Meteorological Drought, Hydrological Drought, and NDVI in the Heihe River Basin, Northwest China: Evolution and Propagation

Figure 10

Intra-annual strongest PC (a–c) and the drought propagation time in months (e–f) for SPI and SDI-1 at six tributaries.

(a)

(b)

(c)

(d)

(e)

(f)