Abstract
In Japan, river training projects designed for efficient flood control, have turned meandering rivers into straight and monotonous concrete-lined channels. Although these measures have been effective to mitigating flood damage, they have had considerable adverse effects on the natural environments of rivers. In its 1981 report, the River Council, an advisory council for the Minister of Construction (now the Minister of Land, Infrastructure and Transport), stressed the importance of managing the river environment so that the flood control, water utilization and river environment goals can be achieved harmoniously. In 1990, a government notification concerning the "nature-oriented river works" was issued, and "nature-oriented river works" measures designed to "conserve or create scenic natural landscapes" were taken on a pilot project basis in many parts of the country, taking natural riverine habitat requirements into consideration. In 1997, the River Law was amended, and "improvement and conservation of river environment" was incorporated as one of the goals of the law. Under this amendment, efforts to conserve and restore river environments were upgraded, and measures such as full-scale implementation of "nature-oriented river works" projects, amendment of related standards and the establishment of Aqua Restoration Research Center have been taken. Most of the conventional "nature-oriented river works" projects had focused only on limited aspects of channel protection or improvement, such as the conservation and restoration of riparian zones, conservation and restoration of channel forms in certain river sections, conservation and restoration of streamside woods and the reduction of the environmental impact of river improvement works. This paper introduces two pioneering river plans (the Kitagawa River in Miyazaki Prefecture and the Otogawa River in Aichi Prefecture) drawn up from the viewpoint of the conservation of the natural river environment. This paper also describes the concept and scope of "nature restoration projects" (instituted in fiscal 2002) designed primarily to restore the natural environments of rivers, lakes and ponds, and wetlands lost as a consequence of human activities. Finally, the paper discusses the roles that have been played by "nature-oriented river works" projects, as well as the next challenges to be addressed in connection with the conservation and restoration of natural river environments.
