Effect of Various Factors on Temporal Variation in Sedimentation Rate over the Past 100 Years : a Case Study of Sajapyeong Catchment, Korea

Sediment profiles of various sedimentary environments can provide important information about hydrological changes, including human activity, precipitation, and so on, in watersheds. This study reconstructed sedimentation rate fluctuations using exPb-210 dating method for sediment cores collected from slackwater deposits in the Sijeoncheon Stream flowing through Sajapyeong wetlands, and analyzes various factors in the watershed that affected the sedimentation rate fluctuations. The results of the analysis of the sedimentation rate fluctuations were divided into three periods (P1: 1912-1963, P2: 1969-2000, P3: 2001-2019), respectively. These three periods were similar to the three periods in the history of reconstructed land-use change: the quasi-natural period, the agricultural deepening period, and the anthropogenic channel adjustment period. The sedimentation rate peaks in each period were attributed to precipitation with a large recurrence period. In particular, earthquakes occurred immediately after anthropogenic river channel adjustment during the period of enormous increase in sedimentation rate after 2015. According to these results, it seems that land use change in the watershed affected the change in the average sedimentation rate, and heavy rainfall, anthropogenic river control, and earthquakes caused a large increase in the sedimentation rate in the short term.