Assessment of TRMM rainfall data for flood modelling in three contrasting catchments in Java, Indonesia

Abstract

This study investigates the use of the Tropical Rainfall Measurement Mission’s (TRMM) rainfall data for predicting water flows and flood events in three catchments on the island of Java, Indonesia, namely, Ciliwung, Citarum and Bengawan Solo. The Shetran model was used for rainfall-runoff simulations, with rainfall input obtained from measured rain gauges (hourly and daily) and TRMM (3-hourly and daily). The daily Nash Sutcliffe Efficiency (NSE) values for the model calibration period were 0.75, 0.70 and 0.85 using rain gauge data and 0.44, 0.44 and 0.75 using the TRMM rainfall data. For the validation period, the NSE values were 0.71, 0.62 and 0.89 using rain gauge data and 0.26, 0.61 and 0.58 for the TRMM data. The Critical Success Index for predicting flooding events was improved using rain gauge data compared to using TRMM data. The results demonstrate that rain gauge data are systematically superior to TRMM rainfall data when used for simulating discharges and predicting flooding events. These findings suggest that rain gauge data are preferred for flood early warning systems in tropical rainfall regimes and that if TRMM or similar satellite rainfall data are used, the evaluated flood risks should be treated with extreme caution.