Sea-level Rise, Coastal Flooding, and Storm Events

Migration induced by sea-level rise could reshape the US population landscape

Hauer ME. Migration induced by sea-level rise could reshape the US population landscape. Nature Climate Change [Internet]. 2017 . Available from: https://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3271.html
Freely available?: 
No
Summary available?: 
No
Approximate cost to purchase or rent this item from the publisher: 
US $32.00
Type: Journal Article

Many sea-level rise (SLR) assessments focus on populations presently inhabiting vulnerable coastal communities123, but to date no studies have attempted to model the destinations of these potentially displaced persons. With millions of potential future migrants in heavily populated coastal communities, SLR scholarship focusing solely on coastal communities characterizes SLR as primarily a coastal issue, obscuring the potential impacts in landlocked communities created by SLR-induced displacement. Here I address this issue by merging projected populations at risk of SLR1 with migration systems simulations to project future destinations of SLR migrants in the United States. I find that unmitigated SLR is expected to reshape the US population distribution, potentially stressing landlocked areas unprepared to accommodate this wave of coastal migrants—even after accounting for potential adaptation. These results provide the first glimpse of how climate change will reshape future population distributions and establish a new foundation for modelling potential migration destinations from climate stressors in an era of global environmental change.

Rehabilitating coastal agriculture and aquaculture after inundation events: Spatial analysis of livelihood recovery in post-tsunami Aceh, Indonesia

Daly P, Halim A, Nizamuddin , Ardiansyah , Hundlani D, Ho E, Mahdi S. Rehabilitating coastal agriculture and aquaculture after inundation events: Spatial analysis of livelihood recovery in post-tsunami Aceh, Indonesia. Ocean & Coastal Management [Internet]. 2017 ;142:218 - 232. Available from: http://www.sciencedirect.com/science/article/pii/S0964569117303095
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

This paper presents GIS time-series land-use analysis of satellite images to quantify the recovery of rice cultivation and aquaculture following the 2004 Indian Ocean tsunami in coastal communities in Aceh, Indonesia. We supplement this with qualitative data to illustrate the post-disaster challenges faced by residents, and the extent to which coastal communities have adapted to post-tsunami realities. Our analysis shows that the rehabilitation of rice cultivation and aquaculture in areas inundated by the tsunami has been limited by extensive degradation of land, diversion of labor by tsunami mortality and transition to alternative livelihoods, and re-purposing of rice fields for residential use during the reconstruction phase. This is especially prominent in areas where subsistence activities are not the primary source of livelihood. The Aceh case study shows that social, economic, and environmental factors can be stronger determinants of how coastal livelihoods rebound and change following destructive inundation events than livelihood rehabilitation aid. Additionally, our case study suggests the human impact of coastal hazards can be felt outside the physical extent of inundation.

Impacts of representing sea-level rise uncertainty on future flood risks: An example from San Francisco Bay

Ruckert KL, Oddo PC, Keller K. Impacts of representing sea-level rise uncertainty on future flood risks: An example from San Francisco Bay. PLOS ONE [Internet]. 2017 ;12(3):e0174666. Available from: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0174666
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Rising sea levels increase the probability of future coastal flooding. Many decision-makers use risk analyses to inform the design of sea-level rise (SLR) adaptation strategies. These analyses are often silent on potentially relevant uncertainties. For example, some previous risk analyses use the expected, best, or large quantile (i.e., 90%) estimate of future SLR. Here, we use a case study to quantify and illustrate how neglecting SLR uncertainties can bias risk projections. Specifically, we focus on the future 100-yr (1% annual exceedance probability) coastal flood height (storm surge including SLR) in the year 2100 in the San Francisco Bay area. We find that accounting for uncertainty in future SLR increases the return level (the height associated with a probability of occurrence) by half a meter from roughly 2.2 to 2.7 m, compared to using the mean sea-level projection. Accounting for this uncertainty also changes the shape of the relationship between the return period (the inverse probability that an event of interest will occur) and the return level. For instance, incorporating uncertainties shortens the return period associated with the 2.2 m return level from a 100-yr to roughly a 7-yr return period (∼15% probability). Additionally, accounting for this uncertainty doubles the area at risk of flooding (the area to be flooded under a certain height; e.g., the 100-yr flood height) in San Francisco. These results indicate that the method of accounting for future SLR can have considerable impacts on the design of flood risk management strategies.

Development and Application of a Method to Identify Salt Marsh Vulnerability to Sea Level Rise

Ekberg MLCole, Raposa KB, Ferguson WS, Ruddock K, Watson EBurke. Development and Application of a Method to Identify Salt Marsh Vulnerability to Sea Level Rise. Estuaries and Coasts [Internet]. 2017 ;40(3):694 - 710. Available from: https://link.springer.com/article/10.1007/s12237-017-0219-0
Freely available?: 
No
Summary available?: 
No
Approximate cost to purchase or rent this item from the publisher: 
US $39.95
Type: Journal Article

Wetlands are commonly assessed for ecological condition and biological integrity using a three-tiered framework of landscape-scale assessment, rapid assessment protocols, and intensive biological and physiochemical measurements. However, increased inundation resulting from accelerated sea level rise (SLR) is negatively impacting tidal marsh ecosystem functions for US Northeast coastal wetlands, yet relative vulnerability to this stressor is not incorporated in condition assessments. This article assesses tools available to measure coastal wetland vulnerability to SLR, including measurements made as part of traditional rapid condition assessments (e.g., vegetation communities, soil strength), field and remote sensing-based measurements of elevation, VDatum, and Sea Level Affecting Marshes Model (SLAMM) model outputs. A vulnerability metric that incorporates these tools was calibrated and validated using recent rates of marsh vegetation losses (1972–2011) as a surrogate for future vulnerability. The metric includes complementary measures of elevation capital, including the percentage of high vs. low marsh vegetation, Spartina alterniflora height, elevation measurements, and SLAMM outputs that collectively explained 62% of the variability in recent rates of marsh vegetation loss. Stepwise regression revealed that all three elements (elevation, vegetation measures, and SLAMM outputs) explained significant and largely unique components of vulnerability to SLR, with the greatest level of overlap found between SLAMM outputs and elevation metrics. While soil strength varied predictably with habitat zone, it did not contribute significantly to the vulnerability metric. Despite the importance of determining wetland elevation above key tidal datums of mean sea level and mean high water, we caution that VDatum was found to perform poorly in back-barrier estuaries. This factor makes it difficult to compare elevation capital among marshes that differ in tidal range and poses accuracy problems for broad-scale modeling efforts that require accurate tidal datums. Given the pervasive pattern of coastal wetland drowning occurring in the Northeastern USA and elsewhere, we advocate that compilation of regional data on marsh habitats and vulnerability to SLR is crucial as it permits agencies to target adaptation to sites based on their vulnerability or mixture of habitats, it helps match sites to appropriate interventions, and it provides a broader regional context to site-specific management actions. Without such data, adaptation actions may be implemented where action is not necessary and to the disadvantage of vulnerable sites where opportunities for successful adaptation will be missed.

Environmental and social recovery asymmetries to large-scale disturbances in small island communities

Aswani S, van Putten I, Miñarro S. Environmental and social recovery asymmetries to large-scale disturbances in small island communities. Natural Hazards [Internet]. 2017 ;86(1):241 - 262. Available from: https://link.springer.com/article/10.1007%2Fs11069-016-2685-2
Freely available?: 
No
Summary available?: 
No
Approximate cost to purchase or rent this item from the publisher: 
US $39.95
Type: Journal Article

People’s livelihoods in tropical small-island developing states are greatly dependent on marine ecosystem services. Yet services such as fisheries and coastal buffering are being degraded at an alarming rate, thus making people increasing vulnerable to protracted and sudden environmental changes. In the context of the occurrences of extreme events such as earthquakes and tsunamis, it is vital to uncover the processes that make people in these island states resilient, or not, to environmental disruptions. This paper compares people’s perceptions of social and environmental impacts after an extreme event in the Western Solomon Islands (11 different villages on 8 different islands) to better understand how knowledge systems influence the coupling of human and natural systems. We examine the factors that contributed to perceptions of respective recovery in the environmental versus the social domains across communities with different traditional governance and modernization characteristics in a tsunami impact gradient. First, we separately assessed, at the community and individual level, the potential determinants of perceived recovery in the environmental and social domains. At the community level, the average values of the perceived environmental and social recovery were calculated for each community (1 year after the tsunami), and at the individual level, normally distributed environmental and social recovery variables (based on the difference in perceptions immediately and 1 year after the tsunami) were used as dependent variables in two General Linear Models. Results suggest that environmental and social resilience are not always coupled correspondingly and, less unexpectedly, that asymmetries during recovery can occur as a result of the underlying social and ecological context and existing adaptive capacity. More generally, the study shows how by evaluating post-disturbance perceptional data in tsunami-affected communities, we can better understand how subjective perceptions of change can affect the (de)-coupling of human and natural systems.

Mobility of maerl-siliciclastic mixtures: Impact of waves, currents and storm events

Joshi S, Duffy GPatrick, Brown C. Mobility of maerl-siliciclastic mixtures: Impact of waves, currents and storm events. Estuarine, Coastal and Shelf Science [Internet]. 2017 . Available from: http://www.sciencedirect.com/science/article/pii/S0272771416306217
Freely available?: 
No
Summary available?: 
No
Approximate cost to purchase or rent this item from the publisher: 
US $35.95
Type: Journal Article

Maerl beds are free-living, non-geniculate coralline algae habitats which form biogenic reefs with high micro-scale complexity supporting a diversity and abundance of rare epifauna and epiflora. These habitats are highly mobile in shallow marine environments where substantial maerl beds co-exist with siliciclastic sediment, exemplified by our study site of Galway Bay. Coupled hydrodynamic-wave-sediment transport models have been used to explore the transport patterns of maerl-siliciclastic sediment during calm summer conditions and severe winter storms. The sediment distribution is strongly influenced by storm waves even in water depths greater than 100 m. Maerl is present at the periphery of wave-induced residual current gyres during storm conditions. A combined wave-current Sediment Mobility Index during storm conditions shows correlation with multibeam backscatter and surficial sediment distribution. A combined wave-current Mobilization Frequency Index during storm conditions acts as a physical surrogate for the presence of maerl-siliciclastic mixtures in Galway Bay. Both indices can provide useful integrated oceanographic and sediment information to complement coupled numerical hydrodynamic, sediment transport and erosion-deposition models.

Forward planning to maintain the attractiveness of coastal areas: Choosing between seawalls and managed retreat

Rulleau B, Rey-Valette H. Forward planning to maintain the attractiveness of coastal areas: Choosing between seawalls and managed retreat. Environmental Science & Policy [Internet]. 2017 ;72:12 - 19. Available from: http://www.sciencedirect.com/science/article/pii/S1462901116304324
Freely available?: 
No
Summary available?: 
No
Approximate cost to purchase or rent this item from the publisher: 
US $35.95
Type: Journal Article

This paper aims to inform forward-planning policies in the face of sea-level rise due to climate change, focusing on the choice of reducing the vulnerability of property at risk through managed retreat or protection behind seawalls. This adaptation is important not only to reduce the cost of future damage but also to maintain the beaches which are an attractive feature for tourism, of vital importance for coastal areas. Some 421 residents with main and secondary homes were surveyed in Hyères-les-palmiers in the Var department (Southeast France). The survey sought to compare the willingness of residents to contribute financially to building a seawall or to relocating sea-front property. Preferences depend both on common variables and variables specific to the proposed arrangement. They reveal common concerns focused on effectiveness and the determining factor of property ownership. The results also show some awareness of the long-term advantages of managed retreat, despite some opposition from older people, who are also more skeptical about the reality of the risk incurred.

Development of a model to simulate groundwater inundation induced by sea-level rise and high tides in Honolulu, Hawaii

Habel S, Fletcher CH, Rotzoll K, El-Kadi AI. Development of a model to simulate groundwater inundation induced by sea-level rise and high tides in Honolulu, Hawaii. Water Research [Internet]. 2017 ;114:122 - 134. Available from: http://www.sciencedirect.com/science/article/pii/S0043135417301276
Freely available?: 
No
Summary available?: 
No
Approximate cost to purchase or rent this item from the publisher: 
US $35.95
Type: Journal Article

Many of the world's largest cities face risk of sea-level rise (SLR) induced flooding owing to their limited elevations and proximities to the coastline. Within this century, global mean sea level is expected to reach magnitudes that will exceed the ground elevation of some built infrastructure. The concurrent rise of coastal groundwater will produce additional sources of inundation resulting from narrowing and loss of the vertical unsaturated subsurface space. This has implications for the dense network of buried and low-lying infrastructure that exists across urban coastal zones.

Here, we describe a modeling approach that simulates narrowing of the unsaturated space and groundwater inundation (GWI) generated by SLR-induced lifting of coastal groundwater. The methodology combines terrain modeling, groundwater monitoring, estimation of tidal influence, and numerical groundwater-flow modeling to simulate future flood scenarios considering user-specified tide stages and magnitudes of SLR.

We illustrate the value of the methodology by applying it to the heavily urbanized and low-lying Waikiki area of Honolulu, Hawaii. Results indicate that SLR of nearly 1 m generates GWI across 23% of the 13 km2 study area, threatening $5 billion of taxable real estate and 48 km of roadway. Analysis of current conditions reveals that 86% of 259 active cesspool sites in the study area are likely inundated. This suggests that cesspool effluent is currently entering coastal groundwater, which not only leads to degradation of coastal environments, but also presents a future threat to public health as GWI would introduce effluent at the ground surface.

Extreme oceanographic forcing and coastal response due to the 2015–2016 El Niño

Barnard PL, Hoover D, Hubbard DM, Snyder A, Ludka BC, Allan J, Kaminsky GM, Ruggiero P, Gallien TW, Gabel L, et al. Extreme oceanographic forcing and coastal response due to the 2015–2016 El Niño. Nature Communications [Internet]. 2017 ;8:14365. Available from: http://www.nature.com/articles/ncomms14365
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

The El Niño-Southern Oscillation is the dominant mode of interannual climate variability across the Pacific Ocean basin, with influence on the global climate. The two end members of the cycle, El Niño and La Niña, force anomalous oceanographic conditions and coastal response along the Pacific margin, exposing many heavily populated regions to increased coastal flooding and erosion hazards. However, a quantitative record of coastal impacts is spatially limited and temporally restricted to only the most recent events. Here we report on the oceanographic forcing and coastal response of the 2015–2016 El Niño, one of the strongest of the last 145 years. We show that winter wave energy equalled or exceeded measured historical maxima across the US West Coast, corresponding to anomalously large beach erosion across the region. Shorelines in many areas retreated beyond previously measured landward extremes, particularly along the sediment-starved California coast.

Using local knowledge to project sea level rise impacts on wave resources in California

Reineman DR, Thomas LN, Caldwell MR. Using local knowledge to project sea level rise impacts on wave resources in California. Ocean & Coastal Management [Internet]. 2017 ;138:181 - 191. Available from: http://www.sciencedirect.com/science/article/pii/S0964569117300613
Freely available?: 
No
Summary available?: 
No
Approximate cost to purchase or rent this item from the publisher: 
US $35.95
Type: Journal Article

Sea level rise will have significant impacts on many coastal resources. Waves are an important resource in California, where they support the recreation of 1.1 million surfers who inject millions of dollars into local economies. The impacts of sea level rise on wave resource quality, however, are unknown. By examining the local knowledge of more than one thousand California surfers collected through an online survey, this study extrapolates their evaluations to estimate the susceptibility of California surf-spots to sea level rise based on the principle of tidal extrapolation. Vulnerability classifications are derived from the relationship between wave quality, tide effects, and sea floor conditions. Applying these classifications to 105 surf-spots in California evaluated by multiple respondents, we project that as a result of sea level rise by 2100: 16% of surf-spots are Endangered due to drowning; 18% are Threatened, but could adapt if natural shoreline processes are not impeded; and 5% might improve as rising sea levels increase the likelihood they will experience optimal conditions. These projections are significant not only for the many surfers who depend on surf-spots, but also for the coastal communities who rely on the availability of high quality wave resources. Results from this study also have important implications for when and how managers might take surf-spot quality and vulnerability into consideration through coastal adaptation. Lastly, this study establishes a baseline of wave resource quality in California and suggests that this baseline will shift as wave quality changes over the coming century.

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