Wadi (Arabic: وادي) is the local term for a valley or riverbed. Although wadis are usually dry, many wadis have permanent pools in the... more » upper reaches, fed by seeping ground water throughout the year. A number of farms have been carved out of the rocky banks of wadis in this region, making use of both surface water and groundwater which is never very far from the surface. Sporadic rainfall in the form of short, sharp thunder showers results in dangerous instances of flash-flooding in wadis, isolating the more remote areas and even causing a number of deaths every year. Historically wadis were used as routes through the rugged Hajar Mountains, the name given to the Semail Ophiolite on the eastern coastal region of the Saudi Peninsula.
At first glance the Hajar mountain range, bisected by myriad wadis, is a harsh, rugged and scenically monotonous area with little to offer. The seasoned “wadi-basher” – an unfortunate term given to the off-road community who practice “wadi bashing” – knows better and a little research and exploration reveals an area with fascinating geological history and a glimpse into the harsh realities of life in this region before oil.
The Hajar Mountains of the UAE are part of the Hajar range of mountains that, geologically, are referred to as the Somail Ophiolite, extending from central Oman, in the south, to Mussandam Oman, in the north, making up the topography of the East Coast Region of the United Arab Emirates in between. The Semail Ophiolite, considered to be the largest, best preserved and most spectacular example of an oceanic lithosphere, was formed during the Cretaceous period, approximately 94 million years ago, is approximately 800km long, up to 150km wide and covers an area of approximately 10,000km².
An ophiolite is, geologically, an area of the seabed – oceanic crust and underlying earth’s mantle – that has been forced to the surface as a result of a volcanic event usually associated with plate tectonics (continental drift).
As a result of its geomorphology ophiolites portray a number of interesting characteristics. The term ophiolite is derived from the Greek words “ophio” meaning "snake", and “lithos” meaning "stone." It is difficult to know why this term was so derived – it could be as a result of the many small magma dykes that crisscross the landscape, or it could be that the colourful, crumbly topography is reminiscent of a snake’s skin. In any event, evidence of an ophiolite’s volcanic birth abounds and once one understands it geomorphology it is fairly easy to identify areas of the earth’s crust interspersed with sheeted magma dykes; seabed sediments of clay, siliceous ooze, shale, cherts and sedimentary debris; and outcrops of volcanically extruded pillow larva.
Wadis were, and still are, extensively used to carve out routes through the mighty Hajar mountains between the eastern coastal region and the trading hubs of old Dubai and Abu Dhabi. Wadi Ham and Wadi Siji were well travelled routes connecting the east coast and the Persian/Arabian Gulf ports and trading stations.
Wadis were, and still are, important resources from a water source and agriculture point of view. Falajs, or irrigation canals – some of them many hundreds of years old, are still in use in the region, moving water from the permanent pools and wells to the farms and even villages found dotted along the relatively fertile banks of these water courses. Dates represent the most important crop, while date palms also provide much-needed shade. Goats represent the most important livestock farming, although many farms will also rear camels.
In recent times recharge dams have been built in wadi beds the purpose of which is to capture the flood waters during the limited rainy season, preventing it from reaching the ocean and allowing groundwater sources to be recharged.
Wadis and the surrounding mountains are dotted with what appear to be abandoned homes. In many instances these are the summer residences of people who spend the cooler winter months on the coat and escape the searing heat and humidity of the hotter summer months in the mountains.
The journey from Murbah on the east coast, through the Omani town of Wadi Madha, to Hajar Bani Hamid, Wadi Shis and on through Wadi Madha itself is representative of both the geological and socio-cultural wonders of this region. less «