RUNOFF MODEL SELECTION BASED ON THE EQUIVALENT FREQUENCY TRANSFER FUNCTION AND DELAY SYSTEM

Abstract

The equivalent frequency transfer function (EFTF) has originally been used by control engineers to describe dynamics non-linear elements such as threshold saturation. Previous study by authors had derived EFTF between rainfall input and discharge using distributed parameter runoff models. Moreover, authors had pointed out that the obtained EFTF is approximated by the delay system. It is considered that the general description of channel flow is the dynamic wave equation. This paper makes clear that the dynamic wave equation is characterized by two non-dimensional parameters, K1, K2. In the case of K1→∞, the dynamic wave equation approaches the diffusion wave equation. Moreover, the diffusion wave equation approaches the kinematic wave equation when K2→∞. In this paper, authors focus on the diffusion and kinmatic wave equation. This paper finds the critical value of K2 which divides the both equations based on parameters include in the delay system for the both equations.