Using LiDAR to Constrain Groundwater Models of an Isolated Ridgetop Wetland in the Daniel Boone National Forest to Quantify Hydrological Connectivity

Hydrological connectivity between groundwater and surface water in wetlands contributes many ecological benefits such as drought resilience, hydrologic connection between other water bodies, and water quality transformation. Geographically isolated wetlands (GIWs) are topographically disconnected from other water sources. GIWs found on the ridgetops in the Daniel Boone National Forest (DBNF) are connected to groundwater processes. This creates the potential of ridgetop GIWs being connected to lowland valley headwater streams, providing a source of upland water that leaks through the subsurface and to lowland headwater streams. Currently, it is not understood how ridgetop GIWs in the DBNF might be connected to lowlands or how groundwater-surface water processes control water storage in the GIWs. Our objective was to use field investigations and Light Detection and Ranging (LIDAR) data to characterize a wetland system in order to create steady-state and transient MODFLOW models to quantify the wetland’s hydrological processes and to explore ridgetop-lowland connectivity. Field investigations of geology, monthly hydraulic head measurements, and hydraulic conductivity measurements were gathered during 2017. LIDAR data was used to identify geomorphic features such as cliff boundaries and ephemeral channels in order to define boundary conditions for MODFLOW. The models indicated that the wetland’s primary outflow was through groundwater leakage from ridgetop ephemeral channels, toward the lowlands, whereas evapotranspiration was a secondary outflow. The wetland system was sensitive to recharge (precipitation). As the wetland dried during the summer, a hydrologic shift occurred, changing the groundwater flow direction north of the wetland pool