LONG TERM CHANGES IN CHANNEL CHARACTERISTICS OF THE JOGANJI RIVER AND ITS RESPONSE TO FLOW DISCHARGE

Abstract

 Long-term field data analysis and numerical simulation were conducted to understand recent morphodynamics and particle size distribution characteristics of the Joganji River. Field data confirmed that sedimentation in the upstream and erosion in the downstream, which was confirmed in the early 2000s, has continued in recent years. The grain size distribution has not changed much, and the average grain size changes greatly around 6 k. Numerical analysis revealed that the low channel path is difficult to move even with 1500 m³/s, resulting in a coarser grain size of the riverbed in the upper reaches. However, the transport limit of bed load material in the lower reaches changed greatly with the flow rate. The discharge which strongly affects the grain size distribution was estimated to be approximately 1500 m³/s, not the annual average maximum discharge(700 m³/s).