SUMMARY
This paper examines for the first time the operation of one of the oldest hydraulic systems. Designed from a series of different types of works which are used to wipe out the floods coming from the Touzouz River and to irrigate the western palm grove (Gharbia) of Ghardaïa. Several work missions were carried out during the period: 2000-2020 in the oasis of Ghardaïa in order to understand the functioning of the great ancestral development of Touzouz. It emerges from this study, that this development is composed of a large regulation dam, a groundwater recharge dam and several hydraulic structures intended for the collection of runoff water. The development that we have called "I.R.S Development" and which works according to the priority: Irrigation, Recharge and Security.