衛星データによる濁りの平面分布を活用した濁り拡散解析の検討
埋立て等の海洋工事では濁りが発生することから，濁りの拡散を精度よく予測できれば，事前に濁りの影響を確認し，生態系に配慮した施工ができる。海洋の濁り拡散は流動解析による予測が有用であるが，濁り拡散解析の初期値が不明であることから解析精度が確保できない。本研究では，工事に活用可能な濁り拡散予測の精度を確保するために，濁りの平面分布をリアルタイムに取得し解析初期値に取り入れる手法の開発を目的とし，衛星データを活用した解析を実施して手法の妥当性を検討した。大阪湾を対象とした衛星データから取得した濁り分布を初期値とした拡散解析の結果，日単位で濁りの初期値を更新することで日々の濁り分布の精度が確保できることが示され，濁度の低減機構（例えば濁度成分の沈降）などを拡散解析に設定することで解析精度を向上できる可能性を確認した。
キーワード：濁り拡散予測，衛星データ，可視域バンド，沈降，埋め立て工事
＊１ 技術センター 社会基盤技術研究部 水理研究室
Study on Turbidity Diffusion Simulation Using Satellite Data
In marine construction in coastal areas such as reclamation work, diffusing turbidity occurs If this turbidity dispersion can be accurately predicted, its influences can be determined in advance, thereby enabling construction that takes into consideration the coastal ecosystem. Even if the numerical simulation of current flow was to be accurately conducted, the accuracy of turbidity dispersion cannot be ensured since the initial value of the turbidity distribution is unknown. The objective of this study was to develop a method to obtain the planar distribution of turbidity in real time to be used as the initial condition of turbidity dispersion predictions, in order to ensure the accuracy of such predictions that can be used practically in coastal construction work. In this paper, the validity of this method was examined by using the turbidity distribution obtained from satellite data as the initial value. From the results of dispersion analysis (in which the initial value was obtained from the satellite data for Osaka Bay), it was found that accuracy of the turbidity distribution can be ensured by updating the initial value of turbidity daily. It was also confirmed that the accuracy can be improved by setting up turbidity reduction mechanisms (e.g., sedimentation) in the dispersion simulations.
Keywords: turbidity diffusion prediction, satellite data, visible band, sedimentation, reclamation work
*1 Hydraulic Research Section, Infrastructure Technology Research Department, Taisei Advanced Center of Technology