Development of an analytical model of river response

A physically based, analytical model of river response is developed. RIVERMOD was designed to aid in the prediction of gravel-bed river channel response to variations in the water and sediment regime. RIVERMOD is a procedure which iteratively solves the governing equations which describe the movement of water and sediment through a channel, calculate the distribution of the boundary shear stresses, and assesses the bank stability. To arrive at a unique solution an additional closure hypothesis is required. The hypothesis of maximum sediment transport potential (MSTP) is proposed which states that a channel will develop a cross sectional geometry such that the potential for sediment transport is a maximum. The MSTP hypothesis is shown to be generally equivalent to the concept maximum transport capacity suggested by White et al (1982), and the minimum stream power theories of Chang (1979) and Yang (1976). RIVERMOD is used to demonstrate the response of the channel geometry to variations in the bankfull discharge, sediment load, and the properties of the bank sediment. Preliminary verification and testing indicate that RIVERMOD models the geometry of existing gravel rivers reasonably well. The river channel responses predicted by RIVERMOD are shown to agree with qualitative observations and empirical regime equations. The analysis in this study indicates that the bank stability exerts a strong control on the geometry of alluvial channels. Further development of RIVERMOD is suggested.Applied Science, Faculty ofCivil Engineering, Department ofGraduat