AFFORESTATION OF DRY AREAS WITH IRRIGATION:
GENERAL: IMPORTANCE OF WATER
- Common chemical substance: H2O.
- Found in all three states simultaneously: solid, liquid and gaseous.
- Collective mass of water on the planet is called Hydrosphere.
- Covers about 71% of the Earth’s surface.
- Total mass is 1021 kg.
- Total volume: 1.36 billion km3.
- 3% is usable.
- Glaciers, polar ice caps, rivers, lakes & ponds.
- Water moves continually in a cycle: Hydrology Cycle.
- 70% of fresh water is consumed by agriculture.
- Covers more than two-thirds of earth’s surface.
- Makes up 50-90% of the weight of living things.
- Constitutes 75% of the human body.
- More than 80% of human brain consists of water.
- Water regulates all the functions & activities of living things.
- Aids in metabolic processes.
- Industry, agriculture, and forestry totally depend upon water.
- Every field of life cannot exist without water.
- Water can alter human cultures and civilizations.
“Irrigation is an artificial application of water to the soil usually for assisting in growing crops”.
- Grow crops with a minimum amount of water required.
- Supplement water/rainfall shortfalls.
History of Irrigation:
- Evidence of irrigation in Egypt in 6th B.C.
- Archaeological evidence of irrigation dates back to 6th millennium B.C in Egypt to grow Barley.
- First water gauge was discovered in Korea I 1441 A.C.
- Pakistan has one of the world’s largest irrigation systems.
- Irrigation water is a very precious commodity now.
- Its conservation & economical use for optimum utilization is a matter of great importance.
- We have to incorporate methods to conserve it & not overuse it.
TYPES OF IRRIGATION
- Surface Irrigation.
- Localized irrigation.
IRRIGATION IN IRRIGATED PLANTATIONS
Surface Irrigation has Two Types:
- Flood Irrigation.
- Flow/Trench Irrigation.
Flow irrigation is very economical than flood irrigation.
- Simple, low-tech.
- Gravity feed.
- Plots of 0.5 or 1 Ac.
- Very low running cost.
- Easy to operate.
- No high skills are required.
- No mechanical or pumping equipment is required.
- Easy maintenance of water channels.
- Flush out salts.
- 50% of water evaporates.
- Flooding causes anaerobic conditions resulting in de-nitrification.
- A highly leveled field is required.
- Reduction in capillary oxygen.
- Can cause run-off & erosion.
- Main, Khal, Passel, Trench System
- Usual spacing: 10’.
- Better utilization of water.
- Species raised: Dalbergia sissoo, Bombax ceiba,
Acacia nilotica, Eucalyptus spp.
Trench Irrigation on 20 Acres under Green Pakistan Programme | Usta Muhammad Jaffarabad | February 22, 2018 | Video by Author
- Reduces loss of water.
- Increases efficient use of water.
- Less weed growth.
- No run-off and erosion.
- Tail-water losses.
- Movement of equipment.
- Fair leveling.
- Volatile irrigation pattern.
- Re-opening is required.
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