Unsteady Flow Model for Forecasting Missouri and Mississippi Rivers

Abstract

Abstract : The objective of this paper is to present methods that can be used to estimate the quantity and gradation of sediment produced from a watershed. These values are necessary for mobile boundary hydraulic modeling and other sedimentation studies. These quantities are needed for designing flood control channels, estimating sediment deposition in reservoirs or navigation channels, and evaluating the sedimentation impacts of proposed projects or land use modifications. Considerable information is available for the estimation of sediment yield from a watershed. These methods use both empirical techniques and land surface erosion theory. The same is true for quantifying sediment transport and sorting processes in rivers. This paper focuses on procedures for using land surface erosion computations to develop the inflowing sediment load for a river sedimentation model, specifically, HEC-6. The limitations of currently available methods and their ranges of applicability are presented and procedures for evaluating computed results for watershed erosion and sediment transport modeling are described. Included herein are the results of an assessment of numerical models for the prediction of land surface erosion. It was concluded from this assessment that these models have not yet evolved from the experimental/developmental phase to routine engineering use. Therefore, this paper presents a suggested strategy for the use of several traditional methods of computation of land surface erosion to prepare inflowing sediment loads for the operation of HEC-6.