Method of Water Harvesting
Method of Water Harvesting
There are three methods of Harvesting
Inter plot water harvesting
- In this method, harvested water is directed to the crop. This method is suitable for areas where rainfall is scanty (< 500 mm) and even if there is difficulty in maturing a single crop. In this technique, a portion of the area is cultivated & the remaining area is used for harvesting water. Usually, the uncultivated area is compacted or treated in such a way that runoff would be induced. Surface modification may be required to get runoff. Such a method is suitable for arid regions. Runoff may be induced by using cover films (plastic or rubber) preparing a hydrophobic layer (wax) compacting the surface or spreading sodic soil on the surface.
Interrow water harvesting
- There may not be enough rain to support a crop in some areas & therefore conserving more water in furrows and planting the crop in furrows may give some yields.
Water harvesting in farm Ponds
- A portion of the excess runoff water next allowing the maximum in situ moisture conservation is collected on farm ponds. As far as possible the pond should be located in the lower patches of the field to facilitate better storage and fewer seepage losses. The size of the farm pond should be worked out considering the annual rainfall of probable runoff and the catchment area. Generally, 10 to 20 per cent of the seasonal rainfall is considered as runoff in medium and deep black soils. A farm pond of 150 m3 capacity with side slopes of 1.5: 1 is sufficient for each hectare of catchment area in black soils. The farm ponds may be circular squared or rectangular. However, eared or rectangular ponds are more convenient for the harvesting of runoff water.
Cost of water harvesting
- Typically, installing a water harvesting system in the building would cost sites Rs 2,500 to 38,000 for the building of about 320 sq.m. The cost estimate mentioned above is for an existing building.
- Some basic rates of construction activities in materials have seen given here, which have helped to calculate the total cost of structures.
|1) Excavation in soils||cu. m.||90.00|
|2) Excavation in rock||cu. m.||150.00|
|3) Brickwork with cement mortar (1:6)||cu. m.||1400.00|
|4) Plain cement concrete (1:3:6)||cu. m.||1500.00|
|5) Reinforced cement concrete (1:2:4) including steel bars, shuttering etc.||cu. m.||4700.00|
|6) PVC piping for rainwater pipes – 110 mm in diameter – 200 mm in diameter||Metre Metre||165.00 275.00|
|7) Making borehole in metre 165.00Soft soil (with 150 mm diameter PVC casing)||Metre||180.00|
|The capacity of the rooftop water harvesting system in litres|
|Total cost in rupees||12,430||12,975||13,970||14,380||15,800|