Analysis Of River Morphology Change Of Wei River's Main Stream From 2000 To 2017

As an important inland river in the construction of"Guanzhong-Tianshui Economic Belt"and"One Belt And One Road",the analysis of the dynamic evolution of river morphology and the construction of ecological civilization of coastal cities are of great significance.However,the continuous and rapid urbanization process has already made new adjustments to the river morphology of Wei River,therefore,the study on the evolution of the"Xian-Xianyang"among the main stream in the Wei River is of great guiding significance for balancing the relationship between urban expansion mode and comprehensive river management under the background of"Big Xi'an".In this paper,based on fractal theory and the regression statistical analysis method,the evolution rules of river morphology from 2000 to 2017 were analyzed,and the influencing factors of river morphology evolution were elaborated.The main contents of the research and the research results were as follows:(1)From the perspective of river surface area,river width and the channel morphology,the surface area of the"Xian-Xianyang"section of the main stream of Wei River decreased year by year from 2000 to 2017,and the area changed from 16.30km~2 in 2000 to 12.17km~2 in 2017.The total area decreased by 4.03km~2,with a contraction rate of 24.7%.The river width first decreased and then increased with the change of water surface area.The average river width decreased by 0.06km.The coefficient of tortuosity K of river channel morphology showed a decreasing trend year by year,indicating that the Wei River channel presented a flattening trend,but the river segment swaying and bending phenomenon was significant.(2)From the perspective of the morphological evolution of the riparian line,the bankline showed a shrinking trend.The overall average change speed of the right bank was 0.21m/y,while that of the left bank was 0.44m/y.In the 18 years,the fractal dimension of the riparian line presented the shape distribution of"V",indicating that the degree of fragmentation of the riparian line of the main stream in the section of Wei River from Xi'an to Xian'yang first decreased and then increased.(3)In terms of the influencing factors of river morphological evolution,annual runoff and annual sediment transport had greater influences on river morphological evolution than precipitation;The variation of Tongguan elevation was consistent with the variation of river fractal dimension(FD),it showed that the variation of Tongguan elevation is consistent with the change of river morphology in the study area;The area of urban built-up area was positively correlated with the fractal dimension of river(FD),indicating that the larger the built-up area was,the larger the fractal dimension of riparian line was,the higher the river tortuosity was,so as the fragmentation,which all presented a greater intensity of external interference in study area.