The influence of the 2022 extreme drought on groundwater hydrodynamics in the floodplain wetland of Poyang Lake using a modeling assessment

Abstract

The 2022 extreme drought in Poyang Lake (China) caused severe damage to a wide range of sectors. It also emphasized the fact that, even in regions with abundant surface water resources, groundwater resource is still a crucial component of drought management strategies. However, providing up-to-date assessments of groundwater response remains challenging due to the limited data in complex floodplain settings. This study uses a groundwater flow modeling FEFLOW to investigate the influences of the most extreme drought in 2022 on groundwater hydrology in the floodplain wetland of Poyang Lake. Model simulation indicates that the extreme drought led to a significant decrease in floodplain groundwater levels, with a maximum drop of about 5 m. In addition, the extent of the groundwater level drop varies significantly across the floodplain wetland, particularly for the strongest impact (drop > 4 m) occurring in the eastern area of the floodplain. It is expected that the extreme drought accelerates the groundwater discharge rate that is about 3 times than that of the normal year, and thus resulting in a losing condition of the floodplain wetland. On an annual scale, the groundwater discharge of the floodplain wetland in 2022 is estimated to be about 14.5 times than that of a normal year, demonstrating a significant attenuation of groundwater storage under drought environments. The reduction in rainfall combined with the associated low lake level is most likely to exert substantial influences on reduced floodplain groundwater storage. This study is the first attempt to interrogate the response of wetland groundwater to the unpredictable drought event in Poyang Lake, contributing to improved understanding of future water resources allocation and drought resistance strategy.