AUTOMATED SEDIMENT EROSION RATE APPARATUS FOR MEASUREMENT OF EROSION RATE OF UNDISTURBED SEDIMENTS Kyu-Nam Hwang 1 , Hong Ryul Ryu 2 , Seung Oh Lee 3 , Yong-Sik Cho 4 1 Associate professor, Dept. of Civil Eng., RCIT, Chonbuk National University (664-14 Dukjin-dong, Dukjin-gu, Jeonju 561-756, Korea) E-mail: khwang@chonbuk.ac.kr 2 Ph. D Candidate, Dept. of Civil Eng., Chonbuk National University (664-14 Dukjin-dong, Dukjin-gu, Jeonju 561-756, Korea) E-mail: ryu1543@chonbuk.ac.kr 3 Assistant professor, School of Urban and Civil Eng., Hongik University (72-1 Sangsu-dong, Mapo-gu, Seoul 121-791, Korea) E-mail: seungoh.lee@hongik.ac.kr 4 Professor, Dept. of Civil Eng., Hanyang University (17 Hangdang-dong, Sungdong-gu, Seoul 133-791, Korea) E-mail: ysc59@hanyang.ac.kr Automated sediment erosion rate apparatus (ASERA) has been constructed and a series of experiments have been performed to verify its efficiency in this study. The replicated results of the noncohesive sediment mixtures for measuring erosion rates showed the excellent agreement among them with an uncertainty of approximately 1%. The experimental results for five different sizes of uniform sediments were discussed and interpreted with the Shields diagram. Showing remarkable results, the efficiency of the advanced apparatus, ASERA, was evaluated to measure the erosion rate of sediments. Key Words: ASERA (Automated Sediment Erosion Rate Apparatus), erodibility, erosion rate, critical shear stress 1. Introduction Accumulated sediments in lakes, rivers and the bottom of the estuaries are generally consisted of cohesive and noncohesive sediments (e.g., clay, silt and sand et al.). These sediments are vulnerable to be eroded and resuspended by the flood wave, tide and wind current and transported due to motion of flow. Fine-grained, cohesive and noncohesive sediments located generally in the upper parts of the bed are apt to combine with serious contaminants. These contaminated sediments and their impact on local environments and 1 201 A-17 Fourth International Conference on Scour and Erosion 2008