Research progress on the formation mechanism of subsurface flow and its eco-hydrological effects

Water is an important basic resource for human survival and economic and social development. However, the water cycle has undergone profound changes under the dual influence of climate change and human activities. Subsurface flow, a key part of the runoff process and a major replenishment source for rivers and lakes, has a critical impact on runoff formation, water conservation, and nutrient transport. The understanding of subsurface flow processes is an important and popular topic in the fields of hydrology, soil science, and ecohydrology, however, it is a complex scientific problem that is difficult to disentangle. In this article, it was found that from 1990 to 2020, the number citation frequency of published articles related to subsurface flow in China have gradually increased. The researches mainly focused on the environment, engineering, water resources, and agriculture, focusing on topics such as purplish soil, wetlands, and nitrogen. In addition, we analyzed the main factors affecting subsurface flow formation, including soil, topography, vegetation, rainfall, etc. Furthermore, we summarized several ecological and hydrological effects of interflow, including the soil nutrient transport effect, soil and water conservation, runoff regulation, and hydrological forecasting effect. Finally, we highlighted some limitations in current research on interflow and discussed future research priorities, ultimately providing an important scientific basis for crucial ecosystem restoration and water conservation improvements.