A geohydrologic analysis of an upland-bedrock aquifer system: applications to interior Alaska

Abstract

Ester Dome, an upland-dome bedrock aquifer system, located nearby Fairbanks, Alaska, was studied to identify important geohydrologic processes occurring in Interior upland aquifer systems. The ground-water dynamics at Ester Dome are complex due to the fractured nature of the aquifer system. The geology at Ester Dome consists of metamorphic and igneous rocks. Valley bottom deposits include gravels and loess. The flow pattern of the dome aquifer system is radial. Ground-water flows from a central high elevation recharge area and discharges into lakes, streams, and wetlands in the valley bottoms. The primary form of recharge to the bedrock aquifer is from spring snowmelt. Snow water equivalent and snow depth increases with elevation. Ground-water levels were observed at fifty sites on Ester Dome for two years. Water levels in wells at high elevations or locations with no silt or permafrost coverage show seasonal fluctuations. However, ground-water levels in the valley bottoms show little seasonal fluctuations, except wells that penetrate gravel deposits and have no overburden. A ground-water flow model was developed to aid in the understanding of these geohydrologic processes. The ground-water flow model shows recharge and bedrock hydraulic conductivity as the most sensitive parameters.