Seven Decades of Coastal Change at Barter Island, Alaska: Exploring the Importance of Waves and Temperature on Erosion of Coastal Permafrost Bluffs

Observational data of coastal change over much of the Arctic are limited largely due to its immensity, remoteness, harsh environment, and restricted periods of sunlight and ice-free conditions. Barter Island, Alaska, is one of the few locations where an extensive, observational dataset exists, which enables a detailed assessment of the trends and patterns of coastal change over decadal to annual time scales. Coastal bluff and shoreline positions were delineated from maps, aerial photographs, and satellite imagery acquired between 1947 and 2020, and at a nearly annual rate since 2004. Rates and patterns of shoreline and bluff change varied widely over the observational period. Shorelines showed a consistent trend of southerly erosion and westerly extension of the western termini of Barter Island and Bernard Spit, which has accelerated since at least 2000. The 3.2 km long stretch of ocean-exposed coastal permafrost bluffs retreated on average 114 m and at a maximum of 163 m at an average long-term rate (70 year) of 1.6 ± 0.1 m/yr. The long-term retreat rate was punctuated by individual years with retreat rates up to four times higher (6.6 ± 1.9 m/yr; 2012–2013) and both long-term (multidecadal) and short-term (annual to semiannual) rates showed a steady increase in retreat rates through time, with consistently high rates since 2015. A best-fit polynomial trend indicated acceleration in retreat rates that was independent of the large spatial and temporal variations observed on an annual basis. Rates and patterns of bluff retreat were correlated to incident wave energy and air and water temperatures. Wave energy was found to be the dominant driver of bluff retreat, followed by sea surface temperatures and warming air temperatures that are considered proxies for evaluating thermo-erosion and denudation. Normalized anomalies of cumulative wave energy, duration of open water, and air and sea temperature showed at least three distinct phases since 1979: a negative phase prior to 1987, a mixed phase between 1987 and the early to late 2000s, followed by a positive phase extending to 2020. The duration of the open-water season has tripled since 1979, increasing from approximately 40 to 140 days. Acceleration in retreat rates at Barter Island may be related to increases in both thermodenudation, associated with increasing air temperature, and the number of niche-forming and block-collapsing episodes associated with higher air and water temperature, more frequent storms, and longer ice-free conditions in the Beaufort Sea.

At the Edge: Rethinking Place and Identity in the Context of Wellington's South Coast

With rapid growth and urbanisation, there is increasing pressure to develop and occupy New Zealand’s coastal edge. In turn, we are seeing naturally dynamic environments collide with static developments, as contemporary architecture converges on universality – becoming uniform, monotone, placeless. Not only does this highlight a clear ‘disconnect’ between architecture and place, but it also threatens to weaken the very connection formed between architecture and its inhabitants.<br><br>This research, therefore, seeks to strengthen the connection between people and place, through an architectural response that helps to negotiate a dynamic coastal environment and developing urban context, basing the research around the specificity of Wellington’s South Coast.<br><br>The method taken demonstrates both a poetic and pragmatic approach to design, whereby abstracted ideas of ‘embodiment’ and ‘time’ are tested against more tangible factors relating to coastal change and coastal development. The research sets out to develop a strong understanding of the different factors that contribute to the South Coast’s unique identity, using this to inform design decisions that further enrich identity of ‘place.’ At the same time, it investigates how architecture might engage with the dynamics present at site to both enhance and intensify the human experience.<br><br>This research ultimately leads to a proposed redevelopment of the Island Bay Marine Education Centre – a design response that negotiates its surroundings, allows for change, and enhances connection to ‘place.’<br>

At the Edge: Rethinking Place and Identity in the Context of Wellington's South Coast

With rapid growth and urbanisation, there is increasing pressure to develop and occupy New Zealand’s coastal edge. In turn, we are seeing naturally dynamic environments collide with static developments, as contemporary architecture converges on universality – becoming uniform, monotone, placeless. Not only does this highlight a clear ‘disconnect’ between architecture and place, but it also threatens to weaken the very connection formed between architecture and its inhabitants.<br><br>This research, therefore, seeks to strengthen the connection between people and place, through an architectural response that helps to negotiate a dynamic coastal environment and developing urban context, basing the research around the specificity of Wellington’s South Coast.<br><br>The method taken demonstrates both a poetic and pragmatic approach to design, whereby abstracted ideas of ‘embodiment’ and ‘time’ are tested against more tangible factors relating to coastal change and coastal development. The research sets out to develop a strong understanding of the different factors that contribute to the South Coast’s unique identity, using this to inform design decisions that further enrich identity of ‘place.’ At the same time, it investigates how architecture might engage with the dynamics present at site to both enhance and intensify the human experience.<br><br>This research ultimately leads to a proposed redevelopment of the Island Bay Marine Education Centre – a design response that negotiates its surroundings, allows for change, and enhances connection to ‘place.’<br>

At the Edge: Rethinking Place and Identity in the Context of Wellington's South Coast

With rapid growth and urbanisation, there is increasing pressure to develop and occupy New Zealand’s coastal edge. In turn, we are seeing naturally dynamic environments collide with static developments, as contemporary architecture converges on universality – becoming uniform, monotone, placeless. Not only does this highlight a clear ‘disconnect’ between architecture and place, but it also threatens to weaken the very connection formed between architecture and its inhabitants.<br><br>This research, therefore, seeks to strengthen the connection between people and place, through an architectural response that helps to negotiate a dynamic coastal environment and developing urban context, basing the research around the specificity of Wellington’s South Coast.<br><br>The method taken demonstrates both a poetic and pragmatic approach to design, whereby abstracted ideas of ‘embodiment’ and ‘time’ are tested against more tangible factors relating to coastal change and coastal development. The research sets out to develop a strong understanding of the different factors that contribute to the South Coast’s unique identity, using this to inform design decisions that further enrich identity of ‘place.’ At the same time, it investigates how architecture might engage with the dynamics present at site to both enhance and intensify the human experience.<br><br>This research ultimately leads to a proposed redevelopment of the Island Bay Marine Education Centre – a design response that negotiates its surroundings, allows for change, and enhances connection to ‘place.’<br>

Patterns and processes of beach and foredune geomorphic change along a Great Lakes shoreline: Insights from a year-long drone mapping study along Lake Michigan

Coastal storms are an important driver of geomorphic change along Great Lakes shorelines. While there is abundant anecdotal evidence for storm impacts in the region, only a handful of studies over the last few decades have quantified them and addressed system morphodynamics. Annual to seasonal lake-level fluctuations and declining winter-ice covers also influence coastal response to storms, yet relationships between hydrodynamics and geomorphology are poorly constrained. Given this, the Great Lakes region lags behind marine coasts in terms of predictive modeling of future coastal change, which is a necessary tool for proactive coastal management. To help close this gap, we conducted a year-long study at a sandy beach-dune system along the western shore of Lake Michigan, evaluating storm impacts under conditions of extremely high water level and absent shorefast ice. Drone-derived beach and dune topography data were used to link geomorphic changes to specific environmental conditions. High water levels throughout the year of study facilitated erosion during relatively minor wave events, enhancing the vulnerability of the system to a large storm in January 2020. This event occurred with no shorefast ice present and anomalously high winter water levels, resulting in widespread erosion and overwash. This resulted in 20% of the total accretion and 66% of the erosion documented at the site over the entire year. Our study highlights the importance of both antecedent and present conditions in determining Great Lakes shoreline vulnerability to storm impacts.

A survey of storm-induced seaward-transport features observed during the 2019 and 2020 hurricane seasons

Hurricanes are known to play a critical role in reshaping coastlines, but often only impacts on the open ocean coast are considered, ignoring seaward-directed forces and responses. The identification of subaerial evidence for storm-induced seaward transport is a critical step towards understanding its impact on coastal resiliency. The visual features, found in the National Oceanic and Atmospheric Administration, National Geodetic Survey Emergency Response Imagery (ERI) collected after recent hurricanes on the U.S. East Atlantic and Gulf of Mexico coasts, include scours and channelized erosion, but also deposition on the shoreface or in the nearshore as deltas and fans of various sizes. We catalog all available ERI and describe recently formed features found on the North Core Banks, North Carolina, after Hurricane Dorian (2019); the Carolina coasts after Hurricane Isaias (2020); the Isles Dernieres, Louisiana, after Hurricane Zeta (2020); and the southwest coast of Louisiana, after Hurricanes Laura and Delta (2020). Hundreds of features were identified over nearly 200 km of coastline with the density of features exceeding 20 per km in some areas. Individual features range in size from 5 m to 500 m in the alongshore, with similar dimensions in the cross-shore direction, including the formation or reactivation of outlets. The extensive occurrence of these storm-induced return-flow and seawardflow morphologic features demonstrates that their role in coastal evolution and resilience may be more prominent than previously thought. Based on these observations we propose clarifying terms for return- and seaward-flow features to distinguish them from more frequently documented landward-flow features and advocate for their inclusion in coastal change hazards classification schemes and coastal evolution morphodynamic models.