Sea level rise and tidal power plants in the Gulf of Maine

The response of the Bay of Fundy and Gulf of Maine to large-scale tidal power plants and future sea-level rise is investigated using an established numerical tidal model. Free stream tidal turbines were simulated within the Bay of Fundy by implementing an additional bed friction term, Kt. The present-day maximum tidal power output was determined to be 7.1 GW, and required Kt�=�0.03. Extraction at this level would lead to large changes in the tidal amplitudes across the Gulf of Maine. With future SLR implemented, the energy available for extraction increases with 0.5�1 GW per m SLR. SLR simulations without tidal power extraction revealed that the response of the semidiurnal tides to SLR is highly dependent on how changes in sea level are implemented in the model. When extensive flood defenses are assumed at the present-day coast line, the response to SLR is far larger than when land is allowed to (permanently) flood. For example, within the Bay of Fundy itself, the M2 amplitude increases with nearly 0.12 m per m SLR without flooding, but it changes with only 0.03 m per m SLR with flooding. We suggest that this is due to the flooding of land cells changing the resonant properties of the basin

Past and future adaptation pathways

Adaptation pathways are increasingly being used as a foresight tool to help guide the implementation of climate change adaptation and deliberate transformation. This paper applies a pathways lens as a hindsight tool to provide new understanding about past change and adaptation relevant for improving future adaptation pathways approaches. Four case studies of past adaptations to change are examined: Solomon Islands Communities, Canadian forest-dependent communities, a Transylvanian village, and responses to climate adaptation policies in Australia. The results highlight that responses to change in these diverse case studies involve complex transitions that gradually create new conditions and trajectories; manifest as multiple but inter-related pathways of change and response at different social or spatial scales (e.g. different paths for different households or communities); have legacies and continuities across time that affect future pathways of change; are affected by power in complex ways; and can create further change and need for adaptation. Analyses also highlight that when working with prospective adaptation approaches as a response to climate change there is a need to consider: (1) underlying assumptions, values and principles associated with the future; (2) the existence of inter-connected multiple pathways and their implications for reinforcing existing social inequalities; and (3) how understanding past change provides inspiration for new and transformative futures. Overall, the paper concludes that shifts towards analyses for change rather than simply about change, such as adaptation pathways, will require more careful consideration of underlying ontological assumptions about the relationships between past, present and future

Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

Impact of sea level rise, land reclamation and tidal power plants on regional tidal dynamics

The response of regional tidal dynamics to sea level rise (SLR), tidal power plants (TPPs), land reclamation and a combination of the above was investigated using two tidal models. The impact of SLR was investigated on, and tidal models validated for, the European Shelf, the Bay of Fundy and the Bohai Sea. The tidal response varied greatly between regions; however the method in which SLR was implemented within the tidal models also caused significant variation in the response. When sea level was increased but no land was allowed to flood (i.e. the coastline did not move) the change in tidal by processes that involved the increased water depth (such as tidal resonance). However, when land was allowed to flood the response was governed by the change in the spatial distribution of tidal energy dissipation. The maximum extractable tidal energy and the impact of the extraction of this energy in the Minas Passage were investigated on the tidal regime of the Bay of Fundy. It was found that the impacts were significant and wide spread. Furthermore, it was demonstrated that SLR could increase the maximum extractable tidal energy. The tides of the Bay of Fundy are close to resonance and SLR with no flooding caused the system to move closer to resonance. However when flooding was enabled the system did not move towards resonance, suggesting the change in tidal dissipation dampened the response. The Bohai Sea has undergone rapid and extensive natural and anthropogenic land reclamation. Tidal gauge observations show that the tidal regime has responded significantly to these changes. We have been able to reproduce these changes using a tidal model, furthermore, future simulations show that the tides of the Bohai Sea may have become more sensitive to impacts of SLR. It was found that the regional tides investigated were particularly sensitive to changes in the spatial distribution of ideal energy dissipation. As demonstrated by the investigation of practical scenarios

Impact of flood defences and sea-level rise on the European Shelf tidal regime

The tidal response of the European Shelf to moderate View the MathML source(<1m) levels of sea level rise is investigated using a high resolution, well established tidal model. The model is validated for present day conditions and the tidal response to sea level rise by comparing the modelled response to long term tide gauge data. The effects of coastal defence schemes are tested, with three levels of present day coastal defences simulated. Full walls are added at the present day coastline, no coast defence schemes are used and a set of present day coastal defence schemes is simulated. The simulations show that there is a significant tidal response to moderate levels of SLR and that the response is strongly dependant on level of coastal defence simulated. The simulation using coastal defence data resulted in the strongest response as the tide was able to build up behind the coastal defence walls and create a patchwork of sea and land at the coastline. This had a strong impact on the spatial tidal energy dissipation field and in turn this has large effects on the tidal regime throughout the domain