Interactions Between Multiple Drought Types Across Temporal Scales

ABSTRACT Understanding the complex interactions between different types of droughts is essential for effective drought prevention and disaster management. This study employed the extended convergent cross mapping (CCM) algorithm to analyse the interactions between meteorological drought (standardised precipitation index), soil drought (standardised soil moisture index), vegetation drought (standardised normalised difference vegetation index), and groundwater drought (standardised groundwater index) in the middle reach of the Heihe River Basin in China at temporal scales of 1, 3, 6, and 12 months. A new method was proposed to assess the convergence of the CCM algorithm. The results showed that the temporal scale affected the intensity and the time lag of unidirectional or bidirectional interactions between different drought types. The intensity of the interaction between meteorological and other droughts increased, and the time lag shortened as the temporal scale increased. Meteorological drought had the longest lag time and the weakest effect on vegetation drought, indicating that precipitation was not the only factor affecting vegetation drought in this region. Groundwater drought influenced soil and vegetation droughts across all temporal scales, highlighting its crucial role in drought propagation in this region and underscoring the need for consideration.