Abstract
At Ara River estuary, the right side bank has a tidal flat. However, the left side bank, being protectedwith concretewall and keeping deeperwater, does not have a tidal flat.At the high and lowtide, nitrate nitrogen concentration in the right side bank was compared with that in the left to evaluate the restoration of water quality by a tidal flat. The observed results indicated that nitrate nitrogen concentration in the right side bank where a tidal flat appearswas remarkably lower than the left at the low tide, although the concentration values were similar at the high tide. Also based on a significant difference in nitrate nitrogen concentration of standing water in a tidal flat and of stream water, the effects of tidal flat on restoringwater qualitywere highly evaluated in this study.
