بررسي مدل رياضي رسوبگذاري در كانال هاي آبرفتي در حالت جريانهاي غير دايمي

Mathematical Modeling of Aggradation and Degradation in Alluvial Channels in the Case of Unsteady Flows

Sediment transport considerations is an important part of analysis and design of any open channel hydraulic system. Sediment transport can change the hydraulic system considerably and often dictate special design conditions. Many transport features, such as aggradation, degradation and scouring have been investigated by numerous researchers and many emperical relationships and formulas have been developed. In this research, a mathematical model is presented for studying aggradation and degradation in alluvial channels. One - dimensional, unsteady, gradually varied flow equations (Saint- Venant equations) and the sediment continuity equation are solved numerically by the second - order, accurate, explicit finite difference scheme developed by Mac Cormak. All three governing equations are solved simultaneously during any computational time step so that the water - flow equations and sediment continuity equation are coupled. For this purpose, Adji -chai riverʹs data in the Nahand station, with three Sediment discharge equations (Engelund -Hansen, Hassanzadeh, and Graf) are used and finally some results about the capability of model are obtained.