Impact of Tides and Surges on Fluvial Floods in Coastal Regions

Fluvial floods in coastal areas are affected by tides and storm surges, while the impact is seldom quantified because dynamics of seawater levels often not represented river routing models. This study established a model framework coupling surge with global hydrodynamic at higher spatiotemporal resolution than previous studies so that flood processes level fluctuation small basins can be investigated. Model implementation Zhejiang Province, China, shows integration dynamic increases stress flooding along coasts. The ocean effect varies space, as it much stronger northern lower landform strong tidal amplification, mountainous rivers southern dominated flow regimes. Typhoon Lekima resulted compound events (i.e., rainfall-induced riverine flood, tides, surges), during which maximum water outlet Qiantang River was 0.80 m default settings constant downstream 0 m), increased to 2.34 (or 2.48 m) when surges) were considered. increase due surges 2.09 1.45 m, respectively, did match time peak. mismatching indicates need consider different physical models rather linearly summing up extreme tide, surge) found studies. integrating various will help prevent risks cities practical future projections under scenarios.