With the recent radical changes imposed on the Egyptian water system by the Southern Valley Development there is a clear need for better water resources management. The entire project water planning relies on discounting the old Nile valley and delta water requirements. A package of five computer models was established in 1993 to be integrated within the improved water resources planning enterprise in Egypt. The core of this task is the high level simulation Operation and Planning Distribution Model (OPDM).The model is shown as a reliable water management tool. The model is successfully used to simulate the water distribution mechanism within a highly dendritic scheme in the Nile delta. The model is utilised to perform some useful analysis on the relative significance of the various parameters involved in the water distribution practice. Issues including night-time irrigation, free cropping pattern, water shortages, and reduction of rice areas can be studied. The technique enables both factual and hypothetical policies to be addressed within the course of water planning. Optimal strategies can be defined thereof.