Challenges to climate change adaptation in coastal small towns:Examples from Ghana, Uruguay, Finland, Denmark, and Alaska

The ability of a coastal settlement to adapt to climate change is largely dependent upon access to a range of resources, which many coastal towns and small cities lack. Coastal small towns of less than 10,000 are therefore at a significant disadvantage compared to larger settlements when it comes to adaptation. One way to begin to overcome this disadvantage is to compare coastal small towns in order to identify efficiencies and support knowledge sharing. In this article we present and analyse five case studies of coastal small towns: Fuvemeh, Ghana; Kiyú, Uruguay; Hanko, Finland; Lemvig, Denmark; and Nome, Alaska, USA. A number of key outcomes and lessons were identified which highlights the need for a formal network of international coastal small towns to encourage and develop knowledge sharing practices going forward. A further lesson is the importance of using a range of indicators in order to establish the regional/national importance of a town. Basing this solely on population size can result in an erroneous interpretation of the significance (and therefore adaptive capacity) of a coastal small town. Finally, despite many barriers to adaptation in coastal small towns, being small offers some potential advantages, such as the possibility of being able to form a community consensus more easily, using 3D visualisations for adaptation planning, and having managed realignment as a realistic management option. It is imperative that climate change resilience in coastal small towns is increased by focussing on overcoming barriers and developing appropriate adaptation approaches by governments, non-governmental organisations, business, and researchers

Challenges to climate change adaptation in coastal small towns: examples from Ghana, Uruguay, Finland, Denmark, and Alaska

The ability of a coastal settlement to adapt to climate change is largely dependent upon access to a range of resources, which many coastal towns and small cities lack. Coastal small towns of less than 10,000 are therefore at a significant disadvantage compared to larger settlements when it comes to adaptation. One way to begin to overcome this disadvantage is to compare coastal small towns in order to identify efficiencies and support knowledge sharing. In this article we present and analyse five case studies of coastal small towns: Fuvemeh, Ghana; Kiyú, Uruguay; Hanko, Finland; Lemvig, Denmark; and Nome, Alaska, USA. A number of key outcomes and lessons were identified which highlights the need for a formal network of international coastal small towns to encourage and develop knowledge sharing practices going forward. A further lesson is the importance of using a range of indicators in order to establish the regional/national importance of a town. Basing this solely on population size can result in an erroneous interpretation of the significance (and therefore adaptive capacity) of a coastal small town. Finally, despite many barriers to adaptation in coastal small towns, being small offers some potential advantages, such as the possibility of being able to form a community consensus more easily, using 3D visualisations for adaptation planning, and having managed realignment as a realistic management option. It is imperative that climate change resilience in coastal small towns is increased by focussing on overcoming barriers and developing appropriate adaptation approaches by governments, non-governmental organisations, business, and researchers

Coastline shift analysis in data deficient regions: Exploiting the high spatio-temporal resolution Sentinel-2 products

In most developing countries, coastline shift monitoring using in-situ (ground-based) data faces challenges due, e.g., to data unreliability, inconsistency, deficiency, inaccessibility or incompleteness. Even where practically applicable, the traditional “boots on the ground” methods are labour intensive and expensive, thus imposing burden on poor countries struggling to meet other urgent pressing daily needs, i.e., food and medicine. Remote sensing (RS) techniques provide a more efficient and effective way of collecting data for coastline shift analysis. However, moderate spatio-temporal resolution RS products such as the widely used Landsat products (30 m and 16 days) may be insufficient where high accuracy is desired. In 2015, Sentinel-2 Multi-Spectral Instrument (MSI) remotely sensed products with higher spatio-temporal resolution (10 m and 5 days) and high spectral resolution (13 bands), which promises to improve coastline movement monitoring to high accuracy, was launched. Using two war-impacted countries (Liberia and Somalia) as case studies of regions with data deficiency or of poor quality, for the period 2015–2018, this contribution aims at (i) assessing the suitability of the new freely available high spatio-temporal Sentinel-2 products to monitor coastline shift, (ii) assessing the possibility of filling the missing Sentinel-2 gaps with Landsat 8 panchromatic band (15 m) products to provide alternative data source for mapping of coastline movements where Sentinel-2 data is unusable, e.g., due to cloud cover, and (iii), undertake a comparative analysis between Sentinel-2 (10 m), Landsat panchromatic (15 m), and Landsat multi-spectral (30 m). The results of the evaluation indicate 23% (on average) improvement gained by using Sentinel-2 compared to the traditional Landsat 30 m resolution data (i.e., 32% for Liberia and 14% for Somalia). A comparison of 100 check points from Google Earth Pro (i.e., surrogate in-situ reference data) show 91% agreement for Liberia and 85% for Somalia, indicating the potential of using Sentinel-2 data for future coastal shift studies, particularly for the data deficient regions. The results of comparative studies for Sentinel-2, Landsat panchromatic (PAN), and Landsat multi-spectral (MS) show that the percentages of Sentinel-2 and Landsat PAN that falls within 10 m threshold is much higher than Landsat MS by 35% and 26%, respectively, and for the 2016–2017 period, they provide more detailed mapping of the Liberian coastline compared to Landsat MS (30 m). Finally, panchromatic Landsat data with 15 m resolution are found to be capable of filling the missing Sentinel-2 gaps, i.e., where cloud cover hampers its usability

Drone as a tool for coastal flood monitoring in the Volta Delta, Ghana

Abstract Background Monitoring coastal erosion and flooding in deltaic environment is a major challenge. The uncertainties associated with land based methods and remote sensing approaches affect the levels of accuracy, reliability and usability of the output maps generated. This study monitored flooding and erosion activities in a flood prone fishing community (Fuvemeh) in the Volta Delta in Ghana using Unmanned Aerial Vehicles (UAVs) or drone technology. Results The study revealed that coastal flooding and coastal erosion have destroyed sources of livelihood and increased risk to life and property in the Volta Delta communities. It was identified that between 2005 and 2017 the shoreline has moved several meters inland (over 100 m along some transects) in some areas, while in other areas about 24,057 m2 land has been gained (about 80 m along some transects) that can serve as natural fish landing site. It emerged that over 77 houses have been destroyed which resulted in the displacement of over 300 inhabitants between 2005 and 2017. The study estimated that about 37% of the total land area in Fuvemeh has been lost as a result of erosion. Conclusion Coastal erosion and flooding are major environmental challenges in the Volta delta. Coastal erosion has destroyed natural fish landing sites, which has affected the local fishing business (the main source of livelihood) and increased poverty. Coastal flooding has displaced inhabitants from their homes and increased migration from the Fuvemeh community

Spectral profiles of beached pelagic Sargassum (S. natans I, S. natans VIII, S. fluitans III)

This dataset includes the spectral reflectance of each morphotype (S. natans I, S. natans VIII, S. fluitans III) collected in situ in Ghana (Sanzule) and Barbados (Consett Bay) in 2022. It also includes reflectance data for freshly deposited (&lt;1 day) and recently deposited (&lt;3 days) mixed species/morphotypes of sargassum in Barbados. For more information on the methods of data collection, see: Fidai et al. (2023) &#39;Innovative spectral characterisation of beached pelagic sargassum towards remote estimation of biochemical and phenotypic properties&#39;, Science of the Total Environment.</span

Misperception of drivers of risk alters willingness to adapt in the case of sargassum influxes in West Africa

Since 2011, large influxes of a brown macroalgae (pelagic sargassum seaweed) have proliferated across the Tropical Atlantic basin, its dispersal and seasonality theorized to be driven by localized and large scale winds and currents, in combination with changes in the Atlantic Meridional Mode and ocean upwelling. These influxes seasonally affect coastal populations across the breadth of the Tropical Atlantic (from central America to West Africa), causing damage to: economies, marine-based and non-marine coastal livelihoods, social functioning, health, ecology, and the aesthetics of the local environment. We use the ongoing sargassum influx in West Africa as a case study of adaptation to an emergent (and compound) risk in progress that also contributes to the empirical gap in sargassum adaptation research in West Africa. The research, in four sites in the Western Region of Ghana employs data from 16 focus group discussions, six key informant interviews, and participant observation. We finds that due to a series of coincidences, participant communities perceive that sargassum influxes were seeded by and then annually driven by oil and gas exploration in Western Ghana. This is in contrast to scientific research that indicates that pelagic sargassum was initially seeded in the tropical Atlantic basin (from the Sargasso Sea) in 2010 following an anomalous weather event in winter 2009–2010. Following Rogers’ Protection Motivation Theory, we explore the sources of information and the processing of that information to understand the divergence between scientific and community perceptions of the physical drivers. We find that community perceptions of oil and gas company responsibility for causing the sargassum problem leads the communities to perceive that the oil and gas companies should be responsible for the clean-up activities. Communities are further constrained by a perceived lack of capacity to act. Solutions to address this adaptation impasse could involve the government working with communities and the oil and gas industry to clarify the actual drivers of sargassum. Such guidance may open opportunities for the government and industry to work with communities to address misperceptions of the scientific nature of the influxes. Collaborative approaches, while addressing extant tensions, may also change the narrative about the problem, support affected communities to engage with adaptive measures, including re-use opportunities, and enhance community capacity to act. As a present-day emergent risk, pelagic sargassum provides an unusual yet contemporary empirical study of real-time adaptation and the central role of perceptions in shaping proactive adaptation and seeking exploitable opportunities from new environmental risks

Remote sensing application of shore-based video and unmanned aerial vehicles (Drones) : complementary tools for beach studies

International audienceVideo camera systems have been used over nearly three decades to monitor coastal dynamics. They facilitate a high-frequency analysis of spatiotemporal shoreline mobility. Video camera usage to measure beach intertidal profile evolution has not been standardized globally and the capacity to obtain accurate results requires authentication using various techniques. Applications are mostly site specific due to differences in installation. The present study examines the accuracy of intertidal topographic data derived from a video camera system compared to data acquired with unmanned aerial vehicle (UAV, or drone) surveys of a reflective beach. Using one year of 15-min video data and one year of monthly UAV observations, the intertidal profile shows a good agreement. Underestimations of intertidal profile elevations by the camera-based method are possibly linked to the camera view angle, rectification and gaps in data. The resolution of the video-derived intertidal topographic profiles confirmed, however, the suitability of the method in providing beach mobility surveys matching those required for a quantitative analysis of nearshore changes. Beach slopes were found to vary between 0.1 and 0.7, with a steep slope in May to July 2018 and a gentle slope in December 2018. Large but short-scale beach variations occurred between August 2018 and October 2018 and corresponded to relatively high wave events. In one year, this dynamic beach lost 7 m. At this rate, and as also observed at other beaches nearby, important coastal facilities and infrastructure will be prone to erosion. The data suggest that a low-cost shore-based camera, particularly when used in a network along the coast, can produce profile data for effective coastal management in West Africa and elsewhere

Innovative spectral characterisation of beached pelagic sargassum towards remote estimation of biochemical and phenotypic properties

In recent years, pelagic sargassum (S. fluitans and S. natans – henceforth sargassum) macroalgal blooms have become more frequent and larger with higher biomass in the Tropical Atlantic region. They have environmental and socio-economic impacts, particularly on coastal ecosystems, tourism, fisheries and aquaculture industries, and on public health. Despite these challenges, sargassum biomass has the potential to offer commercial opportunities in the blue economy, although, it is reliant on key chemical and physical characteristics of the sargassum for specific use. In this study, we aim to utilise remotely sensed spectral profiles to determine species/morphotypes at different decomposition stages and their biochemical composition to support monitoring and valorisation of sargassum. For this, we undertook dedicated field campaigns in Barbados and Ghana to collect, for the first time, in situ spectral measurements between 350 and 2500 nm using a Spectra Vista Corp (SVC) HR-1024i field spectrometer of pelagic sargassum stranded biomass. The spectral measurements were complemented by uncrewed aerial system surveys using a DJI Phantom 4 drone and a DJI P4 multispectral instrument. Using the ground and airborne datasets this research developed an operational framework for remote detection of beached sargassum; and created spectral profiles of species/morphotypes and decomposition maps to infer biochemical composition. We were able to identify some key spectral regions, including a consistent absorption feature (920 – 1080 nm) found in all of the sargassum morphotype spectral profiles; we also observed distinction between fresh and recently beached sargassum particularly around 900 – 1000 nm. This work can support pelagic sargassum management and contribute to effective utilisation of the sargassum biomass to ultimately alleviate some of the socio-economic impacts associated with this emerging environmental challenge