This thesis describes a theorectical study and its computational application for the operation of hidraulic plants within an electric power system. It is besed on the dynamic equations of the system, considering the parameters wihich influence a multi-reservoir (water inflows and demended power both aleatory quantities, transit time of water between two reservoirs).These equations are a first order diferential equations, which are aproximated by a set of diference-equations, in order that in a given instant t, the water transit-time problem between two reservoirs, t(i), is presented. The system in an instant t will depend on (t-l) and (t-,t(i)). Then the recurrence equations with noninstantaneous transmission are transformed in a set of state variables, these represent intermediary states between the reservoirs, so that, increasing the number of state equations the time delay in is eliminated. Once the mathematical model is defined, the objective is to maximize the stored water quantity satisfying an aleatory demand power and the restrictions on hidraulicity and instalations. The relaxation and equal-intervals methods are used the computer programs were implement for the IBM 370-165 system of the PUC/RJ.