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Asi River Basin

The Orontes River, Hama, Syria.
Photo 1: The Orontes River, Hama, Syria. (Source: Jose M, Flickr)

Asi in Arabic means ‘rebel’. Unlike most rivers in the region, which flow from north to south, the Asi River flows from south to north. It rises in the Beqaa Valley in Lebanon and flows northward between Lebanon and the Anti-Lebanon Mountains. Entering Syria near the town of Hermel, it continues to flow northwards past the cities of Homs and Hama and crosses the fertile Ghab Plain. It forms the border between Turkey and Syria for about 31km, turns westward into Turkey and finally discharges into the Mediterranean Sea.[1]

The length of the river is open to discussion. Depending on the source consulted, this ranges from 248km to 556km (see Table 1).

Rainfall in the Asi River basin is about 644mm annually. The average temperature is around 16°C. The climate is semi-arid to arid in Lebanon, with annual rainfall of about 400mm. In the western mountains of Syria, this increases to about 500-1500mm, then drops again to about 400-600mm in the eastern part of the basin. The Turkish part of the basin is a transition zone between the Mediterranean and Eastern Anatolian climatic zones.[8]

The water potential of the river is also disputed. In some sources, this is given as 2.47 billion cubic metres per year (BCM/year).[9] The most realistic estimate is about 2.8BCM/ year.[10]

The groundwater flow is 1.11BCM. The al-Azraq spring makes a significant contribution – approximately 400 million cubic metres (MCM) – to the yearly potential flow. The other major contributors are al-Ghab, al-Roudji and al-Zarqa.[11]

Two major tributaries, the south-flowing Afrin from the west and the Karasu from the east, join the Asi River in Lake Amik. Whereas the Karasu flows in Turkish territory and forms the border between Turkey and Syria for a short distance, the Afrin crosses into Syria before re-entering Turkey. The water potential of the Karasu is 0.39BCM/ year; the discharge rate of the Afrin at the point where it enters Turkey is 0.31BCM/ year.[12]

Orontes River basin
Map 1: Orontes River basin.
Length of river (km)Reference
248Water Problems in the Middle East Report
248 Orontes River Issues Related with Turkey, Syria and Lebanon
556Sustainable Water Management in Hatay: Hydrographic Planning Approach
448 Orontes River Basin: Downstream Challenges and Prospects for Cooperation
453FAO – Irrigation in the Middle East Region in Figures
485Syrian Irrigation Ministry

Table 1. Length of the Asi River, according to different sources.[2], [3], [4], [5], [6],and [7]

[1] Kibaroğlu, A. et al., 2005. Cooperation on Turkey’s Transboundary Waters. Adelphi Research and the German Federal Ministry for Environment, Nature Conservation and Nuclear Safety.
[2] Dışişleri Bakanlığı,1994. Ortadoğu’da Su Sorunu. Ankara.
[3] Salha, S., 1995. Türkiye, Suriye ve Lübnan İlişkilerinde Asi Nehri Sorunu. Dış Politika Enstitüsü, Ankara.
[4] Karataş, A., 2015. Sustainable Water Management in Hatay: Hydrographic Planning Approach. Graduate Instituteof International and Development Studies & MEF University, İstanbul.
[5] Scheumann, W.; Sagsen, I.; Tereci, E, 2011. Orontes River Basin: Downstream Challenges and Prospects for Cooperation. Springer, London.
[6] FAO, 2009. Irrigation in the Middle East Region in Figures. Aquastat Survey, Rome.
[7] Maden, T. E., 2011. Türkiye-Suriye İlişkileri: Sınıraşan Sularda Örnek İşbirliği Olarak Asi Dostluk Barajı. ORSAM Rapor, no: 5.
[8] FAO, 2009. Irrigation in the Middle East. FAO Water Reports, no: 34, Rome.
[9] Toklu, V., 1999. Su Sorunu, Ululararası Hukuk ve Türkiye. Turhan Kitabevi, Ankara.
[10] Scheumann, W.; Sagsen, I.; Tereci, E, 2011. Orontes River Basin: Downstream Challenges and Prospects for Cooperation. Springer, London.
[11] FAO, 2009. Irrigation in the Middle East Region in Figures. Aquastat Survey, Rome.
[12] Kibaroğlu, A. et al., 2005. Cooperation on Turkey’s Transboundary Waters. Adelphi Research and the German Federal Ministry for Environment, Nature Conservation and Nuclear Safety.