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In cooperation with West Dakota Water Development District, City of Rapid City,

Temperature: A useful tracer for separating conduit and diffuse flow in the karstic Madison aquifer. In cooperation with West Dakota Water Development District, City of Rapid City, South Dakota School of Mines and Technology. Andy Long Patrick Gilcrease. Limestone Open passages.

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In cooperation with West Dakota Water Development District, City of Rapid City,

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  1. Temperature: A useful tracer for separating conduit and diffuse flow in the karstic Madison aquifer In cooperation with West Dakota Water Development District, City of Rapid City, South Dakota School of Mines and Technology Andy Long Patrick Gilcrease

  2. Limestone Open passages Model shown conceptually Inflow from sinking stream Spring discharge Slow flow Conduit flow

  3. Heat transport equation for flow in pipe Ts Tr Tq - = + + Heat flow in Heat flow out Heat accumulation Convective heat from conduit wall Heat from slow inflow

  4. Inflow from small openings Change in mass flow rate from slow inflow qs Change in velocity due to change in mass flow rate Final heat transport equation for the conduit

  5. Limestone Open passages Mixing of conduit and slow flow to a well The well is a binary mixture of conduit flow and local slow flow Tq Tl 1+ dimensional model

  6. Black Hills Model application Study area is dominated by streamflow recharge (~90%)

  7. Spring Creek swallow holes

  8. Temperature sensor Omega RTD class A ±0.03°C at 0°C Spring Creek Well house

  9. Cross-section of Madison aquifer and conduit Heat-transport equation is solved in each model cell by finite difference

  10. Data and results

  11. Summary • The model is useful for estimating the conduit flow fraction to a well or spring • Conduit flow to the well varied temporally from 2 to 31% of total flow • Conduit velocity ranged from 44 to 353 m/d • Changes in temperature for the well were influenced by conduit velocity and the changing relative pressures of the conduit and surrounding aquifer

  12. ht = heat transfer coefficient • D = conduit diameter • qs = flow rate of slow flow • Ts = temperature of slow flow • Tq = temperature of rocks • Td = temperature of water at discharge point • = conduit flow fraction (weighted by head)

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