Variability in Groundwater Flow and Chemistry in the Houzhai Karst Basin, Guizhou Province, China

Abstract

Understanding how karst aquifers store and transmit water and contaminants is an ongoing problem in hydrogeology. Multiple flow paths and recharge heterogeneity contribute to the complexity of these systems. This study explored karst-conduit connectivity and water-chemistry variability within the Houzhai catchment in Guizhou Province, China. Artificial tracer tests were conducted during both the monsoon and dry seasons to understand temporal variability in connectivity and water velocity between karst features. Multiple flow paths through the catchment were activated during the monsoon season and partially abandoned during the dry season. Additionally, gradient reversals during monsoonal high-flow events and as a result of pumping were observed. Synoptic water samples from several karst features taken during both monsoon and dry seasons elucidated spatial and temporal variability within the catchment. Water residence time was generally longer during the dry season, and flow within the Houzhai catchment was determined to be temporally dependent. Time-series sampling at the outlet spring following a monsoonal storm event captured chemical variability and identified multiple flow paths. Overall, this study refines widely applicable methods for studying karst systems to this catchment and provides a foundation for future studies in similar settings.