Gash River

Mareb River
The dry river at Kassala
Other name(s)	Gash or al-Qash
Country	Eritrea, Ethiopia, Sudan
Basin features
Main source	15 kilometres (9.3 mi) south-west Asmara
River mouth	dissipate in the sands of the eastern Sudanese plains
Basin size	31,000 km2 (12,000 sq mi)
Tributaries	Left: Sarana River, Balasa River, 'Engweya River, Gala River Right: Obel River
Physical characteristics
Length	440 km (270 mi)
Discharge	Average rate: 21.6 m3/s (760 cu ft/s)

The Mareb River (or Gash River), is a river flowing out of central Eritrea. Its chief importance is defining part of the boundary between Eritrea and Ethiopia, between the point where the Mai Ambassa enters the river at 14°53.6′N 37°54.8′E / 14.8933°N 37.9133°E / 14.8933; 37.9133 to the confluence of the Balasa with the Mareb at 14°38′N 39°1.3′E / 14.633°N 39.0217°E / 14.633; 39.0217.

According to the Statistical Abstract of Ethiopia for 1967/68, the Mereb River is 440 kilometres (270 mi) long. The Ethiopian Ministry of Water Resources reports its Ethiopian catchment area as 5,700 square kilometres (2,200 sq mi), with an annual runoff of 0.26 billion cubic meters. Other sources talking about a catchmant of 21,000 square kilometres (8,100 sq mi) to 44,000 square kilometres (17,000 sq mi) over all, and a discharge of 21.6 cubic metres per second (760 cu ft/s) in average over the year, and 870 cubic metres per second (31,000 cu ft/s) in peaks. Its headwaters rise south-west of Asmara in central Eritrea. It flows south, bordering Ethiopia, then west through western Eritrea to reach the Sudanese plains near Kassala. Unlike the Setit or Takazze rivers, which flow out of Ethiopia and also forms a natural border with Eritrea, the waters of the Mareb do usually not reach the Nile but dissipate in the sands of the eastern Sudanese plains.