Accepted Manuscript Numerical simulation of typhoon-induced storm surge along Jiangsu coast, Part II: Calculation of storm surge Jin-hai Zheng, Jin-cheng Wang, Chun-yan Zhou, Hong-jun Zhao, Sang Sang PII: S1674-2370(17)30033-9 DOI: 10.1016/j.wse.2017.03.011 Reference: WSE 94 To appear in: Water Science and Engineering Received Date: 22 June 2016 Accepted Date: 15 December 2016 Please cite this article as: Zheng, J.-h., Wang, J.-c., Zhou, C.-y., Zhao, H.-j., Sang, S., Numerical simulation of typhoon-induced storm surge along Jiangsu coast, Part II: Calculation of storm surge, Water Science and Engineering (2017), doi: 10.1016/j.wse.2017.03.011. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1 Numerical simulation ofA CCEPTEDtyphoon-induced MANUSCRIPT storm surge along Jiangsu 2 coast, Part II: Calculation of storm surge 3 Jin-hai Zheng a,b,*, Jin-cheng Wang a,b, Chun-yan Zhou a,b, Hong-jun Zhao a,b, Sang Sang a,b 4 a Key Laboratory of Coastal Disaster and Defence (Hohai University), Ministry of Education, Nanjing 210098, China; 5 b College of Harbor Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China 6 Received 22 June 2016; accepted 15 December 2016 7 Available online *** 8 Abstract 9 The Jiangsu coastal area is located in central-eastern China and is well known for complicated dynamics with large-scale radial 10 sand ridge systems. It is therefore a challenge to simulate typhoon-induced storm surges in this area. In this study, a 2D 11 astronomical tide and storm surge coupling model was established to simulate three typical types of typhoons in the area. The 12 Holland parameter model was used to add the background wind field and the offshore boundary information was provided by the 13 improved Northwest Pacific Ocean Tide Model. Typhoon-induced storm surges along the Jiangsu coast were calculated based on 14 analysis of wind data from 1949 to 2013 and the spatial distribution of maximum storm surge levels under different typhoon types, 15 providing references for the design of sea dikes and planning for control of coastal disasters. 16 17 Keywords: Jiangsu coast; Typhoon-induced storm surge; Numerical simulation; Holland parameter model; ADCIRC 18 19 1. Introduction 20 Storm surges induced by typhoons are among the most popular research topics in flood prevention and 21 engineering design along coastal areas (Chen et al., 2009; Zhang et al., 2013). For example, according to the 22 nuclear safety guide HAF0111: The Confirmation of Design Basis Flood on Site Elevation of Seaside Nuclear 23 Power Station , the probable maximum storm surge of the sea area around the nuclear power station is the 24 essential element that determines the design basis of the flood. The design high tide level of nuclear power 25 stations under construction or soon to be under constructionMANUSCRIPT is determined as the sum of the maximum 26 astronomical tide level and the probable maximum storm surge according to international standards (Liang and 27 Zou, 2004). 28 In terms of modeling storm surges along the Jiangsu coast, probable maximum storm surges of Haizhou 29 Bay in the Jiangsu coastal area have been calculated by the numerical model of the storm surge, governed by a 30 depth-averaged flow equation in spherical coordinates, and verified by five cases of remarkable extratropical 31 storm surges with a maximum storm surge of 3.36 m (Yu et al., 2002; Wu et al., 2002). A high-resolution storm 32 surge model along the Jiangsu coast was built using the explicit difference (Zhang, 2008), so the stability was 33 low and the computation time was long. Several typhoons striking Jiangsu Province were simulated using the 34 weather research and forecasting (WRF) model and Delft 3D model in order to investigate the influence of 35 storm surges on the radial sand ridges off the Jiangsu coast with the sea level rising (Yu, 2013). The 36 hydrodynamics in the Jiangsu sea waters during Typhoon Damrey were simulated and a good fit was generated 37 between the simulated and the measured values of the typhoon data (Wang et al., 2015), where the gradient 38 wind field of Typhoon Damrey was computed by a Jele wind parameter model, then compounded with the 39 ambient wind field fromACCEPTED National Centers for Environmental Prediction (NCEP). 40 In this study, hydrodynamic simulations were carried out to investigate the storm surge along the Jiangsu 41 coast during different typhoons, based on the track and parameters of the theoretical typhoons. The calculated 42 surge levels will then show the spatial distribution of maximum storm surge levels under different typhoon 43 types, providing valuable references for planning for control of coastal disasters. 44 ————————————— This work was supported by the National Science Fund for Distinguished Young Scholars (Grant No. 51425901) and the National Natural Science Foundation of China (Grants No. 41606042). * Corresponding author. E-mail address: [email protected] (Jin-hai Zheng). 45 2. Method ACCEPTED MANUSCRIPT 46 2.1. Model description 47 The water levels of tide gauges consist of the astronomical tide level and storm surge level during the 48 typhoon period. This study built an astronomical-tide and storm-surge coupling model and validated the 49 reasonability of model topography, boundary conditions, and the wind field. The surges caused by hypothetical 50 typhoons in the Jiangsu coastal area were calculated using the storm surge model. 51 The numerical model included three sub-models, which were the wind field and wind pressure model, the 52 Northwest Pacific Ocean Tide Model (a large model), and the two-dimensional (2D) typhoon storm surge model 53 for the Jiangsu coast (a small model). The Holland parameter model was used to simulate the wind field and 54 pressure field of the typhoon. The improved Northwest Pacific Ocean Tide Model (Zhang et al., 2012) provided 55 the open boundary water levels for the 2D typhoon storm surge model, and the latter calculated the surge along 56 Jiangsu coastal waters. 57 The Northwest Pacific Ocean Tide Model uses the 2D tidal propagation equation in spherical coordinates 58 (Zhang, 2013), with a domain covering the East China Sea, South China Sea, Philippine Sea, Japan Sea, Sulu 59 Sea, and nearby Pacific Ocean areas. The initial flow velocity is zero. When computing the coupled water level 60 of the astronomical tide level and storm surge level, the open boundary condition for the large model is 61 provided by NAO99 with 16 short-period (M2, S2, K1, O1, N2, P1, K2, Q1, M1, J1, OO 1, 2N 2, Mu 2, Nu 2, L2, and 62 T2) and 7 long-period tidal constituents (Mtm , Mf, MSf , Mm, MSm , Ssa , and Sa), and the boundary condition for the 63 small model is the coupled water level of the astronomical tide level and storm surge level derived from the 64 large model. While the storm surge is simulated alone, the open boundary water level for the large model is set 65 as zero, so that the large model only provides the storm surge for the small model. The model was validated 66 with four main constituents (M2, S2, K1, and O1) of 435 tide gauges listed in the Admiralty Tide Table and the 67 good agreements indicated that the model is able to simulate the tidal system of the Bohai Sea, the Huanghai 68 Sea, and the East China Sea. 69 2.1.1. Wind field and wind pressure model MANUSCRIPT 70 The wind field and wind pressure model adopted the Holland parameter model, which is the most popular 71 method to simulate typhoon storm surges. Tropical cyclone best track dataset, published by the China 72 Meteorological Administration-Shanghai Typhoon Institute (CMA-STI), was used as the input conditions for the 73 model to simulate typhoons (Ying et al., 2014). 74 The Holland parameter model relies on the primary assumption of a radially symmetric pressure field, but 75 with a modified rectangular hyperbola to give the pressure p at any radius ( r) from the center as follows: R B −max ()()= + ∆ r (1) pr pc pe 76 ( ) where p r is the surface pressure (in Pa) at a distance r from the typhoon center; pc is the central pressure; 77 ∆ ∆ = − p is the difference between the ambient pressure ( pn ) and the central pressure ( p pn p c ), and the value of 78 the first anti-cyclonically curved isobar is pn in practice; Rmax is the radius to the maximum wind speed (m), 79 referring to the distance from the typhoon center to the region of maximum wind speed; and B is the so-called 80 profile peakedness used to characterize the shape of the radial pressure profile. 81 Gradient winds inACCEPTED the upper atmosphere are derived from the balance between the centrifugal and Coriolis 82 forces acting outwards and the pressure force acting inwards: V2 ( r ) 1 dp( r ) g +fV() r = (2) g ρ ra dr 83 ( ) where Vg r is the gradient wind speed (m/s) at a distance r from the typhoon center; f is the Coriolis parameter − ϕ 84 and f = 2ω sin ϕ ; ω is the angular speed of Earth’s rotation, set to be 7.2722054× 10 5 rad/s; is latitude; 85 ρ 3 and a is air density (assumed to be constant at 1.15 kg/m in the Holland parameter model).