Incipient motion estimation of sediment on the Chungliao creek at Liukuei experimental forest of southern Taiwan

In this study, estimating peak flows of different recurrence years at Chungliao creek within Liukuei experimental forest of southern Taiwan was carried out with rainfall-duratiion-frequency and design hyetograph estimations as well as SCS curve number stormflow model.Then, incipient motion of sediment on Chungliao creek was estimated with different current incipient motion methods. The estimated particle sizes of different current incipient motion methods were rather similar for Shieds, Marvis & Laushey, Neill and Yang methods. The estimated particles of Carstens method were less than those of the above four methods. Particle sizes of incipient motions incresased as slopes increased. As recurrence years were 1, 2.33, 5, 10, 20, 25, 50, 100 years, peak flows were 41.4 cms, 49.5 cms, 60.1 cms, 70.1 cms 81.4 cms, 85.4 cms, 98.8 cms, 114.0 cms, and particle sizes of incipient motion of sediments being averaged by Shields, Mavis & Laushey, Neill and Yang methods were 23.9 cm, 26.8 cm, 30.3 cm, 33.4 cm, 36.7 cm, 37.9 cm, 41.5 cm, 45.5 cm. The sensitivity orders of particle sizes of incipient motion responding to slopes under different methods were as follows: Neills at first, Shields at second, Carstens at third, Yang and Marvis & Laushey at last. Particle sizes of incipient motions increased as peak flow increased. The sensitivity orders of particle sizes of incipient motion responding to peak flows under different methods were as follows: Neill at first, Marvis & Laushey and Carstens as well as Yang at second, Shields at last. Overall, particle sizes of incipient motions increased faster than slopes and peak flows increased.