IMPACTS OF SEA LEVEL RISE ON MAJOR PROJECTS AND URBAN DEVELOPMENT IN CHINA'S COASTAL PLAINS

Due to the dual dris oftural and man-made factors, relative sea leverise in China's coastal plains can be 2 to 3 times over the global mean dunng thefirst half of the 21st Century, it will strongly whuence the vanous coastal projectsand installations and the development of coastal dhes and towns. Research resultsshow that a 50-cm-nse in relative sea leve will cause maed decline in the functionof coastal defense and drainage projects and seriously endangur the functionalworking of the vast majority of coastal harbors. Meanwhile, it will also whuence thedevelopment of coastal dhes and towns throwi deterioratin water quality of thesource of urban water supply, increasing urban fiood risk and damagin seasidetounst resources etc.. Tianin, Shanghai and Guangzhou, the three most importancoastal dhes of China, will be Strongly affeded.

Numerical Simulation of the Influence of Mean Sea Level Rise on Typhoon Storm Surge in the East China Sea

In this paper, ECOMSED （Estuarine Coastal Ocean Model with sediment transport） model is employed to simulate storm surge process caused by typhoon passing across East China Sea in nearly years. Capability of ECOMSED to simulate storm surge is validated by comparing model result with observed data. Sensitivity experiments are designed to study the influence of sea level rise on typhoon storm surge. Numerical experiment shows that influence of mean sea level rise on typhoon storm surge is non-uniform spatially and changes as typhoon process differs. Maybe fixed boundary method would weaken the influence of mean sea level rise on storm surge, and free boundary method is suggested for the succeeding study.

Adaptation strategy for sea level rise in vulnerable areasalong China's coast

It can be seen from the calculation that the vulnerable area along China's coast in which the elevation is less than 5 m, is 143 900 km2, accounting for about 11. 3% of the total area of the 11 coastal provinces, municipalities and autonomous regions. These areas are threatened to varying extent by sea level rise. According to prediction, the relative sea level rise (including global sea level rise caused by climate change and local relative as level rise caused by vertical crust movement and ground subsidence) along China's coast will be 4～16 cm by the year 2030 with the optimum estimated value of 6～14cm. It will be 9～26 cm by the year 2050 with the optimum estimated value of 12-23 cm. And it will be 31-74 cm by the year 2100 with the optimum estimated value of 47～65 cm. The calcuation result shows that the percentage of the cost for up-grading (heightening and consolidating) sea dykes/walls in adaptation strategy in the losses of submerged areas varies from area to area: 6. 9% in the Zhujiang (Pearl) River Deta, 1. 3% ～24. 6% in the Changjiang (Yangtze) River Delta, and 0. 9%～2. 0% in the Huanghe River Delta.

Comprehensive Risk Assessment of Sea Level Rise and Tropical Cyclones in Dongzhaigang Mangroves,China

Mangroves play a pivotal role in tropical and subtropical coastal ecosystem,yet they are highly vulnerable to the effects of climate change,particularly the accelerated global sea level rise(SLR)and stronger tropical cyclones(TCs).However,there is a lack of research addressing future simultaneous combined impacts of the slow-onset of SLR and rapid-onset of TCs on China's mangroves.In order to develop a comprehensive risk assessment method considering the superimposed effects of these two factors and analyze risk for mangroves in Dongzhaigang,Hainan Island,China,we used observational and climate model data to assess the risks to mangroves under low,intermediate,and very high greenhouse gas(GHG)emission scenarios(such as SSP1-2.6,SSP2-4.5,and SSP5-8.5)in 2030,2050,and 2100,and compiled a risk assessment scheme for mangroves in Dongzhaigang,China.The results showed that the combined risks from SLR and TCs will continue to rise;however,SLRs will increase in intensity,and TCs will decrease.The comprehensive risk of the Dongzhaigang mangroves posed by climate change will remain low under SSP1-2.6 and SSP2-4.5 scenarios by 2030,but it will increase substantially by 2100.While under SSP5-8.5 scenario,the risks to mangroves in Dongzhaigang are projected to increase considerably by 2050,and approximately 68.8%of mangroves will be at very high risk by 2100.The risk to the Dongzhaigang mangroves is not only influenced by the hazards but also closely linked to their exposure and vulnerability.We therefore propose climate resilience developmental responses for mangroves to address the effects of climate change.This study for the combined impact of TCs and SLR on mangroves in Dongzhaigang,China can enrich the method system of mangrove risk assessment and provide references for scientific management.

Extreme Sea Level Rise off the Northwest Coast of the South China Sea in 2012

Tide gauge data are used to investigate sea level variability offthe northwest coast of the South China Sea （SCS） in 2012, and a significant sea level elevation with a magnitude approaching 79 mm is observed. Analysis suggests that an abnormal sea surface heat flux and freshwater flux may have contributed to this abnormal rise in sea level, together with the remote influence of an ENSO event. Further investigation shows that the event was dominated by the positive freshwater flux, where large volumes of water entered the ocean, and a maximum is centered to the south of Guangdong province, China. Simultaneously, a positive anomalous heat flux occurred in the northwestern part of the SCS, which is considered to have made a positive contribution to the high local sea level elevation. In addition to the heat flux, the ENSO event also had a significant effect on the event, where the La Nifia-induced northwest Pacific cyclone contributed to sea level rise over the northwestern SCS through dynamic and thermodynamic interactions.

Sea level rise projection in the South China Sea from CMIP5 models

Future potential sea level change in the South China Sea （SCS） is estimated by using 24 CMIP5 models under different representative concentration pathway （RCP） scenarios. By the end of the 21st century （2081–2100 relative to 1986–2005）, the multimodel ensemble mean dynamic sea level （DSL） is projected to rise 0.9, 1.6, and 1.1 cm under RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively, resulting in a total sea level rise （SLR） of 40.9, 48.6, and 64.1 cm in the SCS. It indicates that the SCS will experience a substantial SLR over the 21st century, and the rise is only marginal larger than the global mean SLR. During the same period, the steric sea level （SSL） rise is estimated to be 6.7, 10.0, and 15.3 cm under the three scenarios, respectively, which accounts only for 16%, 21% and 24% of the total SLR in this region. The changes of the SSL in the SCS are almost out of phase with those of the DSL for the three scenarios. The central deep basin has a slightly weak DSL rise, but a strong SSL rise during the 21st century, compared with the north and southwest shelves.

Modern sea level changes of the Eastern China Seas and their influences on coastal areas

The statistics of tidal gauging records showed that the mean sea level of the China Seas has risen for 14 cm in past 100 years. The annual mean sea levels of the Eastern China Seas have been rising at a speed of about 0.21 -0.23 cm/a since 1960. The annual mean sea levels of the Eastern China Seas in 1989 were 1.45 cm higher than that in 1988 on average.The sea level rise may cause the damage of the dynamical balance of the natural environments in the coastal area? and form or strengthen many coastal disasters, such as storm-tide catastrophic events, sea water invasion landward, soil salinization in coastal lowland and plains, and beach erosion retreat.

Prediction of the joint impacts of sea level rise and land development on distribution patterns of mangrove communities

Mangrove distribution along shorelines shows distinct zonation patterns;thus,different communities may face various influences from sea level rise(SLR)and land use.However,long-term change predictions are usually based only on the total extent of mangroves.Few studies have revealed how SLR and land development such as agriculture,aquaculture,and urbanization jointly affect different intertidal mangrove communities.This study proposed a novel framework combining SLAMM(Sea Level Affecting Marshes Model)and the CLUE-S(Conversion of Land Use and its Effect at Small regional extent)model to assess the potential impacts on upper and lower intertidal mangrove communities.Maoweihai in Guangxi,China,was selected as the study area and the potential impacts from the squeeze effect and mangrove expansion potential were evaluated.We established three scenarios combining SLR and land use patterns to predict mangrove coverage projections by 2070.The results showed that,under a single SLR driver,the upper intertidal mangroves would be more adaptive to rapid SLR than the lower intertidal mangroves.However,under the combined influence of the two drivers,the upper intertidal mangroves would experience larger squeeze effects than the lower intertidal mangroves,with up to 80.5%of suitable habitat lost.Moreover,the expansion potential of upper intertidal mangroves would be considerably more limited than that of lower intertidal mangroves.The length of the expandable habitat patch boundary of upper intertidal mangroves only reached 1.4–1.8 km,while that of the lower intertidal mangroves reached up to99.2–111.2 km.Further,we found that aquaculture ponds and cropland are the top two land development types that could occupy suitable habitat and restrict the mangrove expansion potential.Our results highlight that timely improvement of land use policies to create available landward accommodation space for mangrove migration is essential to maintain the coverage and diversity of mangrove communities under SLR.The proposed method can be a helpful tool for adaptive mangrove conservation and management under climate change.

Coastal Planning Strategies for Adaptation to Sea Level Rise: A Case Study of Mokpo, Korea

Climate change and sea level rise necessitate adaptation strategies for coastal areas. This paper showcases five strategies for sea level rise adaptation: hard protection, soft protection, accommodation, retreat, and attack. This study proposes adaptation measures and a phased development strategy for coastal areas of Mokpo, an old port city on the southwestern tip of the Korean Peninsula that has been expanded by land reclamation. Mokpo presently experiences frequent flooding during high-water and storm events;due to their low elevation and land subsidence, most of the reclaimed areas are susceptible to future inundation via sea level rise. The fundamental adaptation strategies for the impact areas are: hard protection of important infrastructures via multi-tiered terraces;the retreat of coastal developments accompanied by green buffer zones such as wetlands and parks to accommodate temporary inundation;and up-leveling the ground for new development and phased relocation of existing development. Through the case study of Mokpo, the paper emphasizes the importance of resilient planning strategies for urban development, and highlights both the challenges and opportunities for sea level rise adaptation.

Effect of Sea Level Rise and Offshore Wave Height Change on Nearshore Waves and Coastal Structures

In 1994,Townend proposed a method to calculate the relative changes in various wave characteristics and structure-related parameters due to sea level rise for regular waves.The method was extended to irregular waves by Cheon and Suh in 2016.In this study,this method is further extended to include the effect of future change in offshore wave height and the sea level rise.The relative changes in wavelength,refraction coefficient,shoaling coefficient,and wave height in nearshore area are presented as functions of the relative changes in water depth and offshore wave height.The calculated relative changes in wave characteristics are then used to estimate the effect of sea level rise and offshore wave height change on coastal structures by calculating the relative changes in wave run-up height,overtopping discharge,crest freeboard,and armor weight of the structures.The relative changes in wave characteristics and structure-related parameters are all expressed as a function of the relative water depth for various combinations of the relative changes in water depth and offshore wave height.

Impacts of Sea Level Rise on the Coastal Areas to the West of the Bohai Bay

Based on the assumption of global sea level rising between 30 and 100 cm in the future 100 years by IPCC (1990) in addition to the effect of local ground subsidence, the coastline will retrograde for 50-70 km whose altitudes will be 2.6-3 .3m above MSL of Huanghai Sea in the western coastal area of the Bohai bay in 2100. The transgrassive area is about 10,000-11 ,500 km. If the effect of set-up of storm surge is considered, the transgressive area will reach 16,000 km. Sea level rise which is a serious coastal disaster not only inundates a lot of coastal lowland, but also increases the frequency and intensity of storm tides, and results in the salinization of soils. In vies of this situation we recommend a trinity comprehensive measure of treatment, namely, "building seawall to prevent tides-diverting the Hunaghe River to settle its sediment loads -raising the constructional base".

Application of Geo-Processing Model for a Quantitative Assessment of Coastal Exposure and Sensitivity to Sea Level Rise in the Sultanate of Oman

The Sultanate of Oman has a long coastline extending for about 3165 km including a number of bays and islands. Oman’s coastline borders the Arabian Gulf, the Sea of Oman and the Arabian Sea. Most of this coastline is soft and low laying shore subject to the dynamics of sediment transport and the landward retreat of the shoreline, caused by anthropogenic factors and sea level rise associated with climate change. This paper aims to assess the vulnerability of the entire Omani coastal zone to the expected sea level rise and storm surge. Methodology is based on applying Coastal Vulnerability Index (CVI) to identify clusters of high vulnerability areas according to their sensitivity and dynamic nature and increased risk resulted from seal level rise, erosion and extreme weather events. The coastal line of the governorates of Al Batinah, Muscat and Al-Wusta has scored highly due to possessing similar physical attributes. Based on that assessment a coastal vulnerability database utilizing GIS was created to help stakeholders involved in the coastal management to make better decisions.

Empirical Assessment of Coastal Environmental Vulnerability to Sea Level Rise

Sea level rise (SLR) could critically endanger the environment along all the world’s sea coasts. Although sudden SLRs of meters-high waves that might have apocalyptic results would generally be limited to specific areas, on-going SLR of dozens of cms over decades is likely to have adverse impact on coastal environments throughout the world. This study’s objective is to assess relative regional vulnerability of global sea coasts to SLR. The study focuses upon key natural and anthropogenic parameters that might either cause or enhance SLR and thus significantly influence regional coastal environments. Careful assessment can enable reasonable estimates of relative vulnerability of such environments. An initial step involves specifying key parameters and assigning their weightings and ratings. To demonstrate the feasibility of this approach, six seacoast regions from various parts of the world have been considered in this paper, assessing their natural and anthropogenic parameters vis-à-vis general global data. The results emphasize the relative vulnerability of these areas’ environments to SLR. Recommendations are then made for improving global SLR modeling and monitoring.

Sea level change under IPCC-A2 scenario in Bohai, Yellow, and East China Seas

Because of the environmental and socioeconomic impacts of anthropogenic sea level rise （SLR）, it is very important to understand the processes leading to past and present SLRs towards more reliable future SLR projections. A regional ocean general circulation model （ROGCM）, with a grid refinement in the Bohai, Yellow, and East China Seas （BYECSs）, was set up to project SLR induced by the ocean dynamic change in the 21st century. The model does not consider the contributions from ice sheets and glacier melting. Data of all forcing terms required in the model came from the simulation of the Community Climate System Model version 3.0 （CCSM3） under the International Panel on Climate Change （IPCC）-A2 scenario. Simulation results show that at the end of the 21st century, the sea level in the BYECSs will rise about 0.12 to 0.20 m. The SLR in the BYECSs during the 21st century is mainly caused by the ocean mass redistribution due to the ocean dynamic change of the Pacific Ocean, which means that water in the Pacific Ocean tends to move to the continental shelves of the BYECSs, although the local steric sea level change is another factor.

Estimating shoreline response to sea level rise:the equilibrium model

Potential sandy coast erosion and socio-economic impacts under sea level rise scenarios as well as socio-economic pathways were assessed in Liaodong Bay.Results show that sea level is projected to rise by 20-43 cm in Liaodong Bay by 2100.And dry land loss increases in all sea level rise scenarios,with the maximum loss of 32.1 km2 in 2100 under RCP8.5.Coastal erosion results in forced migration,and the forced migration is higher under SSP3 than other pathways due to its higher population growth rate,reaching the highest of 3.1×10^4 under SSP3/RCP8.5 in 2100.Moreover,the differences of forced migration among all scenarios increas after 2050,and the migration increasing rates tend to decrease under RCP2.6 and RCP4.5.The maximum economic loss due to coastal erosion will reach 8.05 billion yuan under SSP5/RCP8.5 in 2100,in which land loss cost is two order less than migration cost,and the share of total erosion-induced economic loss in local GDP varies from 1.12‰ to 4.76‰ under all scenarios,which is an important indicator to draw local government's attention to take measures such as beach nourishment,especially for tourist beaches.Optimally,it is recommended by cost-benefit analysis to carry out nourishment mainly on beaches with high value,while there is no need for nourishment in areas where erosion impacts are negligible.

Future sea level rise along the coast of China and adjacent region under 1.5℃ and 2.0℃ global warming

Although future sea level rise along the China coast has been projected by various studies for different representative concentration pathways(RCPs),the projections for different warming thresholds,e.g.1.5℃ and 2.0℃,have not been done specifically for this region,to the best of our knowledge.We provide such a projection here based on the climate projections of Coupled Model Intercomparison Project Phase 5(CMIP5).The projections are given for 20 tide-gauge stations along the coast of China,Korea,Japan,and Vietnam.Vertical land motion(VLM)is also estimated for stations that have tide gauge records and satellite altimetry both covering the period of 1993-2018.Local land motion(LLM)is then estimated by subtracting the land motion due to glacial isostatic adjustment(GIA)from VLM.Without considering LLM,sea level rise by 2100 at median probability is projected to be 38-49 cm relative to the average sea level over 1986-2005 under warming of 1.5℃,and increase to 46-57 cm when the warming threshold is increased to 2.0℃.The steric component is the main contributor to this increase in sea level.Inclusion of LLM will not affect the sea level increase between the two warming thresholds,but it will make the local sea level rise by 2100 at certain locations substantially higher(up to 36 cm)or lower(up to 13 cm).

Effect of Sea Level Rise and Groundwater Withdrawal on Seawater Intrusion in the Gulf Coast Aquifer: Implications for Agriculture

The two main factors contributing to depletion of freshwater resources are climate change and anthropological variables. This study presents statistical analyses that are local in its specifics yet global in its relevance. The decline in Gulf Coast aquifer water quality and quantity has been alarming especially with the increased demand on fresh water in neighboring non-coastal communities. This study used seawater levels, groundwater use, and well data to investigate the association of these factors on the salinity of water indicated by chloride levels. Statistical analyses were conducted pointing to the high significance of both sea water level and groundwater withdrawals to chloride concentrations. However, groundwater withdrawal had higher significance which points to the need of water management systems in order to limit groundwater use. The findings also point to the great impact of increased groundwater salinity in the Gulf Coast aquifer on agriculture and socioeconomic status of coastal communities. The high costs of desalinization point to the increased signification of water rerouting and groundwater management systems. Further investigation and actions are in dire need to manage these vulnerabilities of the coastal communities.

Sea level rise along China coast from 1950 to 2020

Global mean sea level rise has been reconstructed using tide gauges. However, long-term sea level rise along the China coast is unclear. To address this issue, a data assimilation approach is developed to reconstruct sea level rise along the China coast from 1950 to 2020 using a global distribution of tide gauges(TGs). This approach combines climate models and sea level fingerprints. The climate models provide stereodynamic sea level changes. The sea level fingerprints include increases in ocean mass due to global ice melting and changes in water storage on land. The reconstructed global mean sea level rise agrees well with previous studies. We quantify sea level rise at 20 TGs along the China coast. The results suggest that sea level rise along the China coast(1.95±0.33 mm yr^(-1)) is greater than the global mean(1.71±0.17 mm yr^(-1)). We also find that China's coastal sea level rise is more than three times faster after 1980, increasing from 0.84±0.28 mm yr^(-1)for 1950–1980 to3.12±0.21 mm yr^(-1)for 1980–2020. This finding implies a significant sea level acceleration along the China coast. Our results advance the understanding of long-term sea level changes along the China coast.

Estimation of Peak Water Level in Pearl River Estuary under the Background of Sea Level Rise

[Objective] The study aimed to predict the peak water level in Pearl River Estuary under the background of sea level rise. [Method] The changing trends of peak water level at Denglongshan station and Hengmen station were analyzed firstly on the basis of regression models, and then sea level rise in Pearl River Estuary in 2050 was predicted to estimate the 1-in-50-year peak water level in the same year. [Result] Regression analyses showed that the increasing rate of peak water level over past years was 6.3 mm/a at Denglongshan station and 5.8 mm/a at Hengmen station. In addition, if sea level will rise by 20, 30 and 60 cm respectively in 2050, it was predicted that the 1-in-50-year peak water level will reach 3.04, 3.14 and 3.44 m at Denglongshan station, and 3.19, 3.29 and 3.59 m at Hengmen station separately. [Conclusion] The estimation of peak water level in Pearl River Estuary could provide theoretical references for water resources planning.

Trends of sea level rise in the South China Sea during the 1990s: An altimetry result

Using 7 years of TOPEX/POSEIDON satellite altimetry data, we have identified a general trend of sea level rising in the South China Sea between January 1993 and December 1999. The estimated bulk rising rate of the entire basin is-1 cm/a. The rise of sea level appears to be spatially non-homogeneous, which shows a highest rate of 2.7 cm/a in the deep basin west of Luzon and generally low (even negative) rates over the shallow continental shelves. It is believed that the observed rapid rising of sea level is a regional phenomenon and is mainly caused by warming of the upper layer of the South China Sea, which showed a bulk warming rate of 0.15癈/a in the same period. It is also suggested that the observed rising trend is mainly a decadal signal, which is possibly associated with decadal variation of the Pacific warm pool region.