Spatial associations between NDVI and environmental factors in the Heihe River Basin

Authors: Lihua Yuan*, Beijing Normal University
Topics: Human-Environment Geography, China
Keywords: NDVI; vegetation; environmental factors; Geodetector; q-statistic; spatial heterogeneity; the Heihe River Basin
Session Type: Poster
Day: 4/5/2019
Start / End Time: 1:10 PM / 2:50 PM
Room: Lincoln 2, Marriott, Exhibition Level
Presentation File: Download

The Heihe River Basin is located in the arid and semi-arid regions in northwest China, where the terrestrial ecosystem is vulnerable. So it is necessary to identify the potential factors for terrestrial ecosystem. MODIS NDVI data used as a proxy for terrestrial ecosystem, the potential factors influencing the terrestrial ecosystem distribution in the Heihe River Basin during the period of 2000-2016 are explored and analyzed. The geographical detector (Geo-detector) was employed to explore potential controlling factors for NDVI distribution. The results indicate that: (1) the NDVI of the Heihe River appeared high in southeast and west while low in northwest, showing spatial heterogeneity; (2) The results of Geo-detector showed spatial heterogeneity in the associations between NDVI and environmental factors for the whole basin and the sub-basin. The dominant factor was precipitation with a q-statistic of 0.300 in the whole basin, which was consistent with the result of extant researches that water availability was the major factor influencing the NDVI distribution in large-scale of arid area. In the upper basin, the dominant factor was elevation (q-statistic=0.300), while the interaction of humidity and elevation was dominant with a q-statistic of 0.520. The dominant factor in the middle basin was precipitation (q-statistic =0.358) and closely followed by soil type (q-statistic=0.334), while the dominant interaction was soil type and humidity. In the lower basin, the dominant factor was soil type (q-statistic=0.133), and the dominant interaction of elevation and soil type was bi-linearly enhanced a q-statistic of 0.224.

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