| Storm surge is a phenomenon of abnormal sea level rise and fall caused by strong atmospheric disturbances,usually causeed by strong cold air,extratropical cyclones,and typhoons.It is a common natural marine disaster in coastal areas around the world,especially in Estuary,bay and delta regions.Storm surges not only damage ports,piers,and dikes,but also inundate houses,farms,and aquaculture areas after dikes breach,resulting in serious loss of life and property for local people.The Yellow River Delta is a high-risk area for storm surges in the Western Pacific,affected by various storm surges caused by tropical storms,temperate storms and strong cold air.Moreover,the flat terrain and severe erosion of the Yellow River Delta make its ecological environment extremely fragile,facing serious threats from storm surge disasters.However,in previous studies of the Yellow River Delta,researchers have focused on nearshore bed erosion,construction and maintenance of engineering facilities,and tidal flat vegetation,with insufficient attention to storm surge flooding on land,especially the unclear distribution of storm surge risks in different regions of the Yellow River Delta.Therefore,Therefore,this paper focuses on the storm surge risk zoning in the Yellow River Delta.The risk of storm surge in coastal areas is determined by the risk of storm surge and the vulnerability of hazard-affected bodies.The former generally refers to the strength and frequency of storm surges,while the latter is closely related to the vulnerability of hazard-affected organizations.In view of this,this paper comprehensively considers the risk of storm surge and the vulnerability of ground objects,uses terrain,meteorology,hydrology and other data,establishes a’land-sea’hydrodynamic model,calculates flood inundation of storm surge in the Yellow River Delta under different weather conditions,and draws the risk map of storm surge in the Yellow River Delta with water depth as the standard.At the same time,using satellite images,comprehensive use of NDWI,NDVI and other methods to identify features,determine different land use types such as mudflats,water bodies and vegetation in the Yellow River Delta,and determine the vulnerability level according to its vulnerability,so as to draw the Yellow River Delta storm surge vulnerability distribution map(hereinafter referred to as vulnerability).Based on this,the storm surge risk level was determined for each area and a storm surge risk zoning map was drawn for the Yellow River Delta.Seabed erosion,sea level rise,and the construction of engineering facilities will reshape storm surge flood patterns,changing the distribution of storm surge risk levels.By comparing the results of storm surge flooding under different working cases,the impact factors of typical storm surge risk are discussed and their effects and impacts are quantified.Suggestions on disaster prevention and mitigation measures for storm surge in the Yellow River Delta.After research,the following conclusions were reached:(1)The overall storm surge risk level in the Yellow River Delta is not high,but there are some areas with high-risk areas.The storm surge risk level in most areas of the Yellow River Delta is not high,and the risk level is concentrated in the lower risk(level III)and low risk(level IV).The risk areas are concentrated in the estuary area on the north side of the Yellow River Delta and the Yellow River Estuary Town and the ecological tourism area on the east side.However,on the east side of Dongying City,there is a large area of high-risk storm surge area(level I).(2)Offshore oil fields along the Yellow River Delta face a high risk of storm surges.Many beach oilfields from Diaokou Estuary to the present estuary are at high risk of storm surge(level I).Under the action of east and northeast winds,the delta coast increases by 0.9 m and 1.4 m,respectively,which will further increase the risk of oilfield storm surge disaster.However,due to the action of northerly winds,the risk of a storm surge disaster in the field was reduced to level II.(3)Changes in terrain,sea level rise,and engineering facilities can significantly affect storm surge and flood patterns in the Yellow River Delta.Seabed erosion increases the difficulty of storm surge and reduces the intensity of storm surge flooding,and is most pronounced under the influence of northerly winds.In 2015,296.23 km~2less area was flooded by storm surge than in 1985.Rising sea levels have little effect on storm surge flooded areas,but can significantly increase the depth of inundation in flooded areas.Engineering facilities can effectively prevent storm surge flooding,and when the storm surge increases to 1.5 m outside the seawall,the interior of the seawall is still not threatened by storm surge flooding.Therefore,the core of storm surge defense in the Yellow River Delta lies in the construction of protective projects such as seawalls.On the basis of strengthening the prediction of storm surge disasters,it is necessary to strengthen the maintenance of seawalls and slow down the erosion of the seabed from the Gudong Dike to the north shore of Dongying Port,especially in the sea area with anti-profile shape,to rip the foundation and enhance the strength of the seawall;for the remaining bank sections,salt marsh vegetation such as Spartina alterniflora can be rationally utilized,combined with traditional seawall projects,to enhance the ability to withstand storm surge disasters.Strengthening the study of storm surge in the Yellow River Delta,clarifying the influencing factors of storm surge and the mechanism of disaster occurrence,determining the scope of storm surge,drawing the risk level map of storm surge,and discussing the protection countermeasures of storm surge can provide scientific basis for the prevention of storm surge disaster in the Yellow River Delta,which is of great significance to promote the high-quality development of the Yellow River Delta. |
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