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Groundwater movement Objective
To be able to calculate the hydraulic conductivity of a sample given measurements from a permeameter To be able to evaluate Reynolds Number and the validity of Darcyโs Law for groundwater flow To be able to quantify intrinsic permeability as an inherent property of ground material To be able to quantify the temperature dependence of hydraulic conductivity To be able to estimate hydraulic conductivity from a tracer test and describe limitations of this method
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Determine the hydraulic conductivity of the sample
The figure shows a sample from an unconfined aquifer. L=50 cm, Diameter = 6 cm. The sample is tested for 3 min under constant head difference of 16.3 cm cm3 of water is collected at the outlet. Determine the hydraulic conductivity of the sample Determine the average interstitial velocity assuming a porosity of 0.3 Determine the Reynolds number assuming an effective grain size (d10) of cm From Mays, 2011, Ground and Surface Water Hydrology
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Water Viscosity at different temperatures
From
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Parallel conduit conceptual model for porous media flow.
Intrinsic Permeability vi Ai A Parallel conduit conceptual model for porous media flow.
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Range of values of Hydraulic Conductivity
From Mays, 2011, Ground and Surface Water Hydrology
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Constant Head Permeameter
๐=โ๐พ๐ด ๐โ ๐๐ ๐พ= ๐๐ฟ ๐ด๐กโ From Mays, 2011, Ground and Surface Water Hydrology
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Falling Head Permeameter
A 20-cm long sample of silty fine sand with diameter of 10 cm is tested. The falling head tube has a diameter of 3 cm and the initial head is 8 cm. Over a period of 8 hr, the head in the tube falls to 1 cm. Estimate the hydraulic conductivity. From Mays, 2011, Ground and Surface Water Hydrology
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Tracer Test The water level in two observation wells 20 m apart are 18.4 and 17.1 m. The tracer injected in the first well arrives at the second observation well in 167 hr. Compute the hydraulic conductivity given that the porosity is 0.25 From Mays, 2011, Ground and Surface Water Hydrology
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