Head (hydraulic) facts for kids

Water flows from the top tank to the bottom basin because of hydraulic head pressure.

Hydraulic head is a way to measure the total energy of water at a certain point. Think of it like how high water can push itself up! It tells us about the water's pressure and how much energy it has, compared to a set starting point.

This measurement is usually given as a height, like how many meters or feet the water level is. It shows the energy of the water inside a special tube called a piezometer. In places where water is stored underground, like an aquifer, we can figure out the hydraulic head by measuring how deep the water is in a water well and knowing the well's height.

How Air Pressure Affects Water

When we talk about hydraulic head, we usually focus on the water's own pressure. But the air around us, called atmospheric pressure, also pushes on the water. This air pressure actually helps to move groundwater.

Sometimes, scientists don't always include the exact air pressure in their calculations because it can change a lot and is hard to measure everywhere. However, for a super accurate picture of how water flows, it's important to remember that air pressure plays a part too!

Hydraulic Head is Like Other Energies

Hydraulic head is a type of energy measurement, and it works in similar ways to other kinds of energy you might learn about in physics or chemistry. The same basic rules apply!

• Hydraulic head is similar to:
  • The strength of a magnetic field.
  • The amount of electric charge in something.
  • The amount of heat (which we measure as temperature).
  • How much of a substance is mixed in a solution (its concentration).

Just like you can map out an electric field or a magnetic field, you can also map out a "field" of hydraulic heads. This helps scientists understand:

• The gradient, which shows the direction water will flow. Water always flows from an area of higher hydraulic head to an area of lower hydraulic head.
• The divergence, which tells us if water is spreading out or coming together.

Images for kids

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  The difference in hydraulic head across a hydroelectric dam. This difference helps generate electricity!

• 

  Measuring hydraulic head in an artesian aquifer. Here, the water level is so high it rises above the ground!

See also

In Spanish: Cabezal hidráulico para niños