scholarly journals Impact of Sea-Level Rise on the Hydrologic Landscape of the Mānā Plain, Kaua‘i

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 766
Author(s):  
Basil Gomez
Keyword(s):  
Surface Water ◽  
Sea Level Rise ◽  
Sea Level ◽  
Water Table ◽  
Root Zone ◽  
Storm Runoff ◽  
Transient Event ◽  
Gravity Flows ◽  
Operational Ability ◽  
Event Based

The Mānā Plain is a land apart, buffered from oceanographic influences by ~3–35 m high backshore deposits, and drained by an intricate, >100-y-old ditch system and modern, large-capacity pumps. Quantifying present and prospective inputs and outputs for the hydrologic landscape suggests that, although sea-level rise (SLR) will begin to impact ditch system operations in 2040, transient, event-based flooding caused by rainfall, not SLR induced, multi-mechanism flooding, will continue to pose the most immediate threat. This is because as sea level rises the ability of gravity flows to discharge storm runoff directly into the ocean will diminish, causing floodwater to pond in low-lying depressions. Estimates of the volume of water involved suggests the risk of flooding from surface water is likely to extend to 5.45 km2 of land that is presently ≤ 1 m above sea level. This land will not be permanently inundated, but weeks of pumping may be required to remove the floodwater. Increasing pumping capacity and preserving some operational ability to discharge storm runoff under the influence of gravity will enhance the ditch system’s resilience to SLR and ensure it continues to fulfill its primary functions, of maintaining the water table below the root zone and diverting storm runoff away from farmland, at least until the end of this century.

Adaptation Planning to Mitigate Coastal-Road Pavement Damage from Groundwater Rise Caused by Sea-Level Rise

2018 ◽  
Vol 2672 (2) ◽  
pp. 11-22 ◽  
Author(s):  
Jayne F. Knott ◽  
Jo Sias Daniel ◽  
Jennifer M. Jacobs ◽  
Paul Kirshen
Keyword(s):  
Surface Water ◽  
Service Life ◽  
Sea Level Rise ◽  
Sea Level ◽  
Groundwater Modeling ◽  
Water Flooding ◽  
Base Layer ◽  
Premature Failure ◽  
Groundwater Rise ◽  
Pavement Service Life

Sea level in coastal New England is projected to rise 3.9–6.6 ft (1.2–2.0 m) by the year 2100. Many climate-change vulnerability and adaptation studies have investigated surface-water flooding from sea-level rise (SLR) on coastal-road infrastructure, but few have focused on rising groundwater. Groundwater modeling in New Hampshire’s Seacoast Region has shown that SLR-induced groundwater rise will occur three to four times farther inland than surface-water flooding, potentially impacting 23% of the region’s roads. Pavement service-life has been shown to decrease when the unbound layers become saturated. In areas where groundwater is projected to rise with SLR, pavements with groundwater 5.0 ft (1.5 m) deep or less are at risk of premature failure as groundwater moves into the pavement’s underlying unbound layers. In this study, groundwater hydrology and multi-layer elastic pavement analysis were used to identify two case-study sites in coastal New Hampshire that are predicted to experience pavement service-life reduction caused by SLR-induced groundwater rise. Various pavement structures were evaluated to determine adaptation feasibility and costs to maintain the designed service-life in the face of rising groundwater. This investigation shows that relatively simple pavement structural modifications to the base and asphalt concrete (AC) layers of a regional corridor can eliminate the 80% to 90% service-life reduction projected with 1.0 ft SLR (year 2030) and will delay pavement inundation by 20 years. Pavements with adequate base-layer materials and thickness require only AC thickness modification to avoid premature pavement failure from SLR-induced groundwater rise.

scholarly journals Deriving water content from multiple geophysical properties of a firn aquifer in Southeast Greenland

2020 ◽  
Author(s):  
Siobhan Killingbeck ◽  
Nicholas Schmerr ◽  
Lynn Montgomery ◽  
Adam Booth ◽  
Phil Livermore ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Water Content ◽  
Sea Level ◽  
Water Table ◽  
Liquid Water ◽  
Greenland Ice Sheet ◽  
Liquid Water Content ◽  
Borehole Data ◽  
Wave Velocities ◽  
Aquifer Properties

<p>Warming of the polar ice sheets causes changes in the hydrological regime of surface layers of firn and ice. Surface meltwater may undergo perennial storage of liquid water above the firn-ice transition, which could slow sea level rise or cause sudden release events, when storage capacity is reached. Firn aquifers have been commonly observed within the lower percolation zone of the southeastern Greenland ice sheet during the past decade, and more recently, across some Antarctic ice shelves. Knowledge of the geographic extent and fractional liquid water content (and storage) of such aquifers will enable a better understanding of their effects on the sub- and en-glacial hydrologic system and is crucial for accurate predictions of the contribution of meltwater discharge to global sea level rise.</p><p>Quantitative geophysical analysis from surface observations can be used to infer hydrological properties of the firn and ice without time intensive direct drilling, providing an efficient spatial distribution of properties along with an estimate of their uncertainty. Furthermore, by combining multiple types of geophysical observations, joint inversions allow ambiguities of one methodology to be mitigated by resolution in the other.</p><p>Here, we demonstrate that this joint approach is a powerful complement to the conventional geophysical analysis of firn aquifers, by combining seismic, ground penetrating radar and borehole data to characterise aquifer properties, using the ‘MuLTI’ algorithm. In particular, we incorporate seismic shear wave velocities (Vs), derived from surface (Rayleigh) waves offering a promising means of distinguishing zones containing liquid water, into independent compressional wave velocity, density, and radar soundings of the water table. We find Vs decreases from 1600 m/s in the unsaturated firn above the water table at around 15 m depth, to 800 m/s through saturated ‘clean’ firn aquifer at around 25 m depth. However, at lower elevations, Vs increases to 1250 m/s through thicker, older firn aquifer where there are many ice lenses, which are interpreted to correspond with episodes of refreezing aquifer water as the system has evolved through time. With access to multiple seismic wave velocities (compressional and shear) through the aquifer, a more accurate estimate of liquid water content can be derived. Thus, the application of the MuLTI algorithm to this pressing new problem can deliver an accurate assessment of firn aquifer properties, and provide clear uncertainty limits which will be valuable for predictive modelling.</p>

Coastal Adaptations to the Northern Gulf of Maine and Southern Scotian Shelf

2019 ◽  
pp. 44-80
Author(s):  
Matthew W. Betts ◽  
David W. Black ◽  
Brian Robinson ◽  
Arthur Spiess ◽  
Victor D. Thompson
Keyword(s):  
Surface Water ◽  
Sea Level Rise ◽  
Sea Level ◽  
Gulf Of Maine ◽  
Woodland Period ◽  
Late Archaic ◽  
Scotian Shelf ◽  
Near Shore ◽  
Coastal Adaptations ◽  
Cultural Shifts

The northern Gulf of Maine (NGOM) and its watershed have attracted humans for the last 12,500 years (cal BP), and evidence of Palaeoindian marine economies is well established in adjacent regions by ca. 8000 cal BP. Sea level rise (SLR) has obscured understandings of early coastal adaptations, although underwater research and some near-shore sites are providing important insights. The earliest evidence from surviving shell middens dates to ca. 5000 cal BP, and reveals that shellfish collecting and the seasonal exploitation of benthopelagic fish were important throughout the Late Maritime Archaic and Maritime Woodland periods. However, significant economic shifts have occurred. In particular, a Late Archaic focus on marine swordfish hunting was replaced by a dramatic increase in inshore seal hunting in the Maritime Woodland period. After ca. 3100 cal BP, inshore fishing for cod, flounder, sculpin, sturgeon and other species intensified. During the Late Maritime Woodland period, shellfish exploitation declined somewhat and the hunting of small seals, and, in some areas, white-tailed deer, increased sharply. The extent and nature of coastal economies in the NGOM was controlled, in part, by SLR, increasing tidal amplitude, and concomitant changes in surface-water temperatures, in tandem with broad regional cultural shifts.

scholarly journals Process Controls of the Live Root Zone and Carbon Sequestration Capacity of the Sundarbans Mangrove Forest, Bangladesh

Sci ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 51
Author(s):  
Edwin J. Bomer ◽  
Carol A. Wilson ◽  
Tracy Elsey-Quirk
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Root Zone ◽  
Surface Elevation ◽  
Mangrove Forests ◽  
Elevation Change ◽  
Surface Elevation Change ◽  
Process Controls ◽  
Sundarbans Mangrove ◽  
The Sundarbans

The conservation of coastal wetland ecosystems, like mangrove forests and salt marshes, represents a critical strategy for mitigating atmospheric emissions and climate change in the 21st century. Yet the existence of these environments is threatened by human-induced disturbances, namely deforestation and accelerated sea-level rise. Coastal systems maintain surface elevation in response to sea-level rise through a combination of physical and biological processes both above and below the ground surface. The quantification and relative contribution of belowground process controls (e.g., seasonal water content, organic matter decomposition) on surface elevation change is largely unexplored but crucial for informing coastal ecosystem sustainability. To address this knowledge deficit, we integrated measurements of surface elevation change of the live root zone (0.5 to 1 m depth) with geotechnical data from co-located sediment cores in the Sundarbans mangrove forest (SMF) of southwest Bangladesh. Core data reveal that the primary belowground controls on surface elevation change include seasonal fluctuations in pore-water content and the relative abundance of fine-grained sediments capable of volumetric expansion and contraction, supporting an elevation gain of ~2.42 ± 0.26 cm yr−1. In contrast to many mangrove environments, the soils of the SMF contain little organic matter and are dominantly composed (>90%) of inorganic clastic sediments. The mineral-rich soil texture likely leads to less compaction-induced subsidence as compared to organic-rich substrates and facilitates surface equilibrium in response to sea level rise. Despite a relatively high soil bulk density, soil carbon (C) density of the SMF is very low owing to the dearth of preserved organic content. However, rates of C accumulation are balanced out by locally high accretion rates, rendering the SMF a greater sink of terrestrial C than the worldwide mangrove average. The findings of this study demonstrate that C accumulation in the SMF, and possibly other alluvial mangrove forests, is highly dependent on the continued delivery of sediment to the mangrove platform and associated settings.

scholarly journals Process Controls of the Live Root Zone and Carbon Sequestration Capacity of the Sundarbans Mangrove Forest, Bangladesh

Sci ◽  
2020 ◽  
Vol 2 (3) ◽  
pp. 54
Author(s):  
Edwin J. Bomer ◽  
Carol A. Wilson ◽  
Tracy Elsey-Quirk
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Root Zone ◽  
Surface Elevation ◽  
Mangrove Forests ◽  
Elevation Change ◽  
Surface Elevation Change ◽  
Process Controls ◽  
Sundarbans Mangrove ◽  
The Sundarbans

The conservation of coastal wetland ecosystems, like mangrove forests and salt marshes, represents a critical strategy for mitigating atmospheric emissions and climate change in the 21st century. Yet the existence of these environments is threatened by human-induced disturbances, namely deforestation and accelerated sea-level rise. Coastal systems maintain surface elevation in response to sea-level rise through a combination of physical and biological processes both above and below the ground surface. The quantification and relative contribution of belowground process controls (e.g., seasonal water content, organic matter decomposition) on surface elevation change is largely unexplored but crucial for informing coastal ecosystem sustainability. To address this knowledge deficit, we integrated measurements of surface elevation change of the live root zone (0.5 to 1 m depth) with geotechnical data from co-located sediment cores in the Sundarbans mangrove forest (SMF) of southwest Bangladesh. Core data reveal that the primary belowground controls on surface elevation change include seasonal fluctuations in pore-water content and the relative abundance of fine-grained sediments capable of volumetric expansion and contraction, supporting an elevation gain of ~2.42 ± 0.26 cm year−1. In contrast to many mangrove environments, the soils of the SMF contain little organic matter and are dominantly composed (>90%) of inorganic clastic sediments. The mineral-rich soil texture likely leads to less compaction-induced subsidence as compared to organic-rich substrates and facilitates surface equilibrium in response to sea level rise. Despite a relatively high soil bulk density, soil carbon (C) density of the SMF is very low owing to the dearth of preserved organic content. However, rates of C accumulation are balanced out by locally high accretion rates, rendering the SMF a greater sink of terrestrial C than the worldwide mangrove average. The findings of this study demonstrate that C accumulation in the SMF, and possibly other alluvial mangrove forests, is highly dependent on the continued delivery of sediment to the mangrove platform and associated settings.

scholarly journals Process Controls of the Live Root Zone and Carbon Sequestration Capacity of the Sundarbans Mangrove Forest, Bangladesh

Sci ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 35
Author(s):  
Edwin J. Bomer ◽  
Carol A. Wilson ◽  
Tracy Elsey-Quirk
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Root Zone ◽  
Surface Elevation ◽  
Mangrove Forests ◽  
Elevation Change ◽  
Surface Elevation Change ◽  
Process Controls ◽  
Sundarbans Mangrove ◽  
The Sundarbans

The conservation of coastal wetland ecosystems, like mangrove forests and salt marshes, represents a critical strategy for mitigating atmospheric emissions and climate change in the 21st century. Yet the existence of these environments is threatened by human-induced disturbances, namely deforestation and accelerated sea-level rise. Coastal systems maintain surface elevation in response to sea-level rise through a combination of physical and biological processes both above and below the ground surface. The quantification and relative contribution of belowground process controls (e.g., seasonal water content, organic matter decomposition) on surface elevation change is largely unexplored but crucial for informing coastal ecosystem sustainability. To address this knowledge deficit, we integrated measurements of surface elevation change of the live root zone (0.5 to 1 m depth) with geotechnical data from co-located sediment cores in the Sundarbans mangrove forest (SMF) of southwest Bangladesh. Core data reveal that the primary belowground controls on surface elevation change include seasonal fluctuations in pore-water content and the relative abundance of fine-grained sediments capable of volumetric expansion and contraction. In contrast to many mangrove environments, the soils of the SMF contain little organic matter and are dominantly composed (>90%) of inorganic clastic sediments. The mineral-rich soil texture likely leads to less compaction-induced subsidence as compared to organic-rich substrates and facilitates surface equilibrium in response to sea level rise. Despite a relatively high soil bulk density, soil carbon (C) density of the SMF is very low owing to the dearth of preserved organic content. However, rates of C accumulation are balanced out by locally high accretion rates, rendering the SMF a greater sink of terrestrial C than the worldwide mangrove average. The findings of this study demonstrate that C accumulation in the SMF, and possibly other alluvial mangrove forests, is highly dependent on the continued delivery of sediment to the mangrove platform and associated settings.

Assessing sea-level rise impact on saltwater intrusion into the root zone of a geo-typical area in coastal east-central Florida

2018 ◽  
Vol 630 ◽  
pp. 211-221 ◽  
Author(s):  
Han Xiao ◽  
Dingbao Wang ◽  
Stephen C. Medeiros ◽  
Scott C. Hagen ◽  
Carlton R. Hall
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Saltwater Intrusion ◽  
Root Zone ◽  
East Central ◽  
Central Florida
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