Consideration of the rainfall-runoff-inundation (RRI) model for flood mapping in a deltaic area of Myanmar

Abstract

Formulating countermeasures to flooding risks is important, especially in areas where data are scarce. Numerical modeling techniques may enable hydrologists to model flooding events and access flood risk. Many flooding-inundation models have been developed and successfully applied to many areas. The rainfall-runoff-inundation (RRI) model is one such model that has been applied in various places to estimate river discharges and flooding-inundation depths. However, its applicability to flat river basins is in question. Here, we evaluate the applicability of RRI model to a flat river basin in a data-scarce region. Using the Bago River basin, Myanmar, as a case study, we analyzed past extreme flooding events and developed flooding-inundation maps. The model was calibrated with observed discharge data for a 2011 flooding event and validated for flooding events in 2014 and 2015. The model produced reasonable hydrographs (both peak and base flows). Although the simulated discharges showed good agreement with observed data, the simulated inundation extent showed some discrepancies due to lack of data. Our results indicate that the RRI model may be applicable to flat river basins (short-term analysis). However, for long-term flood simulation, the model may not be the ideal choice as it does not include any land-atmosphere interactions.