Evaluation and Application of the Latest Satellite-Based Precipitation Products with a Distributed Hydrological Model in the Lower Mekong River Basin

Precipitation is a key driving variable for hydrological models. However, in many undeveloped areas, it is hard to obtain reliable and appropriate ground observed precipitation data for hydrology studies, such as the Lower Mekong River Basin (LMRB), which is the most important transboundary river basin in Southeast Asia with sparse coverage of ground level rain gauges. Satellite-based precipitation products could therefore be an alternative choice. In this study, data from the latest released satellite-based precipitation products, the Integrated Multi-satellitE Retrievals for Global precipitation measurement (IMERG) and version 7 of the Tropic Rainfall Measurement Mission (3B42V7), are evaluated and applied with a distributed hydrological model - Geomorphology Based Hydrological Model (GBHM), to examine the effectiveness of satellite-based precipitation products over the LMRB during the period 2014/4/1 to 2015/12/31. The pixel point comparison shows that both the IMERG and 3B42V7 are able to provide reliable precipitation estimate in the LMRB, while the IMERG performs slightly better than the 3B42V7. The hydrological application evaluation suggests that both of the IMERG and the 3B42V7 produced reasonable simulations however, the IMERG simulation outperformed the 3B42V7 simulation, with a higher Nash-Sutcliffe efficiency value at most gauges, besides, the 3B42V7-simulations produced serious overestimations of discharge at Nong Khai during July 2015. This may be due to the fact that the 3B42V7 overestimates the rainfall rate in Lao People’s Democratic Republic, where the TRMM product was not calibrated because it lacks of available ground observations in the region. Our results demonstrate that the IMERG products can provide more accurate precipitation data than the 3B42V7 over the LMRB, and therefore can be reliably used as forcing data of hydrological simulations over the LMRB.