Study On Runoff-sediment Characteristics And Riverbed Evolution Of Ganjiang River Sink

Silt-Discharge condition and human activities influence the evolution of downstream of Ganjiang River.The non-equilibrium sediment transport resultes in the complex evolution of the river bed.Therefore,research on the effect of flow,sediment and human activities is of great significance to exploit and protect the river.The paper studies the flow and sediment,rainstorms and flood,bed scouring,sedimentation and evolution of Ganjiang River based on hydraulic data and remote sensing images.Combining the data from Waizhou hydraulic station and the section topographical method,the scouring and silting volume of the downstream near Waizhou were calculated,which could be used to analyze the erosion and deposition evolution characteristics.The results show there is an obvious erosion trend in recent years.The right bank of the river evolve into a deep trough but this erosion trend is under control after 2012.The topographic data were used to analyze the change of cross-section and the characteristic analysis of the channel was carried out based on the water level data.It shows that the evolution process of the downstream sections are similar.In recent years,the trend of erosion and the river channel slices downwards are obvious,which are mainly result from human activities.The erosion of upstream is more significant than the downstream.The evolution of the main stream and its tributary channels was analyzed by using remote sensing technology.The shoreline of the main river recede and the area of continents decrease.The downstream tributaries are eroded while the estuary deposite.The changes of the main branch is the most significant,followed by the North branch,while the southern branch is relatively stable.Combining the results of river evolution and the condition of coming water and sediment,the internal mechanism of the evolution of Ganjiang River could be summarized,which is caused by natural and human factors.The results show that the evolution of Ganjiang River has a close relationship with coming water and sediment.In recent years,the whole area shows a trend of erosion.The shoreline recedes and the area of continents decreases which mainly caused by sediment trapping by reservoirs and artificial sand extraction.