再生氾濫原における水質の季節変動とその規定要因に関する事例研究

抄録

Floodplains have been affected by human impacts on a global scale. Restoration projects of floodplain have been conducted all over the world. The Azamenose which locates on middle and lower part of the Matsuura river is one of the projects in Japan. As there is little knowledge about floodplain restoration, it seems to be important to conduct scientific monitoring and estimation on some restoration project sites. The purposes of this study are to examine seasonal fluctuations of water quality in Azamenose, and to identify effective factors of the fluctuations. At first, we observed seasonal fluctuations of water quality (water temperature, water level, pH, DO, nutrients). Secondly, we observed coverage of aquatic plants in the field. The results indicated that the main factors of water quality fluctuations were flood and vegetation. We considered that flood increased nutrients level and decreased water temperature in Azamenose. Moreover, we speculated that DO level decreased drastically in summer due to the rank growth of water chestnut (Trapa japonica).