all the countries of the Middle East. In order to master the complex problem of water scarcity there will need to be regional cooperation and assistance.

Iran, with an area of 165 million hectares (Mha), is located in a semiarid region of the Middle East. Distribution of precipitation is uneven. The average amount of precipitation over the country is 252 mm/year, which is less than one-third of the world average. While annual precipitation usually exceeds 2,000 mm in some of the northern parts of the country, it may be less than 20 mm in desert areas. Although water surpluses exist in the mountain regions, the areas of high population concentration and high water demand are hundreds of miles away.

Population growth in Iran is high. The highest recorded rate of 3.9 percent occurred in 1986. But a remarkable achievement of Iran in applying family planning programs during the years of 1986-1996 contributed to a lower rate of population growth of 1.45 percent in that decade (Ghazi, 2002). The latest census figures showed the population of Iran to be 60 million in 1996. Today, it is estimated that the population of the country may be more than 65 million. It is also expected that the population may double by 2021 (Plan and Budget Organization, 1999). Rapid population growth in the last two decades has changed the relative composition of the rural and urban populations. While the ratio of rural to urban population was 40/60 before the revolution, it is now reversed. By 2010 some 80 percent of the total population may live in urban areas and especially in big cities like Tehran, Mashhad, and Isfahan. Most of the water resources that sometime ago were used for agriculture are now used to supply drinking water to these cities. Altogether, population growth, urban and industrial growth, and agricultural development in Iran have created a condition of water stress. This situation is beyond a water shortage or crisis and aggregates the serious scientific, technical, ecological, economic, and social issues surrounding water for now and the years to come (Ghazi, 2002).

Available data for Iran’s freshwater resources are presented in Table 1. As is seen in this table, the average renewable water in Iran is 130 billion cubic meters only. However, since the hydrologists have been involved in measuring rainfall and river flow at catchment scales, these data may not give a complete and accurate image of water availability unless data are also measured at other scales.

The level of water stress depends upon technical scarcity, demographic scarcity, and hydraulic density of population (Falkenmark, 1999). Given the high population increase and recent persistent drought conditions, Iran’s average annual supply of renewable freshwater per person fell from 2,254 m³ in 1988 to 1,950 in 1994, and the estimated figures for the years 2005 and 2020 are 1,750