Characterized Flood Potential in the Yangtze River Basin from GRACE Gravity Observation, Hydrological Model, and In-Situ Hydrological Station

Comprehensive observations of total terrestrial water storage changes (TWSC) which include all the hydrological components (such as snow/glacier, surface water, soil moisture, and groundwater) are rarely available, so the predisposition of a region to flood is not fully clear. This paper combines the gravity recovery and climate experiment (GRACE) gravity observations, a hydrological model, and in-situ hydrological station data to establish the relationship between Yangtze River discharge and TWSC by a time-lagged autoregressive model and presents the TWSC data that apply for Yangtze River basin (YRB) flood forecasting. The TWSC in the YRB is inferred by the Lagrange multiplier method from GRACE gravity observations between April 2002 and December 2013. The root-mean-square error (RMSE) is optimal (2.1 cm) and the trend of TWSC in the YRB increased by 0.63 ± 0.11 cm/year. A case study of the flood catastrophe during summer 2010 is used to establish a relationship between river discharge from the Datong hydrological surveying station and basin water storage changes from GRACE by adopting a time-lagged autoregressive model, which shows that the total water storage changes from GRACE gravity observations can be used to estimate the tendency of a river basin to flood at 3–6 month lead times. This study concludes the basin scale of total water storage changes determined from satellite observations of time-variable gravity provides a new and effective tool for characterizing regional flood potential and may eventually lead to longer early flood warning times.