Abstract. On 23 August 2017 a Category 3 hurricane, Typhoon Hato, struck southern China. Among the hardest hit cities, Macau experienced the worst flooding since 1925. In this paper, we present a high-resolution survey map recording inundation depths and distances at 278 sites in Macau. We show that one-half of the Macau Peninsula was inundated, with the extent largely confined by the hilly topography. The Inner Harbor area suffered the most, with a maximum inundation depth of 3.1 m at the coast. Using a combination of numerical models, we simulate and reproduce this typhoon and storm surge event. We further investigate the effects of tidal level and sea level rise on coastal inundations in Macau during the landfall of a “Hato-like” event.

Typhoons Hato (2017) and Typhoon Mangkhut (2018) struck the Pearl River Delta, China, in two consecutive years, causing intense flooding and severe damage along the coast, especially in Macau. These two typhoons are extreme events because of their record-breaking storm tides, and they are typical typhoons in terms of their track forward directions, which affect the coast of Guangdong Province, China. This paper analyzes and compares the physical processes of these two major typhoons. We first report the results of our posttyphoon surveys in Macau and the constructed inundation maps for both typhoon events. The inundation maps in conjunction with measured wind, atmospheric pressure, and wave data are used to validate a package of numerical models that simulate fully coupled tide-surge-wave fields during a typhoon. We quantify storm surges and wave heights in the Pearl River Delta. The surge around Macau was mainly affected by wind, while atmosphere pressure and ocean waves played a secondary role. In additional to inundation depth, we also investigate inundation durations and flow velocities. Typhoon Mangkhut made its landfall at much lower tidal level than that of Typhoon Hato. However, Typhoon Mangkhut generated much larger storm surge with larger affected areas and significantly longer inundation durations. We attribute the causes mainly to Typhoon Mangkhut's storm size, which was almost three times larger than that of Typhoon Hato. (2017) and Typhoon Mangkhut (2018) are two record-breaking typhoons, which struck the Pearl River Delta, China, in two consecutive years. We conduct timely posttyphoon surveys and construct high-resolution inundation maps in Macau where the severest impacts by both typhoons are evident. By conducting a fully coupled numerical simulation for tide-surge-wave, we reproduce the physical processes of these two typhoon events in the Pearl River Estuary. Typhoon Mangkhut and Typhoon Hato represent two distinct types of typhoons, which are equally dangerous. Typhoon Mangkhut is enormous in size, causing storm surge hazard in a much larger spatial coverage with much longer flood duration in the Pearl River Estuary. Typhoon Hato, which strengthened unexpectedly from Categories 1 to 3 on the Saffir-Simpson scale in 5 hr just before its landfall, increased the risk of inadequate evacuation efforts, large causalities, and property damage. Plain Language Summary Typhoons Hato

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