Abstract
To improve the smell and landscape problems caused by algae growth in Edo Castle Outer Moat (Sotobori), several countermeasures were developed and the effects on the water quality and life cycle costs were evaluated. For the scenario development, previous case studies and existing water sources in Tokyo were reviewed. Besides, the water balance and pollutant loadings were estimated. Based on the data, six countermeasure scenarios were developed and the water quality was simulated using the Ecosystem Model. The result showed that 9,461 m3/d water introduction can avoid the algae growth in summer. The life cycle cost of the best scenario where a sattelite wastewater treatment plant is built in the Sotobori Ground was estimated at 2.0×102 million yen/y. This value can be comparable to the other existing moat-improvement projects.
