岷江上游小流域多尺度NDVI与地形的关系研究

基于2015年OLI遥感影像和DEM数据，运用二维小波变换研究了岷江上游干旱河谷渭门小流域NDVI与地形因子的多尺度耦合关系。结果表明：（1）渭门小流域NDVI的空间分布特征为东南低西北高、河谷低山地高。多尺度下低频部分NDVI与地形因子的空间相似性和相关性大小均为坡向 > 高程 > 坡度。高程、坡度与NDVI低频系数的最强相关性出现在较大尺度，而坡向与NDVI低频系数的最强相关性出现在较小尺度。（2）NDVI的空间波动性随着分解尺度的增大而增强，但波动性的强弱与地形因子并未表现出明显的空间相似性。高频部分NDVI与各地形因子的相关性随小波分解尺度的变化规律不明显。（3）NDVI的空间分布特征是由高程、坡度和坡向共同决定，但是各因子对NDVI的控制作用大小随尺度发生改变。小波变换可以揭示出NDVI和地形因子的多尺度特征，对干旱河谷植被景观的合理布局，提高生物多样性，生态环境保护和农业产业规划具有重要意义。

Study on the Relationship Between Multi-scale NDVI and Topography of Sub-watersheds in the Upper Reach of Minjiang River

The multi-scale relationships between NDVI and topographic factors of the Weimen small watershed, an arid valley in the upper reach of Minjiang River, were studied based on OLI remote sensing image and DEM data of the watershed in 2015 using the two-dimensional wavelet transform method, in which the low-frequency coefficients reflect the global spatial patterns of NDVI and topographic factors and the high-frequency coefficients reflect the fluctuation of NDVI and topographic factors in different locations. The results show that:(1) the northwest area and hilly area of the Weimen small watershed had high NDVI values, the southeast area and valley area had low NDVI values, the low-frequency coefficients of different scales indicated the spatial similarity and correlation between NDVI and terrain factors show a trend of aspect > elevation > slope. (2) The spatial volatility of NDVI increases as the wavelet decomposition scale increases, but no remarkable spatial similarity between the intensity of volatility and topographic factors is found, that is, no obvious correlation between NDVI and topographic factors is found by high-frequency coefficients of different wavelet decomposition scales. (3) The spatial distribution of NDVI is determined by all factors of elevation, slope and aspect, but their controlling effect on NDVI varies under different scales. The wavelet transform method can reveal the multi-scale characteristics of NDVI and topographic factors, provide important basis for ecological environment construction in arid valley, and has great significances in the rational adjustment of vegetation and the enhancement of regional biodiversity.