Author(s): Rocky Talchabhadel; Hajime Nakagawa; Kenji Kawaike; Kazui Yamanoi; Herman Musumari; Tirtha R. Adhikari; Rajaram Prajapati
Linked Author(s): Hajime Nakagawa, Kenji Kawaike
Keywords: Extreme precipitation; Inundation; Satellite-based rainfall estimate; West Rapti River basin
Abstract: Number of occurrences of heavy precipitation events is increasing rapidly in Nepal affecting lives and properties each year, especially in monsoon season (Jun-Sep). We investigated an extreme (heavy) precipitation and subsequent flooding event of Aug 2014 over the West Rapti River (WRR) basin, Nepal. We firstly used ground- based hourly rainfall data (9 stations) and a kinematic wave flow model was validated against ground -based hourly water level at an outlet of WRR basin. A shallow-water inundation model was then used to simulate the inundation process. Our results show similar spatial patterns of inundation with those derived from satellite images. This study also attempts to analyze the effectiveness of satellite-based rainfall estimates (SREs) in capturing extreme precipitation events. We used half-hourly data of IMERG (Early, Late and Final versions), resolution (10 km), and hourly data of 1) PERSIANN, resolution (25 km), and 2) PERSIANN-CCS, resolution (4 km). Similarly, we used 3-hour data of TMPA product real-time (3B42RT), resolution (25 km). In general, SREs represent the pattern of extreme precipitation in the study area but lack the precise representation on a sub-daily scale. This study assesses different corrections of SREs with respect to (wrt) ground-based data and fills data gaps of ground-based rainfall wrt SREs. There exists a great challenge into local flood simulation employing SREs.
Year: 2020