**4. Conclusions**

From this study, we demonstrated how spatially benthic macroinvertebrate communities were closely related to surrounding environmental constraints such as the surrounding land use and ambient water quality. The present study depicted that land-use coverage is a primary factor and water quality is a secondary factor to evaluate benthic macroinvertebrate communities. Our analysis also showed that the water quality change in the Seomjin River basin was mainly influenced by summer precipitation, thereby inducing a community shift of benthic macroinvertebrates in Korea. In addition, we estimated and compared quantitatively the influence of summer rainfall on a spatial scale, and then linked those deviations with the surrounding land-use coverage. The data ordination explicitly accounted for 61% of the explanatory variability in benthic macroinvertebrate communities. We stress that land-use information is primarily an e fficient proxy of ambient conditions to determine benthic macroinvertebrates in a stream ecosystem. Finally, our study highlights that land-use information, which is easily obtainable, is very helpful for delineating the spatial distribution of benthic macroinvertebrate communities in stream ecosystems.

**Author Contributions:** Conceptualization: D.-K.K., H.J., K.P., and I.-S.K.; Methodology: D.-K.K. and H.J.; Formal Analysis: D.-K.K. and H.J.; Investigation: H.J. and K.P.; Resources: I.-S.K.; Writing—Original Draft Preparation: D.-K.K.; Writing—Review and Editing: D.-K.K. and I.-S.K.; Supervision: I.-S.K.; Project Administration: I.-S.K.; Funding Acquisition: I.-S.K.

**Funding:** This research was funded by the National Research Foundation (NRF) of Korea, gran<sup>t</sup> number NRF-2018R1A6A1A03024314, and was also supported by the project 'Stream/River Ecosystem Survey and Health Assessment of Korea Ministry of Environment (KMOE).

**Conflicts of Interest:** The authors declare no conflict of interest.
