Definition of wells | Types and Importance

Wells

Wells can be defined as

“A hole made for collecting underground water.”

Or

” A shaft sunk into the ground to obtain water, oil or gas.”

Collected water depends upon

1. Ease with which water flows through aquifer.
2. Its thickness.
3. Its diameter.

Types:

With respect to type of construction

These are of the following types.

1. Dug wells:

Those which are dug through picks* and shovels are known as dug wells. Their diameter is greater than one meter.

2. Driven wells:

Those which are dug in loose materials by use of pointed pipe. Their diameter is greater than 7cm.

3. Bored wells:

Those which are dug through man power or augers are known as bored wells.

4. Jetted wells:

Those which are dug in loose soil by use of pressurized water are known as jetted wells.

5. Drilled wells:

Water wells excavated by means of drilling procedure in hard soil are known as drilled wells.

They have depth of 80 meter or more.

With Respect to the type of flow

There are three types with respect to the type of flow.

Gravity wells

In this type, the water level is at the atmospheric pressure and the well is vertical. They are sunk in the unconfined aquifer. It is also called as water table well.

Pressure wells

These are the pressure wells and are constructed in the confined aquifer. It is the well that passes through aquiclude to an aquifer, having water under pressure. Pressure is greater than atmospheric pressure in this case. The flow is under pressure rather than gravity.

Horizontal wells

These are infiltration galleries. It is a horizontal tunnel pipe or open channel. It is constructed through or in water bearing strata. It is constructed in the direction normal to the flow of underground water.

These galleries are constructed closed to the river bank or lake to intercept the ground flow towards the body of surface water. These are constructed of masonry or concrete with opening on one side. These are built like open trenches or by tunnel methods. If these are surrounded by the rivers, they will increase their intake capacity. The internal diameter vary according to water requirement.

The internal diameter has generally 2-6 ft strainers. The material used for strainer is usually galvanized iron polished surface. Cast iron is not used. PVC strainers may also be used. The red area of the strainer opening should be such that the entering velocity should not exceed 2-3 in/s . This will prevent the filling of strainer by sand.

Importance:

• Wells are of great importance as we collect water which is used in many ways.
• It is use for many agricultural and industrial purposes.
• It is used for many engineering purposes.
• Water collected is used to produce electricity purposes.

*Pick

(also pick axe) a tool consisting of a curved iron bar with pointed ends, fixed at right angles to its handle, used for breaking up hard ground or rock.