基于改进型TVDI在干旱区旱情监测中的应用研究

Application of modified TVDI in drought monitoring in arid areas

干旱是全球范围内影响最为广泛的自然灾害之一,其所导致的土壤沙漠化、荒漠化和盐碱化给生态环境造成不可逆的危害。通过对MODIS数据进行投影转换、去云等预处理的基础上,利用地形校正对TVDI模型进行改进,构建了改进型的温度植被干旱指数(mTVDI)用于新疆干旱区旱情监测。利用土壤实测数据对mTVDI及传统的TVDI模型进行对比验证。研究结果表明:(1)利用EVI与校正后的LST构建的mTVDIE对干旱区旱情的敏感度最高,与实测土壤水分数据的相关性R^2为0.74。(2)从空间上看,新疆2015年旱情分布以塔里木盆地和准噶尔盆地为两个干旱中心,旱情状况由严重逐步向周围山区递减至湿润状态。从时间上看,新疆6月、7月和8月旱情最为严重。(3)研究利用TRMM降水数据对基于mTVDIE反演的新疆旱情时空分布特征进行对比分析,结果表明二者所表现出的旱情时空分布较为一致,不同时间段内的降水量与mTVDIE之间具有一定的相关性,且均通过了P<0.01显著性检验。综上,基于TVDI所提出的mTVDIE能够有效开展新疆干旱区旱情监测,且精度较高,从而为今后定量化开展大区域尺度旱情监测研究提供参考。

The drought is one of the most influential natural disasters on a global scale.The soil desertification and salinization from drought can cause irreversible damage to the ecological environment.On basis of the preprocessing and cloud removal of MODIS data,this paper modifies the TVDI model through terrain correction and constructed an modified Temperature Vegetation Dryness Index(mTVDI) for drought monitoring in arid regions of Xinjiang,China,and compared it with the traditional TVDI and verified it using soil measured data.The results showed as follows:(1) mTVDI_E constructed by EVI(Enhanced Vegetation Index)and corrected LST(Land Surface Temperature)has the highest sensitivity to drought monitoring in arid area, and the correlation with measured soil moisture data is R^2:0.74;(2) In 2015,the drought in Xinjiang was centered in the Tarim Basin and the Junggar Basin, and the situation was gradually decreased from the serious drought in the centers to a humid state in the mountainous areas. From the time point of view,the drought in Xinjiang was the most serious in June, July and August;(3) The spatial and temporal distribution characteristics of drought in Xinjiang based on mTVDI_E were compared and analyzed with TRMM precipitation data. The result shows that the spatial and temporal distribution of drought was consistent between the two methods.The correlation between precipitation and mTVDI_E in different time periods was high, and passed the P< 0.01 significance test.Above all,mTVDI_E based on TVDI can effectively carry out drought monitoring in arid regions of Xinjiang with high precision.Therefore,this will provide reference for the quantitative research on drought monitoring at large regional scale in the future.