Irrigation

Irrigation is the artificial application of water to land for the purpose of supplying moisture essential for plant growth. Although irrigation is an old art, its importance has increased in recent times with the increased demand for food to meet the needs of a growing population. Today, irrigation accounts for 70 percent of all water used by humans. Although irrigation works are found almost everywhere, they are most important in arid and semiarid regions, where the quantity and timing of rainfall are not inadequate for crops. For instance, in those parts of Asia where rainfall is seasonal, and most precipitation occurs in three to four months of the year, irrigation is highly critical to agriculture.

The importance of irrigation is evident from the fact that, historically, ...