Les puits nabatéens de Mad in āli (Arabie Saoudite)

Close to the monumental graves, numerous ancient wells, some of which reach a depth of 18 m, were found in the Nabatean site of Mad     in     āli     . Their fascinating study was begun by the author, a well-known speleologist. It required a geomorphological and hydrological approach of the site which established the groundwater level and piezometric contours. Furthermore, research was conducted on the palaeoclimates and present-day pluviometry, which has concluded that the fall in the groundwater level since antiquity is mainly the result of modern exploitation. Since 1975 the high-yielding submerged pumps have provided intensive irrigation to the important agriculture of el Hijr, close to the Nabatean site. The wells, their construction, their shape and ancient mechanism are described in this paper.