Modeling of the role of tideland in eutrophication reduction in Mikawa Bay, Japan

Abstract

Nutrient's over-enrichment has resulted in major changes in the coastal system of Mikawa Bay. One important factor which affects eutrophication is decrease of the area of tide land, caused by the change of land use in coastal area. This study examines, by using an eutrophication model with benthic system, to what extent water quality in Mikawa Bay can be improved with the tideland. The benthic system consists of the five state variables of benthic alga, meiobenthos, suspension feeder, deposit feeder and bacteria. Obtained results are summarized as follows:(1) the model simulation acceptably well reproduced seasonal variations of the benthic variables in Mikawa Bay, (2) changes of water qualities by nutrient-reduction scenarios, with and without the benthic system, were analyzed and contribution of the benthic system to decrease of chlorophyll-a concentration was quantitatively evaluated, and (3) the tideland in Mikawa Bay was estimated to be worth, at its largest, 30% reduction of the T-N (total nitrogen) input caused by sediment resuspension.