The size and number of water projects and other development activities which influence the hydrological cycle have reached such proportions that the majority of problems involved extend beyond the boundaries of the traditional disciplines of hydraulics, hydrochemistry, hydrology and hydrogeology. New scientific methods for the solution of the contemporary problems in water management include analogy, operation research, system analysis and cybernetics. The distinctive features of these methods are their emphasis on measurement and on the use of conceptual models described in quantitative terms, the verification of their theoretical predictions, and their awareness that concepts are conditional and subject to growth and continuous change. This new approach should be defined within the framework of water resources management, i.e. within a complex of activities whose objective is the optimum utilization of water resources with regard to their quality and availability and the requirements of society.
