How do you calculate total head in ground water flow?

In summary, the conversation discusses the concept of total head, pressure head, and pore water pressure. The total head is the total pressure, the pressure head is the height of fluid that would produce the same pressure by gravity, and the pore water pressure is the pressure within the pores of soil. The conversation also discusses how to explain these concepts in a tangible way, such as using the example of a pressure casserole. Additionally, the head is defined as a combination of pressure and elevation, and the upward seepage velocity can be calculated using the hydraulic conductivity.
  • #1
question dude
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Its attached below. I don't understand how you work out the total head. Can someone explain how you do it? I'm really struggling.

I know how to do the elevation, which is just the height above/below the datum level. And I've checked the solutions as well, it seems like you're supposed to work out the total head before the pressure head.
 

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  • #2
What are the "total head", "pressure head" and "pore water pressure"?
Can you explain that to you grand-mother?
 
  • #3
maajdl said:
What are the "total head", "pressure head" and "pore water pressure"?
Can you explain that to you grand-mother?

'head' is simply stress (or pressure) mulitplied by depth

for total head is the total pressure as it were
 
  • #4
Do you think your grand mother could understand?
Could you explain those things in a tangible way?
For example, by comparing what you measure if free water versus water in a soil?

In addition, I don't think that "pressure x depth" is related to the "head".
As I am from Belgium, I am not used with this terminology.
However, I looked at http://en.wikipedia.org/wiki/Pressure_head and it looks like that "pressure head" is the height of fluid that would produce by gravity the same pressure. In some way, it is the pressure expressed in meters of fluid.

In a "Pressure Casserol", the pressure is unrelated to the depth of water insided the "Pressure Casserol". Yet, it can be expressed in head of fluid, and the numerical value might be meters while the "Pressure Casserol" would only be 20 cm high.

See also this picture, where head is shown by the measuring tubes.

320px-Venturifixed2.PNG
 
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  • #5
The head is defined as [itex]H=\frac{p}{ρg}+(z-z_0)[/itex], where z-z0 is the distance measured upward from the Ordinance Datum z0. So, at points P and C, the head H is 1 meter (there is no flow resistance between points P and C). At point A, the figure shows that the head is 6 meters above the Ordinance Datum. At point B, because the flow is steady, the head is the average of points A and C, or 3.5 meters. The upward seepage velocity is given by:

[tex]v=- K\frac{(H_A-H_C)}{(z_A-z_C)}[/tex]

where K is the hydraulic conductivity (10-4 m/s).
 

What is ground water flow?

Ground water flow refers to the movement of water through the pores and fractures in the Earth's subsurface. It is an important process that replenishes underground aquifers and affects the water availability in different areas.

What factors influence ground water flow?

Several factors can impact the flow of ground water, including the permeability and porosity of the subsurface materials, the slope of the land, and the presence of fractures or faults that can act as conduits for water movement.

How does ground water flow affect groundwater contamination?

Ground water flow can play a significant role in the spread of groundwater contamination. Depending on the direction and speed of the flow, contaminants can be transported to new areas and potentially impact water quality in other locations.

What methods are used to study ground water flow?

Scientists use a variety of methods to study ground water flow, including hydrologic modeling, groundwater monitoring wells, and geophysical techniques such as ground-penetrating radar. These methods can provide valuable information about the direction, speed, and characteristics of ground water flow.

How does ground water flow impact the environment?

Ground water flow is a crucial component of the Earth's water cycle and has a significant impact on the environment. It can affect the availability of water for plants and animals, contribute to erosion and land formation, and play a role in the distribution of nutrients and pollutants in the subsurface.

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