Coastal Flood Risk Research Articles

An integrated approach for physical, economic, and demographic evaluation of coastal flood hazard adaptation in Santa Monica Bay, California

The increased risk of coastal flooding associated with climate-change driven sea level rise threatens to displace communities and cause substantial damage to infrastructure. Site-specific adaptation planning is necessary to mitigate the negative impacts of flooding on coastal residents and the built environment. Cost-benefit analyses used to evaluate coastal adaption strategies have traditionally focused on economic considerations, often overlooking potential demographic impacts that can directly influence vulnerability in coastal communities. Here, we present a transferable framework that couples hydrodynamic modeling of flooding driven by sea level rise and storm scenarios with site-specific building stock and census block-level demographic data. We assess the efficacy of multiple coastal adaptation strategies at reducing flooding, economic damages, and impacts to the local population. We apply this framework to evaluate a range of engineered, nature-based, and hybrid adaptation strategies for a portion of Santa Monica Bay, California. Overall, we find that dual approaches that provide protection along beaches using dunes or seawalls and along inlets using sluice gates perform best at reducing or eliminating flooding, damages, and population impacts. Adaptation strategies that include a sluice gate and partial or no protection along the beach are effective at reducing flooding around inlets but can exacerbate flooding elsewhere, leading to unintended impacts on residents. Our results also indicate trade-offs between economic and social risk-reduction priorities. The proposed framework allows for a comprehensive evaluation of coastal protection strategies across multiple objectives. Understanding how coastal adaptation strategies affect hydrodynamic, economic, and social factors at a local scale can enable more effective and equitable planning approaches.

Research on and application of the operational storm surge ensemble forecast model in the Bay of Bengal

The coastal region of the Bay of Bengal (BoB) is one of the most vulnerable areas to storm surges caused by tropical cyclones (TCs). Historical data indicate that the BoB experiences two seasons in the annual cycle of TC formation, namely, the pre-monsoon season (April to May) and the post-monsoon season (October–December). The frequency of post-monsoon cyclones is significantly higher than that of pre-monsoon cyclones. Very severe cyclonic storms and stronger-intensity storms can cause disastrous storm surges. Based on the accuracy of current forecasts of the path, intensity and radius of maximum wind of TCs in the BoB, a total of 153 ensemble members are automatically generated according to the subjective deterministic forecast results of the TCs, basically covering all possible TCs. A graphics processing unit (GPU)-based parallel storm surge forecast model is established and validated for the coastal areas of the BoB. The speedup ratio of the model can exceed 300, which can meet the computational time requirements of large-scale ensemble numerical forecasts. For the 2020 Amphan cyclone, the costliest cyclone ever recorded in the North Indian Ocean (NIO), the numerical ensemble forecast model can provide rapid and accurate storm surge ensemble and numerical probability forecast products for the BoB. The probability of coastal flooding risk can be evaluated for the coastal areas of the BoB, enabling reasonable and valuable recommendations to be made to evacuate people and protect property near dangerous areas.

Field observations and numerical modeling of swash motions at an engineered embayed beach under moderate to energetic conditions

Wave run-up is a key factor for the assessment of coastal flood risk during large swell events. The behavior of swash motions along embayed beaches is strongly influenced by particular features such as rocky headlands, irregular morphology, or tides, that have not received much attention in the past. In the present paper, swash motions along an engineered embayed beach were investigated under moderate to energetic wave conditions through field observations and numerical computations. Using pressure sensors and video-derived run-up data a Boussinesq-type nearshore wave model was found to capture the relevant wave transformation and swash zone processes reasonably well. The tidal water level variations were found to have a significant impact on the overall swash amplitudes and to condition the respective role of short- and long-wave components to the swash motions. In the studied configuration, the tidal level rise was shown to cause a transition from a very dissipative to a reflective or intermediate beach configuration depending on incident wave energy. Moreover, swash amplitudes were observed to vary significantly alongshore with differences of up to a factor of 2.2. Numerical results suggest that both the foreshore slope and the sub-tidal morphology play a key-role in the alongshore swash distribution.

Assessing Coastal Flood Risk in a Changing Climate for Dublin, Ireland

With increasing urban expansion and population growth, coastal urban areas will be increasingly affected by climate change impacts such as extreme storm events, sea level rise and coastal flooding. To address coastal inundation risk for impact studies, integrated approaches accounting for flood hazard modelling, exposure and vulnerability of human and environmental systems are crucial. In this study, we model the impacts of sea level rise on coastal inundation depth for County Dublin, the most extensively urbanized area in Ireland, for the current period and for 2100 under two Representative Concentration Pathways RCP 4.5 and 8.5. A risk-centred approach has been considered by linking the information on coastal flood-prone areas to the exposure of the urban environment, in terms of potential future land cover changes, and to the socioeconomic vulnerability of the population. The results suggest significant challenges for Dublin city and the surrounding coastal areas, with an increase of around 26% and 67% in the number of administrative units considered at very high risk by the end of the century under a RCP 4.5 and 8.5, respectively. This study aims to contribute to existing coastal inundation research undertaken for Ireland by (i) providing a first-level screening of flooding hazards in the study area, (ii) demonstrating how land cover changes and socioeconomic vulnerability can contribute to the level of experienced risk and (iii) informing local authorities and at-risk communities so as to support them in the development of plans for adaptation and resilience.

Morphological Analysis of a Nearshore Nourishment along the Atlantic Coast of New Jersey, USA

Nearshore nourishment is a common coastal flood risk management technique that can be constructed beneficially by using dredged sediment from navigation channels. A nearshore nourishment project was completed during the summer of 2021 in Harvey Cedars, NJ, USA, with 67,500 m3 of dredged sediment from Barnegat Inlet placed along approximately 450 m of beach in a depth of 3–4 m. In situ instruments were installed to monitor hydrodynamic conditions before and after dredged material placement, and nine topographic and bathymetric surveys were conducted to monitor nearshore morphological response to the nourishment. Shoreline location was extracted from satellite imagery using CoastSat software to compare historical trends to the shoreline response after construction. Seven months after construction, 40% of the nearshore nourishment was transported from the initial footprint and the centroid of the nourishment migrated towards shore and alongshore (north). The sheltering capacity of the nearshore berm appears to have captured an additional 58% of the placed volume from the longshore transport system and the beach width onshore of the placement increased by 10.9 m. Measured data, satellite imagery analysis, and rapid predictions all indicate that the nearshore nourishment at Harvey Cedars had a positive impact on the adjacent beach.

Coastal subsidence detection and characterization caused by brine mining over the Yellow River Delta using time series InSAR and PCA

• We generate an accurate deformation rate map over the Yellow River Delta. • We propose a quantitative method for driving factor analysis. • We find brine mining contributes over 94% to coastal subsidence. Extensive coastal deltas in the world are subsiding due to natural or anthropogenic activities. As the widest and youngest river delta in the world, serious coastal subsidence in the Yellow River Delta (YRD) has exacerbated the relative sea level rise (RSLR) and increased the risk of soil salinization and coastal flooding. However, there are rarely relevant studies that quantitatively separate the contributions from different driving factors to subsidence. In this work, we aim to provide a detailed and comprehensive analysis of coastal subsidence related to coastal brine pumping activities in YRD. We investigate the land deformation of the entire YRD by time series InSAR analysis (TS-InSAR) of Sentinel-1 images acquired between 2016 and 2021. The results reveal that fast subsiding funnels larger than 50 mm/yr are mainly distributed in the coastal brine mining clusters. We further used Principal Component Analysis (PCA) to extract the principal components and temporal patterns from the deformation time series. Taking geological data, precipitation, temperature, and human activities into consideration, we quantitatively separate the driving factors of coastal subsidence in sub-areas. We find that underground brine mining contributes to more than 94 % of the coastal subsidence of the YRD. In addition, precipitation is the most important natural factor that can affect the process of land subsidence in YRD, whereas other driving factors from soil consolidation, oil extraction and other activities are not noticeable. This study is expected to offer a cost-effective method for detecting and characterizing coastal subsidence in global sinking deltas, which will contribute to more accurate dynamic monitoring of coastal subsidence and a better understanding of land subsidence responses to anthropogenic activities.

Storm Surges and Extreme Wind Waves in the Caspian Sea in the Present and Future Climate

The Caspian Sea is of particular interest. Against the background of long-term sea level changes, low-lying coastal areas in the northern part are subject to constant flooding as a result of storm surges. The elongation of the sea in the meridional direction allows the development of strong waves in the middle and southern parts. A comprehensive understanding of the characteristics of storm surges and storm waves is especially important in the context of ongoing climate change. This study is devoted to the analysis of storm surges for the time period from 1979 up to 2017 and wind waves from 1979 to 2020 in the Caspian Sea region. The circulation model ADCIRC and the wave model WAVEWATCH III with wind and pressure forcing from the NCEP/CFSR reanalysis were used. The modeling is performed on different unstructured grids with spacings of 500–900 m in the coastal zone. Mean and extreme values of surges, wave parameters and storm activity are provided in the research. The maximum significant wave height for the whole period was 8.2 m. The average long-term SWH did not exceed 1.1 m. No significant trends in the storm activity were found. The maximum surge height was 2.7 m. The analysis of the interannual variability of the surges' occurrence showed that 7–10 surges with a height of more than 1 meter were detected every year. The total duration of these surges was 20–30 days per year. Assessment of the risks of coastal flooding was carried out by calculating the extreme values of the sea for different return periods: 5, 10, 25, 50, and 100 years. The extreme sea level values in the northern part of the Caspian Sea for the 100-year return period are close to 3 m, and the areas with big surges are located along the eastern and western coasts. A forecast is made for the recurrence of storm wind waves in the 21st century based on climatic scenarios in CMIP5. A statistically significant increase in the recurrence of storm waves is to be expected in the near future, but that increase is not severe. Doi: 10.28991/CEJ-2022-08-11-01 Full Text: PDF

Mangrove forests as a nature-based solution for coastal flood protection: Biophysical and ecological considerations

Nature-based coastal protection is increasingly recognised as a potentially sustainable and cost-effective solution to reduce coastal flood risk. It uses coastal ecosystems such as mangrove forests to create resilient designs for coastal flood protection. However, to use mangroves effectively as a nature-based measure for flood risk reduction, we must understand the biophysical processes that govern risk reduction capacity through mangrove ecosystem size and structure. In this perspective, we evaluate the current state of knowledge on local physical drivers and ecological processes that determine mangrove functioning as part of a nature-based flood defence. We show that the forest properties that comprise coastal flood protection are well-known, but models cannot yet pinpoint how spatial heterogeneity of the forest structure affects the capacity for wave or surge attenuation. Overall, there is relatively good understanding of the ecological processes that drive forest structure and size, but there is a lack of knowledge on how daily bed-level dynamics link to long-term biogeomorphic forest dynamics, and on the role of combined stressors influencing forest retreat. Integrating simulation models of forest structure under changing physical (e.g. due to sea-level change) and ecological drivers with hydrodynamic attenuation models will allow for better projections of long-term natural coastal protection.

Assessing Future Flood Risk and Developing Integrated Flood Risk Management Strategies: A Case Study from the UK Climate Change Risk Assessment

As Earth’s climate changes, individual nations must develop adaptation plans to respond to increasing or new climate risks. This study focuses on changing flood risk in England, UK, and examines the policy framework and actions that underpin England’s adaptation from a flood risk management (FRM) perspective. Specifically, the flood risk projections that fed into the UK’s Climate Change Risk Assessment were analysed alongside newly developed FRM adaptation portfolios that modified the flood risk projections to identify the potential of different measures to reduce Expected Annual Damages (EAD). The key findings indicate that: the range of EAD for all flood sources combined is projected to increase by 18–160% by the 2080s depending on the climate change, population growth and adaptation assumptions applied; adopting an enhanced adaptation approach presents an opportunity to manage much of the climate driven change in flood risk, particularly from river flooding; EAD from coastal flood risk shows the greatest increase relative to present day; and surface water flooding will become an increasingly more significant source of flood risk. Interpretation of the results in the context of the policy framework shows how greater coordination and integration of risk managers and interventions is required to improve adaptation planning.

Impacts of sea level rise on wave overtopping rates around the coast of England

There is unequivocal evidence that global sea levels are rising. It is therefore inevitable there will be socioeconomic impacts as a result of this. To aid mitigation, and the implementation of adaptation measures, it is vital the magnitude of the potential impact is quantified. Current approaches in the UK make simplifying assumptions regarding the relationship between present-day and future economic damage relating to coastal flood risk. The analysis undertaken here supports studies of an improved impact of sea level rise by providing national-scale estimates of changes in wave overtopping rates and flood defence overflow rates, as a result of different amounts of sea level rise. The analysis involves the application of components of an existing risk-based coastal flood risk analysis method. A subset of almost 600 flood defence assets around the country has been analysed for sea level rise rates up to 1 m. The resulting analysis shows that, on average, the wave overtopping rate increases by up to 150 times above present-day rates for lower return periods and by up to five times for higher return periods. This differential arises as a result of non-linearities in overtopping rates with increasing extreme sea levels.

Nonparametric Approach to Copula Estimation in Compounding The Joint Impact of Storm Surge and Rainfall Events in Coastal Flood Analysis

The joint probability modelling of storm surges and rainfall events is the main task in assessing compound flood risk in low-lying coastal areas. These extreme or non-extreme events may not be dangerous if considered individually but can intensify flooding impact if they occur simultaneously or successively. Recently, the copula approach has been widely accepted in compound flooding but is often limited to parametric or semiparametric distribution settings in a limited number of cases. However, both parametric and semiparametric approaches assume the prior distribution type for univariate marginals and copula joint density. In that case, there is a high risk of misspecification if the underlying assumption is violated. In addition, both approaches suffer from a lack of flexibility. This study uses bivariate copula density in the nonparametric distribution setting. The joint copula structure is approximated nonparametrically by employing the Bernstein copula estimator and Beta kernel copula density, and their performances are also compared. The proposed model is tested with 46 years of rainfall and storm surge observations collected on Canada's west coast. The marginal distribution of the selected flood variables is modelled using nonparametric kernel density estimation (KDE). Based on the different model compatibility tests, the Bernstein copula with normal KDE margins defined the joint dependence structure well. The selected nonparametric copula model is further employed to estimate joint and conditional return periods. It is found that flood hazard characteristics occurrence simultaneously is less frequent in AND-joint cases than in OR-joint cases. Also, the derived model is further used to estimate failure probability (FP) statistics to assess the variation of bivariate hydrologic risk during the project lifetime. It is found that FP statistics could be underestimated when neglecting the compound effect of storm surge and rainfall in the coastal flood risk.

A spatial model for coastal flood susceptibility assessment using the 2D-SPR method with complex network theory: A case study of a reclamation island in Zhoushan, China

Coastal floods are the type of marine disaster that causes the greatest economic losses in coastal areas of China, especially in the current context of global climate change. Mapping the spatial distribution of coastal flood susceptibility is a prerequisite for coastal flood risk analysis, and an important step in risk prevention and management. Based on the actual coastal flood propagation process, this study uses a 2D-source–pathway–receptor (2D-SPR) model to construct a complex network for coastal flood susceptibility analysis. In addition, it uses the decision-making trial and evaluation laboratory (DEMATEL) method and the technique for order preference by similarity to an ideal solution (TOPSIS) multi-attribute decision-making method to calculate the importance of each unit in the system, namely centrality Mi which ranges from 0.0716 to 4.3524, with a higher value indicating a higher importance. Finally, the spatial distribution of coastal flood susceptibility is drawn with ArcGIS software. For a clearer display, we divide the data into 12 levels according to the natural breakpoint method, and it can be seen that coastal flood susceptibility of different regions varies greatly. The classification results have obvious regularity, overall, open-land areas or parks, waters and southeast side have relatively higher values, which belong to the higher susceptibility area among the 12 levels. From the perspective of the integrity of the geographical unit, 15 locations including unbuilt areas and water areas are identified to have high flood susceptibilities relative to the mean values of all the areas. This study fully considers the hazard formation process of coastal floods, especially the complex interaction between hazard sources and receptors. These findings provide a new perspective for the rapid, objective assessment of coastal flood susceptibility.

A typology of responsibility for coastal flood risk adaptation

The management of coastal flood risk is adapting to meet the challenges and increased risks posed by population change as well as by climate change, especially sea level rise. Protection is being targeted to areas where the benefits are highest, while elsewhere there is a shift towards more localized “living with floods” and “resilience” approaches. Such decentralized approaches to flood risk management (FRM) require a diverse range of stakeholder groups to be engaged as “flood risk citizens”. Engagement of households in FRM is central to this process. Despite significant research on stakeholder engagement in coastal and flood risk management, there is less focus on the nature of responsibility in coastal adaptation. There is no framework by which to assess the different types of responsibility in hazard management and adaptation, and little research on the implications of expecting these responsibilities of stakeholder groups. In this paper, we identify five types of responsibility that are embedded throughout the disaster risk reduction cycle of managing coastal flooding. We build this “typology of responsibility” on existing work on the evolution of stakeholder engagement and stakeholder responsibility relationships in risk management processes, and a dataset of institutional stakeholder interviews and households surveys conducted across three case studies in England, the United Kingdom, in 2018 and 2019. We analyze the interviews using thematic analysis to explore institutional stakeholder perceptions of responsibility in coastal FRM, and analyze the household survey through descriptive and inferential statistics. By developing the first disaster risk reduction focused typology of responsibility for coastal flooding, we provide researchers and decision-makers with a tool to guide their planning and allocation of responsibilities in risk management for floods and other climate-driven hazards.

Coastal Flood Risks and the Business Community: Stakeholders’ Perception in Malta

Resilience of coastal communities is increasingly required to adjust to the effects of climate change and its coast-related threats. Climate change is a major global threat to the environment, economy, and health of urban coastal lowlands. Flooding risks from both rising sea levels and increases in the frequency and severity of storm surges are considered to be amongst the most threatening consequences associated with climate change. The aim of this study was to assess the levels of socio-economic preparedness of low-lying urbanized towns in Malta for the impacts of coastal flooding through the triangulation of stakeholders’ participation from three sectors: the business community, local councils, and specialized experts from the governmental and private sectors. The study also included field collection of elevation data for each locality to capture the businesses’ distribution in relation to their height above sea level along the urban waterfront. One-way analysis of variance and NVivo were used to test and compare the business owners’ responses and the experts’ feedback, respectively. The main findings from the business community suggest that there are no long-term contingency plans or strategies in place to address potential flooding impacts from rising sea levels and storm surges, and that the risks of driving owners out of business is high. From the feedback received by the local councils, it was observed that all of them significantly lack the physical and financial resources to effectively manage long-term coastal flooding within their locality, forcing them to completely rely on central government for any future needs caused by the impact of coastal flooding. From a central government perspective, it seems that all interviewed experts operate within a fragmented governance model, and mainly adhere to the set of responsibilities aligned with their respective roles within such a governance model. This evidence of governance disconnect requires more horizontal and vertical integration of cross-sectoral strategies to address coastal flooding, within the broader framework of integrated coastal zone management as established by the Mediterranean ICZM protocol.

Invited perspectives: Managed realignment as a solution to mitigate coastal flood risks – optimizing success through knowledge co-production

Abstract. Nature-based solutions are increasingly suggested for mitigating coastal flood risks in the face of climate change. Managed realignment (MR), a coastal adaptation strategy that entails the landward realignment of coastal defences to restore coastal habitats (often salt marshes), plays a pivotal role in implementing nature-based solutions in the coastal zone. Across Europe, more than 130 sites have been implemented so far, often to harness their potential to mitigate coastal flood risks while restoring coastal habitats (ABPmer, 2021). However, local communities often oppose MR projects, not only because they are seen as returning hard-won land to the sea but also because their coastal protection function is less trusted than traditional hard engineering techniques. This scepticism has foundation. The proclaimed coastal protection function of MRs is based on a broad body of literature on the protective function of natural salt marshes. However, contrary to natural salt marshes, MRs are often semi-enclosed tidal basins with narrow breaches to the open sea/estuary. Recent studies indicate that MR-internal hydrodynamics may significantly reduce their coastal protection, depending on their engineering design. To successfully implement MR, a much-improved scientific knowledge base is needed, as well as a process for addressing community concerns and genuinely engaging stakeholders in decision-making beyond the usual obligatory consultancy approach. Here, we propose the co-production of scientific knowledge with local communities and stakeholders to optimize the success of coastal nature-based solutions and promote community acceptance.

A global analysis of coastal flood risk to the petrochemical distribution network in a changing climate

The global petroleum distribution network already faces a significant threat of disruption due to annual coastal flooding of major refining centers, which is expected to further increase with the effects of climate change. This study considers the impacts that sea level rise projections might have on the annual flood risk to coastal refineries, and how regional disruptions propagate across the network. Both the annual regional risk in terms of expected production disruption under a range of climate scenarios, as well as the expected production disruption due to a major flood event impacting refining hubs of high importance are assessed throughout the 21st century. These risks are propagated across the network to model the global impact of coastal flood-induced refining disruptions. This analysis provides insights on the relative risks that different climate scenarios and flood events pose globally, informing potential mitigation and adaptation needs of critical facilities. Due to the highly interconnected nature of the global petroleum product distribution network, these results highlight the need for mitigation considerations for even regions with low domestic production disruption risk due to coastal flood hazards, as disruptions in remote regions can have cascading consequences resulting in significant disruption to petroleum product supply around the world. Furthermore, such results can inform decisions regarding technology transitions or energy diversification in light of the new understanding of climate risks to coastal refineries and the global petroleum distribution network.

Spatial assessment of coastal flood risk due to sea level rise in China’s coastal zone through the 21st century

Among the climate change-induced threats to coastal regions, coastal flooding caused by sea level rise (SLR) is considered one of the most serious and presents an intensifying trend over time. The negative impacts and risks associated with coastal flooding are difficult to visualize spatially and cause great inconvenience to policy-makers in understanding the distribution of different risk levels and developing adaptation policies. Our study proposes a framework for coastal flood risk (CFR) based on the hazard, exposure & sensitivity, and adaptive capacity of China’s coastal zone (CCZ) and maps the spatial distribution of CFR by GIS in 2030, 2050, and 2100 under RCP2.6-SSP1, RCP4.5-SSP2, and RCP8.5-SSP5, respectively. Our results reveal that (1) low-lying coastal areas with densely populated, economically developed, or industrially diverse are faced with serious CFRs, such as the Yellow River Delta, the Yangtze River Delta, the Pearl River Delta, and the coastal areas in Jiangsu. (2) The area of “Very high” CFR level in the CCZ reaches a peak of 44.10×103 km2 in 2100 under RCP8.5-SSP5. And under the higher emission scenario, the areas of five CFR levels would change dramatically in the future. (3) The coastal area of Guangdong is significantly faced with the massive expected population and GDP affected due to CFR among scenarios and years. (4) As threatened by CFR mostly, built-up and farmland are particularly required to guard against the negative impact of coastal flooding, especially in Guangdong and Jiangsu. Results in this study are expected to provide the intuitive information and basis for governments, policy-makers, and local communities in addressing the increased CFR over the CCZ. Besides, our framework of CFR and methodology are flexible and can be adapted for other countries facing the threat of SLR.

Reconstruction of coastal flooding processes and human response at the end of the Liangzhu Culture, East China

Understanding coastal flooding processes in response to centennial-scale sea-level rise is essential in preparing for the challenge of present-day global warming. Mid-Holocene sea-level rise induced widespread coastal flooding along the East China coast and precipitated the collapse of the Neolithic Liangzhu Culture, the earliest known prehistoric state in East Asia. This paper presents multi-proxy analyses of sedimentology, grain size, total organic carbon (TOC), and alkaline-earth metals extracted by acetic acid (HAc) of a dated sediment core, ZK07, collected from Liangzhu City, with the aim of revealing the detailed progression of coastal flooding phases and the response of prehistoric people at the end of the associated Liangzhu Culture. A three-step succession of coastal flooding processes between ca. 4.6–4.3 cal kyr BP, brought about by relative sea-level rise, is evident in core ZK07. Initially, an increase in the local water level in response to the first phase of sea-level rise is indicated by a gradual increase in TOC at ca. 4630 cal yr BP. Subsequently, at ca. 4520 cal yr BP, a second phase of increased local water-level, consistent with further sea-level rise and salinity intrusion, is suggested by higher Sr concentrations accompanied by a sharp increase in TOC. Thirdly, at ca. 4480–4315 cal yr BP, low TOC content, high - but strongly fluctuating - Sr and Ba concentrations and coarser sediment grain size are all indicative of coastal inundation caused by both storm surges and river flooding associated with typhoon events that correspond with a concurrent phase of accelerated sea-level rise. Considering the evidence of cultural deposits preserved at Liangzhu City, it appears that the Liangzhu people were forced to respond rapidly to the inundation by abandoning the city at ca. 4480 cal yr BP. We suggest that relative sea-level rise and coastal flooding at the terminal stage of the Liangzhu Culture was the regional response to global climate warming and eustatic sea-level rise at that time. Given evidence that a contemporaneous cultural transition took place in the lower Yellow River basin, we further propose that global climate change around 4.5 cal kyr BP had a widespread impact on Neolithic cultural evolution in East China. Furthermore, the rise in local water levels and associated salinity intrusions may be considered as an early warning signal in monitoring future coastal flooding risk.

Sea Level Rise and the Great Barrier Reef: The Future Implications on Reef Tidal Dynamics

AbstractPredicted sea‐level rise (SLR) is anticipated to alter tidal dynamics in the future and this will in turn alter coastal ecosystems, flood risk, and geomorphology. Coral reefs are bathymetrically complex environments where tides play a crucial role in larval and nutrient dispersal. This complexity makes coral reef environments challenging to simulate numerically as a large area needs to be simulated but also with high resolution to capture the complexity. To investigate the influence of SLR on tidal dynamics in coral reef systems we use an unstructured mesh numerical model, with spatially varying resolution, of the Great Barrier Reef (GBR). The present‐day conditions and a total of three future SLR scenarios are considered based on the RCP scenarios. The results focus on the major tidal constituents and tidal range. The M2 constituent generally decreases across gauge locations as sea‐level rises but S2 generally increases. O1 and K1 display small variations or no change. The tidal range experiences ±10% variation depending on the gauge location, meaning it is spatially varying and alters SLR by up to 10%. Overall, SLR will influence tidal dynamics across the GBR altering coastal flooding risk with a spatially varying impact. Management schemes should consider tidal range changes in addition to increases in extreme weather conditions to provide adequate preservation of the coastline, coastal cities and infrastructure in the future. Moreover, changes in tidal patterns and dynamics may alter the distributions of reef spores and larvae and should be included in future plans of reef management.

Enhancing a Coastal Territorial Vulnerability Index: Anticipating the Impacts of Coastal Flooding with a Local Scale Approach

The coastal zone of mainland Portugal is characterized by its morpho-sedimentary diversity such as estuaries, lagoons, barrier islands, beaches, dunes and cliffs. The high population density and the multiplicity of land use, occupation and activities, makes it an area of great national strategic value. This transforms the coastal zone into a multi-hazard zone, where the occurrences related to coastal flooding and overtopping stand out. In the present work, a multidimensional methodology called Coastal Territorial Vulnerability Index (CTVI) was developed and applied in three selected areas with a historical record of coastal impacts, to analyze, evaluate and interpret the local vulnerability. The methodology considers four components of coastal territorial vulnerability: morphology, land value, buildings and public areas characteristics. These four components are combined to calculate the CTVI. The results highlight the differences for the analyzed areas, allowing the differentiation of natural and artificial areas. In the natural areas a moderate CTVI predominates, while in the latter, a high and very high CTVI stands out. The results contribute to the development of a comprehensive coastal flood risk assessment and forecasting the impacts.