EFFECT OF SALT WEDGE INTRUSION IN KUSHIRO WETLAND CONSIDERING SEA LEVEL RISE

Abstract

This paper describes the effect of sea-level rise (SLR) on the salt wedge intrusion in terms of ecological system in Kushiro wetland. Kushiro wetland was registered by Ramsar Treaty and the largest wetland in Japan. A previous study demonstrates that the salt wedge intrusion may not affect ecological system of Kushiro wetland, such as loss of freshwater plants along Kushiro River. However, it is revealed that SLR may occur in the end of the 21st century, which enhances the increase in the distance of the salt wedge intrusion along Kushiro River and the loss of endangered species of Kushiro wetland along Kushiro River. This study thus aims to investigate the influence of the salt wedge intrusion on freshwater plants along Kushiro River, and to clarify the salt wedge intrusion when SLR occurs due to climate change. We attempted to investigate the influence of SLR on endangered species along Kyu-Kushiro River in which sea water is likely to intrude up to about 8 km from the river mouth. As results, it is suggested from field observations that salinity may decrease freshwater plants along Kushiro River, and it clarifies the possibility that the salt wedge intrudes Kushiro River due to SLR by using 3D hydrodynamic model, Fantom3D.