Chapter 6 – storm surge warning, mitigation and adaptation

Chapter 6 – storm surge warning, mitigation, and adaptation Chapter 6 – storm surge warning, mitigation, and adaptation Chapter 6 – storm surge warning, mitigation, and adaptation Chapter 6 – storm surge warning, mitigation, and adaptation Chapter 6 – storm surge warning, mitigation, and adaptation Chapter 6 – storm surge warning, mitigation, and adaptation

Chapter 6

Storm Surge Warning,

Mitigation, and Adaptation

miti-to the amelioration of smiti-torm surge disaster risk through the reduction of existing ards, exposure, or vulnerability The chapter discusses major storm surge barriers such

haz-as the Dutch Delta Works and the Thames Barrier, and describes more recently builtbarriers in St Petersburg (Russia), New Orleans, and Venice The chapter also reviewsstorm surge early warning systems, with examples from Bangladesh, the Philippines,the United Kingdom, and the United States

The physical causes of storm surge are well known, and models are ingly effective at predicting the storm surge associated with particular cycloneconditions Despite this, we continue to see loss of life from storm surges Forexample, the surge from Typhoon Haiyan in November 2013 was not unex-pected; the strength of the storm was predicted and understood and over800,000 people were evacuated, yet it led to 6,111 deaths and over 5 millionwere people displaced (Chan et al., 2013) In comparison, the 2004 IndianOcean tsunami and Hurricane Katrina “only” displaced 1e1.5 million each(Ferris, 2013) The greatest loss of life related to a tropical cyclone is fromstorm surge (Doocy et al., 2013) In the United States, the loss of life in thethree deadliest hurricanes (Galveston, Texas, 1900, over 8,000 deaths; LakeOkeechobee, Florida, 1928, 2,500 deaths; Hurricane Katrina 2005, 1,833deaths) was primarily due to storm surge (Weindl, 2012) Hurricane-surge-induced flooding has killed more people in the United States than all otherhurricane threats combined in the twentieth and twenty-first centuries (NOAA,

increas-2007) The extratropical Cyclone Xynthia claimed 47 lives in 2010, Europe’shighest storm surge toll since 1962 (Kron, 2013) Why does such loss of lifecontinue despite better understanding of the physics of storm surge andCoastal and Marine Hazards, Risks, and Disasters http://dx.doi.org/10.1016/B978-0-12-396483-0.00006-6

Copyright © 2015 Elsevier Inc All rights reserved. 153

improved modeling and warning systems? How can we best reduce thenegative impacts of storm surges?

6.1 MITIGATION AND ADAPTATION

The terms “mitigation” and “adaptation” are used in many disciplines, whichresults in a range of interpretations For example, the term “mitigation” can beused to describe actions taken to reduce the likelihood of an event occurring(e.g., reducing greenhouse gas emissions in order to reduce increases in globaltemperature and thus reduce the rate of sea level rise) or actions taken toreduce the impact if the event does occur (e.g., building flood defenses).Within a particular discipline the meaning of such terms may be clear There is

no interdisciplinary consensus, however, and until recently, climate scientistsand disaster risk reduction researchers had very different definitions of miti-gation In the climate change literature, mitigation refers to the reduction ofthe rate of climate change via the management of its causal factors (emission

of greenhouse gases from fossil fuel combustion, agriculture, land usechanges, etc.) However, in the disaster risk reduction literature, mitigationrefers to the amelioration of disaster risk through the reduction of existinghazards, exposure, or vulnerability Recent Intergovernmental Panel onClimate Change (IPCC) reports have revised their definitions to accommodateboth interpretations of mitigation IPCC definitions now distinguish betweenmitigation of climate change, which is defined as “a human intervention toreduce the sources or enhance the sinks of greenhouse gases,” and mitigation

of disaster risk and disasters, which is defined as “the lessening of the potentialadverse impacts of physical hazards, including those that are human-induced,through actions that reduce hazard, exposure, and vulnerability” (IPCC, 2012).Wilby and Keenan (2012) and Cooper and Pile (2013) reviewed thedifferent definitions of adaptation, as summarized above, and Hallegatte(2009) identified five categories of practical adaptation strategies The first isno-regret measures, which yield benefits even in the absence of increasinghazards (although they are not cost free) The second category is reversiblestrategies, which are flexible enough to reduce as much as possible the cost ofbeing wrong about future risks The third category, safety margin strategies,reduces vulnerability at low or no cost The fourth category, soft strategiessuch as land use planning and insurance, influence individual and institutionaldecisions and therefore can have an effect on hard investments The finalcategory is strategies to reduce decision-making time horizons Hallegatte(2009) also distinguished between “hard” adaptation (e.g., building seadefenses) and “soft” adaptation such as land use planning, early warningsystems, and financial instruments such as insurance Wilby and Keenan(2012)distinguished between the broader enabling environment for adaptation(information provision, institutional arrangements, and preparedness) andspecific implementing measures to reduce flood risk They classified these

154 Coastal and Marine Hazards, Risks, and Disasters

implementing measures into three categories: defending against flood risk,living with flood risk, and withdrawing from flood risk Defense measurestypically involve some form of engineering to protect existing land use Hardengineering structures such as levees and storm surge barriers are probably themost common; however, there is a growing interest in soft engineeringapproaches, such as wetland creation Accommodation actions include raisingbuildings and roads above flood level, establishing evacuation routes andwarning systems, the creation or enhancement of stormwater system capacity,and zoning policies aimed at preventing development in high-risk areas.Retreat policies include those aimed at discouraging rebuilding in high-riskareas and the reclamation or abandonment of highly flood-prone lands.Table 6.1summarizes the range of available approaches to coastal hazards (notnecessarily restricted to storm surge) Cooper and Pile (2013) characterizedadaptation measures as two types, those that modify the environment and thosethat are aimed at changing human activities They noted that the reduction ofharm and the realization of benefits to humans are central to all definitions ofadaptation Wilby and Keenan (2012) argued that in the case of flood riskmanagement (floods in general, not storm surge explicitly), much of what islabeled adaptation could just be described as good practice.

In the context of storm surge, mitigation can be thought of acting to reducethe number and severity of storm surges (which would mean reducing thenumber and severity of tropical, subtropical, and extratropical cyclones), whileadaptation is learning to live with the risk of storm surges Adaptation mea-sures are unlikely to eliminate risk, but should aim to reduce risks to levels thatare acceptable within the limits of available resources The measures discussed

in this chapter are adaptive measures only, which may reduce the vulnerability

to storm surge rather than the storm surge itselfdnone of them can stopcyclones from occurring

6.2 STORM SURGE BARRIERS

The most common hard engineering structure used to protect against induced flooding is a storm surge barrier These structures provide temporaryprotection from flooding, generally for a few hours before and after high tide andare often partly open during normal conditions to allow navigation and salt waterexchange with estuarine areas landward of the barrier (Jonkman et al., 2013) Astorm surge barrier may be only one component of a larger flood protectionscheme, which will often include other structures such as seawalls and levees.Storm surge barriers are usually built at a position where the barrier can beclosed during times where flooding is predicted When the barrier is not closed,

surge-it allows free passage of water and shipping The main disadvantages of a stormsurge barrier system are the huge construction and maintenance costs Movablebarriers also require simultaneous investment in flood warning systems, whichprovide information on when to close the barrier (Aerts et al., 2013b)

155Chapter j 6 Storm Surge Warning, Mitigation, and Adaptation

TABLE 6.1 Coastal Hazard Adaptation Strategies (Not Restricted to Storm Surge)

Adaptation

Option

No-Regret Strategy

Reversible/

Flexible

Safety Margins Available

Soft Strategy

Type of Response

Hard defenses (e.g., seawalls, levees) þ  þ Defend against flood risk Storm surge barriers þ  þ Defend against flood risk Restore natural coastal defenses

(e.g., salt marsh, mangrove, dunes)

þ þ þ Defend against flood risk Temporary/demountable defenses þ þ Live with flood risk

Enhanced drainage systems þ  þ Live with flood risk

Land use planning (e.g rezoning, setback,

compulsory purchase, restrictions on

development in flood zones)

þ þ þ Live with flood risk

Improved building standards/flood-resilient

construction (buildings and infrastructure)

þ þ Live with flood risk Information and warning þþ þ þ Live with flood risk

Evacuation schemes þþ þ þ Live with flood risk

Flood/storm surge shelters þ þ þ Live with flood risk

Insurance (household to national level) þþ þ þ Live with flood risk

Relocation and retreat   Withdraw from flood risk

In the classification used by Hallegatte (2009), þþ indicates options which yield benefits even without climate change, while þ indicates options that are “no-regret” only

in some cases, depending on local characteristics and  indicates that the strategy would entail significant losses in the current climate.

Source: Adapted from Hallegatte (2009) and Wilby and Keenan (2012)

Most storm surge barriers were implemented after a flood disaster occurred(Aerts et al., 2013b) The best known barriers are the Dutch Delta Works andthe Thames Barrier, which were both built in response to the 1953 North Seastorm surge when 305 people died in the United Kingdom and 1835 died in theNetherlands The Delta Works (Figure 6.1) is the largest flood protectionproject in the world and includes dams, sluices, locks, bridges, tunnels, dikes,levees, and storm surge barriers that protect southern Holland against a1:10,000-year storm surge (Zhong et al., 2012) The Oosterscheldekering(Eastern Scheldt storm surge barrier) is the largest of 13 structures which make

up the Delta Works Construction on the Delta Works began in 1958 and wasofficially completed in 1997 at a cost of $7 billion (Bijker, 2002) However,the Netherlands continues to add infrastructure to the system as needed(Pilarczyk, 2012), with a seawall near Harlingen completed in 2010 The DeltaCommittee was set up to investigate the impact of climate change and pro-jected sea level rise in the twenty-first century Their 2008 report (Delta VisionCommittee report, 2008) led to the Delta Programme, which addresses futureflood risk management and freshwater supplies, and the establishment of theDelta Fund Significant investments will need to be made after 2050; for

FIGURE 6.1 The Dutch Delta Works http://en.wikipedia.org/wiki/File:Deltawerken_na.png

157Chapter j 6 Storm Surge Warning, Mitigation, and Adaptation

example, the Maeslant Barrier protecting Rotterdam is due to be replaced after

2070 to build a new closable storm surge barrier The Delta Fund, which wentinto effect at the start of 2013, sets aside money for the governmentinvestments to works set out in the Delta Programme (Zevenbergen et al.,

2013) The central government and the water boards (regional governmentbodies which levy their own taxes) have agreed to pay an equal share of thecosts of current and future flood protection measures (Verduijn et al., 2012).They will each contribute V131 million in 2014 and V181 million annuallyfrom 2015, with a total of V16.6 billon available from all fundingsources between 2014 and 2028 and V22 billion between 2029 and 2050(Kabat et al., 2009) All the resources from the Delta Fund are fully allocateduntil 2019, when funding for investment in new flood risk managementmeasures will be available (Delta Programme, 2014) The impact of the DeltaWorks has been extensively studied, with research investigating the impact onecology (e.g.,Hostens et al., 2003; Tangelder et al., 2012; Jansen et al., 2013;van Wesenbeeck et al., 2014), geomorphology (e.g., Louters et al., 1998;Roelvink et al., 2001; To¨nis et al., 2002; Hudson et al., 2008), and hydrologyand hydrodynamics (e.g.,Jonkman et al., 2008; Augustijn et al., 2011; Zhong

et al., 2012) The references reported here represent only a small number of thestudies which have been carried out on the areas affected by the Delta Works.Zhong et al (2012)evaluated the impact of the Maeslant storm surge barrier

on flood frequency under rising sea levels and showed that the operation of theMaeslant Barrier reduces flood frequency and can partly compensate for theeffect of future sea level rise, although the return periods of all water levelswill decrease as the sea level rises The Maeslant Barrier is currently closedwhen water level in Rotterdam reaches 3.0 m According to the model ofZhong et al (2012), the return period of this water level in 2010 without thebarrier, 10.9 years, is increased to 2,400 years with the barrier Under thecurrent closing decision water level of 3.0 m, the port of Rotterdam will beclosed once every 3.2 years in 2050 and once every 1.1 year in 2100 Thedesign safety level, 4.0 m, will be reached with a return period of 46,948 years

in 2010, 16,420 years in 2050, and 3,849 years in 2100

Although the water level in the 1953 storm surge was the highest everrecorded in London, the height of the storm surge was about 3 h before hightide and the river level was low after a dry spell, and thus only a few locations ineast London were flooded After the lucky escape in 1953, the UK governmentappointed the Waverley Committee to study flood dangers to the city TheCommittee recommended that a structure be constructed across the Thames,backed up with a considered approach to development in the floodplain, and 41proposals at six sites were put forward following the report (Waverley, 1954).However, no action was taken until the problem was passed to the GreaterLondon Council in 1968 with a request that a full investigation into the problem

be carried out as a matter of considerable urgency (Horner, 1979) This led tothe construction of the barrier, begun in 1976 and completed in 1984 at a cost of

158 Coastal and Marine Hazards, Risks, and Disasters

£560 million (equivalent to about £1.6 billion in 2014 prices), including thecost of strengthened defenses both upstream and downstream of the ThamesBarrier and the associated construction of three minor barriers, two majorfloodgates, and nine minor floodgates on tributaries of the Thames The ThamesBarrier was designed to protect against the 1,000-year flood, with an allowancefor an increase in water level up to 2030 In 2010, the UK Environment Agency(EA) published a study (TE2100) on planning for flood risk management in theThames Estuary, which aimed to determine the appropriate level of floodprotection needed for London and the estuary for the next 100 years (Envi-ronment Agency, 2010) The TE2100 policy recommendations were dividedinto three time periods In the first 25 years (2010e2035), the strategy is tocontinue to maintain the current flood defense system including planned im-provements, ensure effective floodplain management is in place, and monitorchange indicators The strategy for the transition period (2035e2049) is toreplace and upgrade current defenses and to make the final decision on building

a new barrier or other end-of-century option, and to start planning for this Theagreed end-of-century option is to be planned, designed, and constructed be-tween 2050 and 2100 The extensive benefitecost analyses carried out in theTE2100 analysis suggested that improving defense standards now is not costeffective, as the extra benefit gained is generally not worth its costs until climateand socioeconomic change begin to create additional risk from 2050 and toward

2070 (Penning-Rowsell et al., 2013a) No costings for the unspecified century option were given in the TE2100 report but other information fromthe EA indicated that investment of £1.5 billion will be needed for the first

end-of-25 years, with another£1.5 billion needed for the middle 15 years, and £6e7billion for 2050e2100 (Environment Agency, 2013) The contracts for the firststage of TE2100 went out for bidding in September 2013 The phase 1 programrepresents the capital-funded work needed to maintain tidal defenses from 2015

to 2025 and includes refurbishment of fixed assets (such as tidal walls andembankments), active assets (including the Thames Barrier gates), and newassets such as pumping stations The contract for phase 1 will be awarded inSeptember 2014

As of April 2014, the Thames Barrier has been closed 174 times since itbecame operational in 1982, with increasingly frequent closures since 2000.Half of these closures were to protect against tidal flooding and half to protectagainst river flooding The closure on December 6, 2013, was associated withthe biggest storm surge since 1953 and the highest tide in response to which theThames Barrier has closed, at an elevation of 4.1 m (Atkin, 2014) The EApublished a map showing the probable impact on central London if the barrierhad not been in place (Figure 6.2) The TE2100 report recommended that theThames Barrier should not be closed more than 50 times a year to reduce thechance of it failing The Thames Barrier was expected to reach this design limitfrom 2135 onward, and the TE2100 report suggested that once this design limit

is reached, it may not be possible to close the barrier to protect against fluvial

159Chapter j 6 Storm Surge Warning, Mitigation, and Adaptation

flooding in order to maintain the reliability of the barrier against tidal flooding(TE2100) The Thames Barrier came under unprecedented pressure in the firstmonths of 2014, reaching its operational safety limit of 50 closures on 4 March

of that year This is the record for the highest number of times it has been closed

in a single season (Figure 6.3), with many of the closures to protect WestLondon against river flooding in the wettest winter since records began in 1766.The EA described these frequent closures as a “blip” and is still forecasting that

a replacement is not needed until 2070 (BBC, 2014) However, the EA willcarry out an investigation of the robustness of the Thames Barrier in response to

a request from the Mayor of London and will report its findings at a ThamesEstuary Steering Group meeting in early summer 2014 (London Assembly,

2014) Even with the impetus of the loss of life in 1953, it took years to planand build the Delta Works and the Thames Barrier.Padron and Forsyth (2013)estimated that the average interval between planning and constructing a majorstorm surge barrier is 27 years, suggesting that perhaps the timetable for theThames end-of-century option should be brought forward and that somethinglike the Delta Fund should be set up now to plan for its financing

Storm surge barriers in other cities are reviewed byDircke et al (2013)andsummarized inTable 6.2; this chapter will describe only a few more examples.The St Petersburg Flood Prevention Facility Complex is a storm surge barrier

FIGURE 6.2 The UK Environment Agency’s simulation of the flooding which should have resulted from the storm surge in December 2013 without the Thames Barrier http://www.nce.co uk/news/nce-live-news-updates-tuesday-10-december-tidal-surge-broke-records-london-will- choke-without-crossrail-2/8656557.article

160 Coastal and Marine Hazards, Risks, and Disasters

FIGURE 6.3 Closures of the Thames Barrier since it was built https://www.gov.uk/the-thames-barrier

TABLE 6.2 Overview of Storm Surge Barriers

Design and Construction Time (years)

Year of Operation

Approx Cost (Million Dollars)

Hollandse Ijssel storm surge barrier Lifting gate Netherlands 4 1958 127

Oosterschelde storm surge barrier Lifting gate Netherlands 10 1986 5,005

Maeslant storm surge barrier Floating sector gate Netherlands 8 1997 709

Europoort Barrier and Hartel Barrier Lifting gate Netherlands 6 1997 329

Ramspol storm surge barrier Rubber dam Netherlands 5 2002 88

Venice storm surge barrier Flap gate Italy 13 estimated 2016 estimated 7.6

New Bedford storm

surge barrier

Rolling sector gate New Bedford,

MA, USA

4 1968 72 Stamford storm surge barrier Flap gate Stamford, CT, USA 4 1968 19

Harvey canal flood protection

barrier, Gulf Intracoastal Waterway

West Closure Complex (GIWWCC)

Sector gate New Orleans,

IHNC New Orleans hurricane

Russia Started in the

1990s, resumed

in 2002

2010 6,600

Eider Barrage Radial gate Germany 6 1973 113

Ems storm surge barrier Lifting gate,

radial gate, segment gate

Germany 5 2002 286

Marina Barrage Crest gate Singapore 3 2008 173

Source: Based on Dircke et al (2013) , Expanded and Updated.

system which includes 11 embankment dams, 67 hydraulic gates, a bridge andtunnel, and two navigation channels with gates that can be closed to protectagainst storm surge (Hunter, 2012) Construction on the barrier began in 1979,halted at the breakup of the Soviet Union, and was completed in 2011 at a cost

of about $3 billion The scheme is designed to protect against a 1,000-yearstorm surge of 4.55 m with an extreme limit of 5.15 m for a 1:10,000-yearflood (Ivanov et al., 2012)

A storm surge barrier system to protect Venice, known as MOdulo imentale Elettromeccanico (MOSE), is under construction The MOSE projectconsists of four tidal defense barriers at the openings in the barrier islandswhere Adriatic tides enter Venice lagoon (Bajo et al., 2007) The MOSEdefenses include 21 gates in a north channel at the Lido inlet, 20 gates in thesouth channel and an intermediate island linking the two barriers, a barrierwith 19 gates at the Malamocco inlet, and a barrier with 18 gates in theChioggia inlet (Fontini et al., 2010) Construction started in 2003 and isexpected to be completed in 2016 with an estimated cost of V5.493 million(about $7.6 million) There has been a long debate about the optimal closinglevel of the MOSE barriers: increasing the barriers’ functioning frequencyimproves the degree of protection against storm surge; however, this also in-creases interference with harbor activities (Fontini et al., 2010) Researchershave also debated whether the yet-to-be-completed Venice barrier will protectthe city as sea level rises (e.g., Pirazolli, 2002; Bras and Harleman, 2002;Pirazzolli and Umgeisser, 2006; Umgiesser and Matticchio, 2006; Rinaldo

Sper-et al., 2008) The current expectation is that the MOSE barriers will protectVenice until sea level rise is greater than 0.60 m; at that stage, new options forthe future of the Venice lagoon will have to be considered (Munaretto et al.,

2012)

Hurricane Katrina highlighted the need for improved defenses for NewOrleans and led to the construction of the Hurricane and Storm Damage RiskReduction System (HSDRRS) for Southeast Louisiana The storm surge fromKatrina breached 50 floodwalls and levees and collapsed a 1,220-m section ofthe Inner Harbor Navigation Canal (IHNC), a waterway that connects theMississippi with Lake Borgne and the Gulf of Mexico (Miller et al., 2013).The $14.45 billion HSDRRS consists of 563 km of levees and floodwalls,

73 pumping stations, three canal closure structures with pumps, and four gatedoutlets (USACE, 2010) Because evacuation is now seen as a major part of thenew emphasis on risk reduction, the HSDRRS also includes an elevated roadand bridge over a new floodwall at the entrance to the Lake PontchartrainCauseway Bridge (Eqecat, 2009; Reid, 2013) One component of theHSDRSS, the 3-km IHNCdLake Borgne Storm surge barrierdwascompleted in 2013 at a cost of $1.1 billion and is designed to protect the areaswhich were hit hardest by Katrina This barrier closes off Lake Borgne, sit-uated at the east side of New Orleans, and closes both the lake and the canalsnorthwest and southwest of the lake The navigable Seabrook surge barrier

164 Coastal and Marine Hazards, Risks, and Disasters

protects the Lake Pontchartrain entrance of the IHNC A movable gate hasbeen built in the canal northwest of Lake Borgne, the Gulf IntracoastalWaterway (GIWW), making navigation possible during normal conditions.The canal southwest of Lake Borgne, the Mississippi RivereGulf Outlet, hasbeen permanently closed by the storm surge barrier The new system isdesigned to withstand the 1:100-year storm event in 2057 (USACE, 2010) TheHSDRSS system was tested by Hurricane Isaac in 2012 and performed asdesigned (Reid, 2013; USACE, 2013), although flooding did occur in areasoutside the system This was attributed to an intense and long-duration surgecaused by the long duration of tropical force winds, which in some cases wereaggravated by extreme local rainfall (USACE, 2013) However, is a 1:100protection standard adequate to protect New Orleans? Compare this to the1:10,000 standard of the Delta Works.

Hurricane Sandy provided a demonstration of the vulnerability of New YorkCity to storm surge, reviving discussion of the possibility of building a pro-tective barrier (e.g.,Bowman et al., 2005; Colle et al., 2008; Aerts and Botzen,2012; Coch, 2013; Hill, 2012, 2013) Proceedings of a conference held in 2009under the sponsorship of the Infrastructure Group of the American Society ofCivil Engineers were reissued in 2013 in the aftermath of Sandy (Aerts et al.,2013a) Aerts et al (2013b) outlined three possible configurations of stormsurge barriers The cost of these barriers is estimated at up to $15 billion,comparable to the amount spent on the Louisiana HSDRSS system (Aerts et al.,2013b) Note that these barriers would also protect against only the 1:100 stormsurge In contrast, other researchers argue that the city should commit to pro-tecting all areas to a 1:500-year standard (Tollefson, 2013) The systemenvisaged by these researchers, including Bowman et al (2005), Colle et al.(2008), andHill (2013), would comprise two or three barriers to protect NewYork and New Jersey, including an 8-km-wide barrier approximately 6 m highthat could be opened and closed at the entrance to New York’s harbor, and asecond barrier at the entrance to Long Island Sound (Tollefson, 2012) The statepanel’s cost estimates for such a system range from $7 to $29 billion,depending on the design (Tollefson, 2013).Wagner et al (2014) argued thathistorically, financial resources, policies, and public support have coalescedafter catastrophic events to act as catalysts for policy change; however, thearrival of Sandy during the economic crisis restricted the availability of funding.Structural measures can never entirely eliminate flood risk, and may notalways be an appropriate response to such risk Storm surge barriers canprotect a large area with relatively small structures, but are not appropriate

on an open coastline In addition, surge barriers are expensive and thereforenot economically feasible for all locations As with all flood defensestructures, the presence of the barrier may encourage development in haz-ardous areas Many coastal cities will not be able to rely on such majorinfrastructure, and will need instead to rely on a mix of structural andnonstructural measures

165Chapter j 6 Storm Surge Warning, Mitigation, and Adaptation

6.3 STORM SURGE WARNING

If it is not possible or desirable to completely eliminate flood risks, adaptationcan be accomplished in the form of adequate provision of emergency pro-cedures (Cooper and Pile, 2013) Improvements in forecasting, early warningsystems, and evacuation and shelter procedures have reduced storm-surge-related mortality (Doocy et al., 2013) Real-time observational and predic-tive modeling techniques make it possible to issue cyclone and related stormsurge warnings, which may trigger the implementation of emergencyprocedures and provide an opportunity for the evacuation of vulnerable areas

To be effective, early warning systems must integrate four elements: (1)knowledge of the risks faced, (2) technical monitoring and warning service, (3)dissemination of meaningful warnings to those at risk, and (4) public aware-ness and preparedness to act (UNISDR, 2009) Although comprehensivecoverage of early warning systems for storms and tropical cyclones is avail-able, disasters such as Hurricane Katrina have highlighted inadequacies intechnologies for enabling effective and timely emergency response (Grassoand Singh, 2009) Storm surge is generally treated as a corollary of cyclones(both tropical and extratropical), with few early warning systems specificallyfor storm surge in existence For example,Grasso and Singh (2009)presenteddetailed tables of early warning systems for different types of events, but theydid not include storm surge in these tables, with one table for floods (whichthey interpreted as primarily fluvial and pluvial) and another table for severeweather, storms, cyclones, and hurricanes The report did show that there areoften inadequate flood warning and monitoring systems, especially in devel-oping or least developed countries In most of the cases that they surveyed,Grasso and Singh (2009) found that communication systems and adequateresponse plans were lacking They argued that predictions are not useful unlessthey are translated into a warning and action plan that the public canunderstand

Storm surge warning systems are most often operated at a national scaleand are usually linked to predictions of the path and landfall of tropical orextratropical cyclones Many countries have or are developing storm surgeprediction models and warning systems: this review has found references to atleast 28 national programs, but only a few will be described here The JointTechnical Commission for Oceanography and Marine Meteorology (JCOMM)has compiled a comprehensive list of national storm surge products (JCOMM,

2014) Although that list is not exhaustive and does not explicitly addressstorm surge warning systems, it gives an indication of international activity inthis area JCOMM is currently carrying out a worldwide survey on operationalstorm surge models and data, with data collection scheduled to be completed

by the end of May 2014 JCOMM has also initiated the World MeteorologicalOrganization (WMO) Coastal Inundation Forecasting Demonstration Project

to assist countries at risk of coastal flooding to operate and maintain a reliable

166 Coastal and Marine Hazards, Risks, and Disasters