| The objectives of this thesis are to statistically study flow resistance and stable channel design, and to experimentally study the effects of accelerating and decelerating steady open-channel flows on the bed shear stress, over gravel and cobble materials.;Two different flow conditions were considered, namely uniform and nonuniform. For the uniform flow, 280 stable rivers through out the world were selected from the literature. For the non-uniform flow cases, 43 velocity profile distributions were measured.;The non-uniform flows, in this study, are confronted to the boundary-layer theory and compared with St-Venant's and zero pressure gradient methods of prediction.;The following conclusions are proposed: Uniform flow case. (1) Flow resistance estimation. According to this study, the existing methods fail to correctly predict the flow resistance. A suggested method, which considers the effect of Froude number and sediment mobility parameter, gives a better estimation of flow resistance than existing ones. (2) Stable channel design. Two kinds of formulations are considered for stable channel design. The first group consists of simple formulations insufficient for accurate prediction. The second group of formulations is more complex, but leads to spurious correlation. Consequently, the available data base on bulk uniform flow characteristic leads to formulations that are either unsatisfactory or unrealistic. The application of estimated bed shear stress by using boundary layers concept can improve considerably the hydraulic geometry of stable channel such as flow depth and channel slope. |
