How reliable are the satellite-based precipitation estimations in guiding hydrological modelling in South China?

With increasing spatiotemporal resolution and accuracy, the satellite-based precipitation estimations have made their exploitation in hydrological applications possible, especially in poorly gauged regions. However, their hydrological utilities still need to be evaluated in different catchments to provide useful knowledge to the end-users. This study investigates the performance of latest version (V06) of Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) products and their capacity to guide hydrological modelling in South China. Both near-real-time (i.e., “Early” run, IMERG-E) and post-real-time (i.e., “Final” run, IMERG-F) IMERG products are evaluated, and the post-real-time TRMM Multi-satellite Precipitation Analysis (TMPA 3B42) product is employed for intercomparison. The hydrological utilities of abovementioned products are further explored over six different medium-sized catchments in South China based on the grid-based Xinanjiang model. The results indicate that the IMERG-F outperforms the IMERG-E in South China, and the quality of TMPA 3B42 falls between them in terms of KGE' and its components. For the hydrological utility, using gauge-based model parameters, the IMERG-E forced simulations show poor performance in most of the selected catchments, whereas much better performance is observed for the IMERG-F forced simulations. Implementation of input-specific calibration significantly improves the simulation performance of three SPEs, and such improvement is much more pronounced for the IMERG-E. The TMPA 3B42 forced simulations generally illustrate comparable reliability to these of IMERG-F but with a slightly degraded performance. Overall, the IMERG-E shows high values in facilitating hydrological modelling over most ungauged catchments, and the IMERG-F shows much better hydrological performance. However, the best performing IMERG-F forced simulations are still inferior to these driven by the benchmark precipitation, and it’s thus still hard to replace gauge observations completely with the SPEs. This study provides a helpful knowledge about hydrological performance of satellite-based precipitation estimations, which potentially promote their widespread applications in hydrological modelling.