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TitleImpact of anthropogenic subsidence on relative sea-level rise in the Fraser River delta
AuthorMazzotti, SORCID logo; Lambert, AORCID logo; Van der Kooij, M; Mainville, A
SourceGeology vol. 37, no. 9, 2009 p. 771-774,
Alt SeriesEarth Sciences Sector, Contribution Series 20070553
PublisherGeological Society of America
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
NTS92G/02; 92G/03
AreaFraser River; Fraser River delta; Delta; Richmond
Lat/Long WENS-123.2000 -122.9167 49.8500 49.0000
Subjectsmarine geology; sedimentology; deltas; deltaic sediments; deltaic deposits; sea level changes; sea level fluctuations; paleo-sea levels; floods; flood potential; erosion
Illustrationslocation maps; plots
ProgramEnhancing resilience in a changing climate
Released2009 09 01
AbstractSubsidence is a common cause of amplifi ed relative sea-level rise, fl ooding, and erosion in coastal environments. In particular, subsidence due to sediment consolidation can play a signifi cant role in relative sea-level rise in large deltas. We use a combination of InSAR (interferometric synthetic aperture radar), leveling, and global positioning system data to map absolute vertical land motion in the Fraser River delta, western Canada. We show that primary consolidation of shallow Holocene sediments is the main cause for the slow subsidence (-1 to -2 mm/a) affecting the delta lowlands. In addition, parts of the delta undergo increased anthropogenic subsidence. Rapid subsidence rates (-3 to -8 mm/a) are associated with recent artifi cial loads and exhibit a fi rst-order exponential decrease with a time constant of ~20 years, consistent with the theory of consolidation. Assuming two sea-level rise scenarios of 30 or 100 cm by the end of the twenty-fi rst century, natural subsidence will augment relative sea-level rise in the Fraser Holocene lowlands by ~50% or ~15%. Anthropogenic subsidence will augment relative sea-level rise by ~130% or ~40%, potentially raising it to as much as 1 - 2 m. In deltaic, lacustrine, and alluvial environments, anthropogenic sediment consolidation can result in signifi cant amplifi cation and strong spatial variations of relative sea-level rise that need to be considered in local planning.

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