No abstract

A general formula is presented to simplify many existing methods of hydrologic frequency analysis. It is shown that the methods differ only in the definition of the frequency factor contained in the formula. The derivation of the formula is simple, and does not require familiarity with advanced mathematics and statistics. The application of the formula is practical so that it provides a valuable tool for the hydrologic design of hydraulic structures.

The optimization of operating policies of multiple unit and multiple purpose water resources systems by traditional dynamic programing with the use of high speed digital computers encounters two major difficulties: memory requirements and computer time requirements. This paper presents an iterative method that can ease the above difficulties considerably. The method starts with a trial trajectory satisfying a specific set of initial and final conditions and applies Bellman's recursive equation in the neighborhood of this trajectory. At the end of each iteration step a locally improved trajectory is obtained and used as the trial trajectory in the next step. The method has proved particularly effective in the case of so‐called ‘invertible’ systems. The merits of the proposed approach are demonstrated through its application to a four‐unit, two‐purpose water resources system. To save computer time the example is restricted to deterministic inflows.

No abstract

The movement of a rainstorm determines the spatial and temporal distributions of the rainfall over a watershed and hence affects the characteristics of the flow on the watershed. In this study the importance of the movement of rainstorms on the time distribution of the surface runoff from watersheds is demonstrated through the use of a laboratory watershed experimentation system. Experiments were performed on the impervious square watershed for 2 rainfall intensities, 4 surface slopes, and 14 rainstorm velocities. Analysis of the mechanics of water flowing on watersheds is attempted to explain the influence of movement of rainstorms on the characteristics of surface runoff hydrographs.