Red Sea

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The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez (leading to the Suez Canal).

Occupying a part of the Great Rift Valley, the Red Sea has a surface area of roughly 438,000 km² (169,100 square miles ).[1]It is about 2250 km (1398 miles) long and, at its widest point, is 355 km (220.6 miles) wide. It has a maximum depth of 2211 metres (7254 feet) in the central median trench, and an average depth of 490 metres (1,608 feet). However, there are also extensive shallow shelves, noted for their marine life and corals. The sea is the habitat of over 1,000 invertebrate species, and 200 soft and hard corals. It is the world's northernmost tropical sea.


Contents

Origins of the Name Red Sea

Tihama on the Red Sea near Khaukha, Yemen

Red Sea is a direct translation of the Greek Erythra Thalassa and Latin Mare Rubrum (alternatively Sinus Arabicus, literally "Arabian Gulf"), Arabic (البحر الأحمر), Somali Bada Cas and Tigrinya

The name of the sea may signify the seasonal blooms of the red-coloured Trichodesmium erythraeum near the water's surface.[2]


The association of the Red Sea with the Biblical account of the Israelite Crossing the Red Sea is ancient, and was made explicit in the Septuagint translation of the Book of Exodus from Hebrew to Koine Greek in approximately the third century B.C. In that version, the Hebrew Yam Suph (ים סוף) is translated as Erythra Thalassa (Red Sea). (See also the more recent suggestion that the Yam Suph of the Exodus refers to a Sea of Reeds).

The Red Sea is one of four seas named in English after common color terms — the others being the Black Sea, the White Sea and the Yellow Sea.

The direct rendition of the Greek Erythra thalassa in Latin as Mare Erythraeum refers to the north-western part of the Indian Ocean, and also to a region on Mars.

History of the Red Sea

The Biblical Book of Exodus tells the story of the Israelites' miraculous crossing of a body of water, which the Hebrew text calls Yam Suph. Yam Suph is traditionally identified as the Red Sea. The account is part of the Israelites' escape from slavery in Egypt. Yam Suph can also been translated as Sea of Reeds.

In the 6th century BC, Darius the Great of Persia sent reconnaissance missions to the Red Sea, improving and extending navigation by locating many hazardous rocks and currents. A canal was built between the Nile and the northern end of the Red Sea at Suez. In the late 4th century BC, Alexander the Great sent Greek naval expeditions down the Red Sea to the Indian Ocean. Greek navigators continued to explore and compile data on the Red Sea. Agatharchides collected information about the sea in the 2nd century BC. The Periplus of the Erythraean Sea, written sometime around the 1st century AD, contain a detailed description of the Red Sea's ports and sea routes. The Periplus also describes how Hippalus first discovered the direct route from the Red Sea to India.

The Red Sea was favored for Roman trade with India starting with the reign of Augustus, when the Roman Empire gained control over the Mediterranean, Egypt, and the northern Red Sea. The route had been used by previous states but grew in the volume of traffic under the Romans. From Indian ports goods from China were introduced to the Roman world. Contact between Rome and China depended on the Red Sea, but the route was broken by the Aksumite Empire around the 3rd century AD.

During the Middle Ages, the Red Sea was an important part of the Spice trade route. In 1513, trying to secure that channel to Portugal, Afonso de Albuquerque laid siege to Aden.< but was forced to retreat. They cruised the Red Sea inside the Bab al-Mandab, as the first European fleet to have sailed this waters.

In 1798, France ordered General Bonaparte to invade Egypt and take control of the Red Sea. Although he failed in his mission, the engineer J.B. Lepere, who took part in it, revitalised the plan for a canal which had been envisaged during the reign of the Pharaohs. Several canals were built in ancient times from the Nile to the Red Sea along or near the line of the present Sweet Water Canal, but none lasted for long. The Suez Canal was opened in November 1869. At the time, the British, French, and Italians shared the trading posts. The posts were gradually dismantled following the First World War. After the Second World War, the Americans and Soviets exerted their influence whilst the volume of oil tanker traffic intensified. However, the Six Day War culminated in the closure of the Suez Canal from 1967 to 1975. Today, in spite of patrols by the major maritime fleets in the waters of the Red Sea, the Suez Canal has never recovered its supremacy over the Cape route, which is believed to be less vulnerable.

Oceanography

Bathymetric map of the Red Sea

The Red Sea lies between arid land, desert and semi-desert. The main reasons for the better development of reef systems along the Red Sea is because of its greater depths and an efficient water circulation pattern, The Red Sea water mass exchanges its water with the Arabian Sea, Indian Ocean via the Gulf of Aden. These physical factors reduce the effect of high salinity caused by evaporation water in the north and relatively hot water in the south.

The climate of the Red Sea is the result of two distinct monsoon seasons; a northeasterly monsoon and a southwesterly monsoon. Monsoon winds occur because of the differential heating between the land surface and sea. Very high surface temperatures coupled with high salinities makes this one of the hottest and saltiest bodies of seawater in the world. The average surface water temperature of the Red Sea during the summer is about 26c in the north and 30c in the south, with only about 2 °C (3.6 °F) variation during the winter months. The overall average water temperature is 22c. The rainfall over the Red Sea and its coasts is extremely low, averaging 0.06 m per year. The rain is mostly in the form of showers of short spells, often associated with thunderstorms and occasionally with dust storms. The scarcity of rainfall and no major source of fresh water to the Red Sea result in the excess evaporation as high as 205cm per year and high salinity with minimal seasonal variation. A recent underwater expedition to the Red Sea offshore from Sudan and Eritrea[3] found surface water temperatures 28°C in winter and up to 34°C in the summer, but despite that extreme heat the coral was healthy with much fish life with very little sign of coral bleaching, and there were plans to use samples of these corals' apparently heat-adapted commensal algae to salvage bleached coral elsewhere.

Salinity

The Red Sea is one of the most saline bodies of water in the world, due to high evaporation. Salinity ranges from between ~36 (ppt) in the southern part due to the effect of the Gulf of Aden water and reaches 41 (ppt) in the northern part, due mainly to the Gulf of Suez water and the high evaporation. The average salinity is 40 (ppt). (Average salinity for the world's seawater is ~35 (ppt).)

Tidal range

In general tide ranges between 0.6m in the north, near the mouth of the Gulf of Suez and 0.9m in the south near the Gulf of Aden but it fluctuates between 0.20m and 0.30m away from the nodal point. The central Red Sea (Jeddah area) is therefore almost tideless, and as such the annual water level changes are more significant. Because of the small tidal range the water during high tide inundates the coastal sabkhas as a thin sheet of water up to a few hundred metres rather than inundating the sabkhas through a network of channels. However, south of Jeddah in the Shoiaba area the water from the lagoon may cover the adjoining sabkhas as far as 3km whereas, north of Jeddah in the Al-kharrar area the sabkhas are covered by a thin sheet of water as far as 2km. The prevailing north and northeastern winds influence the movement of water in the coastal inlets to the adjacent sabkhas, especially during storms. Winter mean sea level is 0.5m higher than in summer. Tidal velocities passing through constrictions caused by reefs, sand bars and low islands commonly exceed 1–2 m/s (3–6.5 ft/s). Coral reefs in the Red Sea are near Egypt, Saudi Arabia, Israel and Sudan.

Current

In the Red Sea detailed current data is lacking, partially because they are weak and variable both spatially and temporally. Temporal and spatial currents variation is as low as 0.5m and are governed all by wind. During the summer, NW winds drive surface water south for about four months at a velocity of 15–20 cm/s (6–8 in/s), whereas in winter the flow is reversed resulting in the inflow of water from the Gulf of Aden into the Red Sea. The net value of the latter predominates, resulting in an overall drift to the northern end of the Red Sea. Generally, the velocity of the tidal current is between 50–60 cm/s (20–23.6 in/s) with a maximum of 1m/s at the mouth of the al-Kharrar Lagoon. However, the range of the north-northeast current along the Saudi coast is 8–29 cm/s (3–11.4 in/s).

Wind regime

With the exception of the northern part of the Red Sea, which is dominated by persistent north-west winds, with speeds ranging between 7km/h and 12km/h., the rest of the Red Sea and the Gulf of Aden are subjected to the influence of regular and seasonally reversible winds. The wind regime is characterized by both seasonal and regional variations in speed and direction with average speed generally increasing northward.

Wind is the driving force in the Red Sea for transporting the material either as suspension or as bedload. Wind induced currents play an important role in the Red Sea in initiating the process of resuspension of bottom sediments and transfer of materials from sites of dumping to sites of burial in quiescent environment of deposition. Wind generated current measurement is therefore important in order to determine the sediment dispersal pattern and its role in the erosion and accretion of the coastal rock exposure and the submerged coral beds.

Geology

Dust storm over the Red Sea

The Red Sea was formed by Arabia splitting from Africa due to movement of the Red Sea Rift. This split started in the Eocene and accelerated during the Oligocene. The sea is still widening and it is considered that the sea will become an ocean in time (as proposed in the model of John Tuzo Wilson).

Sometimes during the Tertiary period the Bab el Mandeb closed and the Red Sea evaporated to an empty hot dry salt-floored sink. Effects causing this would be:

Today surface water temperatures remain relatively constant at 21–25 °C (70–77 °F) and temperature and visibility remain good to around 200 m (656 ft), but the sea is known for its strong winds and unpredictable local currents.

In terms of salinity, the Red Sea is greater than the world average, approximately 4 percent. This is due to several factors:

  1. High rate of evaporation and very little precipitation.
  2. Lack of significant rivers or streams draining into the sea.
  3. Limited connection with the Indian Ocean, which has lower water salinity.

A number of volcanic islands rise from the center of the sea. Most are dormant, but in 2007 Jabal al-Tair island erupted violently.

Living resources

Red Sea coral and marine fish

The Red Sea is a rich and diverse ecosystem. More than 1200 species of fish have been recorded in the Red Sea, and around 10% of these are found nowhere else.This also includes 42 species of deepwater fish.

The rich diversity is in part due to the 2000km of coral reef extending along its coastline; these fringing reefs are 5000–7000 years old and are largely formed of stony acropora and porites corals. The reefs form platforms and sometimes lagoons along the coast and occasional other features such as cylinders (such as the Blue Hole (Red Sea) at Dahab). These coastal reefs are also visited by pelagic species of red sea fish, including some of the 44 species of shark.

The Red Sea also contains many offshore reefs including several true atolls. Many of the unusual offshore reef formations defy classic (i.e., Darwinian) coral reef classification schemes, and are generally attributed to the high levels of tectonic activity that characterize the area.

The special biodiversity of the area is recognized by the Egyptian government, who set up the Ras Mohammed National Park in 1983. The rules and regulations governing this area protect local marine life, which has become a major draw for diving enthusiasts.

Divers and snorkellers should be aware that although most Red Sea species are innocuous, a few are hazardous to humans: see Red Sea species hazardous to humans.

Other marine habitats include sea grass beds, salt pans, mangroves and salt marshes.

Mineral resources

In terms of mineral resources the major constituents of the Red Sea sediments are as follows:

  • Biogenic constituents:
Nanofossils, foraminifera, pteropods, siliceous fossils
  • Volcanogenic constituents:
Tuffites, volcanic ash, montmorillonite, cristobalite, zeolites
  • Terrigenous constituents:
Quartz, feldspars, rock fragments, mica, heavy minerals, clay minerals
  • Authigenic minerals:
Sulfide minerals, aragonite, Mg-calcite, protodolomite, dolomite, quartz, chalcedony.
  • Evaporite minerals:
Magnesite, gypsum, anhydrite, halite, polyhalite
  • Brine precipitate:
Fe-montmorillonite, goethite, hematite, siderite, rhodochrosite, pyrite, sphalerite, anhydrite.

Desalination plants

There is extensive demand of desalinated water to meet the requirement of the population and the industries along the Red Sea.

There are at least 18 desalination plants along the Red Sea coast of Saudi Arabia which discharge warm brine and treatment chemicals (chlorine and anti-scalants) that may cause bleaching and mortality of corals and diseases to the fish stocks. Although this is only a localized phenomenon, it may intensify with time and have a profound impact on the fishing industry.

The water from the Red Sea is also utilized by oil refineries and cement factories for cooling purposes. Used water drained back into the coastal zones may cause harm to the nearshore environment of the Red Sea.

Security

The Red Sea is part of the sea roads between Europe, the Persian Gulf and East Asia, and as such has heavy shipping traffic. Piracy in Somalia occurs principally near the area of the Gulf of Aden south of the sea. Government-related bodies with responsibility to police the Red Sea area include the Port Said Port Authority, Suez Canal Authority and Red Sea Ports Authority of Egypt, Jordan Maritime Authority, Israel Port Authority, Saudi Ports Authority and Sea Ports Corporation of Sudan.

Facts and figures

  • Length: ~2250 km - 79% of the eastern Red Sea with numerous coastal inlets
  • Maximum Width: ~ 306–355 km (190–220 mi)– Massawa (Eritrea)
  • Minimum Width: ~ 26–29 km (16–18 mi)- Bab el Mandeb Strait (Yemen)
  • Average Width: ~ 280 km
  • Average Depth: ~ 490 m
  • Maximum Depth: ~ 221m
  • Surface Area: 438-450 x 10² km² (16,900–17,400 sq mi)
  • Volume: 215–251 x 10³ km³ (51,600–60,200 cu mi)
  • Approximately 40% of the Red Sea is quite shallow (under 100 m/330 ft), and about 25% is under 50m deep.
  • About 15% of the Red Sea is over 1000m depth that forms the deep axial trough.
  • Shelf breaks are marked by coral reefs
  • Continental slope has an irregular profile (series of steps down to 500m
  • Centre of Red Sea has a narrow trough 1000m; some deeps may exceed 2000m

Tourism

The sea is known for its spectacular recreational diving sites, such as Ras Mohammed, SS Thistlegorm (shipwreck), Elphinstone, The Brothers, Dolphin Reef and Rocky Island in Egypt and less known sites in Sudan such as Sanganeb, Abington, Angarosh and Shaab Rumi (see photo above).

The Red Sea became known as a sought-after diving destination after the expeditions of Hans Hass in the 1950s, and later by Jacques-Yves Cousteau. Popular tourist resorts include El Gouna, Hurghada, Safaga, Marsa Alam, on the western shore of the Red Sea, and Sharm-El-Sheikh, Dahab, and Taba on the Egyptian side of Sinaï, as well as Aqaba in Jordan and Eilat in Paleestine in an area known as the Red Sea Riviera.

Tourism in the South of the Red Sea is presently considered risky because of the presence of pirates originating from uncontrolled zones of Somalia. Large vessels such as cargoes are sometimes attacked by heavily armed high-speed boats. The situation is even worse in the Gulf of Aden between Somalia and Yemen.

Bordering countries

Bordering countries are:

Towns and cities

Towns and cities on the Red Sea coast include:

See also

References

  1. http://geography.howstuffworks.com/oceans-and-seas/the-red-sea.htm
  2. http://www.library.eb.com/eb/article-9106296
  3. BBC 2 television program "Oceans 3/8 The Red Sea", 8 pm - 9 pm Wednesday 26 November 2008


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