VARIABILITY IN GROUNDWATER FLOW AND CHEMISTRY IN THE HOUZHAI KARST BASIN, GUIZHOU PROVINCE, CHINA

Understanding how karst aquifers store and transmit water and contaminants is an ongoing problem in hydrogeology. Flowpath and recharge heterogeneity contribute to the complexity of these systems. This thesis explores karst-conduit connectivity and water chemistry variability in 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 flowpaths through the catchment are 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 can be significant. Synoptic water samples from several karst features taken during both monsoon and dry seasons elucidate spatial and temporal variability within the catchment. In general, water residence time is longer during the dry season and flow within the Houzhai catchment is temporally dependent. Time-series sampling at the outlet spring during a monsoonal storm event captured chemical variability and identified multiple flowpaths. Overall, this study refines widely applicable methods for studying karst systems to this catchment and provides a foundation for future studies in similar settings