基于MODIS数据的农业干旱监测方法对比分析

利用2004年4月～6月上旬的MODIS影像数据,结合实测的土壤墒情数据,对比不同深度及不同拟合方式下土壤湿度的估算精度。另外,分别选用植被供水指数(VSWI)、基于EVI的植被供水指数(E-VSWI)、归一化多波段干旱指数(NMDI)与对应的土壤湿度数据进行回归分析,并在此基础上利用最优指数实现研究区土壤湿度的估算及旱情监测。结果表明:在华北平原中部地区冬小麦生长季节,利用MODIS数据进行土壤湿度估算的最佳深度是10cm;最佳拟合方式是线性拟合方式;植被供水指数(VSWI)在研究区整个时间序列具有最好的稳定性,可为今后大区域作物生长期的干旱监测提供一个简单方法。

Comparative Study on Remotely Sensed Methods of Monitoring Agricultural Drought Based on MODIS Data

Currently,drought has become a worldwide problem,which is affecting China more and more seriously.The North China Plain is the main production area of grains and the yield is greatly limited due to drought.Therefore,the drought monitoring for agricultural areas is of great significance.In this paper,we firstly compared the estimation precision of soil moisture at different depths and with different fitting methods.Then,we did regression analysis between soil moisture and traditional VSWI & VSWI based on EVI & NMDI using MODIS data from April to early June in 2004 every 10 days,and the optimal drought index was chosen for soil moisture inversion and drought monitoring in the study area.The results of this study demonstrated that for the middle part of North China Plain during the winter wheat growing season,remotely sensed methods provide the best prediction accuracy for soil moisture at 10cm,and the best fitting method is linear method.Besides,VSWI shows the best stability during the studying period,which can serve as basis for large-scale drought monitoring during crop growing season in the future.