XIONG Yalan1, ZHANG Keli2, LIU Jiafeng1, Yang Zijing1
（1.College of Resource, Sichuan Agricultural University, Chengdu 611130，China;
2.School of Geography, Faculty of Geographical Science, Beijing Normal University, Beijing 100875，China; ）
Abstract: 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.
Key words: NDVI; multi-scale; wavelet transform; topographic factors
EARTH AND ENVIRONMENT Vol.47, No.4, Tot No.330, 2019, Page 412-418