Developing methodologies for supporting groundwater monitoring, management, and sustainability in central Texas and northern Uganda.

In data-scarce and geologically complex aquifers, knowledge building remains an important foundation for further field studies, aquifer modelling, and otherwise supporting sustainable resource development and management. A body of research was undertaken to increase insight into groundwater systems in two challenging contexts, data-scarce regions and highly heterogeneous karst regions, using traditional and novel approaches. Research and education were integrated during an evaluation of groundwater resource sustainability and wastewater management practices in a data-scarce region, northern Uganda. Basic hydrogeologic understanding was established through field work, staff interviews, and literature. An opportunity to collaborate with a visiting surveying and master planning team leveraged time spent onsite for greater results. Hydrologic education occurred formally and informally, through science lessons and daily interactions with stakeholders. Knowledge gained enabled researchers to make recommendations for preserving groundwater quantity and quality. Site-specific information was incorporated into a master plan for future development. Education efforts and trust gained through immersion in local life increased awareness and acceptance regarding groundwater sustainability. Investigating hydrological processes at local and regional scales is an important part of managing groundwater for water supply and critical habitat for aquatic species. However, characterizing aquifer relationships is challenging in a fractured, karsted limestone basin. Using a natural, non-invasive tracer such as radon can help understand groundwater flow and differentiating reaches of surface versus groundwater-dominated flow for water supply and habitat. The groundwater radon conceptual model was tested at several spatial scales in the Northern Segment of the Edwards BFZ aquifer. Results indicate that flow magnitude and the exposed surface area of porous media impact measured radon concentration in groundwater and surface waters. Flow rate and aquifer composition are important considerations when interpreting natural radon concentrations particularly beyond the site scale. Though groundwater-surface water interactions have been described and studied in riverine, wetland, and natural lacustrine settings, there has been less research attention on interaction between constructed reservoirs and adjacent aquifers. Surface and groundwater were collected from Stillhouse Hollow Reservoir and surrounding springs; traditional hydrogeochemical parameters were integrated with a novel environmental tracer, environmental DNA, to confirm and document surface water influence from a reservoir in karst springs. Though all measured parameters confirm some degree of groundwater-surface water interaction at groundwater sites, different parameters provided different insights into the system.