ESTIMATION OF RESERVOIR YIELD AND STORAGE DISTRIBUTION USING MOMENTS ANALYSIS

Formulations are presented for the first and Second moments of the sto rage state distribution in terms of the moments of the inflow distribu tion. These expressions give explicit consideration to the maximum and minimum storage bounds in the reservoir system, a feature which is no t incorporated in some existing formulations based on traditional cont rol, theory. Using these formulations, solutions are derived for the m ean and variance of the storage state variables for specified drafts, using a non-linear solver. The approach presented does not involve any discretization of the system variables. Estimates are obtained for th e probability of spills and deficits (or alternately reliability). The se estimates are used for approximating the storage state distribution using a double bounded density function. The results of an annual rel iability study and estimates of the storage state distribution for a s ingle reservoir system, based on the formulations proposed, are presen ted and compare favourably with corresponding results derived from sim ulation.