Remote sensing drought monitoring under dense vegetation cover condition based on Perpendicular Drought Index

Regional drought brought by global climate changes is menacing directly human´s food supply and survival environment, and it becomes a hotspot of many scientists and government administrations. Remote sensing has many advantages such as large land cover, high spatial resolution, short time interval, and convenient data acquisition, which makes remote sensing drought monitoring become an important research field. In the NIR(Near Infrared)-Red reflectance spectral feature space, if it is supposed that the spectral characteristic of bare soil conforms to the linear distribution, PDI(Perpendicular Drought Index) is established (Zhan, 2005; Abuduwasit, 2004). In order to verify the feasibility of PDI under dense vegetation cover condition, Hubei Zhanghe Irrigation System is selected as research area, PDI is calculated with ETM+ data, and 2-5 cm soil moisture in-situ observation is used for the purpose of comparing with PDI. Result shows that 2-5 cm in-situ observation and PDI calculation displays basically the same curve trend, their coefficient is 0.76, and it is consistent with insitu measured drought indicator. To sum up, PDI can effectively reflect local land cover and water-heat combination, which achieves many advantages such as simple, practical, easy-to-use, versatility and universality. And it is successful to monitor regional drought under dense vegetation cover conditions.