||CREATION OF GARDENS ON THE SIDES OF RIVERBED
Definition characters description and diffusion
Flow sharing systems such as dams allow gardens to be created on the sides of riverbeds, producing tilled lands, supplying humus and watering soils.
General characters description and diffusion
A titanic irrigation system is situated in Marib, the Queen of Sheba’s Arabian capital, in the North of Yemen, now completely deserted. It consists of a large dam and a series of sluices and water flow sharing systems which allowed the northern and southern well-known gardens to be created on both sides of the bed of wadi Dhana. The ruins of the irrigation and cultivation systems that made this miracle possible can be still admired. The cyclopean masonry has been established as the starting point of the powerful dam. Considered as one of the wonders of the ancient world, it harnessed the floods, enabling them to be wisely used for agriculture. It stopped the flow of wadi Dhana running east-west by means of an embankment 620 m. long, 16 m. high and 60 m thick at the base. It had not been built to create a water basin upstream of the wall, but rather to lift water and spread the floods on both the shores of the wadi. Huge sluices and channels conveying water to the north and the south of the town were built, in fact, at the two extremities of the wadi. Thus, it is easy to understand the meaning of the two gardens mentioned by all the authors: the flow sharing system created two tilled areas and fanned out the deposit of fertile land beyond both the shores. Taking into account the accumulation of mud that can reach even 30 m. in height and its sedimentation rate equivalent to 1.1 cm. per annum the period of activity of the water system can be calculated at 2,700 years, at least. As the water control practice has not been adopted since the end of the 6th century AD, the gardens are estimated to have existed since the 3rd millennium. The recent excavation of similar shearing systems that had been covered with sediments and abandoned in archaic time show that the Sabean civilisation dates back to even more ancient times. The sharing systems of Marib worked at full capacity during floods, otherwise other water production systems assured drinking water.
Advantages and sustainability
These techniques make more usable land for growing while at the same time creating humus and watering the soils.