Abstract
The purpose of this study is to develop a new enhanced IDP (Incremental Dynamic Programming) model which is suitable for analysis of operation policies of multipurpose and multi-unit water resources system. The proposed new IDP approach deals with the optimization of trajectories is applied to a four reservoir system in the Nakdong River. The results of optimization in system operation show significant benefits. From this optimization two kinds of benefits are obtained; increasing benefit of domestic, industrial, irrigation, power generation water supply and reduction the computing time.