CALCULATING SURFACE AND SUBSURFACE WATER STORAGE VOLUME ON RIDGETOPS IN THE DANIEL BOONE NATIONAL FOREST

Isolated wetlands found on ridgetops in Eastern Kentucky are an important hydrologic system because they store water at high elevation. This can sustain forest health throughout periods of drought. Additionally, the amount of groundwater and surface water stored at these ephemeral wetlands may be a significant source of water to uplands. Many of the flat ridges of the Cumberland Plateau region in Eastern Kentucky are associated with perched groundwater resources that emerge to create surface pools. The hydroperiod of water resources has been observed as highly variable from ridge to ridge, and the physical factors controlling the drying rate are not well-defined. The objective of this work was to quantify the volumes of water stored on different ridges and to conduct water budgets for comparison of the ridge hydrology. Surface water storage was measured by constructing high resolution bathymetry maps of ten ridgetop wetlands. Using high resolution geometry of the wetland, a depth to volume rating curve was constructed and applied to sensor readings of water level to calculate volume. Total water input to the wetland catchment surface was estimated by using available precipitation data and the Revised Gash Method for canopy interception to calculate throughfall. Water loss due to evapotranspiration was calculated using Turc’s method. Combining these compartments of the water budget for each wetland allowed the comparison of surface water volumes and the estimation of subsurface water volumes between each wetland. Volumes calculated from bathymetric maps show that maximum surface water volumes in ridgetop wetlands range from ~1 m³ to 131 m³, yet lower volume did not always indicate faster drying. Data indicates that certain smaller wetlands may possess more groundwater than larger wetlands. Preliminary results show that subsurface storage can be as high as 25% of the water budget for a single storm. Moreover, these relatively small hydrologic systems can process hundreds of cubic meters of surface water storage in summer months—and are likely important hotspots for hydrological and ecological processes.