福建宁德海洋工程风暴潮灾害风险特征参数分析

Risk characteristics of storm surge hazards on marine project in Ningde,Fujian Province

宁德地区是我国受风暴潮影响较为严重的区域之一,同时也是宁德核电站等众多沿海大型工程所在地.鉴于该区域特殊的地理位置和海洋灾害的严重性,以宁德核电站为中心,对该区域所面临风暴潮风险的特征参数进行全面、综合的定量评估,包括潮汐特征、平均海平面变化、台风和风暴潮基本特征,特别是可能最大风暴潮的计算.研究结果表明,该区域10%超越频率的天文潮高、低潮位分别为355、-341 cm;平均海平面变化速率为0.162 cm/a;千年一遇的台风中心气压约为895h Pa,该气压时的最大台风风速半径为40 km.在进行大量敏感性实验的基础上,对台风移速、移向和风暴增水/减水的关系,以及增水和减水的差异就行了详细的研究,得出:台风增水主要是由移向在305°左右(295°~315°)、路过核电站下方(核电站以南)的台风引起,且增水随台风移速增大而增大;可能最大台风风暴增水由路径经过核电厂址南40 km的台风(移向295°、移速28 km/h)引起,最大台风增水值为526.8 cm;对于可能最大台风减水而言,最有利于台风风暴减水的移向在355°~360°和0°~15°之间,其中可能最大台风减水为-301.9 cm,由移向5°、移速30 km/h、路径经过核电厂址南30 km(0.75台风最大风速半径)的台风引起.

Ningde is one of the regions that face serious storm surge hazards,where major marine projects including the Ningde nuclear power plant( NNPP) are located. Considering the specific geographical location and serious marine hazards,this study aims to provide a comprehensively quantitative assessment on the risk characteristics of storm surge centered on the site of NNPP,including tides,Mean Sea Level( MSL) change,fundamental characteristics of typhoons and storm surges,and particularly the Probable Maximum Storm Surge( PMSS). The results show that the highest and lowest astronomical tidal level exceeding 10% of tidal sea levels are over 355 cm and-341 cm below the MSL in this region,respectively. The variability of MSL,based on the tide gauge observations for last 60 years is about 0. 162 cm/a. The air pressure at the typhoon center with return period of 1 000 years is 895 h Pa,and the corresponding radius of the maximum weed speed is 40 km. A large number of numerical experiments havebeen carried out in this study for the impact of movement directions and typhoon speeds on the storm surges and the difference between positive and negative storm surges forced by typhoons. Model results show that positive storm surges have mainly caused by the typhoons with movement directions around 305°( 295° ~ 315°) and passing through the south of the NNPP and the surge goes up with stronger typhoon wind speed. The maximum storm surge is 526. 8 cm,which is induced by the typhoon in direction of 295° and the speed of 28 km/h as well as by the track of passing through the point 40 km to the south of NNPP. For minus storm surges,the typhoons in movement directions of 355° ~ 360° and 0° ~ 15° provide the largest probability of the sea level decreasing. Among them,the minus PMSS is-301. 9 cm,which is induced by the typhoon in the movement direction of 5° and the movement speed of 30 km/h with the track of passing through the point 30 km to the south of NNPP.