Criteria for a suitable irrigation method

The irrigation method must suit the site, crop, water and farmers. The principal criteria are:

1. Topography: slope and shape of the land. Flat land suits basin, border and check methods; moderate slopes suit furrows; steep or undulating land suits sprinkler or drip.
2. Soil: infiltration rate and water-holding capacity. Sandy soil suits sprinkler or drip; clay soil, with its low intake rate, suits basin or border methods.
3. Crop: rice suits basin/check; row crops suit furrows; orchards suit ring basin or drip; close-growing crops suit border or sprinkler.
4. Water availability and quality: scarce water needs high-efficiency methods (drip, sprinkler); saline water favours drip, or flooding with leaching.
5. Climate: wind and evaporation affect sprinklers; cold areas may need frost protection.
6. Economic factors: capital cost, energy, labour cost, land levelling and the market value of the crop.
7. Labour, skill and tradition: availability of skilled workers and farmers' acceptance.
8. Field size and shape: large regular fields suit mechanised surface methods and centre pivots.
9. Drainage and environment: drainage condition, salinity and erosion risk.
10. Water delivery system: whether water is available under pressure, by gravity or by lift.