MATHEMATICAL MODELLING OF GRAVEL BED RIVER WITH ARMOURING

Abstract

Numerical models for river simulation are becoming increasingly popular fbr their advantages, such as quick run, easy calibration etc., over physical counterparts. However, validity of such models are greatly affected by the sacrifice • of accuracy made in the approximations, while transforming the governing partial differential equations into linear algebraic simultaneous equations. The effects of such approximations are readily exhibited while running a unsteady flow models. Sediment routing in unsteady flow is far more complicated process to simulate. Instability and numerical oscillations occur even with so called implicit fully coupled models. In the present work, a fully coupled unsteady flow model has been developed with two alternative transport functions (a) Schoklitsch's bed load equation together- with Holtorff's suspended load equation and (b) Yang's total load equation. Preissmann's four point scheme has been used as the numeric scheme in the model.Similarly, Krishnappan's alternative solution procedure (ASP) has been used to solve the linear simultaneous equation's.....