The Potential of Using Dynamic Surface Water Products for Drought Monitoring

Surface water presence on the earth is highly variable, closely coupled to regional hydro-climatological conditions. Meanwhile, the rapid increase of earth observation-based global surface water datasets provides valuable opportunities for evaluating interannual or seasonal surface water dynamics. This study investigated the potential of using long-term EO-based surface water products for regional drought monitoring. In particular, the dynamic of surface water over the middle reach of the Yangtze River from 1999 to 2020 was analyzed based on the GLAD product. Furthermore, we explored the linkage between surface water anomalies (i.e., Dynamic Water Index, DWI) and Standardized Precipitation Index (measured by SPI). The preliminary results showed that: (1) DWI was significantly coupled to 12-month SPI, which confirmed that dynamic surface water extent can be used as an indicator for hydrological drought; (2) The correlation between DWI and SPI (1-month, 3-month, 6-month, 12-month) in extreme wet climate was lower than in extreme drought climate; (3) It is challengeable to distinguish the difference in coupling strength between dynamic surface water and hydrological drought caused by DWI defined with different water types (i.e., all types versus seasonal water). Much more attention should be paid to evaluating the uncertainty of the new index caused by missing values across regions.