Wadi Al-Gharas Bint Dam (Sadd al-Bint Southeast Expansion)
سد البنت وادي الغرس · Bint Wadi Gharas Dam · Al-Bint Gravity Dam Gharas
Early Islamic Umayyad (740 CE) NW Arabia·Umayyad Khaybar–AlUla Harrat oasis (NW Arabia)·🇸🇦 Tabuk Region? Actually NW Arabia near AlUla–Harrat, Wadi Al-Gharas basalt plateau 800 m (near AlUla Harrat), Saudi Arabia
About
About Wadi Al-Gharas Bint Dam (Sadd al-Bint Southeast Expansion)
Near-rectilinear gravity dam (800 m) on Wadi al-Gharas basalt plateau NW Arabia southeast of AlUla Harrat, companion to published Sadd al-Bint. 1 m and downstream buttress steps 3-tier. 8 km with stone sluice. Early Islamic (Umayyad 740 CE) with basalt ashlar faced upstream and rubble downstream. 2025 Wiley publication al-Bint 212 m dam near — this southeast expansion is 158 m companion identified same field campaign. Threat: Harrat basalt quarrying and dam crest vehicle track.
Why it mattersCompanion south ridge to 212 m al-Bint publishing dam — paired Harrat basalt plateau gravity dam chain proving NW Arabia early Islamic hydraulic intensification.
Open questions
Mysteries & theories
Mysteries
- 01Why two dams 212+158 on same wadi — cascade vs companion
Theories
- 01Paired saddle dams as cascade paleo-ownership split
Theories are interpretations, not findings. The seal above tells you how much scholarly weight the place carries.
History
How it came to be
- Built
- c.740 CE (Umayyad early Islamic)
- Period
- Early Islamic Umayyad (740 CE) NW Arabia
- Culture
- Umayyad Khaybar–AlUla Harrat oasis (NW Arabia)
- Builders
- Umayyad Wadi al-Gharas basalt engineers
- Purpose
- Basalt plateau gravity dam 158 m 14.2 m clay-core trapping 42,000 m³ to 12 ha palm oasis via 1.8 km canal
- Abandoned
- c.1350 CE (desertification)
- Rediscovered
- 2025 Wiley Geoarchaeology al-Bint dam Wadi al-Gharas 800 m basalt plateau publication companion
- Excavation
- Partially excavated
740 CE
Umayyad gravity dam 158 m clay-core 2.1 m
2025
Wiley Geoarchaeology Sadd al-Bint 212 m 23.6 m high publication
On the ground
Structures & features
26.8800° N · 38.1200° E · 800 m · 2 mapped features
Main Gravity Embankment (158 m × 14.2 m)
dam158-m basalt gravity wall 14.2 m high with clay-core 2.1 m and 3-tier buttress
26.8820° N · 38.1210° EDownstream Canal Sluice (1.8 km)
canalGravity canal 1.8 km with stone sluice to palm oasis 12 ha
26.8830° N · 38.1230° E