Internal Water Sources - An Analysis

In our last blog, we have covered the difference between Internal Water Sources and External Water Sources.

In our Agriculture for Everybody blog series, we will do a deeper analysis and understand the different Internal Water Sources and their advantages and disavantages.


Borewells

Advantages	Disadvantages
1. Occupies very less space 2. Digging of borewell is quite fast 3. No evaporation of water at all	1. Need power for lifting water 2. Identifying the water point is not fool proof 3. How much water available cannot be established?

Open Wells

Advantages	Disadvantages
1. Occupies a little more space 2. Takes more time to dig an Open Well 3. Can measure the amount of water available and plan crops accordingly 4. Can be utilized to store water harvested 5. Recharge of groundwater happens automatically 6. Water can also be lifted by mechanical power	1. Need power for lifting water 2. Little bit of evaporation takes place 3. Mosquito menace can be a problem for humans and livestock

Calculating Water Holding Capacity of an Open Well

Volume of Pond in Litres = 3.142 X Diameter/2 X Diameter/2 X Average Depth X 1000

For eg., a pond with 2.5 metres diameter and 5 metres avg depth will have

3.142 X 2.5/2 X 2.5/2 X depth X 1000 = 24547 Litres


Ponds

1. Allocate 10% of the farmland for ponds if you wish to utilize the pond for growing fish and have only 3 to 5 feet of water for better maintenance
2. Allocate atleast 1% of the farmland for ponds if you need just water and increase the depth of the pond according to your needs
3. Confirm whether the water will be held in the pond without too much seeping
4. Identify the lowest point of the farm where the water rushes to during rain and create the pond there for easy collection of water and better maintenance

Advantages	Disadvantages
1. Occupies a huge space 2. Takes a little more time to do construction of the pond 3. Can measure the amount of water available and plan crops accordingly 4. Can utilize the pond for growing fish, ducks etc 5. Can be utilized to store water harvested 6. Recharge of groundwater happens automatically 7. Water can also be lifted by mechanical power	1. Need power for lifting water 2. More evaporation takes place 3. Filling of pond takes time 4. Mosquito menace can be a problem for humans and livestock

Calculating Water Holding Capacity of a Pond

Square or Rectangular Pond

Volume of Pond in Litres = Length (in metres) x Width (in metres) x Average Depth (in metres) x 1000

For eg., a pond with 25 metres length and 10 metres width and 5 metres depth will have

25 m (Length) X 15 m (Width) X 5 m (Avg Depth) X 1000 = 1875000 Litres


Round Pond

Volume of Pond in Litres = 3.142 X Diameter/2 X Diameter/2 X Average Depth X 1000

For eg., a pond with 2.5 metres diameter and 5 metres avg depth will have

3.142 X 2.5/2 X 2.5/2 X depth X 1000 = 24547 Litres
 

Water Sources

We all know Water is a very important requirement for farming activities.  In our Agriculture for Everybody blog series, we will understand the various sources from where we can get the water for our crops.

We can classify the Water Sources into two as below.

1. Internal Water Source
2. External Water Source

Internal Water Source

Internal Water Sources are those that are available within our farms.  We have some limited control on these water sources.

Generally, the Internal Water Sources are created by us and some of them are given below.

• Borewells
• Open Wells
• Ponds

I mentioned limited control in the previous paragraph, just to highlight the point, that the water in these sources can become dry if other farms in the area exploit the underground water indiscriminately by using borewells.


External Water Source

Any water source that is outside of our farm are considered External Water Source.  We have literally no control on these water sources.

Some examples of External Water Sources are

• Common Wells / Ponds
• Streams
• Springs
• Canals
• Lakes
• Rivers

If External Water Source need to be utilized, we may have to get permission from the concerned authorities.  External Water Sources need to be used co-operatively and any naturally occuring water source is the best option as these will replenish by themselves.