Seepage, Velocity, Hydraulic Conductivity

  • #1

Homework Statement


Hi there I am doing a mine engineering degree by correspondence. The lecture notes that I have calculating seepage and velocity etc is not very helpful and other then discussing darcys law and other concepts does not go through the formulas. My lecturer has gone on holdiays and my assignment is due next Wednesday.
I have the following questions to answer and I am really hoping someone can help me with these. If you discuss the formula can you give me some example of how to do it. I appreciate any help you can give. Thanks

33. Calculate the discharge and seepage velocities for water flowing in a pipe filled with sand, with a hydraulic conductivity of 0.2m/day and an effective porosity of 0.25. The hydraulic gradient is 0.02. How far will the water move in one year?

34. A cylindrical column, 0.2m in diameter and 5m long is filled with relatively homogenous sand. If the porosity of the sand is 35% and distilled water is continuously introduced into the column, saturating the sand and establishing steady state flow conditions for which the discharge is measured to be 9.6 x 10-2 m3/day, determine:
a. The specific discharge
b. The average velocity of flow through the column

35. A confined sand aquifer has an effective porosity of 20% and a hydraulic conductivity of 30 m/day. The hydraulic gradient in the aquifier is 0.002. The overlying confining bed is composed of clay with a porosity of 45% and a hydraulic conductivity of 0.0002 m/day. Hydraulic gradient in the clay is 0.15. Determine the specific discharge and seepage (average linear) velocity for flow of ground water in both the aquifer and the overlying aquitard.

36. Field investigations indicate that the hydraulic gradient in a 10m think sand aquifer is 0.01. The transmissivity of the aquifer has been determined from pumping tests to be 500 m2/day. The porosity of the sand is 0.25. Calculate the discharge and the linear velocity.

37. The hydraulic gradient measured in two observation bores positioned along the direction of groundwater flow in a 30m thick confined aquifer is 0.001; the aquifer’s tranmissivity is 550 m2/day. Determine the groundwater flow through a 6km wide section at right angles to the direction of groundwater flow.

38. A unconfined aquifer is 33m thick and 7km wide. Two observation bores are located 1.2km apart in the direction of flow. The head in bore 1 is 97.5m and in bore 2, it is 89m. Hydraulic conductivity is 1.2m/day.
a. What is the total daily flow of water through the aquifer
b. What is the elevation of the potentiometric surface at a point located 0.3km from bore 1 and 0.9km from bore 2


Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
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You need to make an attempt to solve these problems before you can get help here. You gave no equations. At least articulate the definitions of the terms so we know that you know them: specific discharge, hydraulic gradient, hydraulic conductivity, transmissivity.

Write down equation for the specific discharge as a function of the hydraulic gradient and the hydraulic conductivity. Write down the equation for transmissivity as a function of hydraulic conductivity and height of formation. Write out the equation for seepage velocity as a function of specific discharge and porosity. Show us that you understand the fundamentals. If you are familiar with these equations, you should have no difficulties solving the problems that you have listed. But the first step in learning any technology is understanding the terminology.

Chet
 

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