Failure of Tube Well

A tube well may fail for the following reasons:

• Corrosion
• Incrustation

Corrosion of the Well Pipes

The Corrosion of the well pipes is caused by the presence of acid, chloride and sulphate in the groundwater. The following measures can be taken to reduce the corrosion of the well pipes.

1.  Always thick pipes should be used.
2.  Always galvanized or other anti-corrosion coated pipes should be used. 
3.  Periodic cleaning of the well pipe should be performed with sulphuric acid.

Incrustation

The groundwater also holds calcium bicarbonate, magnesium, sulphate, etc. For a long duration, these components are deposited inside the tube wells pipes, this reduces the diameters of the pipe. This is known as incrustation. 
The incrustation can be detained as follows:

1. In order to determine the presence of alkali salts, the water of the tube well is tested in the laboratory. Salts responsible for incrustation may be removed by titration. 

Titration is performed by forcing sufficient doses of acid into the well. The water in the tube well is then washed by pumping.

2. The tube well should not be left unused for a long period.

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 Methods of River Bank Protection

Methods of River Bank Protection

4 methods of river bank protection are as follows:

1.  Brick Pitching
2. Stone Riprap
3. Boulder Pitching
4. Concrete Slab Lining 

1. Brick Pitching 

In this method of river bank protection, first of all, around 3m length of bamboo or timber piles are driven along a line about 1 m away from the toe of the river embankment, and the center to center distance between one pile and the next pile is kept 15 cm.

The layer of brick flat soling is provided on the space between the toe and the pile line. Then usually, 15 cm thickness of cement concrete (1:3:6) is laid over the brick flat soling on the room between the toe of the embankment and the pile line. 

The sloping side of the bank is protected by double-layer brick pitching with cement mortar of 1:6 ratio.

2. Stone Riprap 

In this method of bank protection, Around 3 m length of timber piles are driven at 1 m center to center along the line about 1 m away from the toe of the embankment. The piles are projected about 45 cm above the ground surface. 

Then the boulders enclosed in wire net is provided along the space between the toe and the pile line. And for the protection of the sloping side of the embankment, stone riprap finished with cement mortar is provided.

3. Boulder Pitching 

In this method of river bank protection, around 4 m to 5 m length of timber piles are driven at 1 m center to center, along the line about 1 m away from the toe of the embankment. The piles are projected about 50 cm above the ground surface.

Then, within the space between the toe and the pile line, two layers of boulder apron are provided. The sloping side is lined with boulder pitching which is finished with cement mortar.

4. Concrete Slab Lining 

In this method of bank protection, A wall is constructed along the bank of the river. This type of wall is called the toe wall. 

Then the concrete slabs are placed on the space between the toe of the embankment and toe wall,  and it is set by using cement mortar. The sloping side of the embankment is lined with concrete slabs, and joints are finished with cement mortar.

Depending on the site condition, concrete slabs may be of different sizes. Usually, the size of the concrete slab (50 cm X 50 cm X 10 cm) is used.

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Types of Irrigation

Advantages of Canal Lining

Factors Affecting Evaporation From Water Surface

5 major factors affecting evaporation from water surface are as follows:

1. Area of Wate Surface

If the surface of the water is large, the evaporation will be more. But if the water surface is small, then evaporation will be less.

2. Depth of Water

If the depth of water is more, evaporation will be less, but less depth of water causes more evaporation.

3. Humidity

If there is more humidity in the atmosphere, the evaporation will be less.

4. Temperature

If the temperature of the atmosphere is more, the saturation vapor naturally increases as well as the rate of evaporation also increases and vice versa.

5. Wind Velocity

If the rate of wind flow is more, the loss of evaporation will be also more and vice versa.

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Method of Improving Duty of Water

Types of Rainfall

The water that comes back to the surface of the earth in its various forms like rain, snow, hail, etc. is called precipitation. Rain is one type of precipitation. When precipitation occurs in the form of water is known as rainfall. A major part of the precipitation occurs in the form of rain and a minor part of the precipitation occurs in the form of snow. Other forms of precipitation such as hail, sleet, mist, are very small and generally ignored. Depending on the different atmospheric conditions, rainfall may be of the following types:

1. Cyclonic Rainfall

This type of rainfall is caused by the difference of pressure within the air mass on the earth’s surface. If low pressure is generated somewhere, warm moist air rushes with violent forces from the adjacent area to the low-pressure zone. 

The heated moist air rises up with the circular motion and gets condensed at the higher altitude, and finally, heavy rainfall occurs. 

Cyclonic rainfall is classified into the following two categories:

i. Frontal type: Front is a boundary joining warm moist air mass resulting in the precipitation of the moist air mass.

ii. Non-frontal type: In this cold air mass moves whereas moist air mass is stationary.

2. Frontal Rainfall

Frontal rainfall is a type of cyclonic rainfall. When the moving warm moist air mass is blocked by the zone of the cold air mass, the warm moist air rises up (as it is lighter than cold air mass) to a higher altitude where it gets cooled adiabatically to form a cloud and ultimately heavy rainfall occurs.

3. Non-frontal rainfall

Non-frontal rainfall is also a kind of cyclonic rainfall. When a mass of warm moist air rushes from the surrounding zone to the lower pressure zone, a pocket is formed, and the warm moist air rises to a higher altitude like a chimney. 

At higher altitudes, it gets cooled adiabatically to form a cloud. Rainfall caused by such clouds is known as non-frontal rainfall.

4. Convective Rainfall

In tropical countries, when the ground surface is unevenly heated, especially on hot days, warm air rises to high altitudes and cold air takes its place with high velocity.  

Thus, at high altitude, the warm, moist air mass condenses and causes heavy rainfall. This is called convective rainfall.

5. Orographic Rainfall

When the moving warm moist air is barred by some mountain, then it rises up to a high altitude along the mountain slope. 

At the high altitude, it gets condensed and heavy rainfall occurs. This type of rainfall is called orographic rainfall.

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 Types Of Irrigation