Water Sources

01-Water Sources

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 on 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 is 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 needs to be utilized, we may have to get permission from the concerned authorities. External Water Sources need to be used cooperatively and any naturally occurring water source is the best option as these will replenish by themselves

02- Internal Water Sources - An Analysis

we will do a deeper analysis and understand the different Internal Water Sources and their advantages and disadvantages.

Borewells

Advantages

1. Occupies very less space

2. Digging of bore well is quite fast

3. No evaporation of water at all

Disadvantages

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

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

Disadvantages

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 Open Well in Litres = 3.142 X Diameter/2 X Diameter/2 X Average Depth X 1000 For eg., a Open Well 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 at least 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 seepage.

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

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

Disadvantages

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

03- Water Irrigation Methods

we will cover the water irrigation methods generally followed in and around the country. Only the important methods are covered here.

• Flood Irrigation

o This is the traditional method that is being used even today in most parts of our country

o This is the cheapest method in terms of cost and maintenance is very less

o The water loss is very high in this method

o This method is suitable for Paddy, Wheat etc

• Furrow Irrigation

o This is another traditional method that is being used even today

o This method is cheaper as well as easy to maintain

o The water loss is somewhat average in this method

o This method is suited for row crops or tree crops

o This method is suitable for Coconut, Mango, Sugarcane, Vegetables etc

• Pot Irrigation

o This method is generally used in areas where the waterfall is very less and hence recommended for dryland agriculture

o This involves filling up the pot every week or so and hence is a tedious work

o No or minimal water loss due to evaporation/heat

o Cost is negligible

o This method is suitable for Tree based crops

• Drip Irrigation

o This is the newly introduced method mainly for the purpose of reducing/saving the water to a greater extent

o This method needs infrastructure and materials (like PVC pipes etc) and hence the cost is higher

o This method requires maintenance at regular intervals and there is a nominal cost associated with it

o This method requires power for the water to be pumped across

o Very less water loss due to evaporation

o This method is suitable for Tree based crops as well as for Vegetables

• Sprinkler Irrigation

o This is also newly introduced method and is a better alternative than flood irrigation for certain crops

o This method needs infrastructure and materials (like PVC pipes etc) and hence the cost is higher but less than that of Drip Irrigation

o Little more of water loss is associated with this method

o This method requires power for the water to be pumped across

o This method is generally used for Vegetable based crops or even can be used for growing crops like Maize, Grasses etc where the requirement of water is minimal

• RainGun Irrigation - This method is similar to Sprinkler Irrigation except for the coverage and reach of the water

04- Water Harvesting Methods

we will see the different types of Water Harvesting Methods from a farmland point of view. We will highlight each one of them and anybody wishes to implement them can look for more detailed information elsewhere.

• Trenches

o Trenches need to be created against the flow of the water to get maximum benefit

o Trenches are best-suited water harvesting method where plants or trees are the main crops. For eg, Coconut Tree Plantations, Mango Tree Plantations etc

o Trenches can be created in between the rows of the Trees

• Swales = Continuous Contour Trenches

o Swales need to be created against the flow of the water to get maximum benefit

o Swales generally are bigger in size (in terms of width, depth & length) compared to trenches

o Swales are best-suited water harvesting method where plants or trees are the main crops. For eg, Coconut Tree Plantations, Mango Tree Plantations etc

• Bunds

o Bunds are created around the borders or periphery of the farmland to retain maximum water

o The size of the bund is bigger and deeper so that water is retained as well as ensuring that cattle and other animals do not trespass

• Open Wells

o Open Wells are best-suited water harvesting (storage) method when there is run-off of rain water

o Any excess water needs to be channelled into this after filtering the sediments

• Farm Ponds

o A small portion of the land is allocated for Farm Ponds

o Generally, the Farm Pond is located at the lowest point of the farmland

o Farm Ponds are best-suited water harvesting (storage) method when there is run-off of rain water

o Farm Ponds is required when we need to store large amounts of water

o Any excess water needs to be channelled into this after filtering the sediments

• Check Dams

o Check Dams are built for retaining the water in the upstream

o Check Dams ensure seepage of water into the soil thereby increasing the ground water

o Check Dams can be built in Swales and other similar structures

05- Water Storage Methods

we will discuss the specifics of Water Storage Methods. Generally, the water storage methods can be classified into two groups and they are as follows.

1. Underground Water Storage

2. Over ground Water Storage

We can opt to utilize one or the other of the methods or a combination of both.

Underground Water Storage 

The water is stored below the surface and can be retrieved at a later point of time by using the available options.

Advantages

• Evaporation is very minimal as the water is stored below the ground

• Contamination possibility is very less

• No need to allocate any land for this purpose

Disadvantages

• Water can only be retrieved by using bore well and other means

• Water availability is not guaranteed as other farmers can also exploit the underground water

Over ground Water Storage 

The water is stored above the surface and can be utilized directly for many purposes and that too whenever we require them. Examples of this method are Farm Ponds, Open Wells etc

Advantages

• Can utilize the water & space for Fish Farming

• Can utilize it as drinking water for Cattle, Poultry etc

• Can utilize it for the crops during the summer season when the water availability is generally low

• Seepage of water in the soil will benefit the entire farmland

Disadvantages

• Need to allocate land

• Evaporation is very high and hence possibility of loss of available water to some extent

• Contamination is possible

• Will attract Snails and other similar things which may not be good to our Livestock

06- Single Pond Design for Water Storage

we will be dealing with Pond Design related to Water Storage. This design is mainly for Dug Out Pond otherwise called as Excavated Pond or Sunken Pond. Picture to be placed here at a later point of time

• Pond Area or Size

o Based on need

o Min: 1% of Total Land Bank

o Max: 10% of Total Land Bank

• Pond Shape

o Round or Square is optimal

o Reason: Round or Square will have the least surface area and hence evaporation is minimal, as well as seepage of water into the soil, is also minimal

• Pond Length

o Based on need

• Pond Breadth

o Based on need but similar to Pond Length is optimal

• Pond Depth

o Based on need but 6 ft is minimum. The Pond Depth (Height) is inclusive of the Bund. A gap of 1 ft is required between the top of the water surface and the top of the Pond

o Reason 1: If you wish to do Fish Farming in future, 5 ft is the maximum required water depth

o Reason 2: If the depth is more, need safety measures like fencing off the pond to avoid humans, cattle etc falling into the pond

• Internal Slope

o Min Ratio is 1:2 but can be more like 1:3, 1.4, 1:5 etc

o The Internal Slope should have provision to enable the water to flow without the soil being washed away by placing rocks or similar objects in the path of the water

o Reason 1: Generally, the Min Ratio is suited for most of the soils, but for loose soils, you can go for bigger ratios to avoid collapsing of the soils.

o Tip 1: While making the slopes, pound them hard so that the air & water is removed from the soil and the soil becomes hard. This way we can avoid collapsing of the soil to a great extent

o Tip 2: Plant Vetiver on the slopes. This will ensure the roots of the grass grips the soil and the collapsing of the soil is avoided altogether

• External Slope

o Min Ratio is 1:1 but can be 1:2 or more

o Tip 1: While making the slopes, pound them hard so that the air & water is removed from the soil and the soil becomes hard. This way we can avoid collapsing of the soil to a great extent

o Tip 2: Plant Vetiver on the slopes. This will ensure the roots of the grass grips the soil and the collapsing of the soil is avoided altogether

• Bund or Embankment Size

o Breadth - Min of 1.5 Metres at the top (excluding the Internal Slope & External Slope)

o Height - 2 ft Min

o Reason 1: The Bund is mainly used for walking along the pond to see whether everything is intact and any cracks or gaps have occurred and repair them before the monsoons

o Reason 2: The Bund can also be used to grow fodder for cattle as well as vegetables

o Reason 3: To a certain extent, can protect humans & cattle from falling into the pond

• Inlet Water Path

o Length: Based on Need

o Breadth: 2 ft Min

o Depth: 1 ft

o The Inlet Water Path should be aligned with the top of the bund

• Outlet Water Path

o Length: Should be at least 1 ft beyond the end of the External Slope

o Breadth: 1 ft Min

o Depth: 1 ft

o Generally, it is recommended that the Outlet Water Path should be at the bottom of the pond. This is possible only when the land is on a higher plane and the water goes out by natural gravitational forces

o For Dugout ponds, the Outlet Water Path should be at the ground level

o Tip 1: To remove the water that is below the ground level, we need to pump out the water by artificial means

• Overflow Water Path

o Length: Should be at least 1 ft beyond the end of the External Slope

o Breadth: 2 ft Min

o Depth: 1 ft

o The Overflow Water Path should be 1 ft below the Inlet Water Path

o There should be an equivalent Outlet Water Path for each Inlet Water Path or at least to the sum of the Inlet Water Paths

• Silt Pit

o Length: 1 Metre Min or more

o Breadth : 1 Metre

o Depth : 0.5 Metre

o This has to be placed across/perpendicular to the Inlet Water Path. This will filter the sediments if the water is coming from rain water harvesting source or from any other sources

o Tip 1: If we have multiple Inlet Water Path, each should have an equivalent Silt Pit

• Misc

o A Pond Example

 Length : (Bund Breadth X 2) + Need Based Length (for eg., 10 ft)

 Breadth : (Bund Breadth X 2) + Need Based Length (for eg., 10 ft)

 Depth: 6 ft (including the Bund Height)

 Bund :

• Height: 2 ft
• Breadth : 9.2 ft (1.5 Metres=3.2 ft + Internal Slope Breadth + External Slope Breadth)

 Internal Slope

•  Breadth: 4 ft (Based on Bund Height)
•  Slope 1:2

 External Slope

•  Breadth: 2 ft (Based on Bund Height)
•  Slope : 1:1

o Tip 1: Trees which have longer roots need to be avoided near the pond as this may cause cracks or collapse of the bund

o Tip 2: Trees like Coconut Or Palmyra Tree are best suited as they grip the soil very well

07- Multiple Ponds Design for Water Storage

we will discuss the need for Multiple Ponds and the ways to achieve that. In a small farm, a single pond is dug at the lowest point or at a convenient place and it may be optimal for small farms just having a single pond. In a big or large farm, a single pond may not be the right choice as water stored need to be moved around to the crops in need by either option like trenches or pipes etc. If there is less rainfall, even a single pond of bigger size may not reach its full capacity and also evaporation and seepage will further reduce the water stored because of the bigger size. Multiple Ponds avoids above mentioned pitfalls and has other benefits which are mentioned below.

1. Small Ponds (Multiple Ponds) get filled easily compared to a single big pond (even when rainfall is less)

2. Small Ponds (Multiple Ponds) evaporation as well as the seepage is less as the size of the pond is less. This is true only when not all the ponds are filled

3. Due to many Small Ponds, Soil moisture is available for the crops near the ponds

4. Water is available nearby as the pond is placed in the centre of the farm and this can cater to the crop on both sides of the pond. This reduces overhead like extra

pipes etc

How to go about creating the Multiple Small Ponds Design? There are 4 components in the above picture and this picture is planned keeping in view the Rain Water Harvesting model.

1. Border Trenches (in Brown Colour)

2. Internal Trenches (in Light Green Colour)

3. Water Flow Channel (in Yellow Colour)

4. Multiple Small Ponds (in Dark Green Colour)

Note: If the water source is different from RWH, a simpler water flow channel can be created which in turn will connect to the individual ponds rather than connecting through the ponds

Border Trenches

• Border Trenches have to be dug on all sides of the farm

• The border trenches have to be 2 Ft Width & 1 Ft Depth or as required

• Only one opening is allowed in the border trench to connect to the water flow channel which in turn will connect to the first pond

• There should be an outlet in the border trench for drainage (at 0.5 Ft Depth from the top of the trench)

Internal Trenches

• Internal Trenches have to be dug on both sides of the pond (parallel to the pond)

• Internal Trenches have to be dug for the entire length of the farm and it should connect with the border trenches

• The internal trenches have to be 0.5 Ft to 1 Ft Width & 0.5 to 1 Ft Depth

• The internal trenches have to be 3 Ft or 1 Metre away from the pond. This will ensure that the water does not reach the pond directly and as well keep the pond from collapsing during heavy rains

• The internal trenches will collect the water from the farm during the rains and send it to the border trench

• Can have bushes or plants between the internal trenches and the pond for safety purposes

Multiple Small Ponds

• Multiple ponds are created in the centre of the farm (either east-to-west direction or north-to-south direction)

• The ponds will not have any slope or bund as we are creating small ponds. You can use the Single Pond Design for Water Storage specifications if the soil is very loose or collapsing

• The pond can be of any desired depth but 5 Ft Depth pond is desirable if fishes are grown

• The pond should be east to west if fishes are grown

• The pond can be north to south if fishes are not considered as north to south direction will minimize evaporation

• The pond should be either rectangle or square

• Rectangular pond is preferred if the breadth of the farm is less or if the length of the farm is more

• Each pond will be separated by 10 Ft gap (or less depending on the soil type) or more as this will ensure the ponds don't collapse

• Even the gaps between the ponds can be used for planting crops like bananas etc

Water Flow Channel

• The water flow channel size should be similar to the internal trenches in size

• The water flow channel has to be from the border trench to the first pond

• The water flow channel has to be at least 1 Ft below the pond height

• There will be a water flow channel connecting each pond as well

• Once the first pond is filled, the next pond will get filled and so on