Several wells where built in Dumat Al-Jandal and reflect and advanced irrigation management system. These wells are dated from the Nabataean period more than 2000 years ago. The wells are impressive structures all having a name, often that of the owner’s. Built of horizontal courses of irregular size stones, they generally measure between 3 and 6m in diameter, even though they are not all perfectly round. The wells often have a corbelled structure at the top, made of long blocks protruding from one side of the well, standing over the central void. These structures presumably facilitated drawing water by using a system of ropes (pulled by camels), as is the case for example at Bi’r Haddaj, in Tayma. The wells of Dumat Al-Jandal differ substantially from those found at Madain Salah, by the presence of external stairs (rather than simple steps cut in the walls of the well), and those of the vicinity, like Sisra Well in Sakaka, known for its spiral staircase dug inside the well. At Dumat Al-Jandal, some wells have a staircase integrated into their masonry, entered from outside the well. These staircases led to openings at regular heights inside the well that provided access for cleaning and necessary repairs. Preliminary study of the hydraulic system in the oasis has confirmed that the wells are positioned above underground channels. An aerial photograph taken in 1964 shows many lines of wells oriented east west roughly in the direction of the dried up lake in the south east of the depression. Wallin, who visited the oasis in 1845, described the presence of very well built underground aqueducts of stonework, big enough for a man to stand up. At that time, they extended into areas devoid of cultivation or settlements. The system was widely renovated in the mid-19th century, but is now largely in disuse and filled up with sand or rubble.
