Valleys in Saudi Arabia

The Valleys in the Kingdom of Saudi Arabia are watercourses formed primarily during the rainy ages. Many of them are seasonal and are commonly referred to as valleys (Wadis) and ravines (Shi‘ab). They are distributed across all provinces of the Kingdom, although they are less common in the southern part of the Eastern Province and are absent in ar-Rub' al-Khali (Empty Quarter).

The valleys in the Kingdom are divided into two groups: valleys with external drainage and valleys with internal drainage.

These are valleys that flow into the Red Sea or the Arabian Gulf. They are characterized by short, steep channels and deeply carved tributaries. The water flow in these channels varies from one area to another along the Tihama Plain. In the central Tihama of the Hejaz and northern Tihama al-Sham, rainfall is lower on the Hejaz and Midian Mountains, resulting in reduced flow in the valleys there. Examples of these valleys include Wadi Fatimah, Rabigh, al-Hamd, 'Ifal, and Aynunah. Agricultural crops in these valleys include vegetables and certain types of grains, with date palms being widely cultivated.

In the southern Tihama Plain of Aseer, rainfall on the Sarawat Mountains provides the valleys with a continuous flow throughout the year. Among these valleys are: Wadi Bishah, extending from the northeast to the southwest within Jazan Province, with a length of approximately 155 km; Wadi Hali, which stretches from the southeast to the northwest, passing through Abha City and the governorates of Mahayil in Aseer Province and al-Qunfudhah in Makkah al-Mukarramah Province, covering around 160 km; Wadi 'Itwid, one of the steepest valleys, flowing through ad-Darb Governorate, western Jazan, from the territories of al-Mathnah village and emptying into the Red Sea basin at 'Itwid village in ad-Darb Governorate, measuring about eighty-five km; and Wadi Jazan, which originates from Yemen to the east and flows into the Red Sea basin through the territories of Jazan City to the west, running across Fayfa, Damad, al-'Idabi, and Jizan, with a length of approximately seventy-five km. These valleys support agriculture, with crops such as grains like corn, millet, and sesame, as well as various vegetables and fruits.

These are valleys that descend from the western highlands of the Kingdom toward the east, flowing into internal basins and plains, forming seasonal lakes, meadows, and pools that serve as recreational spots. They are characterized by wide, gently sloping channels. Among these valleys is Wadi Rumah, a seasonal watercourse extending 510 km. It flows within the geographic regions of Hail and Qassim Provinces, running from northwest to east across seven governorates: Unayzah, Riyadh al-Khabra, ar-Rass, al-Asyah, Uqlat as-Suqur in Qassim Province, and al-Ha'it and as-Sulaymi in Hail Province. Among the valleys with internal drainage is Wadi Hanifah, which runs within the boundaries of ad-Dir'iyyah Governorate. It originates west of al-Uyaynah and flows into the village of as-Sahba in al-Kharj Governorate, with a length of approximately 160 km. Another example is Wadi ad-Dawasir, which stretches from the southwest to the northeast across three governorates: as-Sulayyil and Wadi ad-Dawasir in Riyadh Province, and Tathlith in Aseer Province. It flows into Wadi al-Ghar, east of as-Sulayyil Governorate, with a length of around 350 km.

Wadi as-Sirhan is also an internally draining valley, formed by a collection of small wadis in the Tabarjal Governorate in al-Jawf Province. It flows into Sabkhat Hadawda' to the north, extending from southeast to northwest within Tabarjal Governorate, with a length of approximately 180 km.

Tributary names vary from one region to another and include: Ba'ija, Bahrah, al-Khirr, Khanaqa, Khoor, Dahla, Di'ab, Duaykhla, Rijla, Sahiba, Sayila, Sir, Silil, Sahib, Shijna, Shitna, Shighya, Aa'ira, Aa'ila, Ghawya, Ghir, Faj, Nassifa, Nazim, and Hithlool.