Definition characters description and diffusion
In arid areas and in the presence of temporary underground flows, underground dams are built sunken into the bed of the stream. The dams consist of several series of barriers of stone block sediment and act as dams to the silt accumulation in which micro flows of water are intercepted and detained upstream of the dam. The sediment fills the entire height of the dam, thus creating a series of high platforms with steps suitable for cultivation.
General characters description and diffusion
Dams of this type were used in Baluchistan in very ancient times prior to the Harappan civilization (III millennium) Barriers of a larger size and of this same culture were rather ‘diversion dams’ (see). The technique is still in used in the Sahara. Along the wadi Saura Qsur in the north at the foot of the Saharan Altas imposing systems of ancient underground dams are visible. In Ghardaia, Algeria at the so-called dam of Beni Usguen is actually a massive underground dam. The dam will not hold a water basin, but instead it holds soils with the palm trees and crops. In it are also dug wells that allow you to draw the water retained by the dam sediments. Only during floods that occur every 10 years are there flows of water that overflow the top of the dam equipped with functional barriers to blow the flow of debris.
Advantages and sustainability
These sunken dams act to catch water from microflows and are then held upstream of the dam. Sediments from the water then form platforms which become then suitable for cultivation.