A regional, two-dimensional, areal ground-water-flow model was developed to simulate the ground-water-flow system and ground-water/surface-water interaction in the Rock River Basin. The model was developed by the U.S. Geological Survey (USGS), in cooperation with the Rock River Coalition. The objectives of the regional model were to improve understanding of the ground-water-flow system and to develop a tool suitable for evaluating the effects of potential regional water-management programs. The computer code GFLOW was used because of the ease with which the model can simulate ground-water/surface-water interactions, provide a framework for simulating regional ground-water-flow systems, and be refined in a stepwise fashion to incorporate new data and simulate ground-water-flow patterns at multiple scales.

This dissertation investigates groundwater-surface water interactions and stakeholder engagement for an unconfined aquifer in the Central Sands region of Wisconsin, USA. The study focuses on two surface water systems, the Little Plover River and Long Lake, which over the last several decades received much public attention related to consecutive years of low flows and water levels. The dissertation is comprised of four papers. The first paper applied collaborative modeling and scenario analysis using soil water balance and groundwater flow models to simulate stakeholder-identified water management scenarios in the Little Plover River basin under historically-informed dry, average, and wet weather conditions. The process provided a forum for solution-based discussion between multiple interest groups. Results compared impacts of ten scenarios on the Little Plover River and showed that scenarios must be applied in combination to have significant impacts on stream flows. The second paper applied qualitative research methods - group meetings, surveys, and individual interviews - to investigate stakeholder perspectives of groundwater flow models and the scenario analysis process in the Little Plover River basin. Narrative inquiry, a qualitative method that has not been applied to water resources research, elucidated key tensions that can be the focus of future collaborative modeling efforts. The third paper developed a method for reconstructing a long-term record of lake levels using personal photos along with aerial photos and available, but limited, monitoring data. The method resulted in reconstruction of an 80-year lake level record (1938-2017) showing a long-term lake level fluctuation of 9.4 feet over the record. The approach could be used to create datasets in areas that have little to no monitoring data. In addition, visual documentation of personal photos and aerial photos can build stakeholder trust in reconstructed long-term records. The final paper investigated lake-aquifer connectivity of Long Lake. Methods characterized the local hydrostratigraphy, calculated groundwater flow with a stable isotope water budget, and analyzed lake and groundwater levels and vertical gradients. Results from all methods showed the lake is well-connected to the surrounding aquifer, and how using multiple lines of evidence is a useful approach for investigating lake-aquifer connectivity.