Abstract: Algeria is located in the category of countries poor in water resources, fast silting up passing the 65 millions of m3 year 1. It reduced considerably storage capacity of many reservoirs. In order to remedy several inconveniences of dredging used mainly in Algeria, we propose a method that is like the Water Injection Dredging (WID). It consists in injecting water resulting in an overtaking of material resistance, from where it appears a failure area. Underflow provoked by opening of outlet gate acts like a flushing. It was possible to us to value volume recovered of restraint with a simplified theoretical formulation of injection and modelling of behaviour hydromechanics of injected soil massifs and resolution equations gotten by finite element. Survey is completed by a scale model study. One could provide interesting indications on efficiency of method proposed while showing existence of critical values for pressure and speed of injection; values open to several technological interpretations.