FARM POND AND Percolation POND BY agri studentsPPT.pptx

Soil and water consecration engineering

1. FARM POND AND PECOLATION POND SWE 112 SOIL AND WATER CONSERVATION ENGINEERING (1+1)

2. RAINWATER HARVESTING : Rainwater Harvesting is the main source to feed the demand of groundwater recharge or filling the surface water bodies. Rain water harvesting is defined as the method for inducing, collecting, storing and conserving local surface runoff for agriculture in arid and semi-arid regions. Major techniques of rainwater harvesting are: Groundwater recharge Surface runoff harvesting

3. GROUNDWATER RECHARGE : Groundwater recharge is a hydrologic process where water moves downward from surface water to groundwater. Recharge is the primary method through which water enters an aquifer. The aquifer also serves as a distribution system. The surplus rainwater can then be used to recharge groundwater aquifer through artificial recharge techniques. Rainwater in rural areas can be harvested through: • Gully Plug • Contour Bund • Dug well Recharge • Percolation Pond

4. SURFACE RUNOFF HARVESTING : In this method of rainwater harvesting away as surface runoff and can be stored for future use Surface water can be stored by diverting the flow of small creeks and streams into reservoirs on the surface or underground. It can provide water for farming, for cattle and also for general domestic use. Surface runoff harvesting is most suitable in urban areas. Rooftop rainwater/storm runoff can be harvested in urban areas through: • Recharge Pit • Recharge Trench • Tubewell • Recharge Well

5. SHORT TERM RUNOFF HARVESTING TECHNIQUES : Contour Bund Semicircular Hoop Trapezoidal Bund Graded Bund Rock Catchment Groundwater Catchment

6. LONG TERM RUN OFF HARVESTING TECHNIQUES :

7. FARM POND : Farm ponds are small tanks or reservoirs constructed for the purpose of storing water essentially from surface runoff. Farm ponds are useful for irrigation, water supply for the cattle, fish production etc.

8. OBJECTIVES : To provide water for life saving irrigation in a limited area. To provide drinking water for livestock and human beings in arid areas. To serves as water storage for providing critical irrigations to limited number of fruit crops for establishment purpose.  To moderate the hydrology of small watersheds.

9. Water spreading area ( sq.m ) Depth of water (m) Suitable uses 2000 to 10000 2.5 - 3.0 Irrigation, fisheries and drinking water 2000 to < 10000 1.5 – 2.5 Irrigation & drinking water < 2000 1.5-2.5 Pot irrigation for trees and drinking water Specifications : In the selected farm land the farm pond dimension of 8m x 8m x 1.5m can be constructed for the every 1 or 2 ha of land area.

10. 1 Bottom Area 20 m x 20 m 2 Top Area 35 m X 35 m 3 Depth 2.2 m 4 Cost of lining material (Rs) 85,000 5 Excavation (Rs) 20,000 6 Coir dust & spreading (Rs) 2,000 7 Spreading plastic lining and sheet welding (Rs) and with earth cover 27,000 8 Cost of inlet and outlet structures 66,000 9  Total cost (Rs)  2,00,000 AREA AND COST :

11. TYPES : EMBANKMENT TYPE FARM POND : Emba nkment type farm pond are generally constructed across the stream or water course. Such ponds consist of an earthen embarkments which dimension are fixed on the basis of the volume of water to be stored. These farm ponds are usually constructed in the area having gentle to moderately steep land slope.

12. DUGOUT TYPE FARM PONDS : Dugout type farm ponds are constructed by excavating the soil from the ground relatively flat areas. The depth of pond is decided on the basis of its desired capacity, which is obtained almost by excavation. These ponds preferred ,when small supply of water is required.

13. COMPONENTS : Storage area Earthen embankment Mechanical spillway Emergency spillway The mechanical spillway is used for letting out the excess water from the pond and also as an outlet for taking out the water for irrigation. The emergency spillway is to safeguard the earthen dam from overtopping when there are inflows higher than the designed values.

14. SITE SELECTION : From an economic point of view, a pond should be located at site where the largest storage volume can be obtained with le ast amount of earthwork. If ponds are constructed for the purpose of livestock storage the transportation distance of water will not be more than one quarter mile in rough area. Water can be conveyed for various uses such as for irrigation or protection very easily . Ponds to be used for fishing or other forms of recreation should be readily accessible by transportation facilities. For selecting the site, a check should also made to ensure that there is no buried pipe lines or cables at the construction Site.  

15. POND CAPCITY: The capacity of farm pond is determined with the help of the watershed area, contributing the runoff to the site of pond construction. Form the contour plan of the site, the capacity of pond is computed for different stages using area estimating formula. Generally trapezoidal rule and prismoid rules are used for determine the capacity of pond The Prismoidal rule gives more accurate value than the Trapezoidal rule . The area enclosed by each contour line is measured with the help of planimeter and by using Trapezoidal or Prismoidal rule is used to determine the capacity of farm pond.

16. PRISMODIAL RULE : V = D/3 { A1+An+4(A2+A4+…+An-1)+2(A3+A5+…+An-2)} Where D is common distance between sections,A1,A2,…An are the cross sectional areas. TRAPEZOIDAL RULE : V = D/2 {A1+An+2 ( A2+A3+…+An-1)}

17. USES : It collects excess runoff during rainy period. Stored water can be used for supplemental irrigation to crops. It is useful as drinking water for cattle’s during drought situation. It can be used for spraying pesticides. It conserves soil moisture. Bunds can be used to raise vegetables and fruits tress, thus supplying the farm household with an additional source of income and nutritious food. LIMITATIONS: Farm ponds reduce the water flow to neighbouring tanks and ponds situated in lower lying areas. Farm ponds occupy a large portion of farmers lands.    

18. PERCOLATION POND: Percolation ponds are small water harvesting structures artificially constructed across small natural streams and water courses to collect and impound the surface runoff during monsoon. Percolation ponds are small ponds located mostly in low lying areas of lands and formed in order to store the run-off of rainwater and to allow it to percolate downwards and sideways. Deep ponds are preferred since evaporation of the stored water therein will be less.  

19. BENEFITS : It replenish ground water during rainy season . It reduces velocity of water thereby reduce soil erosion. Reduces siltation in water tank, ponds and check dams. Floods can be avoided. Generates employment during dry period. Increased cultivable area. ce PONITS TO BE REMBEMBER : Area shouldn't be hard and rocky. Capacity of the ponds depends upon amount and frequency of water flow. In the downstream there should be farm lands and irrigation well. The depth should be atleast 1.5 m. Strengthen the bunds with soil .  

20. DIFFERENCE BETWEEN FARM POND AND PERCOLATION POND : Farm ponds are constructed on impermeable beds to harvest water. Farm pond surface is lined to arrest seepage loss. Farm pond is of dugout type and located within the farm. Catchment area is small and includes only cropped land. Stored water is used for irrigation or any other farm use. Percolation ponds are constructed on permeable beds to promote recharge of substrata. Percolation ponds are unlined. Percolation ponds are impounding type and located outside farm. Catchment area is large and includes both cropped and hilly area. PERCOLATION POND : FARM POND :

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