4/4/2022 – 10/4/2022

Need of project:

Lowering losses by evaporation can reduced overall water consumption for agriculture. This is typically more important for rain shadow areas like Pabal. Vigyan Ashram experience severe water shortage and required water to be carried out by tanker. The experiment is to be carried out to estimate the impact of  Azolla and water Hyacinth on evaporation losses.


1.To find out the water evaporation rate at Pabal.

2.To control the evaporation of water in farm pond.

3.To study application of water Hyacinth and Azolla as biological method of evaporation reduction.

4. To study application of Cetyl alcohol and Stearyl alcohol as chemical method of evaporation reduction.

5. To compare between chemical and biological methods.

Trials to measure evaporation rate:

Fig: Placing of tray to measure evaporation loss

For rough estimation of evaporation losses, tray of size 38×27 cm and of depth 7 cm was taken. It was filled with water of quantity 5 litre. Then it was placed in the sun for 24 hours. After 24 hours the loss of water in tray was measured and it was 1 litre. The evaporation rate of water per hour is calculated as follows:

  • Initial quantity of water : 5 litre
  • Quantity of water after 24 hour : 4 litre
  • Loss in quantity of water for 24 hours : 1 litre
  • Loss in quantity of water for 1 hour = 1/24 = 0.04166 Litre/hr = 41.66 ml/hr
  • Surface area of tray = 38×27cm = 1026 cm2

It is seen that, for every 1026 cm2 area there was 41.66 ml water per hour is evaporated.

Next day, another one tray is placed on top of memorial hall for 24 hours with quantity of water 5 litre. After 24 hours loss of water was measured.

  • Initial quantity of water : 5 litre
  • Quantity of water after 24 hour : 3.540 litre
  • Loss in quantity of water for 24 hours : 1.460 litre
  • Loss in quantity of water for 1 hour = 1.460/24 = 0.06083 Litre/hr = 60.83 ml/hr
  • Surface area of tray = 38×27cm = 1026 cm2

It is seen that, for every 1026 cm2 area there was 60.83 ml water per hour is evaporated.

Fig. Tray placed on the top of memorial hall


Measurement of dimensions of farm pond:

Fig .Measurement of dimensions of farm pond

Following are dimensions of farm pond:

  • Length : 50 m
  • Breadth : 30 m
  • Depth : 15 ft

Surface area of farm pond = 50×30 = 1500m2

Volume of farm pond = 50×30×4.572 = 6858m3

11/04/2022 – 17/04/2022

Rough calculation of evaporation losses from the farm pond :

On the basis of above experiment, rough calculation of water losses through evaporation from the farm pond were done. It is as follows:

  • Water loss from tray of area 1026 cm2 per hour = 60.83 ml
  • Water loss from farm pond of area 1500m2 per hour = ?

Therefore,1026 cm2 = 60.83 ml

1500m2 = ?

= ( 15000000 cm2 × 60.83 ml)/1026 cm2

= 889327.4853 ml

= 889.327 litre / hour

And for 24 hours it is 889.327×24 = 21,343.859 litre

From above, it is seen that there is 21,343.859 water evaporate per day.

Measurement of dimensions of IBC’s tank:

Fig . Measurement of dimensions of tank

The dimensions of IBC’s tank were measured with the help of tape. After that, volume and surface area of tank’s were calculated. It is as follows:

  • Lenght = 114.3 cm
  • Breadth = 104.14 cm
  • Depth = 50.8 cm

Surface area of tank = 114.3 × 104.14

= 11,903.202 cm2 = 1.19 m2

Volume = 114.3 × 104.14 × 50.8

= 6,04,682.6616 cm3 = 604.683 litre

Chemicals used for the experiment:

  1. Cetyl alcohol
  2. Stearyl alcohol

Hexadecanol or Cetyl alcohol and Octadecanol or stearyl alcohol or a mixture of these two chemicals is commonly used for suppressing evaporation from lakes and reservoirs. Mixture of Cetyl and Stearyl alcohols may be used for suppressing evaporation from lakes and reservoirs by spraying on water surface so as to cover the entire surface with this film. The chemical can be used in solution, in powder form or as an emulsion. Spraying in powder form is the simplest and most widely used process. A dose of 1.2 kg/hectare/day is adequate for wind velocities below 8 kmph.

Plants selected for the experiment:

Azolla: Azolla is used to reduce evaporation from water bodies such as natural and artificial ponds and lakes. Ponds in which azolla covers the entire surface, and from which azolla slowly harvested, maintain a clean, fresh water source that is better for irrigation. Due to the azolla cover, some ponds maintain water all year, in contrast to ponds without azolla that often lose all of their water due to evaporation.

Hyacinth : Hyacinth will also used to reduce evaporation of water from farm pond. Water Hyacinth can absorb minerals and inorganic substance from the sewage. It can be grown rapidly in every kinds of condition. As a result, after using it to clean the sewage, it is brought to use as organic fertilizer like compost or mulching.

Fig. Selected plants for experiment

Welding to tanks:

The tank was well packed by metal rods welded together to it’s 3 sides only. If the tank is fill with water, there are chances of buckling of it .Hence, to prevent it from buckling, welding to the empty side is done.

Fig . Tank of the experiment

18/04/2022 – 24/04/2022

Filling of tanks with water:

After installation of tanks, they are filled with water. Water was filled in the tank upto height 17 cm. Marking to the depth of 17 cm was done with the help of measuring tape. Total 202 litre water is required to fill the tank upto depth 17 cm. After that, readings were taken after 24 hours. Following are the readings and calculations of the experiment.

20/04/2022 – 21/04/2022

Tank A ( Contain only water)

Tank B ( Contain only water)


  • Depth of water in tank A (Initial height) =17 cm
  • Depth of water in tank B (Initial height)=17 cm
  • Depth of water after 24 hours in both A and B tank (Final height)=16 cm


Loss in water :

Lenght of tank × breadth of tank × fall in depth of tank

= 114.3 ×104.14 × 1

= 11,903.202 cm3

= 11.903.202/1000

= 11.90 litre per day

= 11.90 / 24

= 0.495 lit / hr = 495 ml/hr

21/04/2022 – 22/04/2022

Spreading of Azolla :

Fig . Azolla spreading on water

To check the effect of azolla on evaporation of water azolla was spread on the water. About 1 kg of Azolla is required to spread it on water. After spreading it water is filled in the tank upto 17 cm and readings were taken after 24 hour. Following are the observation and readings :


Tank A ( Contains water only)= 17 cm

Tank B ( contains water + azolla) =17 cm

Depth of water after 24 hours in tank A = 15.6 cm

Depth of water after 24 hours in tank B = 15.7 cm


Loss of water in tank A –

= 114.3 × 104.14 × 1.4

= 16,664.48 cm3

=16,664.48 / 1000

= 16.66 litre per day

= 16.66/24 = 694 ml/hr

Loss of water in tank B –

= 114.3 × 104.14 × 1.5

= 17,854.80 cm3

= 17,854.80 / 1000

= 17.85 litre per day

= 17.85 / 24 = 743 ml/hr

26/04/2022 – 27/04/2022

Spreading of mixure of alcohols on the water surface:

The mixure of cetyl alcohol and stearyl alcohol is spread on the water in the ratio 1:1 to check it’s effect on water evaporation. For the prepartion of mixure cetyl alcohol and stearyl alcohol both are taken in same quantities i.e 94.5 mg for the area of 1.19 m2.


Spreading of Hyacinth on water surface:

To check the effect of Hyacinth on evaporation of water Hyacinth was spread on the water surface.After spreading it, water is filled in the tank upto 17 cm and readings were taken after 24 hour.

Fig . Hyacinth spread on the water surface
Dateloss of water in tank A per day ( contains water only)loss of water in tank B per day(Contains water+ azolla)loss of water in tank C per day (contains water+ mixture of cetyl and stearyl alcohol)loss of water in tank Dper day (Contains water+ Hyacinth)loss of water in tank E per day (water+ mixture of cetyl and stearyl alcohol+ azolla)
30\04\2022- 1\05\202211.909.525.95
Table Name – Loss of water per day ( liters)
Fig no. Experimental set up of evaporation losses

Get these readings ,there will be some environmental and physical noises. The environmental noises like rainfall, weather condition and physical noises such as animal disturbances.  Therefore, we changed the location of setup and the tanks were shifted on the terrace of memorial hall.

DateLoss of water in Tank per day A(Contains water only) (liters) Loss of water in Tank B per day (Contains water + azolla) (liters) Loss of water in Tank C per day ( contains water + mixure of cetyl and stearyl alcohol) (litres) Loss of water in tank D per day ( Contains water + Hyacinth) (liters)Loss of water in tank E per day ( contains water + Azolla + Chemical ) (liters)
Average loss per day11.638.617.612.7436.29
Table: Loss of water per day

Cost of water:

In summer days, the water is provided by tankers in Vigyan Ashram. The cost of 1 tanker containing 14,000 liter water is 1800 ₹.

Therefore, for 1 liter it is 0.12 ₹. From these data, following calculations were done.

TankA (Water)B (Water+ Azolla)C (Water + mixture of chemicals)D ( Water+Hyacinth)E (Water+Hyacinth+ mixture of chemicals)
Average loss of water per day (liters )11.638.617.612.76.29
Loss of water for 30 days (liters) for area 1.19m2348.9258.3228382.2188.7
Loss of water for 30 days (liters) for area 1500 m24,39,7893,25,5882,87,3944,81,7642,37,857
% of water saved with respect to control26 %35 %– 9%46 %
Cost for evaporated water (₹)52,77439,07034,48757,81128,542
cost for saved water with compared to control (₹)13.70418,287-5,03724,230


  • It is seen that, from all the above trials, the trial of Azolla+ Mixture of chemicals showed better results than other trials. The rate of reduction of evaporation losses by this trial is 46%.
  • It is followed by the trials of mixture of chemicals. The rate of reduction of evaporation losses by only chemicals is 35%. These is because the chemicals are capable of farming a thin molecular film which has been found to be effective for reducing evaporation losses from water surface.
  • The rate of reduction of evaporation losses by floating Azolla is 26%. Though some water was lost in the form of evapotranspiration there is an additional benefit as the azolla can be incorporated in the soil as nitrogen supplement or as the feed for the livestock.
  • It is seen that, Water hyacinth took more water and the rate of evaporation is more than control , also it has no additional benefits to farmers as compared to Azolla. Therefore, use of hyacinth to control evaporation losses is not very effective.

For the farm pond of area 1500 m2, the required quantity of azolla and chemicals are as follows:

Quantity of Azolla:

1.19m2 = 1 kg

1500 m2 =1260 kg

Quantity of chemicals: ( Mixture of both Cetyl alcohol and chemical alcohol in the ratio 1:1)

1.19m2 = 0.189 gm

1500 m2 = 238.23 gm/ day

Cost and Profit analysis:

If we add 1260 kg Azolla at a time and 238.23 gm mixtures of chemicals, we need to invest some Rs. The material required and their price is listed here.

Material requirements Investment(₹)
Azolla@1260 kg
Price – ₹2/ kg
Chemicals 952.92 gm/ month
Price – ₹ 708/kg/chemical
Labor charges
₹ 250/day / man
Total investment18,194.64
Table no. Cost Analysis

【Note: The values can be taken as a reference only because there may be a slight deviation in the original set up cost. The cost of the land, transport, electricity, etc. have not been included in this estimation, but have to be considered while implementing the structure.

In a month, the azolla will be harvested at 5 times. In that manner,we will get, 1260 kg azolla each time. Therefore, monthly income = 1260×2×5 = ₹ 12,600 If we subtracted all the initial investment from monthly income we will get loss of ₹ 5.594. But as compared to control, ₹ 24,332 can be saved by application of Azolla + Chemicals.

=24,332 – 5,494 = ₹18,638. We can save water of ₹ 18,638. Amount of water that can be saved by reducing evaporation losses using Azolla+ Mixture of chemical is 1,40, 000 liters and it is equal to 10 tankers. In April months Ashram needed 8-10 tanker for daily purpose. In future, these need of water can be fulfilled by saving water using azolla and chemicals.