The chloride ion (Cl) can adversely affect an aquatic ecosystem, but it is not clear how Cl moves with runoff and how its transport processes are related to land uses and covers. This study investigated how the loading characteristics of Cl vary depending on storm events and land covers in temperate region. We monitored Cl concentrations in three study watersheds that have the different compositions of urban and agricultural land uses. In addition, a Mass First Flush ratio (MFFn) was determined to quantify the effect of first flush on Cl loading. Overall, the observed concentrations and loadings in this study were found less than those reported in the cold northern regions. The monitoring data showed that Cl concentrations and loads observed in an urban watershed were significantly larger than that of a rural watershed. The results suggest water management plans to focus on urbanized areas and their storm water to efficiently reduce chloride loading to downstream waterbodies. However, a further study is recommended to identify the sources and pathways of Cl loaded to waterbodies.


  • Cl loading varies depending on storm events and land covers.

  • The first flush effect on Cl loading was strong in the urban storm runoff.

  • The urban watersheds had significantly larger Cl loads than the rural watershed.

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