河川水位実時間予測手法の開発とその遊水地樋門操作への応用

Abstract

A real-time stage prediction system which takes account of backwater effect is developed. The system is made up of a real-time runoff prediction system and a flood routing system. The real-time runoff prediction system is used to forecast the discharge which flows into the upstream end of a channel reach.This system is based on the filtering and prediction theory developed by Kalman and others. A lumped runoff model is transformed into a stochastic model by incorporating noise terms.The resulting stochastic differential equations are solved by an iterative difference method with the aid of a statistical linearization technique. In the flood routing system, the flow of the channel reach is modeled using the one-dimensional equations of unsteady flow and these equations are solved with the four-point implicit method.The upstream boundary condition is given by the predicted discharge and the downstream boundary condition is given by the stage-discharge relationship as provided by the rating curve. As a case study, this system is applied to the prediction of the stages at the sluice ways located along the Ueno Retarding Basins.