SUMMARY
This paper examines the problems that have contributed to the degradation of the two millennial irrigation techniques; it is foggara and ghout. This study was conducted during the period: 1990-2019 in the oases of Touat, Gourara, Tidikelt and Souf. Investigations and surveys were conducted with the ksourienne population, the owners of foggaras and ghouts. The results obtained show that the deep drilling carried out in these regions is the main cause of the decline of a hydraulic heritage. If the foggara is abandoned following the drawdown of the tablecloth. On the other hand, for ghout it is the rise of the water table which has caused the decline of this hydraulic heritage.