Application of a 1-D numerical model to estimate the sediment transported along a river

Abstract

Natural rivers tend to adjust their plane shape and longitudinal profile in order to assume a configuration compatible with the changing hydraulic and man-made constraints. The causes of these bed variations are related to changes in independent river channel variables (increase in water discharge, decrease in sediment discharge, etc..) or to changes in river slope. River bed degradation and aggradation, often occurring as result of river morphological changes, modify the longitudinal bed profile of the river and the amount of sediment transported along the river until to reach the outlet. As an example, the construction of river dams produces large morphological consequences: when the stream passes through a large capacity reservoir much of the incoming sediment is trapped and practically clear water flows out. The computation of the evolution in time of the river bed variations is rather complex since it is influenced by many interrelated factors. In this work, a 1-D numerical model recently developed is applied in order to to simulate the bed longitudinal profile variations and to quantitatively estimate the material transported by the flow at each river section as far as the outlet. For the application, data collected both in testing river reaches and in laboratory channels have been considered.