Factors influencing sedimentation in the riparian zone of the Three Gorges Reservoir, China
Wang Binyan, Wen Anbang, Yan Dongchun
1. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, 610041, Chengdu, China;
2. University of Chinese Academy of Sciences, 100049, Beijing, China
[Background] Various factors may affect the sedimentation and erosion process in riparian zone, including terrain, sediment transport, water level fluctuations and human activity. [Methods] In order to reveal the influence of these environmental factors and the disturbance of human activity on the sediment deposition process in the riparian zone of the Three Gorges Reservoir, using in situ observations, canonical correlation analysis, partial correlation analysis and variance analysis, this study investigated the amount of deposited sediment under different environmental conditions and the potential factors affecting sediment deposition in the riparian zone of the Three Gorges Reservoir and the relationship between them, including microtopography, hydro-sediment conditions of the river, soil erosion, vegetation condition and human activity. [Results] Results showed that human activity was the main controlling factor in the upper reach from Jiangjin to Fuling, including gravel dredging, bank revetment and ports and wharfs constructing which disturbed considerable amounts of deposited sediment due to regular sediment cleaning, as a result, there was no natural law to dictate the distribution. Slope gradient and elevation being part of terrain features were the main controlling factors in the middle reach from Fuling to Fengjie with correlation coefficient of -0.508 and -0.714 respectively, and the amount of sediment deposition was greater in areas with a gentler slope or lower elevation. However, the influence of elevation on sedimentation played its role with the conducting of inundating duration which was a result of hydrologic regime controlled by the operating strategy of the Three Gorges Reservoir, since sites with lower elevations would be drowned by sediment-laden flow with a longer duration, leading to a larger amount of sediment deposition. Slope gradient also was a primary factor, particularly affecting the sedimentation in the lower reach from Fengjie to Zigui with correlation coefficient of - 0.517. Theamount of deposited sediment was greater in the areas with a gentler slope but there was no difference between sampling points with different elevations but similar slopes. Because the slopes in this area were much steeper than other sections and the kinetic energy and velocity of the overland flow were much higher, making it difficult to deposit. [Conclusions] This study found that slope gradient, elevation, hydro-sediment conditions of the river and human activity were the main factors that influenced sedimentation in the riparian zone of the Three Gorges Reservoir, while vegetation condition had no effect on sedimentation. Moreover, the four factors influenced a section of the river channel respectively instead of the entire channel in the reservoir, which represented obvious spatial variability.
王彬俨1,2, 文安邦1, 严冬春1. 三峡水库干流消落带泥沙沉积影响因素[J]. 中国水土保持科学, 2016, 14(1): 12-20.
Wang Binyan, Wen Anbang, Yan Dongchun. Factors influencing sedimentation in the riparian zone of the Three Gorges Reservoir, China. SSWC, 2016, 14(1): 12-20.