# Seepage, Velocity, Hydraulic Conductivity

• Poco Express
In summary, the student is struggling with a mine engineering degree by correspondence and is looking for help with their assignments while their lecturer is on vacation. They have several questions related to calculating discharge, seepage velocities, specific discharge, average velocity of flow, hydraulic gradient, hydraulic conductivity, transmissivity, and porosity in various scenarios involving sand and water. The student is asked to articulate definitions and equations for these terms in order to better understand the fundamentals and be able to solve the problems.
Poco Express

## 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

## The Attempt at a Solution

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

## 1. What is seepage?

Seepage is the slow movement of water through soil, rock, or other porous materials. It can occur naturally or be caused by human activities such as irrigation or construction.

## 2. How is seepage measured?

Seepage is typically measured by calculating the rate at which water flows through a specific area, known as the seepage velocity. This can be done using various methods such as seepage meters or infiltration tests.

## 3. What is velocity in relation to seepage?

Velocity refers to the speed at which water flows through a material. In the context of seepage, it is an important factor in determining the rate of seepage and the potential for erosion or contamination.

## 4. What is hydraulic conductivity?

Hydraulic conductivity is a measure of how easily water can move through a material. It is dependent on factors such as the type of material, its porosity, and the properties of the water itself.

## 5. How is hydraulic conductivity calculated?

Hydraulic conductivity can be calculated using Darcy's Law, which states that the rate of seepage is directly proportional to the hydraulic gradient (difference in water levels) and hydraulic conductivity of the material. It can also be determined through laboratory experiments or field tests.

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