基于温度植被干旱指数的西北干旱区干旱时空变化

Temporal and Spatial Variation of Drought in Northwest Arid Region Based on Temperature Vegetation Drought Index

西北干旱区常年降雨稀少、干旱频繁,严重影响当地的生态平衡、农业生产以及经济可持续发展。为厘清西北干旱区干旱时空分布特征,基于增强型植被指数(enhanced vegetation index,EVI)和地表温度(land surface temperature,LST)构建温度植被干旱指数(temperature vegetation dryness index,TVDI)模型获得2000—2022年6—9月西北干旱区干旱时空变化特征,利用Sen+Mann-Kendall趋势分析法明确干旱趋势,分析不同土地利用类型与干旱的关系。结果表明:①西北干旱区TVDI空间分布呈现“西北低东南高”的特征,多年TVDI的均值为0.67,处于中旱的水平;②西北干旱区TVDI呈干旱加剧趋势,增加速率为8.8×10^(-4)年^(-1),显著加剧的面积约占总面积的21.04%,轻微加剧的面积约占总面积的62.33%;③未利用地TVDI值均高于其他土地类型,干旱程度越高未利用地对TVDI贡献度越大。

The northwest arid region has scarce rainfall and frequent droughts all year round,which seriously affects the local ecological balance,agricultural production and sustainable economic development.In order to clarify the spatiotemporal distribution characteristics of drought in the northwest arid region,based on the enhanced vegetation index(EVI)and land surface temperature(LST)was constructed to construct a temperature vegetation dryness index(TVDI)model to obtain the spatiotemporal variation characteristics of drought in the northwest arid region from June to September from 2000 to 2022,and the Sen+Mann-Kendall trend analysis method was used to clarify the drought trend,analyze the relationship between different land use types and drought.The results show these as follows.The spatial distribution of TVDI in the northwest arid region shows the characteristics of“low in the northwest and high in the southeast”,with the average multi-year TVDI value of 0.67,which is at the level of medium drought.TVDI in the northwest arid region shows a trend of drought intensification,with an increase rate of 8.8×10^(-4)a^(-1),the significantly intensified area accounts for approximately 21.04%of the total area,and the slightly intensified area accounts for approximately 62.33%of the total area.TVDI values of unused land are higher than other land types,and the higher the degree of drought,the higher The greater the contribution of unused land to TVDI.