A probabilistic methodology to estimate future coastal flood risk due to sea level rise

In this paper we present a methodology to estimate the probability of future coastal flooding given uncertainty over possible sea level rise. We take as an example the range of sea level rise magnitudes for 2100 contained in the IPCC Third Assessment Report [Church, J.A., Gregory, J.M., Huybrechts, P., Kuhn, M., Lambeck, K., Nhuan, M.T., Qin, D., Woodworth, P.L., Anisimov, O.A., Bryan, F.O., Cazenave, A., Dixon, K.W., Fitzharris, B.B., Flato, G.M., Ganopolski, A., Gornitz, V., Lowe, J.A., Noda, A., Oberhuber, J.M., O'Farrell, S.P., Ohmura, A., Oppenheimer, M., Peltier, W.R., Raper, S.C.B., Ritz, C., Russell, G.L., Schlosser, E., Shum, C.K., Stocker, T.F., Stouffer, R.J., van de Wal, R.S.W., Voss, R., Wiebe, E.C., Wild, M., Wingham, D.J. and Zwally, H.J., 2001. Changes in sea level. In Houghton, J.T. et al. (eds), Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom, 881pp.] and infer a plausible probability distribution for this range. We then use a Monte Carlo procedure to sample from this distribution and use the resulting values as an additional boundary forcing for a two-dimensional model of coastal inundation used to simulate a 1 in 200 year extreme water level event. This yields an ensemble of simulations for an event of this magnitude occurring in 2100, where each member represents a different possible scenario of sea level rise by this time. We then develop a methodology to approximate the probability of flooding in each model grid cell over the ensemble and by combining these hazards maps with maps of land use values (consequence) we are able to estimate spatial contributions to flood risk that can aid planning and investment decisions. The method is then applied to a 32 km section of the UK coast in Somerset, South-West England and used to estimate the monetary losses and risk due a 1 in 200 year recurrence interval event under: (a) current conditions; (b) with the IPCC's most plausible value for sea level rise by 2100 (0.48 m) and (c) using the above methodology to fully account for uncertainty over possible sea level rise. The analysis shows that undertaking a risk assessment using the most plausible sea level rise value may significantly underestimate monetary losses as it fails to account for the impact of low probability, high consequence events. The developed method provides an objective basis for decisions regarding future defence spending and can be easily extended to consider other sources of uncertainty such as changing event frequency–magnitude distribution, changing storm surge conditions or model structural uncertainty, either singly or in combination as joint probabilities.     

Visualising the spatial extent of predicted coastal zone inundation due to sea level rise in south-west Western Australia

Visualising coastal zone inundation is crucial for both a quick assessment of coastal vulnerability and a full understanding of possible implications to population, infrastructure and environment. This study presents a simple but effective method of assessing the spatial extent of coastal zone inundation due to predicted sea level rise using commonly available elevation and image data as well as GIS software. The method is based on the geometrical principle of matching the raised sea level with the corresponding elevation contour line on land. Results for a test area along the south-west coast of Western Australia (∼200 km of coast line) show that a sea level rise of less than 0.5 m over the 21st century will have only minor impact but will become important when added to an extreme sea level event (e.g. storm surge). Both century-scale (∼0.5 m) based on tide gauge records and larger (>few metres) longer-term sea level rise predictions based on the melt of ice covered areas show essentially the same areas that are most vulnerable. Furthermore, the effectiveness of the method is demonstrated by the detection of areas that can be protected by relatively small flood protective structures at river and estuary entrances, thus providing valuable information for policy makers and local councils.     

Potential impact of sea level rise on coastal surges in southeast Louisiana

Potential impacts of 0.5 and 1.0 m of relative sea level rise (RSLR) on hurricane surge and waves in southeast Louisiana are investigated using the numerical storm surge model ADCIRC and the nearshore spectral wave model STWAVE. The models were applied for six hypothetic hurricanes that produce approximately 100 yr water levels in southeastern Louisiana. In areas of maximum surge, the impact of RSLR on surge was generally linear (equal to the RSLR). In wetland or wetland-fronted areas of moderate peak surges (2-3 m), the surge levels were increased by as much as 1-3 m (in addition to the RSLR). The surge increase is as much as double and triple the RSLR over broad areas and as much as five times the RSLR in isolated areas. Waves increase significantly in shallow areas due to the combined increases in water depth due to RSLR and surge increases. Maximum increases in wave height for the modeled storms were 1-1.5 m. Surge propagation over broad, shallow, wetland areas is highly sensitive to RSLR. Wave heights also generally increased for all RSLR cases. These increases were significant (0.5-1.5 m for 1 m RSLR), but less dramatic than the surge increases.     

Projected sea level rise in Florida

Future sea level rise will lead to salt water intrusion, beach/dune recession, and many other coastal problems. This paper addresses a data based forecasting approach to provide relative sea level rise estimates at locations in Florida where historical water level data exist. Many past estimates of sea level rise have treated the rise as a linear straight line trend over the historical data set. The present paper has allowed for acceleration (or deceleration) in sea level rise to account for the possibility of anthropogenic global warming and consequent higher (than linear straight line) future sea levels similar to values noted by global climatic modelers. Results of the present analysis show sea level rise for Florida being higher than past straight line trend results.     

气候变暖与海平面上升

本文通过大量实际资料分析认为,现代全球变暖与海平面上升,源于200多年前小冰期冷峰出现后的气候返暖、海平面回升过程演变的结果。近30年的世界海平面上升的速率,有着上世纪80、90年代和本世纪前10年世界平均气温每10年以0．2F°（0．11℃）为梯度的连续抬升为背景。在此以CO。含量为气候指标,划分出了公元200年以来的八个暖段（暖期）。若按冷暖极值距200年或250年计算,则由目前正在发展的暖期,将在公元2050年或2100年前后结束,而后开始降温。作者依据最近30年同一时段国内外验潮资料计算获得的绝对海平面升降速率为＋1．52±0．27mm／a及相对海平面升降速率为＋1．39±0．26mm/a。按照2010年坎昆气候大会决议要求,在对前人有关研究成果进行考量时,对将来的2050和2100年世界海平面预测及我国地面沉降较明显的沿海城市如天津、上海、厦门、海口等相对海平面升降值,进行了测算与评估。     

海平面上升、强台风和风暴潮对厦门海域极值水位的影响及危险性预估

气候变化背景下海平面上升、强台风和风暴潮对我国东南沿海地区的洪涝灾害影响日益严重,为应对气候变化的影响,本文以位于我国东南沿海的厦门地区为例,应用多种海洋大气观测资料和数理统计及模拟方法,分析了历史上9914号和1614号两次台风对厦门海域极端海面高度(极值水位)的影响,预估了未来海平面上升情景下厦门海域极值水位的变化及其危险性。结果表明：(1) 9914号台风期间,天文大潮、风暴增水和强降水的同时出现造成了厦门沿海地区超警戒极值水位(732 cm)的出现;(2) 风(向岸强风)、雨(强降水)、浪(巨浪)、潮(高潮位)、流(急流)等多致灾因子的共同作用是厦门沿海地区发生严重灾情的重要原因;(3) 在温室气体中等和高排放(RCP4.5和RCP8.5)情景下,到2050年(2100年),当前百年一遇的极值水位将分别变为30年(2年)一遇(RCP4.5)和25年(低于1年)一遇(RCP8.5)的频繁极端事件。这表明未来厦门沿海极值水位的危险性将显著上升,应采取充分的适应措施降低洪涝灾害风险。     

Climate change, sea level rise and integrated coastal zone management: An IPCC approach

Expansion of economic activities, urbanisation, increased resource use and population growth are continuously increasing the vulnerability of the coastal zone. This vulnerability is now further raised by the threat of climate change and accelerated sea level rise. The potentially severe impacts force policy-makers to also consider long-term planning for climate change and sea level rise. For reasons of efficiency and effectiveness this long-term planning should be integrated with existing short-term plans, thus creating an Integrated Coastal Zone Management programme.As a starting point for coastal zone management, the assessment of a country's or region's vulnerability to accelerated sea level rise is of utmost importance. The Intergovernmental Panel on Climate Change has developed a common methodology for this purpose. Studies carried out according to this Common Methodology have been compared and combined, from which general conclusions on local, regional and global vulnerability have been drawn, the latter in the form of a Global Vulnerability Assessment.In order to address the challenge of coping with climate change and accelerated sea level rise, it is essential to foresee the possible impacts, and to take precautionary action. Because of the long lead times needed for creating the required technical and institutional infrastructures, such action should be taken in the short term. Furthermore, it should be part of a broader coastal zone management and planning context. This will require a holistic view, shared by the different institutional levels that exist, along which different needs and interests should be balanced.     

Vulnerability assessment of coastal wetlands in Minjiang River Estuary based on cloud model under sea level rise

The change of coastal wetland vulnerability affects the ecological environment and the economic development of the estuary area. In the past, most of the assessment studies on the vulnerability of coastal ecosystems stayed in static qualitative research, lacking predictability, and the qualitative and quantitative relationship was not objective enough. In this study, the “Source-Pathway-Receptor-Consequence” model and the Intergovernmental Panel on Climate Change vulnerability definition were us...     

Modelling of morphological changes due to coastal structures

Two different concepts are applicable to model the nearshore morphodynamics. The first one takes into account only final consequences of acting mechanisms and is aimed at the prediction of long-term trends in beach development. Another approach implies the modelling of the whole suite of elementary processes responsible for changes in nearshore bottom topography during a given storm, and it is the approach used in the present work. A coastal area model complex is proposed that allows to reproduce the local morphological changes due to both the natural processes and the influence of coastal structures, such as a groin, a detached breakwater and a navigable channel (underwater trough). Consisting of a traditional series of basic components, the model differs from other ones in essential aspects concerning the treatment of transport mechanisms. In particular, the determination of wave-induced near-bed mean flow is based on the hypothesis that the direction and magnitude of bottom drift depend on difference between the actual rate of energy dissipation and its threshold value marking the flow reversal point. This hypothesis is shown to explain a general trend of cross-shore mean flow distributions observed in the nearshore region. Besides, the influence of the wave breaking process on sediment suspension is taken into account and the contribution of the swash zone to total sediment transport is included. Examples of computed morphological response are represented to demonstrate the model capability. A satisfactory agreement of computations with available data is pointed out.     

Analyzing sea level rise and tide characteristics change driven by coastal construction at Mokpo Coastal Zone in Korea

This study investigates a construction-induced sea level rise and tide characteristics change, using a regression analysis to separate the local construction effect such as sea-dike/seawalls and global warming from total sea level change. The study also makes it clear why and how the extreme high water level has risen just after constructions at Mokpo harbor in Korea. As a result of the regression analysis, it is found that the high water level rise for the period of 1960–2006 is ～60 cm, which is summation of four components: ～23 cm for Youngsan River sea-dike (1981), ～15 cm for Youngam seawall (1991), ～8 cm for Geumho seawall (1994), and ～14 cm for gradual rise (due mainly to global warming). Then, a numerical simulation at Mokpo coastal zone is performed to identify each component, and the results support the premise that the tidal amplification caused by constructions is due mainly to the extinguishment of the tidal choking effect at outer Mokpogu. The tidal flat effect makes the amplification greater at spring tide or extraordinary high tide, which would result in the increase of inundation risk at the Mokpo coastal zone. Frequency distribution of observed high water level data shows increasing trend for both maximum value of astronomical tide component (simulated high water level) and meteorological tide component (surge height) after the coastal constructions. A frequency analysis presents that the high water level for 50 year return period, which is often used for design in practice, is 474 cm before the construction, and while that is 553 cm after the construction. Furthermore, design height might steadily be elevated considering future global sea level rise.     

广东省沿海月均海平面变化研究

利用广东省沿海珠江三角洲河口区、粤东和粤西17个验潮站潮(水)位资料,通过经典谱分析、最大熵谱法(MEM)和小波分析分析等方法,对广东省沿海的月均海平面变化进行了研究。结果表明,广东沿海月均海平面呈现显著的季节变化和年际变化规律,海平面呈上升趋势,上升速率为1.2～2.0mm/a。     

Observed subsurface signature of Southern Ocean sea level rise

Satellite altimetry data show a strong increase in sea level in various parts of the Southern Ocean over the 1990s. In this paper, we examine the causes of the observed sea level rise in the region south of Australia, using 13 years of repeat hydrographic data from the WOCE SR3 sections, and the SURVOSTRAL XBT and surface salinity data. The hydrographic data show a poleward shift in the position of the Subtropical and the Subantarctic Fronts over the period. In the Antarctic Zone, the Antarctic Surface Water has become warmer and fresher, and the Winter Water tongue has become warmer, fresher, thinner and shallower. Increased freshening south of the Polar Front is linked to increased precipitation over the 1990s. Temperature changes over the upper 500 m account for only part of the altimetric sea level rise. The CTD sections show that the deeper layers are also warmer and slightly saltier and the observed sea level can be explained by steric expansion over the upper 2000 m. ENSO variability impacts on the northern part of the section, and a simple Sverdrup transport model shows how large-scale changes in the wind forcing, related to the Southern Annular Mode, may contribute to the deeper warming to the south.     

考虑海平面上升影响的极值水位计算

本研究基于非平稳序列极值理论,定量分析极端水位事件年超越概率受海平面上升的影响;以工程设计使用年限内极端水位发生概率作为控制条件,构建考虑海平面上升的极值水位计算方法;结合平均海平面的长期变化过程,推算海平面上升下的极值水位。基于全球10个验潮站历史水位观测资料,验证历史平均海平面长期变化与高、低水位耿贝尔分布位置参数变化的一致性以及构建方法的合理性。结合政府间气候变化专门委员会对海平面上升的预测,推算和对比分析不同海平面上升情景下的极值水位,并评估相应极值水位在当前极值分布中的重现期。     

Risk assessment and zoning of sea level rise in Shandong Province

Sea level rise is a slow-onset disaster.We collected information about the natural and ecological environments,tides and sea levels,and socio-economic aspects to investigate the distribution and zoning of the risks from sea level rise across Shandong Province.The trends in sea level in different counties of Shandong Province were predicted using moving averages and a random dynamic analysis forecasting model,and the model outputs and socio-economic indicators were combined to assess the risks.The results show that the risks of sea level rise along the western coast of Bohai Bay and Laizhou Bay in Shandong Province were sufficiently large to warrant attention.     

Coastal vulnerability assessment of the future sea level rise in Udupi coastal zone of Karnataka state, west coast of India

Udupi coast in Karnataka state, along the west coast of India, selected as a study area, is well known for sandy beaches, aquaculture ponds, lush greenery, temples and major and minor industries. It lies between 13°00′00″–13°45′00″ north latitudes and 74°47′30″–74°30′00″ east longitudes, the length of the coastline is 95 km, and is oriented along the NNW–SSE direction. It is vulnerable to accelerated sea level rise (SLR) due to its low topography and its high ecological and touristy value. The present study has been carried out with a view to calculate the coastal vulnerability index (CVI) to know the high and low vulnerable areas and area of inundation due to future SLR, and land loss due to coastal erosion. Both conventional and remotely sensed data were used and analysed through the modelling technique and by using ERDAS Imagine and geographical information system software. The rate of erosion was 0.6018 km²/yr during 2000–2006 and around 46 km of the total 95 km stretch is under critical erosion. Out of the 95 km stretch coastline, 59% is at very high risk, 7% high, 4% moderate and 30% in the low vulnerable category, due to SLR. Results of the inundation analysis indicate that 42.19 km² and 372.08 km² of the land area will be submerged by flooding at 1 m and 10 m inundation levels. The most severely affected sectors are expected to be the residential and recreational areas, agricultural land, and the natural ecosystem. As this coast is planned for future coastal developmental activities, measures such as building regulation, urban growth planning, development of an integrated coastal zone management, strict enforcement of the Coastal Regulation Zone (CRZ) Act 1991, monitoring of impacts and further research in this regard are recommended for the study area.     

海平面上升研究进展的文献分析

采用文献分析法对ISI Web of Science (institute for scientific information, ISI)核心合集数据库中关于海平面上升文献综合探究,得出结论:(1)海平面上升的发文量从1993—2016年整体呈上升趋势,尤其在2010年后产量大增。(2)发表越久的文献被引次数越高。文献作者数量逐年增多,引用参考文献数量也逐年增加,文献之间联系越来越紧密。(3)美国主导海平面上升研究。对于发文量较多的国家,该国独立发文量和其与他国合作文献量基本持平;对于发文量较少的国家,大部分文献为与他国合作完成。(4)不同机构之间合作是为常态,机构间合作明显多于国家间的合作。(5)关于海平面上升文献发文量最高的期刊刊登文献数占本研究总文献的近6%;期刊研究领域所属学科种类均与geology和environmental sciencesecology以及physical geography等相关。(6)通过关键词研究发现,除气候变化外,盐沼、风暴潮等是近期海平面上升的研究主流。希望通过对目前已出版文献的梳理为后续的研究提供指引及借鉴的依据,并通过对文献分析法的运用,能够使研究者更有针对性地将该方法运用到相关学术领域。     

秦皇岛沿岸海平面变化与地壳升降

本文研究发现,近43年来秦皇岛沿岸相对海平面变化呈总体下降趋势,其变化速率为-2.1~-2.4mm/a,经地壳升降观测资料修正后,确定海平面变化速率为-1.3~-1.6mm/a,并分岸段讨论了相对侮平面变化的年速率.由此证明,秦皇岛沿海海岸侵蚀并非由海平面变化引起.预计未来10余年内,海平面变化将不会对海岸带经济发展构成威胁.     

海平面上升对海岸潮差响应的理论解析

应用海湾和半封闭矩形海域改进的Taylor问题的解研究海平面上升对M2分潮旋转潮波系统及沿岸潮差的变化.将南黄海概化为一等深矩形海域,初步研究在海平面上升3 m和5 m条件下该海域旋转潮波系统的演化趋势,继而分析沿岸潮差变化特征.初步分析研究表明:随着海平面上升,该海域M2分潮的无潮点有向东南方向偏移的趋势,受此影响,沿岸潮差呈现不同的变化特征,靠近无潮点的左侧及湾顶海岸变化明显,而远离无潮点的右侧及湾顶海岸则变化不大.     

Adaptation strategy for sea level rise in vulnerable areas along China's coast

I~IOXThe sea level rise threatens China's coastal plains and river deltas and makes them the vulnerable areas due to their loW elevation.Since the 1980s, the Chinese scientists have paid great attention to the problem of the sealevel rise caused by the global warming. They have analyZed and calculated the trend of the relative sea level change along the China's coast in the past 50 a. The result of study shows that therising rate of the sea level along China's coast is (1. 7 i 0. 3) rum/a.…     

Extreme sea level events in the coastal waters of western Estonia

Extraordinarily low and high sea level events are analysed on the basis of historical data and their mechanisms of occurrence are studied with the 1 km grid size 2D hydrodynamic model in the two almost tideless semi-enclosed sub-basins of the Baltic Sea, the Gulf of Riga and the Väinameri. The sea level is modelled with realistic meteorological forcing and comparison data from 1999 and 2001. Resonance properties of the sub-basins are studied and their possible role in the formation of extraordinary sea level events is discussed. While the extremely low levels (−1.23 m below the mean sea level) in the Estonian coastal waters do not generally originate locally, the high levels (up to 2.53 m above the mean as measured in the Pärnu Bay) are short-term and local. They occur in combination with several forcing and morphometrical factors and are localised in the shallow and narrow bays exposed to the direction of the strongest possible storm winds, SW and W. Model simulations show that extremely high and low sea levels in some small bays of western Estonia can exceed the corresponding values in the Pärnu Bay.