Water Quality Evaluation With Entropy Weight‒Grey Correlation Technique for Fishing Operation Area in Tianjin, China

ABSTRACT The discharge of domestic sewage and waste oil from fishery activities can cause adverse impacts on coastal seawater in bays and estuaries. The Bohai Sea near Tianjin features strong water closure and weak self‐purification ability. The objective evaluation and analysis of pollution characteristics are crucial for assessing the quality of coastal seawater. This evaluation is essential for the sustainable development of traditional marine fisheries and serves as a powerful tool for government decision‐making. To this end, we constructed an entropy weight‒grey correlation technique for order preference by similarity to an ideal solution (TOPSIS) model (EWGCT) based on the traditional TOPSIS evaluation approach to evaluate the water quality of five fishing ports and operation areas. The spatial distribution characteristics, pollution characteristics, and key impactful indicators were identified via a geographic information system (GIS) and multivariate statistical analysis. The results show that (1) the EWGCT has the ability to rank water quality universally and evaluate it based on the comprehensive impact of all pollution factors; (2) petroleum (PETRO) was affected mainly by the waste oil discharged, and suspended solids (SS), dissolved inorganic phosphate (DIP), and fecal coliform bacteria (FCB) were affected mainly by the domestic sewage discharged; and (3) effective management of fishing vessel discharge is important for ensuring the quality of the seawater environment. By establishing the EWGCT, the reliability and rationality of the evaluation results are verified, which can provide a reference for the formulation of development strategies for coastal cities.