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

Figure 9

Pearson’s correlation coefficien between SDI-1 and SPI (a, b) for different timescales at different periods, and VCI (c, d) with different timescales of SPI and SDI in the UHRB (Ylx) and in the MHRB (Zyx).

(a)

(b)

(c)

(d)