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In this study, the existing Water Resources Agency MOEA observed rainfall data of Da-Pu, Zhong Keng-3, Xi-Kou-3, Bei-Gang (2), and Hu-Shan Reservoir in Beigang River Basin, and the existing observed discharge and sediment transport data of Bei-Gang-2, Xi-Kou, and Tu-Ku Bridge stream-gaging stations were adopted. The Mann-Kendall (M-K) trend test and analysis was employed, with the 5% significant level (α=5%). In addition to using an anomaly map to assist in determining changes in the basin rainfall and discharge trend, the discharge and sediment transport relationship curve and empirical formula were also established. Finally, with September 21, 1999 as the time point, the analysis of variance in terms of sediment transport before and after the 921 Earthquake was carried out. The M-K Trend analysis results of the annual rainfall, annual 1-day max rainfall, annual 2-day max rainfall, and annual 3-day max rainfall selected in this study. The results show that the rainfall data in respective rainfall stations in Beigang River Basin has no significant trend. As for, the M-K trend analysis results of the Beigang River Basin annual runoff, maximum daily discharge, daily discharge show that the annual runoff of Beigang (2) Stream-gaging Station (1941~2020) and the minimum daily discharge of Tu-Ku Bridge Stream-gaging Station (1984〜2020) show a significant downward trend. Other than the minimum daily discharge of Beigang (2) Stream-gaging Station (1941~2020), the annual runoff and the minimum daily discharge of the Xi-Kou Stream-gaging Station (1957~2020), and the maximum daily discharge of Tu-Ku Bridge Stream-gaging Station (1984~2020) show a significant upward trend, the rest of the discharge data show no significant trend change. This study shows that the daily mean discharges and sediment transport of the respective observatories in Beigang River Basin have a good rating curve relationship. The results of the rating curves drawn before and after the 921 Earthquake in 1999 show that the rating curves of the respective observatories before the 921 Earthquake are relatively steeper. After a thorough observation of the constant discharge intervals of the respective observatories, the sediment transport at a specific discharge (Bei-Gang-2 Station reaching 50C.M.S, Xi-Kou Station reaching 100C.M.S, Tu-Ku Bridge Station reaching 100C.M.S) before the 921 earthquake exceeds the unit runoff sediment transport after the 921 Earthquake. This indicates that the 921 Earthquake has caused an impact on the amount of sediment yield on the slope of Beigang River Basin.
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