Abstract
Coastal inundation resulting from unusual sea level rise triggered by extreme weather events such as tropical cyclones or intense storms bears significant implications for coastal populations, infrastructure, and socio-economic activities. The conditions are further exacerbated when a cyclone brings heavy rainfall over the land area. To manage such disasters and foster resilient coastal communities, it's crucial to conduct comprehensive analyses of storm surges and resulting inland inundations. This study examines the combined effects of storm surge and inland flooding during a cyclone and proposes mitigation measures. Cyclone Mocha made landfall on the Myanmar coast bordering the Bay of Bengal (BoB) in 2023, resulting in significant storm surge and widespread inland flooding. This potentially impacted around 670,000 ha of land of which 327,000 ha is cropland. A detailed analysis of satellite imageries of this event revealed inundation resulting from storm surges extending over 70 km inland, a dimension often overlooked in previous research. Evaluating such events during a cyclone requires a modeling framework capable of simulating surge propagation in both ocean and inland areas. The Integrated River and Ocean Modelling System (IROMS) model is utilized for this purpose. The model outputs are validated using buoy water levels and satellite imageries of inundation extent. The results highlight the substantial risk of extensive coastal and inland flooding, evident from surge heights reaching 3.5 meters near Sittwe Port. The surge propagation patterns further illustrate the risk when water breaches onto floodplains. In addition, potential worst-case scenarios are evaluated, and mitigation measures are proposed. This study underscores the significance of proactive strategies in mitigating vulnerability and bolstering resilience in flood-prone regions of Myanmar.