Dynamic drought recovery patterns over the Yangtze River Basin

Abstract

Abstract Droughts exert far-reaching societal and economic impacts over the globe. A full recovery of drought-stricken areas depends on so many factors that a deterministic estimation of the timing is difficult. This study explores an alternative way to inform how likely a drought-prone region can recover from meteorological droughts over time. We focus on exploring the drought recovery patterns over Yangtze River Basin (YRB) with the development of a modified joint drought index (MJDI) model based on the principal component analysis (PCA) and vine copula. Regarding the seasonal difference in drought recovery, our results show that during April-August the required precipitation to recover from a drought is around 100–350% above the long-term averaged precipitation, and the probabilities of receiving such substantial excess precipitation exceed 0.4 in most regions. In contrast, less precipitation is required during the winter months, i.e., below 50% of their climatologies (i.e., long-term mean) in large parts of the basin. Moreover, we explored the recovery patterns for each drought category (i.e., slight, moderate, severe and extreme droughts) across the basin. It can be found that precipitation needed for terminating a slight or moderate drought is mostly 50–150% of their climatologies with the recovery probability between 0.5 and 0.7. Our results also reveal that most of the northwest regions are unlikely (probabilities close to zero) to end the extreme droughts in a short time span (e.g., 1\xa0month), where the expected precipitation reaches nearly 200% above normal. We also examined variations in vegetation responses to drought recovery. Generally, the forests need an amount of near-normal precipitation to achieve a full recovery from the droughts, while the grasslands which tend to recover with the recipient of approximately 50% of their long-term averages. These findings could provide proactive information for drought managements to make decisions on replenishing water supplies.