# International Association for Hydro-Environment Engineering and Research

IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
 You are here : eLibrary : IAHR World Congress Proceedings : 35th IAHR Congress - Chengdu (2013) : THEME 5 - FLUVIAL HYDRAULICS AND RIVER MANAGEMENT : Comparison and Modification of Methods for Predicting Incipient Motion for Gravel Beds
 Comparison and Modification of Methods for Predicting Incipient Motion for Gravel Beds Author : Shengfa Yang, Xuhui Fu and Jiang Hu In this paper, 13 groups of gravel incipient motion experiment data are obtained and 50 groups of data from 7 researchers are collected. The data contain a wider range of slope (0.05 ? 20%) and grain diameter (1.8 - 45 mm). Comparison is made between the experiment data and the formulas of incipient motion drag force and incipient motion velocity, and the result demonstrates that the two types of incipient motion formulas fail to fully obey the gravel incipient motion law. By selecting the major factors which influence gravel movement and through dimensional analysis and relative analysis of experiment data, gravel incipient motion formula is modified in which the non-dimensional unit width discharge is inversely proportional to the slope. The formula corroborates an assumption proposed by Chien (1999) that gravel non-dimensional incipient motion flow power is a constant of 0.09. Comparison is made between the experiment data and the four incipient motion formulas of unit width discharge such as incipient motion formula in this paper, Schoklitsch (1962) formula, Bettess (1984) formula and Bathurst (1987) formula, and the result demonstrates that the calculated value of incipient motion formula in this paper agree best with the measured value. File Size : 257,843 bytes File Type : Adobe Acrobat Document Chapter : IAHR World Congress Proceedings Category : 35th IAHR Congress - Chengdu (2013) Article : THEME 5 - FLUVIAL HYDRAULICS AND RIVER MANAGEMENT Date Published : 18/07/2016 Download Now