RIVER ENGINEERING ADAPTATIONS AGAINST THE GLOBAL WARMING−TOWARDS GENERALIZATION OF CLOSE-TO-NATURE RIVERS

Abstract

  Firstly, as a representative realization of water-related disasters due to the global warming, emphasis is placed on the importance of river maintenance works as well as river improvement works for reducing flood disaster damages in Shikoku Island that was struck by 6 severe typhoons in 2004. Secondly,a dynamic equation (Fukuoka equation) describing a relationship between dimensionless river width, dimensionless depth and dimensionless discharge was derived on the basis of data of natural rivers in Japan and Canada and the first class rivers in Japan. Fukuoka equation derived thus suggests that a desirable river cross section for flood control and river environment shoud be a cross-section shaped like a ship bottom and dimensionless sediment transport rate be shown to be regulated by the same mechanism as the determination of dimensionless width and depth of the stable river.
  Finally, the framing of comprehensive plan of close-to-nature rivers for the harmonization of flood control and river environment is discussed as well as methods of river engineering adaptation in the global warming age.