| Cite this article: | 杨亮彦,程杰,黎雅楠.2000—2018年陕北地区NDVI时空变化及其对水热条件的响应[J].灌溉排水学报,0,():-. |
| yang liangyan,Cheng Ji,Li Yanan.2000—2018年陕北地区NDVI时空变化及其对水热条件的响应[J].灌溉排水学报,0,():-. |
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| Spatial and Temporal Variation of NDVI and Its Response to Hydrothermal Conditions in Northern Shaanxi from 2000 to 2018 |
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yang liangyan,Cheng Ji,Li Yanan
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1.Institute of Land Engineering Technology of Shaanxi Land Engineering Construction Group;2.Shaanxi Province Land Engineering Construction Group
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| Abstract: |
| Abstract:【Background】Northern Shaanxi is located in the central part of the Loess Plateau and belongs to the gully region of the Loess Plateau. Its climate is dry and rainfall varies greatly seasonally, so it is a transitional zone from forest to grassland. In the early stage, due to unreasonable economic structure and over-development for a long time, soil and water loss in northern Shaanxi was intensified, resulting in a vicious circle of ecological destruction and economic poverty, resulting in extremely fragile ecological environment in northern Shaanxi. As the link of energy exchange, water cycle and biological cycle between earth and atmosphere, vegetation plays an important role in water cycle and energy conversion. The spatial distribution of vegetation can reflect the regional temporal and spatial distribution of soil moisture, shallow groundwater depth and air temperature. And the vegetation ecosystem in arid areas is very sensitive to climate change, so exploring the process of vegetation change can provide an important basis for climate change research. 【Objective】Therefore, analyzing the temporal and spatial variation of NDVI in northern Shaanxi and exploring the response of NDVI to hydrothermal conditions can provide a basis for the restoration of ecological environment and sustainable economic development in this area.【Method】Based on MODIS remote sensing data, the difference method and linear regression slope method were used to analyze the vegetation change at pixel scale in NDVI of northern Shaanxi from 2000 to 2018.【Result】Between 2000 to 2009 and 2009 to 2018, the vegetation index change speed in northern Shaanxi is quite different. The average slope of the former is 0.013 0/10a, and the latter is 0.007 6/10a. In terms of spatial distribution, the degraded areas from 2000 to 2009 are mainly distributed in the western mountainous areas and the edge of Maowusu sandy land, while the degraded areas from 2009 to 2018 are mainly distributed in the periphery of Yan'an and the edge of other cities and towns. The trend of annual NDVI is basically consistent with rainfall and temperature, but the correlation between NDVI and them is quite different. There is a significant positive correlation between NDVI and annual rainfall (R = 0.63, P < 0.01), and a weak correlation between NDVI and temperature (R = 0.23).【Conclusion】Linear regression slope method is more suitable for the study of vegetation dynamic change in long time series, considering the process and results of change comprehensively, and has better applicability. The vegetation growth in northern Shaanxi is affected by both rainfall and temperature. Compared with temperature, rainfall can better determine vegetation growth in the study area. There is a lag relationship between vegetation index and temperature and precipitation.
Key words: NDVI; MODIS; temporal-spatial variation; northern Shaanxi; hydrothermal condition |
| Key words: NDVI; MODIS; temporal-spatial variation; northern Shaanxi; hydrothermal conditions |
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