A detailed record of the Late Holocene sea level rise and landscape evolution that has taken place on the Georgia coast is contained within the sedimentary stratigraphy of its salt marsh depositional basins. Global relative sea level (RSL) has risen during the Late Holocene, and the rate of rise has accelerated during the Anthropocene. Jones Narrows marsh stratigraphy and radiocarbon analysis indicate increasing rates of RSL rise for the late Holocene on the Northern Atlantic Coast of Georgia, while FPXRF analysis of the marsh sediments facilitates a chemostratigraphic study of Jones Narrows salt marsh deposition and landscape evolution. Sedimentation and hydrology at the site have been heavily influenced by recent local anthropogenic impacts, which are examined through stratigraphic and spatial methods.

Thesis advisor: Tara Pisani Gareau / Salt marshes provide important ecosystem services, including carbon sequestration. Permanently inundated ponds are prominent features in the marsh landscape, encompassing up to 60% of the total marsh area, but they are rarely considered in biogeochemical assessments. I investigated two ponds in Plum Island Estuary, MA to measure and analyze their metabolism. The ponds varied in size and vegetation cover. Oxygen concentrations and pH values were recorded in 15-minute intervals during the entire study period. The ponds regularly become hypoxic or anoxic during night. This is a problem for the estimation of respiration rates which are based on nighttime measurements. To investigate this potential underestimation, several approaches to estimate respiration were used. First, additional measurements of surface water concentrations of dissolved inorganic carbon were made. A comparison of respiration estimates based on oxygen and DIC changes during tidal isolation revealed a reasonable agreement for the most time but not during periods of high productivity during the day or late at night. At this point, oxygen concentrations are so depleted that a change in concentration – the indicator of respiration – is barely detectable. However, DIC based respiration rates indicate that respiration is occurring under these hypoxic/anoxic conditions. This saturation changes during periods of tidal inundation, when a nighttime peak in oxygen concentrations indicates that the flood water is relatively enriched in oxygen compared to the pond water. On three days, it was tested whether under these conditions the oxygen-based respiration rate was higher than under hypoxic conditions (i.e., during tidal isolation). The rates were indeed higher than those under tidal isolation but still not in the range of DIC-based rates. Overall, metabolic rates differed between the two ponds in magnitude, which is likely caused by different vegetation cover, but may be influenced by size, sampling period, and duration as well. / Thesis (BS) — Boston College, 2018. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Departmental Honors. / Discipline: Earth and Environmental Sciences.

Floodplain fens represent an important component of the global carbon cycle through their role in carbon sequestration. Peat development depends upon rate of production exceeding rate of decomposition, yet there is little understanding of the effects of sea-level rise on these processes in lowland environments. This thesis investigates the impacts of projected sea-level rise from climate change on carbon storage in floodplain fens, using a combination of field, laboratory and simulation modelling techniques. A gradient of saline influence was determined for the Broads, UK, based on analysis of water chemistry and published water level data, allowing for the application of a space-for-time substitution technique. Increased water level had a positive effect on above-ground production of Phragmites australis (cav.) Trin. Ex Steud. (1841) - perhaps because water stress limits important photosynthetic processes. An increase in salinity had a negative effect on the growth of P. australis, probably due in part to osmotic stress. Previous management practice significantly impacted on production - as uncut vegetation became less productive with time. There was evidence to suggest that sea-level rise may lead to faster decay rates, but this will be partially offset by litter quality. Saline influenced sites had lower carbon accumulation potentials. Radiometric dating confirmed that these sites have lower carbon sequestration rates - probably as a result of increased mineral deposition in floodwaters. Carbon stock ranged between 33 and 144 kt C but depended greatly on peat depth and bulk density. Results from both field data and the model indicated that peat accretion in the Broads would not offset projected sea-level rise. Floodplain fen development under the influence of sea-level rise will be dependent on the majority of assimilate being allocated to above-ground vegetation.

Tongatapu coastal zone vulnerability assessment study was conducted to examine the degree of current and future risks of projected climate change and sea level rise on the coastal zone of the main island of the Kingdom of Tonga-Tongatapu. Inundation, and flooding hazards generated by tropical cyclone storm surges are the common threats to Tongatapu coastal towns and villages because of their low-lying settings. Flooding problems are exacerbated by the social trends of population growth and migration from the outer islands of the Kingdom, to Tongatapu the main island where the capital town of the Kingdom, Nuku'alofa is located. Other threats include beach erosion, saltwater intrusion, and seawater spraying of coastal vegetations and properties. A survey of the local people of Tongatapu, mapping of vulnerable areas with GIS, and using my local knowledge of the island coastal zone were the three methods were used to conduct this study. The main objective of this research was to assess the vulnerability of the coastal zone of Tongatapu to local impacts of inundation and flooding hazards associated with climate and sea-level rise related risks. The results of the survey indicated that more than 95% of the respondents agreed that the coastal zone of Tongatapu is vulnerable to inundation and flooding risks generated by tropical cyclones that visit Tongatapu coastal water every year, based on their recollection, knowledge, and experienced of the past storm events that hit Tongatapu. GIS work showed that those coastal towns and villages of Tongatapu that are located in areas less than 5 meter above sea level are vulnerable to the local impacts of inundation and flooding hazards. It is concluded that the yearly visited tropical cyclones to Tonga that are actually hit Tongatapu coastal zone had increasing the vulnerability of the coastal towns and villages of Tongatapu that are located in areas below 5 meters above sea level to inundation and flooding hazards associated with climate change and sea level rise related risks. Other possible cause might be the gradual uplifted of the south coast of Tongatapu due to ongoing earthquake activities in Tonga since the last 200 years. But in facts more research it has to be done to confirm this argument. The response to the local impacts of inundation and flooding hazards in the coastal zone of Tongatapu should be focused on adaptation, risk and hazard management.

This thesis aimed to investigate how a rising sea level would affect the livable area of the island Fongafale, Tuvalu. Through the IPCC stabilization scenarios it was examined which areas of the island that would be affected by flooding. The local population’s perceptions of the effects of climate change were studied to see how the consequences of a world-wide problem such as global warming affect people's lives. The paper clarified the Tuvaluans place in the discussion of climate refugees, explained IPCC's work and described the results of previous studies concerning people in Fongafales perceptions and concerns about climate-related changes. The result shows already flooded areas with important buildings, such as airport and government buildings and that with a rising sea level, an increasing part of the island will suffer. The survey shows a stronger tendency to concern for lack of water and work than for a climate-related sea level rise, and that the main reason for a possible emigration would primarily be work-related.

More frequent and harsh storms coupled with sea level rise are affecting Canada’s sensitive coastlines. This research studies Isle Madame in Cape Breton, Nova Scotia which has been designated by Natural Resource Canada as a sea level rise vulnerable coastal community in Canada. The research models the spatial and temporal impacts of sea level rise from storm surge by focusing on identifying vulnerable areas in the community via geographical information systems (GIS) using ArcGIS, as well as modeling dynamic coastal damage via system dynamics using STELLA. The research evaluates the impacts in terms of the environmental, social, cultural, economic pillars that profile the coastal community for a series of modelled Storm Scenarios. This research synthesizes information from a variety of sources including the coastal ecology and natural resources, as well as human society and socioeconomic indicators included in the four mentioned pillars. The objective of the research is to determine vulnerable areas on Isle Madame susceptible to storm damage, and consequently, to improve local community knowledge and preparedness to more frequent harsh storms. This research therefore presents a dynamic model for the evaluation of storm impacts in Isle Madame designed with the goal to help the community ultimately to plan and implement a strategy to adapt to pending environmental change.

More frequent and harsh storms coupled with sea level rise are affecting Canada’s sensitive coastlines. This research studies Isle Madame in Cape Breton, Nova Scotia which has been designated by Natural Resource Canada as a sea level rise vulnerable coastal community in Canada. The research models the spatial and temporal impacts of sea level rise from storm surge by focusing on identifying vulnerable areas in the community via geographical information systems (GIS) using ArcGIS, as well as modeling dynamic coastal damage via system dynamics using STELLA. The research evaluates the impacts in terms of the environmental, social, cultural, economic pillars that profile the coastal community for a series of modelled Storm Scenarios. This research synthesizes information from a variety of sources including the coastal ecology and natural resources, as well as human society and socioeconomic indicators included in the four mentioned pillars. The objective of the research is to determine vulnerable areas on Isle Madame susceptible to storm damage, and consequently, to improve local community knowledge and preparedness to more frequent harsh storms. This research therefore presents a dynamic model for the evaluation of storm impacts in Isle Madame designed with the goal to help the community ultimately to plan and implement a strategy to adapt to pending environmental change.

Numerous studies project that climate change will accelerate the rise in global sea levels, leading to increased coastal inundation, greater potential damage from storm surge events, beach erosion and other coastal impacts which threaten vital infrastructure and facilities that currently support the economies of island nations. There is a broad consensus amongst experts that small island developing states (SIDS) face the greatest risk to the projected impacts of climate change. Unfortunately, few sea level rise (SLR) impact assessment studies have been conducted in SIDS due to the limitations of the geospatial data with regard to currency, accuracy, relevance and completeness. This research improves upon previous SLR impact assessment research by utilizing advanced global digital elevation models to create coastal inundation scenarios in one metre increments for 19 Caribbean Community (CARICOM) nations and member states, and then examine the implications for seven key impact indicators (land area, population, economic activity, urban areas, tourism resorts, transportation infrastructure and beach erosion). The results indicate that a one metre SLR would have serious consequences for CARICOM nations. For example under this scenario over 10% of the 73 identified study area airports and 30% of the 266 major tourism resorts were identified as prone to flooding. Projected effects were not found to be uniform across the region; low-lying island nations and mainland countries with coastal plains below ten metres were identified as the most vulnerable countries. Recommendations for adaptive actions and policies are provided.

Global climate change threatens the survival of microtidal wetlands by altering fundamental hydrological aspects such as precipitation patterns and tidal exchange. The combination of these stressors results in increased flooding period and soil salinity in coastal wetlands. In this study, we combined the use of detailed hydrological measurements (wetland water level and salinity), LIDAR elevation models, and water stable isotopes tracers (δD, δ18O) to study the balance between freshwater and saltwater inputs on two microtidal wetlands: a saltmarsh in Matagorda, Texas and a freshwater-forested wetland in Humacao, Puerto Rico. In Matagorda, Texas, we described the process of connectivity between different hydrologic units (isolated and connected ponds) within the saltmarsh. Pond connectivity only occurred when water levels in major water bodies adjacent to our study site reached a threshold elevation of 0.39 m. Connections events were correlated to rainfall and— to a lesser extent— wind speed and direction. We conclude that connectivity within the saltmarsh is driven by the combined effect of tidal influence and rainfall inputs, factors that will be altered by sea level rise and climate change-related changes in long term weather patterns. In Humacao, Puerto Rico, we gathered a detailed dataset of changes in salinity and water level in a freshwater forested wetland dominated by the endangered salt intolerant species Pterocarpus officinalis. In addition, we studied tree water use and identified important water sources to the wetland using stable isotope tracers. Firstly, we provide evidence that recent hydrological alterations have effectively transformed the system from mostly freshwater, to a saltwater wedge estuary. Salinity inputs travel via a tidal creek channel that allows the progression of a saltwater wedge to the inland parts of the forest. Our results suggest that inland progression of the saltwater wedge is influenced by amplitude of tidal exchange in the middle portions of the tidal creek and by extended dry periods in the headmost part of the tidal creek. Isotope data showed that surface standing water was influenced by tidal water sources during the dry season, although the spatial extent of this influence was constrained to areas of the forest that had been previously deforested. The isotopic content of groundwater samples taken at increasing distances from the tidal creek revealed that— although surface waters are dominated by freshwater inputs (rainfall and runoff) during the wet season— the influence of tidal water sources at soil depths greater than 60 cm persists throughout the year. Nonetheless, isotopic content of Pterocapus officinalis stem water samples suggest that tree water uptake is constrained to very shallow, unsaturated parts of the soil. We conclude from both case studies that the long term vulnerability of microtidal wetlands to climate change is determined by the interaction of increased annual variability of freshwater inputs along with a steady increase in mean sea levels, and aggravated by extreme climatic events.

Despite the uncertainties that exist within climate change projection models, the only way to reduce our vulnerability to future changes in sea level is to implement adaptation strategies. The primary goal should not be to determine a worst-case scenario, but instead to identify the most vulnerable areas first, and to gradually introduce phased adaptation strategies into relatively lower risk areas. The present study looks at how we assess the potential impacts of sea level rise and how we can make use of these assessments in planning and design practice. As a case study for impact and vulnerability assessments, the flood risk areas on the coast of Prince Edward Island are mapped and a method for conducting a vulnerability assessment for individual properties is proposed. Finally, design strategies that were generated through the assessment process are presented as examples of no-regrets adaptation strategies.