Appraising the Potential of Using Satellite-Based Rainfall Estimates for Evaluating Extreme Precipitation: A Case Study of August 2014 Event Across the West Rapti River Basin, Nepal

Heavy precipitation events are recurrently occurring in Nepal, affecting lives and properties every year, especially in the summer monsoon season (i.e., June-September). We investigated an extreme (heavy) precipitation event of August 2014 over the West Rapti River (WRR) Basin, Nepal. First, we forced a rainfall-runoff model with ground-based (gauge) hourly rainfall data of nine stations. Second, we validated against hourly water level at an outlet of the WRR Basin. This study then evaluated the performance of different satellite-based rainfall estimates (SREs) in capturing an extreme precipitation event. We considered the use of half-hourly data of Integrated Multi-satellite Retrievals for GPM (IMERG) (Early, Late, and Final versions), spatial resolution (10 km), and hourly data of Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN), spatial resolution (25 km), and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Cloud Classification System (PERSIANN-CCS), spatial resolution (4 km). Also, we used 3 h data of Tropical Multi-satellite Precipitation Analysis (TMPA) product real-time (3B42RT), spatial resolution (25 km). In general, we find that all selected SREs depicted a similar pattern of extreme precipitation as shown by the gauge data on a daily scale. However, we find these products could not replicate precisely on a sub-daily scale. Overall, IMERG and TMPA showed a better performance than PERSIANN and PERSIANN-CCS. Finally, we corrected poor-performed SREs with respect to gauge data and also filled data gaps of gauge rainfall using the information of good-performed SREs. Our study reveals that there is a great challenge in local flood simulation employing SREs at high-temporal resolution in Nepal. Plain Language Summary We assessed a heavy precipitation event of August 2014, where hourly rainfall data were applied in a hydrologic model in the WRR basin, Nepal. We evaluated the performance of different SREs and found all selected SREs demonstrated a similar tendency compared to gauge data on a daily scale. However, they failed to replicate on a sub-daily scale. Finally, we corrected poor-performed SREs (PERSIANN family) with respect to gauge data and also filled data gaps of gauge rainfall using the information of good-performed SREs (IMERG family and TMPA). Thus, we find there is a great challenge in local flood simulation using SREs at high-temporal resolution in Nepal.