph separation (IHS) research based on data from a large body of published scientific work
Frequency calculations are widely used in bibliometric analyses to investigate the influence of research units, such as publications, authors, and countries/regions, by counting the number of documents and total citations (TC) or global citation scores (GCS), local citation scores (LCS), and themes based on counting words of interest [28]
Summary
In 1969, Hubert et al [1] published their pioneering paper on hydrograph separation using stable isotope tracers. Isotope hydrograph separation (IHS) has gradually become the principal method for determining the relative contributions of different sources of runoff or streamflow (i.e., event or pre-event water) [2,3,4,5]. In 2013, Klaus and McDonnell [7] published a qualitative and comprehensive review of IHS and concluded that, despite certain limitations, water stable isotopes were still the most effective technology for understanding runoff generation processes and mechanisms. Since 2013, there has been a rapid increase in scientific output in the field, which provides an unprecedented opportunity to explore the dynamics of IHS research based on data from a large body of published scientific work. To our knowledge, there has not been a quantitative assessment of the publication data in this field, and Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
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