Discussion of Hydrogeologic Data to Develop a Numerical Ground-Water-Flow Model of Mt. Desert Island, Maine

Nielsen, Martha

'Abstract: Existing geologic and hydrologic data were compiled for the construction of a generalized ground-water-flow model of Mt. Desert Island for the National Park Service, Acadia National Park. This report discusses some of the limitations of those data for use in a model. A conceptual model of ground-water-flow on Mt. Desert Island is discussed. Existing data on the hydrologic properties of the aquifer system are summarized. Suggestions are made for possible discretization of the hydrologic system for model development, boundary conditions, initial hydraulic conductivity values, stresses, and calibration targets. Finally, suggestions for additional data that would be necessary for completion of an island-wide model are discussed.' 'Need for Additional Data: Although data for Mt. Desert Island may exist that are sufficient to construct a highly generalized ground-water-flow model for parts of the island, these data are not detailed enough to answer questions about water flow in and around wetlands on the island, or to predict the movement of possible ground-water contamination as it relates to the locations of wetlands or other water bodies. Additional data would be needed to accurately construct and calibrate a ground-water-flow model for Mt. Desert Island, whether the whole island or just parts of the island are modeled. Additional data needed for such a model would include: more detailed information on the distribution and thickness of the Presumscot Formation and other surficial geologic units; water-level data in shallow wells in the surficial geologic units and in bedrock units; data from nested wells that show vertical hydrologic gradients within the bedrock and between the bedrock and the surficial units; detailed geologic mapping (both bedrock and surficial) at a scale of 1:24,000; additional information on the hydraulic conductivities of the various geologic units (bedrock and surficial materials); and information on direction and magnitude of anisotropy in the bedrock units.' /STUDY LOCATIONS:/ /MOUNT DESERT ISLAND/