Underwater (phreatic) caves are a ubiquitous landform on coastal karst terrain, but the marine geological processes operating in these systems are largely unknown. This dissertation redresses the problem by asking if Bermudian phreatic cave sediments archive sea-level and climate information? An important premise is that coastal cave environments are not identical. They can be categorized based on whether they are terrestrially-influenced (anchialine), completely flooded by saline groundwater (submarine), positioned at sea level (littoral) or in the vadose zone (vadose). For the first time the boundary between modern anchialine and submarine cave environments has been distinguished in Green Bay Cave using a multi-proxy approach (benthic foraminifera, sedimentary organic matter content and carbon isotopic composition - ?13Corg, and grain-size analysis). Twelve push cores were extracted from Green Bay Cave and dated with twenty 14C dates, recovering the first underwater cave succession spanning the Holocene (13 ka to present). Green Bay Cave transitioned through all major cave environments during Holocene sea-level rise (vadose, littoral, anchialine, and submarine), providing a sedimentary model for global cave successions. These relationships provide a novel means to solve Quaternary sea-level and climate problems. For sea level, two examples indicate that the littoral cave can be used as a sea-level indicator, distinguished stratigraphically by microfossil or sedimentary proxies. First, the elevation and timing of when Green Bay Cave was a littoral environment indicates Bermuda experienced an abrupt ~6.4 m sea-level rise at 7.7 ka, coinciding with final collapse of the Labrador sector of the Laurentide Ice Sheet. Second, microfossils preserved in elevated caves at +21 m above modern sea level and dated to marine isotope stage 11 (U-series, amino acid racemization) are consistent with modern Bermudian caves and co-stratigraphic sea level. For climate problems, annual temperature monitoring in Walsingham Cave indicates that cave water is thermally comparable to regional oceanographic conditions in the Sargasso Sea. Three sediment cores dated with sixteen radiocarbon dates indicate that Bermuda’s coldest and stormiest conditions of the last 3.2 ka occurred during the Little Ice Age (proxies: ?18Oc, grain size, bulk organic matter).

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.

No description available.

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.

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.

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.

It is no longer a question of scientific debate that research declares our climate is changing. One of the most important and visible impacts of this phenomenon is sea level rise which has impacts on coastal cities and island communities. Sea level rise also magnifies storm surges which can have severely damaging impacts on different human made infrastructure facilities near the shorelines in coastal zones. In this research we are concerned about the proximity of water systems as one of the most vulnerable infrastructures in the coastal zones because of the impact of stormwater combining with sewage water. In Canada, the government has plans to address these issues, but to date, there needs to be further attention to stormwater management in coastal zones across the country. This research discusses the impacts of severe environmental events, e.g., hurricanes and storm surge, on the water systems of selected coastal communities in Canada. The purpose of this research is to model coastal zone water systems using the open source StormWater Management Modelling (SWMM) software in order to manage stormwater and system response to storms and storm surge on water treatment plants in these areas. Arichat on Isle Madame, Cape Breton, one of the most sensitive coastal zones in Canada, is the focal point case study for this research as part of the C-Change International Community-University Research Alliance (ICURA) 2009-2015 project.

The goal of this thesis is to improve our understanding of the Greenland ice sheet (GrIS) and how it responds to climate change. This was achieved using ice core records to infer elevation changes of the GrIS during the Holocene (11.7 ka BP to Present). The inferred elevation changes show the response of the ice sheet interior to the Holocene Thermal Maximum (HTM; 9-5 ka BP) when temperatures across Greenland were warmer than present. These ice-core derived thinning curves act as a new set of key constraints on the deglacial history of the GrIS. Furthermore, a calibration was conducted on a three-dimensional thermomechanical ice sheet, glacial isostatic adjustment, and relative sea-level model of GrIS evolution during the most recent deglaciation (21 ka BP to present). The model was data-constrained to a variety of proxy records from paleoclimate archives and present-day observations of ice thickness and extent.

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.

Thesis (PhD)--University of South Australia, 2000