4. Conclusion
This research summarized a comprehensive scientometric review on hydrological connectivity from multiple perspectives based on web of science retrieval and combined with CiteSpace. The relevant information of hydrological connectivity research is conducted, including the contribution analysis of subject categories, keywords, and co-cited analysis of authors, journals, and references. Valuable insights can be obtained from the results accordingly. Over the past decades, there were 3,307 publications on hydrological connectivity, and the published number has steadily increased each year, which has significantly improved the depth and breadth of hydrological connectivity research. Studies on hydrological connectivity are mainly carried out from a multi-disciplinary perspective, among which the most important fields are Environmental Science and Ecology, Water Resources, GeoScience, Environmental Science and Ecology. Additionally, Hydrological Processes, Journal of Hydrology, Water Resources Research, Freshwater Biology and Science are the top 5 most frequently cited journals as well as several representative journals in the direction of hydrological connectivity. Moreover, Ward JV, Junk WJ, Tockner K are the researchers who have made outstanding contributions in this field due to their publications have a better citation rate, and Bracken LJ has the Strongest Citation Bursts, indicated the publications of whose are of great value.
Several hot spots and the high co-occurrence frequency points in the research field are found based on the co-occurrence analysis of keywords in 3 periods, and it may have certain reference significance for the study of the development and frontier evolution of hydrological connectivity. Early studies mainly focused on the hydrological connectivity in small scale floodplains as well as the impact on ecosystems and biodiversity. With time going on, the topic of the study has shifted to the dynamics of hydrological connectivity and the use of hydrological models for simulation. Recently, more attention has been paid to integrity and comprehensiveness of hydrological connectivity, the climate change as well as the evolution of spatial patterns have attracted more attention, and the management of hydrological connectivity has also received a lot of attention. According to co-cited analysis and clustering results of references, amphibians is the largest clustering cluster, and channel network is the most cited clustering cluster, which is currently the main research direction. It is worth noting that giws (geographically isolated wetlands) is the latest cluster of clustering, and due to its potential impact on regional hydrological connectivity, giws has received a lot of attention, which may be a research hotspot in the future.
As time progresses and with the development of the environment, economy, and society, the research subjects in different stages vary, but on the whole, the research on hydrological connectivity presents a stage of steady development and continuous innovation. The scale of hydrological connectivity is from small patch to large watershed and landscape, also the development of dimension is from single dimension to multi-dimensional spatio-temporal coupling. In addition, we applied CiteSpace software to conduct co-occurrence and co-cited analysis of literatures. However, due to some problems of CiteSpace software itself, some small deviations in our research are inevitable. The results of this study are based on objective data analysis which are less affected by subjective experience, with stability and objectivity.