金沙江观音岩库区植被覆盖度时空差异影响机制分析OA北大核心CSTPCD

The dry-hot valley area in the middle and lower reaches of the Jinsha River is characterized by hot and little rain,serious soil erosion,and a fragile ecological environment.The construction and operation of large-scale hydropower stations have various impacts.Exploring the temporal and spatial variation characteristics and response mechanisms of vegetation coverage around hydropower stations in dry-hot valleys is of great significance.Taking the Guanyinyan reservoir area as an example,based on Landsat series remote sensing image data from 2000 to 2022,the Normalized Difference Vegetation Index was used to invert the Fraction Vegetation Coverage based on the dimidiate pixel model,and the Fraction Vegetation Coverage Change Index was constructed to explore the spatial and temporal evolution characteristics of vegetation coverage.Six geographical influencing factors,land surface temperature,precipitation,elevation,slope,aspect,and distance from the river were selected.Ordinary least squares and geographically weighted regression were used to explore the influence mechanism of the Fraction Vegetation Coverage in the area surrounding hydropower station construction.The results showed that:1)the spatial distribution of the Fraction Vegetation Coverage in the study area was regular,with obvious characteristics of the dry-hot valley.The Fraction Vegetation Coverage along the valley was low.With an increase in distance from the river,the Fraction Vegetation Coverage increased.2)The impact on the Fraction Vegetation Coverage before and after the construction of a hydropower station had a negative effect on the construction of the station and the gain effect after the construction of the station.During the construction of the hydropower station,the surrounding vegetation was destroyed,and the proportion of areas with slight and significant decrease in the Fraction Vegetation Coverage was 11.6%.After the completion of construction,the proportion of areas with a slight and significant increase in the Fraction Vegetation Coverage was 41.2%.3)The correlations between different geographical influencing factors and the Fraction Vegetation Coverage were different.Overall,land surface temperature showed a strong negative correlation,slope showed a positive correlation,precipitation showed a strong correlation,and elevation,aspect,and distance from the river showed weak correlations.At a land surface temperature of 32.6-36.8℃,precipitation of 775-796 mm,elevation below 1448 m,gentle slope,and sunny slope within 1000 m from the river,construction of a hydropower station had the greatest positive impact on the Fraction Vegetation Coverage,and the restoration of vegetation was the best.This study provides a useful decision-making reference for the construction of hydropower stations and restoration of ecological barriers in dry-hot valley areas.