Statistical evaluation and hydrologic simulation capacity of different satellite-based precipitation products (SbPPs) in the Upper Nan River Basin, Northern Thailand

Study region: The Upper Nan River Basin, Northern Thailand Study focus: Precipitation is a major component of the hydrological cycle. A large number of remotely sensed precipitation products are used in hydro-meteorological studies. The accuracy of these relies on basin climatology, basin topography, precipitation mechanism and precipitation sampling techniques used in satellites. Hence, the precipitation products should be validated. Numerous studies have evaluated the reliability of satellite-based precipitation products (SbPPs) in the tropical Asia. However, a handful of research has yet examined the reliability of these in Thailand. Therefore, in this study the reliability of six SbPPs namely, PERSIANN, PERSIANN−CCS, PERSIANN-CDR, TMPA-3B42, TMPA-3B42-RT and IMERG was tested by comparing against ground measured rainfall records and through simulating a hydrology model at daily and monthly time scales for a major head water catchment of the Northern Thailand. New hydrological insights for the study region: The results of this study revealed that SbPPs had considerable differences, when compared to rain gauge records and in reproducing observed streamflow of the Upper Nan River. For instance, PERSIANN-CDR and TMPA-3B42-RT demonstrated significant over estimates (5–54%), while PERSIANN and PERSIANN−CCS showed considerable under estimates (-6 to -39 %). In terms of the hydrological utility, the lowest skills were in PERSIANN (Nash Sutcliffe Efficiency: NSE monthly ≤0.48). IMERG was superior among the tested in capturing gauge measured daily (with Correlation Coefficient: R² = 0.60) and monthly (with R² = 0.90) rainfall amounts and in simulating the hydrological model (with NSE_monthly≥0.63). Hence, IMERG demonstrates promising prospects for future hydro-meteorological applications in this region. The dynamic parameter approach which calibrated the hydrologic model with specific SbPPs showed substantial improvements in reproducing observed streamflow, when compared to the static approach which uses the same set of parameters calibrated through simulating the model with rain gauge data. The results of this study essentially provide valuable feedback to identify the most suitable SbPPs in watersheds under limited data availability with climatic and topographical features similar to the Upper Nan.