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

Figure 11

Heat map showing Intra-annual PC of SPI accumulation periods of 1–48 months with SDI-1 in the UHRB (Ylx) and MHRB (Zyx) (note: the x-axis represents the correlation between the SDI-1 and SPI at different timescales and the y-axis represents the 12 months of the year; the up arrow represents the correlation coefficients that increased in the postreservoir period (Pos-R) in the Ylx and Zyx compared to the period of prereservoir (Pre-R), or vice versa); (a) (1965–1979, PC ≥ 0.52, p < 0.05), (b) (1980–2012, PC ≥ 0.35, p < 0.05), and (c) (1965–2012, PC ≥ 0.29, p < 0.05) in the UHRB (Ylx), and (d) (1965–1984, PC ≥ 0.45 or ≤− 0.47, p < 0.05), (e) (1985–2012, PC ≥ 0.38 or ≤−0.48, p < 0.05), and (f) (1965–2012, PC ≥ 0.29 or ≤ −0.33, p < 0.05) in the MHRB (Zyx).

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(b)

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