Spatio-temporal dynamics of physical habitat of gravel rivers - Integrated simulation model of riverbed environment -

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04612
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22040:Hydroengineering-related
• Research Institution: Gifu University
• Principal Investigator: Harada Morihiro 岐阜大学, 流域圏科学研究センター, 准教授 (00647042)
• Co-Investigator(Kenkyū-buntansha): 三輪 浩 鳥取大学, 工学研究科, 教授 (70190832) ; 永山 滋也 岐阜大学, 流域圏科学研究センター, 研究員 (70540558)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 河床環境 / 河床変動 / 生息場寿命 / 石礫床河川 / 砂州 / Physical habitat

Outline of Final Research Achievements

This study focuses on the middle and upper reaches of rivers, where sediments of a wide range of grain sizes form the topography and the river environment is shaped by the transport of sediments in grain size clusters in response to flow fluctuations. This study clarified how the "riverbed environment" of rapids, which are highly productive habitats for aquatic organisms, changes in response to increases or decreases in stream flow, through flume experiments and field surveys. Based on these findings, the "Integrated simulation model of riverbed environment" was improved to simulate both riverbed fluctuations and the riverbed environment simultaneously. Furthermore, we proposed the concept of "flow stage," which is an indicator of riverine environmental change based on flow rate for each river section. As an example of application of the integrated model, the model was applied to a method for evaluating suitable spawning habitat for ayu Plecoglossus Altivelis.

Free Research Field

水工学

Academic Significance and Societal Importance of the Research Achievements

本研究の成果は，河川管理において治水と河川環境保全を両立することに資する．近年極端な豪雨が増加する中で，河道内の土砂を掘削して河川断面を大きくするなどの工事が増加しつつある中で，例えば，保全対象とするアユの産卵場がどこに存在するのかを，シミュレーションにより抽出することができる．また，河川区間ごとに，どの程度の規模の洪水の際に河道内で生じる変化の指標となる「流量ステージ」を用いることで，洪水後に河川環境に生じている変化を予測することができ，治水と環境を両立した河川管理への応用が可能である．