Jordan River | River, Middle East - Britannica

Physical environment

The Jordan Valley constitutes a segment of the extensive East African Rift System, a rift valley running north and south that extends from southern Turkey southward via the Red Sea and into eastern Africa. The valley itself is a long and narrow trough, averaging about 6 miles (10 km) in width but becoming narrower in some places—e.g., at each end of the Sea of Galilee. Throughout its course the valley lies much lower than the surrounding landscape, especially in the south, where the surrounding land can rise some 3,000 feet (900 metres) or more above the river. The valley walls are steep, sheer, and bare, and they are broken only by the gorges of tributary wadis (seasonal watercourses).

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The Jordan River has three principal sources, all of which rise at the foot of Mount Hermon. The longest of those is the Ḥāṣbānī, which rises in Lebanon, near Ḥāṣbayyā, at an elevation of 1,800 feet (550 meters). From the east, in Syria, flows the Bāniyās River. Between the two is the Dan River, the waters of which are particularly fresh.

Just inside Israel, those three rivers join together in the Ḥula Valley. The plain of the Ḥula Valley was formerly occupied by a lake and marshes, but in the 1950s some 23 square miles (60 square km) were drained to form agricultural land. By the 1990s much of the valley’s soil had been degraded, and portions of the area had become flooded. It was decided to retain the lake and surrounding wetlands area as a protected nature reserve, and some of the plants and animals (notably migratory birds) returned to the region.

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At the southern end of the valley, the Jordan has cut a gorge through a basaltic barrier. The river then drops sharply down to the northern shore of the Sea of Galilee. That lake, which historically was measured at 686 feet (209 meters) below sea level, has for decades averaged some 6.5 to 13 feet (2 to 4 meters) lower annually than that value. The lake nonetheless helps govern the river’s rate of flow. Exiting from the southern shore of the lake, the Jordan receives its main tributary, the Yarmūk River, which marks part of the frontier between Syria and Jordan. It is then joined by two more tributaries, the Ḥarod on the right bank and the Yābis on the left. The Jordan River’s plain then spreads out to a width of about 15 miles (24 km) and becomes very regular. The flat arid terraces of that area, known as the Ghawr (Ghor), are cut here and there by wadis or rivers into rocky towers, pinnacles, and badlands, forming a maze of ravines and sharp crests that resemble a lunar landscape.

The valley that the Jordan has cut into the plain is between about 1,300 and 10,000 feet (400 and 3,000 meters) wide and about 50 to 200 feet (15 to 60 meters) deep. Along that stretch, the Jordan’s floodplain is known as the Zūr, and it describes so many meanders that, although it course runs for some 135 miles (215 km), the actual distance it covers between the Sea of Galilee and the Dead Sea is only 65 miles (105 km). The Zūr, which floods frequently, was formerly covered with thickets of reeds, tamarisk, willows, and white poplars, but, since dams were built to control the river’s flow, that land has been converted to irrigated fields. Finally, the Jordan drains into the Dead Sea through a gently sloping broad delta.

Although the bordering plateaus receive relatively abundant rainfall, the Jordan Valley itself is not well watered. The Ḥula Valley receives about 22 inches (550 mm) a year, whereas only about 3 inches (75 mm) fall north of the Dead Sea. Winters along the river are mild, especially in the south, but summers are torrid, again increasingly toward the south.

Arabic: Nahr Al-Urdun (Show more) Hebrew: Ha-Yarden (Show more) See all related content

The Jordan is fed by rains falling on the neighboring plateaus; the waters then flow downward through rivers or wadis. The Jordan itself is shallow. Its high-water period lasts from January to March, while its low-water period occurs at the end of summer and the beginning of autumn. The current is relatively swift, and the river transports a considerable load of silt. The rate of flow, however, diminishes downstream as a result of evaporation losses and the seeping away of water. Inflow from the Yarmūk River once nearly doubled the Jordan’s flow, but the Yarmūk’s contribution was subsequently reduced as a result of damming upstream. The existence of thermal springs, notably in the Tiberias region on the western side of the Sea of Galilee, as well as the concentration of gypsum, give the Jordan’s waters a relatively high degree of salinity, which can leave a salt residue in the soil when the water is used for irrigation.