Review of current methods and technologies for measuring water salinity

Saltwater intrusion is the phenomenon where seawater infiltrates inland areas during high tide, leading to soil salinisation with salt concentrations exceeding permissible levels and the depletion of freshwater resources.Given the increasing severity of saltwater intrusion today, coastal regions in our country are currently addressing this issue through a combination of saltwater prevention systems and early intrusion warning solutions.To ensure the effectiveness of these solutions, the method for determining salinity must be chosen to meet specific requirements.In this article, current exemplary methods and technologies for measuring water salinity, including hydrometer, chlorinity titration, a group of optical methods, and conductivity measurement, were systematically presented from principles and measurement techniques to the advantages and disadvantages of each method.The results show that the method of determining salinity based on electrical conductivity is the most suitable, as it offers several advantages such as low cost, high accuracy and reliability, and low energy consumption.The discussion section at the end of the article presents the authors' viewpoints and perspectives on current methods, as well as directions for future research and applications.