Author(s): Y. Imanishi; H. Matsuzaki; N. Shirakawa; N. Tamai
Linked Author(s):
Keywords: Ecological flushing discharge; Time series analysis; Deterministic chaos; System dynamics; Fuzzy control
Abstract: Water supply of Tokyo Metropolis is heavily dependent on transfer from the Tonegawa River basin. The Tonegawa River serves as a major source of water for south part of the Kanto region where total population amounts to 32 millions. Main seven multipurpose reservoirs are all located in the upstream catchment of the Tonegawa River basin. In recent years, environmental and ecological aspects of reservoir construction and operation have attracted higher and higher concern. Special attention should be paid to ecosystem in rivers. It is necessary for benthos in rivers to flush silt deposited on cobbles according to experiences of ecologists and inland fishermen. This discharge which keeps desirable condition of substrate is called ecological flushing discharge in this paper. The ecological flushing discharge is necessary for living things in rivers. The purpose of this study is to derive a network operation rule among the reservoirs in order to enhance instream flow to provide the ecological flushing discharge in the upper Tonegawa River basin in Japan. The framework consist of the following three steps, 1) the analysis and predictions of the chaos in discharge, 2) the route selection by system dynamics, 3) the control of water transfer by the fuzzy theory. It is shown that occurrences of small-scale or medium-scale floods are increased by using proposed operation for the ecological flushing.
Year: 2003