基于温度植被干旱指数法(TVDI)的朝阳县干旱监测

Monitoring drought in Chaoyang County of Liaoning Province using temperature vegetation drought index( TVDI)

利用Landsat 8数据,将归一化植被指数(NDVI)和地表温度(Ts)结合建立二维特征空间,依据二维特征空间分布图拟合干、湿边方程,进而计算温度植被干旱指数(TVDI),并对旱情分布进行分析和评价。利用土壤含水率实测值与反演的地表温度建立模型,并通过模型反演出土壤含水率与实测值进行精度检验。结果表明,随着归一化植被指数的增加,最大地表温度(Tsmax)随之减小,最小地表温度(Tsmin)基本上随之增大,Tsmin和Tsmax的趋势线交汇于一点组合成近似的三角形形状;2016年5—8月,朝阳县全县范围内基本都存在不同程度的旱情,其中6月份旱情最为严重;TVDI与不同深度的土壤含水率的相关性显著,可以较好的实现对旱情的监测。

In order to explore the drought in Chaoyang County of Liaoning province from May to August in 2016,to combine the normalized difference vegetation index(NDVI)and surface temperature(Ts)to establish a two-dimensional characteristic spatial distribution using Landsat 8 data.The two-dimensional characteristic spatial distribution was used to fit the dry and wet side equations,calculate the temperature vegetation dryness index(TVDI),and analyze the drought distribution and evaluation.The model was established by using the measured values of soil water content and the retrieved land surface temperature.Model verification and accuracy analysis were relayed by the measured values and the retrieved soil water content.The results showed that the maximum surface temperature decreased,and the minimum surface temperature basically increased with the increase of NDVI.Minimum surface temperature and the maximum surface temperature trend line intersected in one point into triangle shape approximation.In 2016,from May to August,there were different levels of drought in Chaoyang County,and the worst drought occurred in June.The correlation between TVDI and soil moisture at different depths was significant.Thus,TVDI can be used to monitor drought conditions.