土地利用数据在TVDI干旱监测方法中的应用研究——以甘肃省河东地区为例

温度植被干旱指数（Temperature Vegetation Dryness Index，TVDI）因其物理意义明确而被广泛应用。然而不同土地利用类型的植被指数（Ⅵ）、陆地表面温度（LST）存在一定的差别，这种差别可能在利用TVDI监测干旱时带来一定的影响。以甘肃省河东地区为例，探讨了TVDI方法在研究区的适用性及土地利用类型对TVDI指数监测干旱的影响。结果表明:（1）TVDI对河东地区的庆阳、平凉、临夏、定西北部、甘南等地土壤相对湿度（RSM）有一定的指示作用，但对定西市南部地区、陇南地区、天水市的指示相对较差；（2）用不同土地利用类型的遥感数据建立的特征空间，能够提高TVDI对RSM指示的准确性和合理性。一方面，农地类型的TVDI值有所下降而林地、草地类型的TVDI值有所升高，这在陇东及甘南局部地区取得较好的改进作用；另一方面，历史TVDI各区间站次统计表明，经过土地利用类型数据的改进，TVDI值的分布范围得以扩大，从0.5～0.9扩大为0.2～0.9，这与实际RSM的分布特征有更好的对应，有利于区分不同干旱等级的RSM。

Research of Application of Land Use Data to TVDI Method on Drought Monitoring in the Eastern Region of Gansu

Clear principle and concise physical meanings make Temperature Vegetation Dryness Index (TVDI)be a wildly used method to monitor drought.The Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) would not the same on different land use types,and the difference would affect the drought monitoring by using TVDI method.Taking the eastern region of Gansu as an example,TVDI was calculated based on history MODIS data,and improvement of TVDI for different land use types was discussed.The results are as follows.(1) On the whole,TVDI had the indication to the relative soil moisture (RSM) in Qingyang,Pingliang,Linxia,the north of Dingxi and Gannan.However,TVDI could not indicate the RSM well in the south of Dingxi,the southern region of Gansu and Tianshui.(2) Feature space was built on different land types,which was more precise and reasonable for indicating the RSM.On the one hand,the monitor ability of TVDI for RSM status was improved in the east of Gansu and some parts of Gannan because of TVDI decreasing for farmland type and increasing for woodland and meadow land type.On the other hand,the distribution of TVDI,which did not consider the land types,was more centralized than RSM.By contrast,the distribution can be broadened by taking land type into account feature space,and it is helpful for distinguish RSM of different drought grades.