Proposal of new measures for flow and water quality control in urban coastal seas and verification of their effects

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H03312
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Hydraulic engineering
• Research Institution: Osaka University
• Principal Investigator: Nishida Shuzo 大阪大学, 工学研究科, 教授 (40172663)
• Co-Investigator(Kenkyū-buntansha): 入江 政安 大阪大学, 工学研究科, 准教授 (00379116) ; 中谷 祐介 大阪大学, 工学研究科, 助教 (20635164)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 閉鎖性海域 / 港湾 / 水交換 / 栄養塩循環 / 流況制御 / 発電所取放水 / 環境影響評価

Outline of Final Research Achievements

The possibility of improving the water environment in highly enclosed coastal sea by actively using the water discharge of factories and plants was examined.
From the analysis of the factories and plants data, it was found that the flow rate discharged from them located in the coastal area in the head of Osaka Bay is comparable to the river discharge into the bay, and the thermal discharge of the power plant is about 80% of the total discharge. It was suggested that it could be used to improve the flow structure in the coastal area. Field surveys and numerical simulations were carried out in the sea area around the power plants to predict the effects of changes in the water intake and discharge method and flow rate on the water exchange and water quality in the port area. The results showed that changes in the flow structure (residual flow system) and promotion of water exchange were observed, but it was clarified that the effect depends greatly on the scale of the port area.

Free Research Field

環境水理学

Academic Significance and Societal Importance of the Research Achievements

海域の負荷削減施策による海域の環境偏差の問題や生物生産性の低下など、いま日本の都市沿岸域が抱える新たな課題に対して、従来の水質の規制・管理ではなく、都市沿岸域に特化した新たな環境改善策となることが期待できる。また、環境の「保全」を目的とした事業アセスメントの課題を抽出し、これまで積極的な利用ができなかった事業所からの取放水を利用した停滞水域の流動・水質の制御による水環境の「再生」と「創造」と一体化した、アセスメントの必要性と重要性を提示した。