Basin-Scale Groundwater Flow and Advective Heat Flow: An Example from the Northern Great Plains

摘要: Gravity-driven groundwater flow in a confined aquifer system that extends several hundred kilometers eastward from the Black Hills causes anomalous surface heat-flow over an 80,000 km2 area southern South Dakota and northern Nebraska. Data 16 new heat- holes, existing data, values calculated BHT data show systematic variation 20 mW m−2 recharge zone to 140 discharge zone. Ninety-four conventional 62 yield average of 58 ± 9 for Great Plains exclusive area. The advective is unusual temperature gradients boreholes ranging 2000 meters deep near 500 central only conductive heat-flow. In effect, masked by low permeability marine shales overlie 600- meter thick system. Numerical models coupled suggest water at Darcy velocities 3.17 × 10−8m s−1 6.34 (1 2 m y−1))