The Arabian Gulf is a shallow semi-enclosed sea between the Arabian Peninsula and
Iran. It is bordered by Oman and the United Arab Emirates on the south, Qatar, Bahrain and Saudi Arabia on the west, Kuwait and Iraq on the north and Iran along the entire east coast. The Arabian Gulf is separated from the Gulf of Oman and the open ocean through the Strait of Hormuz, where the narrowest point is only 56 km wide. From the Strait of
Hormuz, the Gulf stretches northwest to Shatt Al Arab of Iraq over a distance of approximately 1000 km, its width ranging between 200 and 300 km. The western coast of the Gulf is bounded by vast desert plains, the northern coast by the river delta of Shatt al Arab and the eastern coast by extensive mountain ranges of Iran. The Gulf sits on top of the largest hydrocarbon reserve in the world, which makes this area extremely important for oil production and one of the most important strategic waterways in the world.
Surface area 260,000 km
Volume 9,100 km
Average depth 35 m
Maximum depth > 100 m
Since the Gulf region is surrounded by arid land masses, it has high seasonal and daily air temperature fluctuations. Air temperature can drop to 0°C in winter and reach up to 50°C in summer. The average air temperature in January is around 16°C and in July around
35°C. In the Gulf there are four types of wind prevail in year. These include the most common the Shamal (North); the Kaus (South-east); the sea breezes of coastal areas; and the Monsoon. Dust and sand storm are among the most important weather phenomena in
Kuwait, southern Iraq and Iran. Dust storm can deposit up to 1,002.7t/km2 of sediment in the inner Gulf in the month of July alone. The dust storm passing over the northern part of the Gulf are a major source of marine sediments.
The amount of precipitation in the region varies greatly, but the general trend is decreasing precipitation as one goes from north to south, it varies from 48mm in Doha, Qatar to 275mm in Bushehr, Iran. The average precipitation in the Gulf over a period of
17 years has been calculated at about 78mm/yr, which correspond to 1.9 x 1010 m3/yr.
Evaporation from open water of the Gulf has been estimated at 144cm/yr. Maximum and minimum mean monthly evaporation from the coastal and the central regions of the Gulf have been estimated at 29.3cm in June and 8.1cm in February, respectively.
The bottom topography of the Gulf is mostly flat and featureless, dominated by soft sediments. It is generally deeper in the southeast, where depths of over 100 m are found, and is deepest near the opening of the Strait of Hormuz. The western part of the Gulf is very shallow, with extensive intertidal areas that are less than 5 m deep and up to 5 km wide. The dominant water circulation pattern in the Gulf is counter-clockwise and driven by density gradients. Water of normal oceanic salinity enters the Gulf through the surface waters of the Strait of Hormuz, moves northwards along the Iranian coast, turns southward along the western coast and exits along the bottom of the Strait as dense
hypersaline water. This process takes between 1 and 3 years.
The major freshwater inflow (1,456 m3/s) into the Gulf comes from the Shatt Al Arab, which is a combination of the Euphrates, Tigris and Karuan Rivers. Despite its large inflow rate, salinity is high in the Gulf due to low precipitation and high evaporation, and can reach up to (60 – 70 part per thousand) in some regions with limited water exchange.
Water temperatures in the Gulf show high seasonal fluctuations. For example, the water temperature in the northwestern region can reach up to 35°C in summer and drop to 15°C in winter. Also, a unique temperature environment exists in the southern region, where
southwestern monsoon winds (June September) generate upwelling along the western coast. The surface water temperature during this period can drop to between 16°C and
A series of islands extending along the western coast have fringing and patch coral reefs, representing one of the most diverse habitats of the Gulf. Their presence in the Gulf is a unique example of the adaptation of marine organisms in such extreme environmental conditions. Productive seagrass beds are found along the coast of Bahrain and Qatar.
Some mangrove vegetation (approximately 90 km) occurs along the southern coast of
Iran. Despite the extreme environmental conditions, a wide variety of marine life is found in the Gulf, including sea turtles, marine birds, dugongs, whales, dolphins and over 500 fish species. Many of these animals are endemic and heavily dependent on the Gulf environment. Some beaches are important sea-turtle nesting grounds, while the offshore islands are breeding grounds for many seabirds, and the intertidal and shallow subtidal zones are important feeding grounds for migrating birds. Also the Gulf region is estimated to support over 7,000 dugongs, which makes the area second only to Australia in global importance for this species. The Qarnein Island has recently been declared a marine protected area by the United Arab Emirates (UAE) Government. This is the first protected marine area in the Gulf. The island has a mixture of sand, rocks and corals around its shores, providing three types of shallow marine environments. The endangered green and hawksbill turtles nest on the beaches, and the island is also recognized as the most important breeding ground in the Gulf for various seabirds.
Approximately 15 million people live and work along the Gulf’s highly developed coastline. For the past three decades, the Gulf region has experienced one of the world’s highest rates of economic growth, which is mainly due to the exploitation of abundant oil and gas reserves. Other major industries in the region include manufacturing (fertilizers, chemicals, petrochemicals, minerals, plastic), oil refineries, agriculture (dates) and fisheries. By far the most important and biggest industry in the region is oil production, with over 76 billion metric tons of recoverable oil and 32.4 trillion cubic meters of reserve gas in the region. About 25,000 tankers sail in and out of the Strait of Hormuz annually and transport about 60 per cent of all the oil carried by ships throughout the world. There are about 800 offshore oil and gas platforms and 25 major oil terminals in the region. Saudi Arabia produces almost half of the net oil export in the region.
Gas production is also an important and developing industry in the Gulf, especially for
Iran and Qatar, holding the world’s second and third-largest gas reserves (behind Russia), respectively. The fishing industry in the Persian Gulf has been important since ancient times, but the per capita fish catch has been slowly decreasing. The decline is due to adverse climatic and ecological conditions and unsustainable fishing practices. Major target species include shrimp, Spanish mackerel and various percid fishes, but the abundances of these species are declining. Although pearl fisheries in the Gulf were famous in the past, they now operate at a fraction of the level of former times.
The greatest threat to the marine environment of the Arabian Gulf is oil pollution. Large numbers of offshore installations, tanker terminals, petrochemical plants and oil tankers operate in the Gulf. These operations spill vast amounts of oil and waste into the Gulf waters, causing considerable damage to water quality, habitats (mangroves, coral reefs, beaches) and marine resources. Another major source of pollution comes from land-based activities, as the Gulf region has experienced a rapid rise in industrialization, population growth and urbanization. Major land-based sources of pollution include industrial effluents, coastal development (dredging and landfilling), sewage discharge and the disposal of solid waste.
Oil spills from oil tankers and oil-related industries have contributed extensively to the deterioration of the environment. Approximately 25,000 oil tankers navigate in and out of the Strait of Hormuz every year, and with all this oil being pumped and transported, the area’s waters have become heavily contaminated with oil residues and tar balls. Roughly
2 million barrels of oil are spilled into the region every year from the routine discharge of dirty ballast waters and from the 800 or so offshore oil and gas platforms. The illegal discharge of crude and fuel oil by tankers has also been a major source of pollution.
In addition to the routine discharges, an estimated 2 to 4 million barrels of oil were spilled into the Gulf during the Iran/Iraq war and a total of 6 to 8 million barrels were intentionally spilled into the Gulf and the Arabian Sea during the Gulf War. The oil spill during the Gulf War is the largest spill recorded in human history; over 700 km of coastline from southern Kuwait to Abu Ali Island were smothered by oil and tar, killing many seabirds, sea turtles and other marine life. Although habitats such as rocky shores, sandy beaches and mangroves have shown dramatic recovery, widely distributed salt marshes are still heavily polluted and will take decades to fully recover.
Millions of tons of industrial effluents are dumped into the Gulf shallow waters every year, with little or no treatment. As a result, high concentrations of heavy metals occur in some areas. For example, high levels of lead, cadmium and zinc were found in oysters, and the sediment contained high levels of cadmium, nickel and chromium in some regions. Also, eutrophication is common in some industrialized areas, where dense mats of filamentous green algae are observed and indicate high nutrient levels.
Since the 1950’s, the Arabian Gulf region has become more reliant on desalination plants for freshwater supply. However, thermal pollution, waste brine and pre- and post-treatment chemicals pose a serious threat to the marine environment. Despite these problems, reliance on desalination plants is predicted to increase.
The shallow coastal areas of the Gulf are being used as repositories for industrial, commercial and residential solid waste, including plastics, metal containers, wood, tyres, scrapped vehicles and oil sludge. Oil sludge represents 15% of the total industrial solid waste, and some of the sludge is inadequately contained.
To accommodate the expanding industries and increasing population, large areas of important and biologically productive coastal habitats, such as intertidal flats, mangrove forests and shallow embayments have been altered or lost. By the early 1990’s, some countries had developed more than 40% of their coastline, and significant proportions of the shoreline of Kuwait and Bahrain are now artificial.
1. SOMER (2003) State of the Marine Environment Report, ROPME/GC-11/003,
Regional Organization for the Protection of the Environment, Kuwait, 217 pp.
2. UNEP. Overview on Land-based Sources and Activities Affecting the Marine
Environment in the ROPME Sea Area. UNEP/GPA Coordination Office &
ROPME (1999). 127pp.
3. UNEP, 2002. Global Environmental Outlook 3. United Nations Environment
Programme. London and NewYork, Earthscan.
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