Surface Water

Surface water in most of the region drains to the Mediterranean, Red, or Dead Seas. In the large desert watersheds, most streams flow only in response to storms and drain internally, the water evaporating or infiltrating the ground.

WATERSHEDS

Natural flow characteristics of streams in the region are related first to watershed location with respect to rainfall patterns, and secondly, to watershed size.

The Mediterranean watershed includes the Coastal Plain and parts of the Mountain Belt and Negev. The streams generally have small watersheds with headwaters in the western mountains. Many of the streams are affected by water supply diversions and wastewater discharges.

Jordan River below Lake Tiberias

The Jordan River watershed has the largest water yield in the region and provides most of the usable surface-water supply. The annual flow volume of the upper Jordan River above Lake Tiberias is about three times greater than the combined annual volume of the streams in the much larger Mediterranean watershed. The Jordan River watershed is in the Mountain Belt, Jordan Rift Valley and Escarpments, and the Jordan Highland and Plateau. The largest tributary to the Jordan River is the Yarmouk River, which is the principal surface-water resource for Jordan. The Jordan River is perennial throughout its course, but its flow downstream from Lake Tiberias is substantially reduced in quantity and quality.

Yarmouk River during a flood

The Dead Sea watershed includes streams with headwaters in the eastern side of the Mountain Belt, the Eastern and Western Escarpments of the Jordan Rift Valley, and the Jordan Highland and Plateau. The larger of these streams, such as the Wadi Wala and Wadi Mujib, flow perennially during their steep decent into the lowest point on the surface of the earth.

The North and South Wadi Araba and the Red Sea watersheds contain ephemeral streams that typically flow only during winter storms that may cause dangerous flash floods in the deeply incised wadis. The watersheds are in the Negev, the Jordan Highland and Plateau, the Jordan Rift Valley and Eastern Escarpment, and the South Jordan Desert. Near the mouth of the Hiyyon River lies the internal divide of the Wadi Araba from which water flows north to the Dead Sea or south to the Red Sea.

Large parts of the Jordan Highland and Plateaus and the South Jordan Desert physiographic provinces are characterized by Desert watersheds that drain internally. Stormwater flows in these streams generally decrease in the downstream direction as water is lost through evaporation and infiltration. The stream courses of the El Jafr watershed provides a vivid example of this.