Introduction

Abstract

During the last four decades, irrigated agriculture has provided the major share of the increase in world crop production with 36% of the total crop production coming from less than 15% of the arable land that was irrigated. The annual expansion of irrigated land which made this positive development possible, increased by 1% in the early 1960s, and reached its maximum of 2.3% per year between 1972 and 1975; the rate then began to decline in the mid-1970s. According to World Bank/ICID statistics, the irrigated area expanded from 1953 to 1970 by about 5 million ha per year; from 1970 to the early 1980s the rate still averaged about 4 million ha/year. Then, however, the rate of expansion declined and, since the early 1980s, has reached not more than 2 million ha per year.²