Remote Sensing Monitoring Research Of Vegetation Change In The Dadu River Basin

Vegetation is an important part of terrestrial ecosystems.Mountain vegetation is undergoing significant changes due to global climate change.The Dadu River Basin is located on the eastern edge of the Qinghai-Tibet Plateau,and the terrain is severely cut.Vegetation is an important factor in maintaining the ecosystem of the basin.Changes in vegetation cover have had a significant impact on environmental factors such as climate and water resources in the Dadu River Basin.Therefore,the monitoring of vegetation change in this area is of great significance to the vegetation protection and economic construction of the Dadu River Basin.The Dadu River Basin was selected as the study area,and the basic and thematic geographic data were integrated.The normalized vegetation index(NDVI)and surface vegetation coverage were selected as research objects.Remote sensing technology and GIS technology were used as processing data,extracting and analyzing information.The pixel dichotomy was used to extract the vegetation coverage information from 2000 to 2015,and the distribution pattern of vegetation coverage was analyzed.The trend of NDVI was detected during the 16 years.The Geographical Weighted Model(GWR)was used to analyze the relationship between geographic factors such as meteorology,terrain and socio-economics and vegetation changes.Finally,a response strategy for vegetation changes in the basin was proposed.Through the research of this article,the following understandings have been made:(1)In terms of interannual variation of vegetation cover,the vegetation coverage of the Dadu River Basin is generally at a high level from 2000 to 2015,mainly due to high vegetation coverage.NDVI trend detection shows that the area of NDVI increase is much larger than the area of NDVI reduction,and the overall trend is rising from 2000 to 2015 and meets the significance test.(2)In terms of seasonal changes in vegetation cover,seasonal changes in vegetation coverage vary significantly.During the transition period of spring and summer,the vegetation coverage of middle and low grades changed the most,and the vegetation of this grade mainly improved.In the summer-autumn transition,the medium-high-level vegetation coverage changes the most,mainly degenerating.In the autumn-winter conversion,the medium-level vegetation coverage changes the most,mainly degenerating.In the transition between winter and spring,the vegetation coverage of medium and high grades changed the most,mainly improved.(3)Vegetation coverage is closely related to elevation,slope and aspect.The vegetation coverage below 5000 m elevation is on the rise,the vegetation coverage on the slope with gentle slope is higher,and the vegetation coverage on the northwest slope is the highest.The interannual variation of vegetation coverage is positively correlated with precipitation and temperature.(4)Based on the geographically weighted comprehensive analysis of the relationship between NDVI changes and topographic factors,meteorological factors and socio-economic factors,the study found that the regression coefficient distribution of precipitation factors and temperature have strong spatial similarity,and the elevation of topographic factors has the best regression effect on NDVI changes.Among the three factors of social and economic factors,GDP has the strongest interpretation of NDVI changes.Comprehensive analysis of the impact of various factors on NDVI changes,according to the size of the regression,from high to low are: socio-economic factors,meteorological factors,topographic factors.