Topography: Iraq has four main topographical regions. The desert zone of Iraq’s west and southwest is part of the Syrian Desert, dominated by wide, flat, sandy expanses. The uplands region occupies most of Iraq’s northern part, beginning about 120 kilometers north of Baghdad and including the watersheds of the Tigris and Euphrates rivers to the Syrian border. Primarily desert, the region is characterized by deep river valleys. The third region is the northern highlands, which includes all of Iraq’s northeasternmost territory and extends into neighboring Turkey and Iran. A series of elevation rises, interspersed with steppes, gives way to mountains as high as 4,000 meters near the Iranian and Turkish borders. The fourth region is the alluvial plain that extends from north of Baghdad southward to the Persian Gulf, following the lower Tigris and Euphrates rivers. The area, which is a large delta, includes lakes and marshlands. The extent of marshland in the alluvial plain varies according to the volume of water carried by the rivers in flood season. In their lower reaches, the two rivers break into several channels.
Principal Rivers: The Tigris and Euphrates, which rise in Turkey, form the dominant river system of Iraq. About 150 kilometers north of the Persian Gulf, the rivers join at Al Qurnah to form the Shatt al Arab, which then flows into the gulf. Several major tributaries of the Tigris flow through Iraq. The Khabur, the Great Zab, the Little Zab, the Uzaym, and the Diyala all flow into the Tigris from the northeastern highlands.
Climate: Most of Iraq has a desert climate, with mild winters and dry, hot summers. The northeastern uplands have cold winters with occasionally heavy snowfalls. In the western desert and the northeastern foothills, average winter temperatures range from a low of 0° C to a high of 15° C, and average summer temperatures range from a low of 22° C to a high of 38° C. In the alluvial plain, the winter range is 4° C to 17° C, and the summer range is 29° C to 43° C. About 90 percent of Iraq’s rainfall occurs between November and April. Except in the northern uplands and the northeastern highlands, average annual rainfall is 100 to 170 millimeters. In the uplands, the range is 320 to 570 millimeters, and in the mountains the annual total may reach 1,000 millimeters.
Natural Resources: Iraq’s arable land has been rich and productive, particularly in the lower alluvial plain. The substantial amounts of arable land in the northwestern uplands region require irrigation. Because of its river systems, Iraq has the most abundant water reserves in its region. Hydrocarbons are Iraq’s most important natural resource. Depending on the estimate, Iraq has the second or third largest oil deposits in the world. Confirmed reserves total 112.5 billion barrels. Natural gas deposits are estimated at 3.1 trillion cubic meters, about 2 percent of total world reserves. Other mineral resources include phosphates, estimated to total 10 billion tons, and sulfur deposits located near Mosul.
Land Use: About 13 percent of Iraq’s land surface is classified as arable; some 0.78 percent of the total land is planted to permanent crops. In 1998 some 35,250 square kilometers of cropland were irrigated.
Environmental Factors: Events of 1980–2005 have created environmental crises of emergency proportions. Military operations in three wars (1980–88, 1991, and 2003 to present) have left unexploded ordnance and land mines in exposed positions, killing or wounding an estimated 100,000 people in the early 2000s. Because of infrastructure damage, significant parts of the population do not have adequate water supply or sanitation systems, and sites where municipal and medical wastes have accumulated carry the risk of disease epidemics. The wartime destruction of military and industrial infrastructure has released heavy metals and other hazardous substances into the air, soil, and groundwater. Numerous spills have resulted from damage to Iraq’s oil infrastructure, and the lack of water treatment facilities at Iraqi refineries has led to pollution from those installations. In the alluvial plain, soil quality has been damaged by the deposit of large amounts of salts, borne by irrigation overflows and wind and promoted by poor soil drainage. Desertification and erosion also have reduced arable land. Transboundary pollution and a lack of river basin management by the government have led to the degradation of Iraq's major waterways. Under Saddam Husayn, the government drained the extensive marshes in the lower reaches of the alluvial plain, changing water circulation and wildlife patterns over a wide area; beginning in 2004, some restoration has occurred. Flooding danger in the alluvial plain has decreased since construction of dams upstream on the Euphrates. Although the interim government appointed in 2004 included a Ministry of Environment, long-term environmental crises such as the depletion of marshland in the Shatt al Arab have a low priority.
Time Zone: Iraq’s one time zone is three hours ahead of Greenwich Mean Time.