Global Water Resources and Agricultural Use

Abstract

With the world’s population growing from 1.6 billion to more than 5 billion in the twentieth century, agricultural use of water has progressively increased to meet the growing demands for food and fiber. About 17%, or 250 million ha of the world’s cropland is irrigated today (Postel 1989). In some countries, more than half of the domestic food production relies on irrigated agriculture. Development of new irrigation projects in the past two decades have markedly slowed down. The factors contributing to this slowdown include: (1) a general economic demise, with fewer investments made in agriculture and water development; (2) increase in competition for scarce water resources from other sectors of society; (3) rising costs of developing new supplies; and (4) potentially detrimental off-site environmental and ecological effects from irrigated agriculture, such as wildlife toxicity from the discharge of agricultural drainage waters into the Kesterson National Wildlife Refuge in California’s San Joaquin Valley (NRC 1989), and the desiccation of the Aral Sea and the accompanying ecological, environmental, and public health impacts in the Commonwealth of Independent State’s central Asian plains (Micklin 1991).