The geologic and hydrologic terms pertinent to this report are defined as follows:Aquifer. A formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells or springs. Base flow. Sustained streamflow, composed largely of ground-water discharge. Evapotranspiration. Water withdrawn by evaporation from water surfaces and moist soil and by plant transpiration. Glacial drift. All deposits resulting from glacial activity. Ground water. That part of subsurface water that is in the saturated zone. Hydraulic conductivity. The rate of flow of water transmitted through a porous medium of unit cross-sectional area under a unit hydraulic gradient at the prevailing kinematic viscosity. Loess. Wind-blown sand or silt. Out wash. Sorted, stratified drift deposited beyond the ice front by meltwater streams. Saturated zone. Zone in which all voids are ideally filled with water. The water table is the upper limit of this zone, and the water in it is under pressure equal to or greater than atmospheric. Specific yield. The ratio of (1) the volume of water which is saturated rock or soil will yield by gravity to (2) its own volume. Storage coefficient. The volume of water an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in head. In an unconfined aquifer, it is virtually equal to the specific yield. Till. Unsorted, unstratified drift deposited directly by the glacial ice. Transmissivity. The rate at which water of the prevailing kinematic viscosity is transmitted through a unit width of an aquifer under a unit hydraulic gradient. Water table. That surface in an unconfined water body at which the pressure is atmospheric.
