Abstract:
This study investigates drought and flood in the Pearl River Basin using long-term terrestrial water storage anomaly (TWSA) data from the mascon solutions based on the Gravity Recovery And Climate Experiment (GRACE) satellite measurements (2002-2019) and the reanalysis data (1980-2019). To characterize drought, water storage deficit (WSD) and WSD index are used. The GRACE mascon solutions capture two major drought periods (2003-2006, 2009-2012) with similar onsets and endings over the last two decades, but show considerable differences in quantifying total drought severity. The reanalysis data significantly overestimates drought duration and severity during 1980-2000 owing to underestimated TWSA forced by incorrect precipitation data. Flood is monitored using a flood potential index (FPI) calculated using TWSA and precipitation. The GRACE mascon solutions identify four major flood events (FPI > 0.7) in Aug. 2002, Jun. 2008, and Jul. in 2006 and 2019. The flood potential is influenced by the precipitation in both the current and antecedent months. The spatial variability of the most recent flood in 2008 is analyzed, showing a similar spatial pattern between FPI and precipitation at monthly and sub-basin scales. The precipitation/TWSA in the PRB is mainly influenced by El Niño–Southern Oscillation (ENSO). TWSA exhibits a lag of 1-3 months responding to ENSO during 1980-2019. This study emphasizes the significance of removing water storage changes in large reservoirs before long-term drought, flood characterization and teleconnection analysis. This study highlights the intensifying drought conditions in the PRB over the last four decades under the circumstances of more frequent human activities (reservoir construction and regulation) and the complex changing climate system.
