The rate at which sea level is rising in recent years due to global warming has become a
growing concern, most especially as it affects coastal areas of the world. The devastating impact
of sea level rise (SLR) on coastal communities, ranging from coastal beach erosion, nuisance high
tide flooding, and saltwater pollution of low-lying farmlands to loss of tidal wetlands is leading to
a decline in social and economic activities especially in coastal areas. According to the National
Oceanic and Atmospheric Administration (NOAA), 40% of the US population living on the coast
is inevitably vulnerable to SLR. Therefore, the objective of this study is to project relative sea level
rise (RSLR) for Anne Arundel County and to estimate the contribution of land subsidence to RSLR
at this location. To project RSLR for Anne Arundel County, this study combines global mean sea
level rise (GMSLR) scenarios with local land subsidence measured at GPS LOYF station in
Annapolis, Anne Arundel County, Maryland. Current quadratic trend of RSLR in Anne Arundel
County projects that by 2100, RSLR for the county will be approximately 1.2 m forecasting from
1992, which is 86% and 174% of the GMSLR intermediate-high and intermediate-low scenarios,
respectively. Land subsidence significantly contributed to RSLR in the 20th century; however,
since 2001 absolute sea level rise (ASLR) driven by climate change has significantly contributed
to RSLR in this location. The results in this paper suggest considering the intermediate-high RSLR
scenario for planning and decision-making in Anne Arundel County, Maryland, in relation to SLR.
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Land subsidence contributions to relative sea level rise at tide gauge Galveston Pier 21, Texas
Relative sea level rise at tide gauge Galveston Pier 21, Texas, is the combination of absolute sea level rise and land subsidence. We estimate subsidence rates of 3.53 mm/a during 1909–1937, 6.08 mm/a during 1937–1983, and 3.51 mm/a since 1983. Subsidence attributed to aquifer-system compaction accompanying groundwater extraction contributed as much as 85% of the 0.7 m relative sea level rise since 1909, and an additional 1.9 m is projected by 2100, with contributions from land subsidence declining from 30 to 10% over the projection interval. We estimate a uniform absolute sea level rise rate of 1.10 mm ± 0.19/a in the Gulf of Mexico during 1909–1992 and its acceleration of 0.270 mm/a2at Galveston Pier 21 since 1992. This acceleration is 87% of the value for the highest scenario of global mean sea level rise. Results indicate that evaluating this extreme scenario would be valid for resource-management and flood-hazard-mitigation strategies for coastal communities in the Gulf of Mexico, especially those affected by subsidence.
more » « less- Award ID(s):
- 1832065
- NSF-PAR ID:
- 10198670
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 10
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract The vulnerability of coastal environments to sea-level rise varies spatially, particularly due to local land subsidence. However, high-resolution observations and models of coastal subsidence are scarce, hindering an accurate vulnerability assessment. We use satellite data from 2007 to 2020 to create high-resolution map of subsidence rate at mm-level accuracy for different land covers along the ~3,500 km long US Atlantic coast. Here, we show that subsidence rate exceeding 3 mm per year affects most coastal areas, including wetlands, forests, agricultural areas, and developed regions. Coastal marshes represent the dominant land cover type along the US Atlantic coast and are particularly vulnerable to subsidence. We estimate that 58 to 100% of coastal marshes are losing elevation relative to sea level and show that previous studies substantially underestimate marsh vulnerability by not fully accounting for subsidence.
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ABSTRACT The compaction measurements of Quaternary and Tertiary Gulf Coast aquifer system sediments in the Houston-Galveston region (TX) show spatially variable compression of 0.08 to 8.49 mm/yr because of geohistorical overburden pressure when groundwater levels in the aquifer system were stable after about the year 2000. An aquifer-system creep equation is developed for evaluating this variable compression, with a thickness-weighted average creep coefficient based on Taylor's (1942) secondary consolidation theory. The temporal variation of aquifer system creep can be neglected in a short-term observation period (such as a decade) after a long-term creep period (such as over 1,000 years) in geohistory. The creep coefficient of the Gulf Coast aquifer system is found to be in a range of 8.74 × 10−5 to 3.94 × 10−3 (dimensionless), with an average of 1.38 × 10−3. Moreover, for silty clay or clay-dominant aquitards in the Gulf Coast aquifer system the creep coefficient value varies in the range of 2.21 × 10−4 to 3.94 × 10−3, which is consistent with values found by Mesri (1973) for most soils, which vary in the range of creep coefficient, 1 × 10−4 to 5 × 10−3. Land subsidence due to secondary consolidation of the Gulf Coast aquifer system is estimated to be 0.04 to 4.33 m in the 20th century and is projected to be 0.01 to 0.64 m in the 21st century at the 13 borehole extensometer locations in the Houston-Galveston region. The significant creep should be considered in the relative sea level rise, in addition to tectonic subsidence and primary consolidation.more » « less
