Assessment of Extreme Storm Surges over the Changjiang River Estuary from a Wave-Current Coupled Model

Abstract

Disastrous storm surges and waves caused by typhoons are major marine dynamic disasters affecting the east China coast and the Changjiang River Estuary, especially when they occur coincidentally. In this study, a high-resolution wave–current coupled model consisting of ADCIRC (Advanced Circulation) and SWAN (Simulating Waves Nearshore) was established and validated. The model shows reasonable skills in reproducing the surge levels and waves. The storm surges and associated waves are then simulated for 98 typhoons affecting the Changjiang River Estuary over the past 32 years (1987–2018). Two different wind fields, the ERA reanalysis and the ERA-based synthetic wind with a theoretical typhoon model, were adopted to discern the potential uncertainties associated with winds. Model results forced by the ERA reanalysis show comparative skills with the synthetic winds, but differences may be relatively large in specific stations. The extreme surge levels with a 50-year return period are then presented based on the coupled model results and the Gumbel distribution model. Higher risk is presented in Hangzhou Bay and the nearshore region along the coast of Zhejiang. Comparative runs with and without wave effects were conducted to discern the impact of waves on the extreme surge levels. The wave setup contributes to 2–12.5% of the 50-year extreme surge level. Furthermore, the joint exceedance probabilities of high surge levels and high wave height were evaluated with the Gumbel–logistic statistic model. Given the same joint return period, the nearshore region along the coast of Zhejiang is more vulnerable with high surges and large waves than the Changjiang River Estuary with large waves and moderate surges.

Toward a High-Resolution Wave Forecasting System for the Changjiang River Estuary

“…Other human reconstructions, such as the Deep Waterway Project, with the purpose of deepening the navigation channel, have also been implemented [6]. Meanwhile, the CRE experiences severe typhoon storms almost every year, leading to coastal hazards such as catastrophic waves and storm surges [7][8][9]. In addition to typhoons in the summer, severe wave disasters have also been observed frequently over the CRE during cold weather events in winter.…”

Wave–Tide Interaction by Typhoon Ampil on Wave and Storm Surge in the Changjiang River Estuary and Its Adjacent Coastal Areas

“…Over the past 30 years, many typhoons have struck this coastal area, causing severe coastal flooding, infrastructure damage and huge economic losses [4]. For example, the super typhoon Chan-hom in 2015 caused economic losses of over RMB 9.8 billion [5]. However, due to the complex coastline and topography, as well as the many offshore islands, it is complex and difficult to accurately predict the storm surge and waves in the Changjiang River Estuary and adjacent seas.…”

SWAN Modeling of Dredging Effect on the Oued Sebou Estuary

“…Wave prediction is of crucial importance to human activities as it provides useful information for many coastal engineering applications such as the coastal protection, environmental monitoring, navigation, safe port management, and good control of recreational activities in popular coastal areas [14]. Both observational and measurement data, as well as physical and numerical models, are often used to assess extreme marine events around the world [15]. Chi and Rong [15] confirmed that long-term in situ observations can accurately estimate the sea level variation but are usually spatially limited.…”

“…Both observational and measurement data, as well as physical and numerical models, are often used to assess extreme marine events around the world [15]. Chi and Rong [15] confirmed that long-term in situ observations can accurately estimate the sea level variation but are usually spatially limited. The authors also indicated that many numerical models have been developed and validated to reproduce the spatial and temporal variation of wave spreading and uncover the underlying dynamics.…”