An effective evaluation methodology for assisting in water resources development planning is developed. A new model was contemplated for solving two principal problems associated with the present practices of water resources development planning - the considering of individual development as isolated entity and the using of the benefit and cost ratio as the only analysis in the evaluation process. The model was developed by using game theory concepts. The principal tactics employed in the model are the competitive measuring between benefit categories and the competitive evaluation of the development objectives. The procedures used in the model enables the identifying of the following: the overall system of water resources development as well as the individual or local development, the relationship and priorities of developments in different locations and between various purposes of development. The model is also able to recognize the competitive nature of water resources development and to augment some new measurements. The model as a whole provides a new approach for summarizing a large number of data into a simple and meaningful form in order to formulate systematic recommendations for the decision-maker. (Modified author abstract)