The Wadi Hadf (Arabic: وادي حدف, romanized: Wādī Ḩadf)[1][5] is a dry river valley or river valley, with ephemeral or intermittent flow, which flows almost exclusively during the rainy season, located east of the United Arab Emirates, in the enclaves of Masfut (Ajman) and Hatta (Dubai), and north of Oman, in the Al Batinah North Governorate.

[9][10] At that point the Wadi Hadf turns northeast towards the Sinadil Pass through a narrow, steep-sided gorge cut mainly through cemented gravel deposits.

[6] At the exit of the spectacular gorge formed by the main channel of Wadi Hadf as it passes through Hadf and Sinadil, the wadi heads northeast across the international dividing line between Oman and the United Arab Emirates, and enters the enclave of Masfut, crossing the great gravel plain of Sayh Muzayri' / Sayḩ Muḑayrah, leaving to the north the urban area of Mudayrah / Muzairah / Muzayri', with its neighborhood of Sayh Al Zahra, and the catchment basin and waterways that flow into the Persian Gulf.

Upon meeting the natural barrier formed by the mountain ridge of Jabal al Abyad / Jabal al Bayd 559 m (1,834 ft),[3] right at the place occupied by the Hadf Dam dam and reservoir, the wadi turns east-southeast, crossing the old town and current city of Masfut, which concentrates some of its most representative historical buildings (castle and current museum, watchtowers and mosques).

The name of Wadi Hadf (spelled Wādī Ḩadf), its tributaries, mountains and nearby towns were recorded in the documentation and maps produced between 1950 and 1960 by the British Arabist, cartographer, military officer and diplomat Julian F. Walker, during the work carried out to establish the borders between the then called Trucial States,[19] and later completed by the Ministry of Defence of the United Kingdom, on scale maps 1:100,000 published in 1971.