Since humans
abandoned their hunter gatherer methods and adopted agriculture to provide their
food for them, agriculture has followed a path of ever increasing
intensification. The use of natural and then later artificial fertilizers has
lead to increased growth rates, higher density of crops, and subsequently higher
water use per given area. To meet the demand for water as far back as 256BC
large scale irrigation projects such as the Dujiangyan Irrigation System, China
B
Now thousands of years later we are entrenched in a system
whereby the amounts of food needed to support the human race would be impossible
to produce without irrigation, and in many places the water supplies that have
been taken for granted can no longer keep up with demand. As the world
population more than tripled in the twentieth century, water use for human
purposes grew six fold, with the bulk of that water going to irrigationI.
Southwest
Environmental Limited