Study of fluvial geomorphic development of the middle and upper reaches of Yeongdeok Songcheon River

In this study, we investigated the river development process in the middle and upper reaches of the Songcheon River in Yeongdeok-gun, Gyeongsangbuk-do, Korea, with a focus on tectonic movements. The middle and upper reaches of the Songcheon River follow along the Yeongdeok Fault, where misfit streams have developed along these curves. The results of the study showed that the upper reaches of Songcheon is eroded along the fault damage zone formed around the Yeongdeok Fault, and a meandering area is formed between two faults running parallel to each other. The Songcheon channel flows in a relatively straight line near the fault, with a broad valley bed, while a meandering section develops between the faults. In the meandering reach of the studed river, the channel and valley width narrows, and the channel gradient steepens. Additionally, In the Songcheon basin, more than three levels of river terraces have developed. The lower part of the low-level terraces contains fluvial deposits from the Last Interglacial period, while the upper part is covered by colluvium of last glacial maximum period. It is inferred that downward incision occurred thereafter. In conclusion, channel formes of the middle and upper reaches of the Songcheon River were mainly controlled by the influence of the movement of Yeongdeok Fault, with subsequent modifications driven by climate change.