Geoscience Reference
In-Depth Information
beaches.to.become.narrower,.reducing.biotic.diversity.and.abundance.(Dugan.et.al..
2008),.or.they.may.even.be.lost.entirely.(Pilkey.and.Wright.1989)..Given.accepted.
conservation.objectives.that.entail.the.protection.of.biodiversity.and.ecological.pro-
cesses,.seawalls.would.fail.as.an.ecological.management.strategy..Moreover,.seawall.
protection.may.only.be.a.short-term.solution.as.sea.levels.continue.to.rise..In.the.long.
term,.“our.coastal.communities.may.have.to.rethink.their.location.and.may.be.forced.
to.consider.a.retreat.from.the.beach”.(Tomlinson.2002).
An. alternative. to. seawalls. is. the. soft-engineering. approach. of. beach. nourish-
ment—a.process.whereby.beaches.are.raised.by.the.importation.of.sand,.often.from.
offshore.. Nourishment. has. become. popular. because. it. can. maintain. beaches. in. a.
seminatural.state.(Finkl.and.Walker.2004)..Thus.it.is.more.attractive.than.seawalls.
for.societal.purposes.and,.moreover,.well-designed.projects.enable.ecological.recov-
ery.to.be.fast,.i.e.,.weeks.to.months.rather.than.years.(Speybroeck.et.al..2006;.Jones.
et.al..2008)..Nevertheless,.drawbacks.exist,.e.g.,.engineering.is.expensive,.ecologi-
cal.impacts.occur.at.both.borrow.and.deposition.sites,.repetition.is.needed,.and.the.
supply. of. sand. may. run. out.. In. addition,. replacement. sediments. should. match. the.
original. beach. sediments;. otherwise,. ecological. recovery. is. retarded. or. prevented.
(Nelson. 1993;. Bilodeau. and. Bourgeois. 2004;. Peterson. and. Bishop. 2005;. Peterson.
et.al..2006).
Management. recommendations. for. nourishment. made. by. Speybroeck. et. al..
(2006).include
•.
Importing. sediments. and. creating. beach. proiles. that. match. the. original.
beach.conditions.as.closely.as.possible
•.
The.avoidance.of.sediment.compaction
•.
Careful.timing.of.operations.to.minimize.biotic.impacts.and.enhance.recovery
•.
The.selection.of.locally.appropriate.techniques
•.
The.implementation.of.several.small.projects.rather.than.a.single.large.project
•.
Interspersion.of.nourished.beach.sections.with.unaffected.areas
•.
Repeated. application. of. sediment. in. shallow. layers. (<30. cm). rather. than.
single.pulses.that.kill.the.fauna.by.deep.burial
In.addition,.the.positioning.of.dredged.sand.is.a.management.issue..For.example,.
the.deposition.of.sand.on.ebb-tide.deltas.may.be.ecologically.preferable.to.direct.depo-
sition.on.beaches.(Bishop.et.al..2006)..Similarly,.the.across-shore.positioning.of.spoil.
(from.high.tide.to.shallow.subtidal).is.likely.to.be.an.ecological.factor..Furthermore,.
periodic.renourishment.(and.consequent.economic.and.ecological.costs).will.be.mini-
mized.if.the.beach.proile.is.engineered.to.be.stable.(Blott.and.Pye.2004)..Certainly,.
the. choice. of. option. will. depend. on. local. economic. considerations. (Knogge. et. al..
2004).and.different.approaches.may.be.integrated.(Finkl.and.Walker.2004).
Concerning. other. consequences. of. climate. change. (e.g.,. higher. temperatures,.
lower. pH,. and. changed. hydrodynamics),. management. options. are. limited. to. miti-
gation. and. minimizing. additional. stresses. such. as. pollution,. beach. grooming,. and.
ORVs.. These. not. only. impose. ecological. impacts. in. their. own. right. (Godfrey. and.
Godfrey.1980;.Defeo.et.al..2009;.Schlacher.et.al..2007),.but.also.may.interact.with.
climate.factors.(see.previous.text)..Perhaps.the.best.hope.is.that.these.climate.changes.
