Correspondence of Drought Occurrences at Multi‐Temporal Scales Between North China and Upper Hanjiang River

Abstract

AbstractUsing the drought and flood grades, the historical co‐drought probabilities of the water source area (i.e., the Upper Hanjiang River or UH) and the receiving area (i.e., North China or NC) of the Middle Route of the South‐to‐North Water Diversion project from 1470 to 2017 were analyzed. It was found that there is relatively high possibility for co‐droughts to occur in the UH and NC at interannual to multi‐decadal time scales. When extreme drought occurred in NC, there was a 52% probability that the UH was on the drier side and even a 40% probability of severe drought. During the three typical severe drought events that occurred mainly in NC (i.e., 1637–1643, 1877–1878, and 1997–2002), severe droughts also appeared in the UH, with 1877–1878 even more severe than in NC. Among the seven driest years of the study period in NC (i.e., 1640, 1641, 1832, 1920, 1965, 1968, and 1997), only 1832 was wet in the UH, and 1920 even experienced the same severe region‐wide drought as NC did. Furthermore, when severe consecutive droughts occurred in NC, there was at least a 66% probability that the UH was also experiencing a drought. In addition, there were obvious cycles of drought and flood variability of around 3–6 years, 10 years, 30 years, and 55–80 years in both the UH and NC. These findings are of importance to in‐depth understanding of the regional drought variability and its mechanism at varied temporal scales and the effective management of the world‐class hydro project.