北海道トキサタマップ湿原の保全対策工(<小特集>水環境)

概要

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Recently, mires have been regarded as conservation subjects, with understanding of the various roles. Tokisatamappu Mire is a part of Yufutsu Mires located in the Ishikari Lowland, Hokkaido. In order to conserve the mire from the river improvement, the relationships between the groundwater levels in Yufutsu mires and the vegetation were investigated. The results show that the difference in annual mean groundwater levels between Phragmites australis and Alnus japonica, indication of drying mire, is some 10 cm. To keep the groundwater levels, four countermeasures including a cutoff wall were proposed and constructed based on the finite element analysis. Major part of the groundwater levels were successfully maintained, and the water level of Lake Utonai, designated wetland under the Ramsar Convention and located downstream of the mire, has also recovered to that in 1973. Additionally, countermeasures to prevent the influence of construction work on mires are compared.
2007-08-01