Abstract
There is a growing concern over river environment degradation related to artificial flow control. Many countries in the world are now trying to develop appropriate environmental flow setting methodologies to handle this problem. Leaders in this field are U. S., Australia, South Africa and some European countries. Current methodologies used in those countries are reviewed and categorized into four groups. Most basic methodology is the one based on hydrological indices. Environmental flow requirements are classified into three types according to their objectives. Relationship with flow regime components is now clear.
Availability of hydrological approach is then discussed. The Tennant Method and the Range of Variability Approach (RVA) are applied to Japanese rivers. Result of macroscopic application of the Tennant Method suggested that some action should be taken at least 30% of Japanese rivers to enhance low flow. RVA is tested in the Kitakami River basin and it turned out to be a useful approach to assess the flow regime alteration by reservoir control.
