There are currently three main strategies for protecting coastal areas

Germanovich and Murdoch Solid Injection to Lift Coastal Areas, Appendix A

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APPENDIX A PROTECTING COASTAL AREAS

There are currently three main strategies for protecting coastal areas from flooding [Pugh 2004]: (1)

Retreat; (2) Protection; or (3) Accommodation. Retreating involves abandoning a region altogether and

relocating inland. This approach is applied incrementally as building codes are revised to move set-back

requirements further inland. The typical result is that houses are reconstructed further inland following

one storm to reduce damages during the next one. In particular, the Retreat strategy was suggested for

parishes in New Orleans hard hit by Katrina [MacAskill 2007, Bourne 2007]. This strategy is feasible for

lightly populated areas, but it appears to be less viable for large communities or facilities that are

particularly valuable.

(a) Protection

The Protection strategy is currently the most widely used technique for protecting cities or valuable

land. The levee system protecting New Orleans is one example, but there are many others along the

coast of the North Sea [Sever 2006], in Shanghai [Wei 2006], St. Petersburg [Gerritsen et al., 2005], or

the delta region in California [Florsheim and Dettinger 2007], and new levees are being suggested to

protect coastal cities like New York [Hill 2008]. Innovative implementations of this strategy use

moveable barriers, such as the proposed Venice floodgates (Project MOSE), which are raised only when

high water conditions are a threat [Ammerman and McClennen 2000; Nosengo 2003].

The Protection strategy is helpful in many locations [Pugh 2004] because under most conditions it allows

the productive occupation of land that would otherwise be submerged. But on the rare occasions that it

does fail, the Protection strategy can result in catastrophe [Kates et al. 2006]. The more than 1500

deaths and $100B in damages following Katrina resulted from levee failure [Waltham 2005; NOAA

2010]. Some of the more than 50 breaches in the New Orleans levees may have been prevented with

better designs [Seed et al. 2006]. Nevertheless, levees sometimes create a false sense of security [Cigler

2009] and can fail in many ways [Seed et al. 2006]; even a well maintained, robust design may become

increasingly vulnerable [Kates 2006]. The reliability of the levee system protecting the Netherlands is

among the best in the world, but even it has been called into question [Delta Commission 2008] in the

face of rising sea level [Rahmstorf 2007; Solomon et. al. 2007]. Furthermore, impoundments behind

dams trap sediment that would otherwise be deposited and offset subsidence, further increasing the

vulnerability of delta regions to flooding [Syvitski et al. 2005; Ericson et al. 2006].

Not all Protection strategies involve levees or related barriers. A design for protecting New Orleans with

a broad zone of reconstructed barrier islands and wetland vegetation is described in the Coast 2050 Plan

[Louisiana Task Force 1998; Fischetti 2005]. This design would use the restored natural system to

dissipate a storm surge before it reached New Orleans. Simulations of storm surges indicate that this

approach has promise, and certainly a restored coastline would have wide appeal. Nevertheless, the

long-term performance of the 2050 Plan remains uncertain [Day et al. 2007].


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(b) Accommodation

The Accommodation strategy [Pugh 2004] typically involves elevating buildings above the level of a

storm surge. Many beachfront houses are elevated on pilings high above the surf with the hope that

they will be safeguarded against damage by future storms. The Accommodation strategy can be more

sophisticated than supporting buildings on pilings, however.

In 1900, Galveston, Texas, was struck by a Category 4 hurricane that left 8000 dead and decimated

buildings and infrastructure [Rappaport and Partagas 1995; Frank 2003]. This event caused the largest

death toll of any natural disaster in U.S. history, yet the residents were still unwilling to abandon

Galveston—not even this catastrophe was able to make the Retreat strategy viable at the scale of a city.

Instead, Galveston decided to build a seawall (figures A1a, A1b) and permanently elevate 500 city blocks

behind it in an effort to rise above the threat of future storms [Bixel and Turner 2000]. This was

accomplished by raising existing buildings up to 5 m using jacks and scaffolding and then filling the space

under them with sediment dredged from nearby channels (figure A1c). Logistics were facilitated by

using dikes (figure A1d) to divide the city into a series of cells and then filling the cells individually with

dredge spoil (figure A1b). Even a large masonry church (St. Mark’s Catholic Church) was elevated and

supported by fill using this approach (figure A1e).

The Galveston Grade Raising took 8 years to accomplish (20 years were required for a similar project in

Chicago [Brown 1894; Andreas 1975; Miller 1996]), and the project was tested soon after completion by

a Category 4 storm that came ashore in 1915. While tragic, the 11 [according to Cigler 2009] or 275

[according to Franc 2003] casualties from this big storm were only a small fraction of the deaths caused

by the 1900 hurricane. Since then Galveston has been hit by many hurricanes, including those in 1919,

1932, 1941, 1943, 1949, 1957, 1961 (Carla), 1983 (Alicia) [McComb, 1986], 2005 (Rita) [Knabb et al.

2006] and a recent Category 2 hurricane (Ike) in September 2008 [Cigler 2009] with a storm surge that

was typical of a much stronger Category 4 or 5 hurricane [Ashmore and Owen 2009]. These storms have

certainly caused death and damage [e.g. Cigler 2009], but the region of the Grade Raising has avoided a

repeat of the 1900 catastrophe, and it seems to have seen fewer deaths and less damage than

neighboring communities at ambient elevations [Frank 2003]. St. Mark’s Church is an important

landmark in Galveston today, just as it was prior to the Grade Raising (figure A1e).

By all accounts, the century-old Galveston Seawall and Grade Raising projects have been successful at

safeguarding a city against hurricane flooding. It is easy to see why grade raising has been more

successful than levees in nearby New Orleans. Galveston was raised high above sea level so that storm-

induced flooding would be too shallow and short-lived to be catastrophic. In contrast, New Orleans

remains near or below sea level, so levee failure filled the city with water that was deep and persistent.

Flood waters remained in New Orleans for more than 2 weeks following Katrina [Russell and Meeks

2005; Seed et al. 2006], and damages in New Orleans were primarily caused by the flooding due to

breaches of the levees after the hurricane hit [Cigler 2009]. Ike’s surge of up to 20 feet, hitting with high

tide, was higher than the seawall and flooded 75% of the island and three-quarters of Galveston’s

buildings [Cigler 2009]. Yet, in contrast to the situation in New Orleans, water levels in Galveston

dropped within approximately a day after Ike hit Galveston [NHC 2008]. Although flood water from the

storm surge did cause serious damage to homes, the city was spared.


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[Bixel and Turner, 2001]

Sea wall

[Bixel and Turner, 2001] [Bixel and Turner, 2001]

Sea wall

(a)

(b)

(c)

(d)

(e)

Figure A1 (a) Design and (b) photograph of raising grade behind seawall, Galveston, Texas [Bixel and Turner 2000].

The grade raising and seawall construction are considered here as a single project, although logistically Frank

[2003] considers them to be separate efforts. (c) Filling space under houses with dredged sediment [Bixel and

Turner 2000]. (d) Dike and elevated house during Galveston grade raising [McComb 1986]. (e) St. Mark’s Catholic

Church supported on jacks prior to filling during grade raising in 1906 [Cartwright 1991].


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The Galveston Grade Raising was successful, but it is not without shortcomings. This approach requires

existing buildings to be elevated and temporarily supported at the ultimate elevation of the fill. This can

certainly be done today [e.g. BAMS 2008; Sandri, 2008] for the scale of buildings that were elevated in

1900, but some modern buildings could be too large, and subsurface infrastructure too complex, for the

Galveston method to be practical. Community reaction is another factor that may cause much more of a

problem today than it did in Galveston 100 years ago. The inconvenience of life in Galveston during the

Grade Raising was considerable [Bixel and Turner 2000; Frank 2003]. A city was forced to live in difficult

conditions (e.g. figures A1c, A1d) as the ground beneath their buildings was filled with dredged

sediment. It seems unlikely that this type of hardship would be tolerated today in many places even if it

meant a safer community in the future [see also Kates et al. 2006].

(c) Accommodation in Venice

Flood surges from large storms are rare in Venice, but ground elevations are low and flooding occurs

during periodic high tides. This means that elevation increases of tenths of a meter could significantly

reduce flood damage in Venice [Gallavresi and Carbognin 1987; Comerlati et al. 2004]. To achieve this

level of ground displacement, Comerlati et al. [2003, 2004] suggested the concept of ‘anthropogenic

Venice uplift’ – an elegant variation of the Accommodation approach that is based on the poroelastic

effect [Detournay and Cheng 1993; Wang 2000]. Their strategy proposes to inject seawater (or carbon

dioxide) into a ring of wells to elevate the pore pressure in a 200-m-thick brackish sandy layer whose

upper surface is at a depth of 600 m beneath Venice. The layer is sandwiched between clay below and a

relatively impermeable cap rock above [Abbott 2004]. As a result of the poroelastic effect, the sandy

layer would expand elevating the ground surface by 30 cm in 10 years [Comerlati et al. 2003, 2004]. This

strategy could reduce the frequency of raising MOSE floodgates, extend their useful life, and decrease

side effects associated with repeatedly restricting water flow into the Venetian lagoon [Abbott 2004;

Smith 2004].

The advantage of the approach proposed by Comerlati et al. [2003, 2004] is that it would provide the

security of elevation without the logistical difficulties of elevating individual buildings using jacks [e.g.

Bixel and Turner 2000; Franc 2003], as was done in the Galveston Grade Raising. This approach appears

well suited to Venice, but unfortunately it is by no means a panacea. The poroelastic approach requires

elevated pore pressures to be maintained by continuous pumping because the region will subside when

the pumps are turned off [e.g. Castelletto et al. 2008, fig. 8]. This may be a relatively minor concern,

however, because maintaining the necessary pumping infrastructure should be straightforward. A more

significant issue is that the total displacement achieved using the poroelastic effect will probably be

limited to fractions of a meter (Section 1 of the main text). Therefore, it seems unlikely that it would

elevate other areas sufficiently to provide flood protection from storm surges of many meters [e.g.

Figure A2 and Pugh 2004, Table 6.1].

Although there are concerns that the surface displacements generated by the injection of seawater

beneath Venice would be uneven [Schrefler et al. 2009], this effect could be mitigated by a slow

injection rate and the smoothing influence of the overburden [Gambolati et al. 2009]. Local uneven

displacements could also be mitigated by using hydraulic jacks to control movement of individual

buildings. Furthermore, using hydraulic jacks can be considered a modern version of the Galveston

Grade Raising and has been proposed as an alternative to building MOSE barriers to block flood waters


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[Project Rialto, Sandri 2008]. Project Rialto would utilize a Galveston-style strategy by placing hydraulic

equipment under the foundations to raise buildings as much as one meter [BAMS 2008].

Figure A2. Katrina storm surge going over a levee, Paris Road Bridge in New Orleans [Anderson et al. 2007].

REFERENCES TO APPENDIX A

Andersen, C F., Battjes, J. A., Daniel, D. A., Edge, B., Espey, W., Gilbert, R. B., Jackson, T. L., Kennedy, D.,

Mileti, D. S., Mitchell, J. K., Nicholson, P., Pugh, C. A., Tamaro, G., Traver, R., Buhrman, J.,

Dinges, C. V., Durrant, J. E., Howell, J. & Roth, L. H. 2007. The New Orleans hurricane protection

system: what went wrong and why. A Report by the American Society of Civil Engineers

Hurricane Katrina External Review Panel. Reston, Virginia: ASCE, 84 pp. (ISBN-13: 978-0-7844-

0893-3, ISBN-10: 0-7844-0893-9)

Abbott, A. 2004 Plans resurrected to raise Venice above the encroaching sea. Nature 427, 184.

Ammerman, A. J. & McClennen, C. E. 2000 Saving Venice. Science 289 , 1301-1302.

Andreas, A. T. 1975 History of Chicago, Vol. 1. New York: Arno Press, 644 pp. (Reprint of the 1884−186

edition published by A.T. Andreas, Chicago).

Ashmore, R. A. & Owen, D. E. 2009 Comparing and contrasting the storm surges of hurricane Rita and

Ike. In Abstracts with programs, Geological Society of America, 43rd Annual Meeting, 16-17

March 2009, Vol. 41, No. 2, p. 7, Paper No. 5-1.

BAMS 2008 Raise the roof (and everything else). Bulletin of the American Meteorological Society, 89(6), p. 788.

Bixel, P. & Turner, E. 2000 Galveston and The 1900 Storm. Texas University Press, 174 pp.

Bourne, J. K. 2007 New Orleans: a perilous future. National Geographic 112(8), 24−58.

Brown, G. P. 1894 Drainage channel and waterway. Chicago: R.R. Donnelleey & Sons Company, 476 pp.

Cartwright, G. 1991 Galveston: A History of the Island. Atheneum Publishers, 338 pp.

Castelletto, N., Ferronato, M., Gambolati, G., Putti, M. & Teatini, P. 2008 Can Venice be raised by

pumping water underground? A pilot project to help decide. Water Resources Research 44,

W01408. (doi: 10.1029/2007WR006177)

Cigler B. A. 2009 Post-Katrina Hazard Mitigation on the Gulf Coast. Public Organiz. Rev. 9, 325–341. (doi:


Page 6 of 7

10.1007/s11115-009-0095-6)

Comerlati, A., Ferronato, M. Gambolati, G., Putti, M. & Teatini, P. 2004 Saving Venice by seawater. J.

Geophys. Res. 109, F03006. (doi: 10.1029/2004JF000119)

Comerlati, A., Ferronato, M., Gambolati, G., Putti, M. and Teatini, P. 2003. Fluid dynamic and geome-

chanical effects of CO2 sequestration below the Venice Lagoon. Env. Engrg. Geosci. 12, 211–226.

Day, J. W., Boesch, D. F., Clairain, E. J., Kemp, G. P., Laska, S. B., Mitsch, W. J., Orth, K., Mashriqui, H.,

Reed, D. J., Shabman, L., Simenstad, C. A., Streever, B. J., Twilley, R. R., Watson, C. C., Wells, J. T.

& Whigham, D. F. 2007 Restoration of the Mississippi delta: lessons from hurricanes Katrina and

Rita. Science 315(5819), 1679–1684. (doi: 10.1126/science.1137030)

Delta Commission 2008 Report of the Dutch Delta Commission describing future recommendations or

the Dutch levee system. http://www.deltacommissie.com/en/advies

Detournay, E. & Cheng, A., H-D. 1993 Fundamentals of poroelasticity. In Comprehensive Rock

Engineering: Principles, Practice, Projects. Vol. 2. Analysis and Design Method (ed. C. Fairhurst),

pp. 113−171. Oxford: Pergamon.

Ericson, J. P., Vörösmarty, C. J., Dingman, S. L., Ward, L. G. & Meybec, M. 2006 Effective sea-level rise in

deltas: sources of change and human-dimension implications. Global Planet. Change 50, 63−82.

Fischetti, M. 2005 Protecting against the Next Katrina. Scientific American 293 (5), 18

Florsheim, J. L. & Dettinger, M. D. 2007 Climate and floods still govern California levee breaks. Geophys.

Res. Lett., 34, L22403. (doi: 10.1029/2007GL031702)

Frank, N. L. 2003 The Great Galveston Hurricane of 1900. In Hurricane! Coping with disaster, progress

and challenges since Galveston, 1900 (eds. R. Simpson, R. Anthes, M. Garstang & J. Simpson), pp.

129–140, American Geophysical Union, Washington, D.C.

Gallavresi F. & Carbognin L. 1987 Il sollevamento del suolo mediante iniezioni quale intervento a

salvaguardia di zone altimetriche deficitarie. L’applicazione a Venezia come caso peculiare. In

Istituto Veneto di Scienze, Lettere ed Arti, Commissione di Studio dei Provvedimenti per la

Conservazione e Difesa della Laguna e della Città di Venezia, X, Rapporti e studi, Venezia, pp.

33−47 [BNM Cont. 1395].

Gambolati G. A., Teatini, P., Ferronato, M., Strozzi, T., Tosi, L., & Putti, M. 2009. On the uniformity of

anthropogenic Venice uplift. Terra Nova 21, 467–473.

Gerritsen, H., Vis, M., Mikhailenko, R. & Hiltunen, M. 2005 Flood protection, environment and public

participation - case study: St Petersburg Flood Protection Barrier. In Flooding and Environmental

Challenges for Venice and its Lagoon: State of Knowledge (eds. C.A. Fletcher & T. Spencer), pp.

341 – 351, Cambridge University Press.

Hill, D. 2008 Must New York City have its own Katrina? Leadership and Management in Engineering 8(3),

132−138.

Kates, R. W., Colten ,C. E., Laska, S. & Leatherman, S. P. 2006 Reconstruction of New Orleans after

Hurricane Katrina: a research perspective. Proc. Natl. Acad. Sci. USA 103(40), 14,653–14,660.

Knabb, R. D., Brown, D. P. & Rhome, J. R. 2006 Tropical cyclone report, hurricane Rita, 18-26 September

2005, National Hurricane Center, Miami, FL, 33 pp.

Louisiana Task Force, 1998 Coast 2050: toward a sustainable coastal Louisiana. Louisiana Dept Nat.

Resour, Baton Rouge, LA, 161 pp. http://www.lca.gov/net_prod_download/public/lca_net_pub_

products/doc/2050report.pdf


Page 7 of 7

MacAskill, E. 2007 Rebuild or retreat: US debates evacuation of Gulf coastline. The Guardian, 11 October

2007. http://www.guardian.co.uk/world/2007/oct/11/usa.environment.

McComb, D. G. 1986 Galveston: a history. University of Texas Press, 293 pp.

Miller, D. L. 1996 City of the century: the epic of Chicago and the making of America. Simon & Schuster,

704 pp.

NHC 2008, National Hurricane Center, 2008 Atlantic Hurricane Season. http://www.nhc.noaa.gov

/2008atlan.shtml

NOAA 2010 Hurracane Katrina. http://www.katrina.noaa.gov

Nosengo, N. 2003 Save our city! Nature 424, 608–609.

Petroski, H. 2006 Levees and other raised ground. American Scientist 94(1), 7−11.

Pugh, D. T. 2004 Changing sea levels: effects of tides, weather, and climate. Cambridge University Press,

265 pp.

Rahmstorf, S. 2007 A semi-empirical approach to projecting future sea-level rise. Science 315, 368 −370.

Rappaport, E. N. & Partagas, J. F. 1995 The deadliest atlantic tropical cyclones, 1492−1994. NOAA

Technical Memorandum NWS NHC-47, 41 pp.

Russell, G. & Meek, D. 2005 I-10 drained, paving way for relief crews. New Orleans Times Picayune. Sept.

15, 2005.

Sandri, A. 2008 C'e' l'acqua alta? Alziamo pure i palazzi Venezia, progetto fantascientifico a base di pompe e

stantuffi Il sindaco Cacciari "Un piano da seguire con interesse", La Stampa, 21 March 2008, p. 16.

Schrefler, B.A., Ricceri, G., Achilli, V., Menin, A. & Salomoni, V.A. 2009 Ground displacement data around

the city of Ravenna do not support uplifting Venice by water injection. Terra Nova 21, 144–150.

Seed, R. B., Bea, R. G., Abdelmalak, R. I., Athanasopoulos, A. G., Boutwell, G. P., Bray, J. D., Briaud, J. L.,

Cheung, C., Cobos-Roa, D., Cohen-Waeber, J., Collins, B. D., Ehrensing, L., Farber, D., Hanemann,

M., Harder, L. F., Inkabi, K. S., Kammerer, A. M., Karadeniz, D., Kayen, R. E., Moss, S., Nicks, J.,

Nimmala, S., Pestana, J. M., Porter, J., Rhee, K., Riemer, M. F., Roberts, K., Rogers, J. D.,

Storesund, R., Govindasamy, A. V., Vera-Grunauer, X., Wartman, J. E., Watkins, C. M., Wenk J. E.

& Yim, S. C. 2006. Investigation of the Performance of the New Orleans Flood Protection Systems

in Hurricane Katrina on August 29, 2005. Report of the Independent Levee Assessment Team.

http://www.ce.berkeley.edu/projects/neworleans

Sever, M. 2006 When Levees Fail. Geotimes August 2006.

Smith, H. J. 2004 Science 9 January 2004 High and dry. 303, 146 (doi: 10.1126/science.303.5655.146c)

Solomon, S., Qin, D., Manning, M., Chen Z., Marquis, M., Averyt, K., Tignor, M. M. B., & Miller, H. L. 2007

Climate Change 2007. The Physical Science Basis. Contribution of Working Group I to the fourth

assessment report of the Intergovernmental Panel on Climate Change. Cambridge University

Press.

Syvitski, J. P. M., Vörösmarty, C. J., Kettner, A. J. & Green, P. 2005 Impact of humans on the flux of

terrestrial sediment to the global coastal ocean. Science 308, 376−380.

Waltham, T. 2005 The flooding of New Orleans. Geology Today 21(6), 225–231.

Wang, H. F. 2000 Theory of linear poroelasticity. Princeton: Princeton University Press.

Wei, Q. 2006 Land subsidence and water management in Shanghai, Master’s Thesis, TU Delft, Delft, The

Netherlands, 65 pp.

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There are currently three main strategies for protecting coastal areas