The Asian and Pacific region extends over a total area of about 35 million square kilometres, or 26 per cent of the world's land area. With nearly 60 per cent of the world's population and over 60 per cent of the total irrigated land, the region is more densely populated and more intensively cultivated than elsewhere. Although the countries of the region have experienced varying rates and patterns of economic development, the region, as a whole, has been the most dynamically developing part of the world with stable overall annual growth rates during the last two decades. This remarkably rapid expansion of many Asian economies accompanied by the population growth has not only raised the standards of living of the people in the region but has also created in its wake problems of sustainability of water resources development.

In recent years pressure has been growing on water resources in many countries of the region, with increasing demand from the domestic, industrial and agriculture sectors, as well as for the disposal of industrial effluent and sewage. Water use is increasing rapidly in most countries owing to the growth of population, the high pace of industrialization and slow but steady expansion of irrigated agriculture. Many countries have reached the end of an era when water was considered an unlimited resource and are entering another era when water is to be recognized as an economic commodity and must be used more rationally and protected from degradation. Moreover, a number of countries are already approaching a water crisis with serious seasonal water shortages, and heavily contaminated and depleted surface water and groundwater resources. Although most countries seem to have an ample total quantity of water resources to meet rising demands for water, adequate water may not be readily available in the place where it is needed or at the time of greatest demand. Therefore, the steadily growing demands of water are an issue of particular concern throughout the region.

The Guidebook on Water Resources, Use and Management in Asia and the Pacific, Volume One: Water Resources and Water Use is the first attempt of its type to present the available information on water resources and their uses in the countries and areas of Asia and the Pacific.