The Ghab plain (Arabic: سهل الغاب) is a fertile depression lying mainly in the Al-Suqaylabiyah District in northwest Syria, near Muhradah (35°15′N 36°35′E), around 25 km north-west of Hama. The valley was flooded for centuries by the waters of the Orontes River, which rendered it a swamp.  The "Ghab project", beginning in the 1950s, drained the valley to make it habitable, arable land, providing an extra 41,000 hectares (160 sq mi) of irrigated farmland.
The valley separates the al-Ansariyah mountains in the west from the Zawiyah mountain range and the plateau region to the east. It is 63 kilometres (39 mi) long and 12.1 kilometres (7.5 mi) wide.
The project started in 1953 and is considered one of the most important hydraulic projects in northern Syria. Owing to a slight slope (0.10%) in the Orontes in the area of Asharnah, the river did not provide enough water to the surrounding territories. The project drained the plain where the River Orontes flowed. The plain was entirely drained in 1968 and provided 11,000 families with lands.
The Ghab project made large areas suitable for agriculture, and new irrigation systems were employed. The system included barrages, canal networks for irrigation and canal networks for drainage. Large barrages were built in Mhardeh, Zayzun, Qarqur and other villages. The dam at Mhardeh, built in 1961, is 40 metres (130 ft) high, and 200 metres (660 ft) long and holds 65,000,000 cubic metres (85,000,000 cu yd) of water. The Zeyzoun Dam, built in 1996, was 32 metres (105 ft) high and held a maximum of 71,000,000 cubic metres (93,000,000 cu yd) of water; it failed in June 2002, leading to the deaths of 22 people and the displacement of over 2,000 as a large hole opened in the embankment and flooded 80 square kilometres (31 sq mi) of the countryside downstream.
Other advantages of the Ghab project were the improvements in the systems of communication through the building of road and rail networks, previously not possible due to the swamps. In addition, malaria decreased because there was no longer stagnant water.
- Federal Research Division, 2004, p. 74.
- Sofer, 1999, p. 205.
- South, Coleman. Syria. Tarrytown, N.Y.: Marshall Cavendish Benchmark, 2006. Print.
- de Miranda, 2007, p. 267.
- Salman, 2009, p. 28.
- J. Gaulmier, "Notes sur la pêche du silure dans la vallée du Ĝāb", Mélanges de l'Institut Français de Damas 1 (1929), p. 19-25
- Federal Research Division (2004), Syria a Country Study, Kessinger Publishing, ISBN 978-1-4191-5022-7
- Sofer, Arnon (1999), Rivers of fire: the conflict over water in the Middle East, Rowman & Littlefield, ISBN 978-0-8476-8511-0
- de Miranda, Adriana (2007), Water architecture in the lands of Syria: the water-wheels, L'ERMA di BRETSCHNEIDER, ISBN 978-88-8265-433-7
- Salman, Salman M. A. (2009), The World Bank Policy for Projects on International Waterways: An Historical and Legal Analysis, World Bank Publications, ISBN 978-0-8213-7953-0