Preliminary study on the applicability of several remote sensing drought indices to agricultural drought monitoring in Gansu province of China

Abstract

The spacing of Gansu Province from the eastern to western regions is very large and adjacent to the Qinghai–Tibet Plateau. On the one hand, Agriculture in western area is irrigated rather than non-irrigated agriculture in eastern area. On the other hand, elevation where adjacent to the Tibetan Plateau is much higher than other places. In this study, remote sensing drought indices, such as temperature vegetation dryness index (TVDI), vegetation condition index (VCI), temperature condition index (TCI), perpendicular drought index (PDI), and modified perpendicular drought index (MPDI), were calculated using historical MODIS data. The applicability of these remote sensing indices was preliminarily studied by comparing the Relative Soil Moisture (RSM) of the sites. Results showed that:1) In whole area, irrigated areas and high-altitude areas, the remote sensing indices have different degree of indication for the spatial distribution of RSM in the superficial layer in spring, summer, and autumn. Among them, TVDI has the best indication, followed by VCI and TCI, and PDI and MPDI have very limited indication. But TVDI has no indication in May in irrigated areas at all. 2) None of them can indicate the temporal variation characteristics of the RSM in the irrigated areas, and TVDI and TCI based on the surface temperature can indicate the temporal variation of the 10 and 20 cm-deep RSM in the high-altitude areas. In general, TVDI is a good indicator for RSM in the superficial layer in Gansu Province during spring, summer, and autumn.