Karst hyporheic zone and its aquatic environmental effects: a preliminary study in South China

Groundwater (GW)–surface water (SW) interactions profoundly impact aquatic systems. In karst regions characterized by the coexistence of various media, the hyporheic zone (HZ) remains poorly understood. This study explores the HZ by examining karst development and various hydrological, hydrochemical, and biological processes. The research reveals high development of karst and difference in water environment may suggest a diversity of water sources beyond GW, leading to the formation of a karst hyporheic zone (KHZ). Four common KHZ types are proposed based on karst development, with a focus on spring outlet and karst window types. Interactions in these zones are driven by river backflow and GW abstraction in high- and low-water periods, respectively. KHZs may have water quality purification capabilities, but further research on biogeochemical processes is needed. This study provides preliminary insight into KHZs in karst water systems and suggests key scientific questions for future research in South China.