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Coastal hazards involve the interaction or effects of natural coastal processes on shoreline development, infrastructure, and human activities. Future sea-level rise will affect California’s coastal development and infrastructure through both
flooding of low-lying areas and erosion of cliffs, bluffs, and dunes. The global rate of sea-level rise is...
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... decade later in 2018, seawall and revetment totals had reached 239.3 km (13.9%) of the entire state's coastline and 141.8 km (38%) of southern California's 373-km shoreline (Figure 9). For all of California, this represents a 5.5-fold increase in shore protection in 47 years. ...
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... Assigned by the cabinet, the DPT has to ensure the well-being of coastal communities. It realized that the revetments can induce many environmental impacts (such as downdrift erosion, beach inaccessibility, and shortened front beach berm (Griggs and Patsch 2019). The DPT has carefully designed its revetment to minimize such negative shortcomings (Saengsupavanich 2022; Sanitwong-Na-Ayutthya et al. 2022). ...
Different countries practice various approaches to coastal erosion management, which have characteristics strengths and weaknesses. Protection of the land from coastal erosion is a complex task, and it depends on many socioeconomic and environmental factors. Asian countries have unique cultural, social, environmental, and political behaviors. Therefore, the objectives of this study are to analyze the current status of coastal management in Thailand, Malaysia, and Sri Lanka, and to synthesize a common coastal management framework for those countries. In this study, we analyzed the situation of coastal erosion, and the existing responsible government department and their legal authorities in Thailand, Malaysia, and Sri Lanka. After that, we evaluated specific challenges and common issues in the management of coastal erosion. The main challenges can be summarized as rapid urbanization and the construction of infrastructure along the coasts, rising sea levels as a consequence of climate change, inadequate coastal zone planning and management framework, a deficit of sediment supply compared to erosion rates, and face constraints in terms of financial and technical resources for coastal erosion management. A multi-faceted approach is required to address these challenges, and it combines both structural and non-structural measures. For example, this approach involves (i) sustainable coastal zone planning, (ii) the implementation of nature-based solutions, (iii) restoration of natural coastal features, (iv) regulation of coastal development activities, and (v) the integration of climate change considerations into coastal management practices. Finally, collaborative efforts among government agencies, researchers, local communities, and international organizations are crucial for successful coastal erosion management in Thailand, Malaysia, Sri Lanka, and potentially other Asian regions.
... In Italy, front beaches gradually became narrower after the implementation of revetments, and eventually disappeared altogether because they were experiencing a deficit in sediment supplies from rivers [46]. This conclusion was also supported by the findings of [18,45,47]; who mentioned that the fronting beach would be lost because of wave interactions with the revetments. The revetments can interrupt local sediment balance, whiles waves hitting the revetment are reflected downwards, scouring the toe of the revetment [48]. ...
... Beach beauty is a personal preference. Some coastal practitioners agree that the revetments enhance beach aesthetics [16,67], while some consider them an eye sore [18]. Reference [66] stated that repairing an aged revetment and topping it with a new pedestrian walkway was a preferred alternative to promote recreational activity and enhance an aesthetic view. ...
... They claimed that the recreational beaches in Puerto Rico were seriously degraded and even destroyed because the revetments were built on a crisis basis without considering other approaches. References [18,34] supported that the revetments would cause a loss in beach width, accessibility, and landscape quality, leading to a reduction in tourism attraction and a long-term negative impact on the tourism industry. However, removing the revetments for aesthetic reasons is not a wise choice because it can allow coastal erosion to re-happen and threaten nearby buildings' safety [41]. ...
... Humans are one of the world's great geomorphic agents and can both directly and indirectly influence the rate and nature of transgression (Lazarus et al. 2016); even modest amounts of development can override natural processes, altering coastal-system behavior across distances of hundreds of kilometers and for time periods lasting many decades (Armstrong & Lazarus 2019, Hapke et al. 2013). Along open-ocean coasts, direct human interference can accelerate transgression by reducing the resilience afforded by dunes (e.g., Nordstrom 2000) or slowing beach recovery following storms (e.g., Wernette et al. 2020) or can slow transgression through hardening of eroding cliffs or permafrost (e.g., Griggs & Patsch 2019, Liew et al. 2020, beach nourishment (e.g., Lazarus et al. 2016), and emplacement of hard or soft engineering structures and/or living shorelines (e.g., Alves et al. 2020, Cooper & McKenna 2008b. ...
Marine transgression associated with rising sea levels causes coastal erosion, landscape transitions, and displacement of human populations globally. This process takes two general forms. Along open-ocean coasts, active transgression occurs when sediment-delivery rates are unable to keep pace with accommodation creation, leading to wave-driven erosion and/or landward translation of coastal landforms. It is highly visible, rapid, and limited to narrow portions of the coast. In contrast, passive transgression is subtler and slower, and impacts broader areas. It occurs along low-energy, inland marine margins; follows existing upland contours; and is characterized predominantly by the landward translation of coastal ecosystems. The nature and relative rates of transgression along these competing margins lead to expansion and/or contraction of the coastal zone and—particularly under the influence of anthropogenic interventions—will dictate future coastal-ecosystem response to sea-level rise, as well as attendant, often inequitable, impacts on human populations.
Expected final online publication date for the Annual Review of Marine Science, Volume 16 is January 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
... However, these dynamic sandy ecosystems can also offer a key element of defense for coastal areas in terms of nature-based protection from climate change (Newkirk et al., 2018;Griggs and Patsch, 2019). Beaches and dunes can provide a natural buffer from sea level rise (SLR), erosion, and storms (Brown et al., 2013;Bryant et al., 2019) that can protect homes, roads, and other infrastructure. ...
Coastal dunes are globally recognized as natural features that can be important adaptation approaches for climate change along urban and natural shores. We evaluated the recovery of coastal dunes on an intensively groomed urban beach in southern California over a six-year period after grooming was discontinued. Restoration actions were minimal and included installation of three sides of perimeter sand fencing, cessation of mechanical grooming and driving, and the addition of seeds of native dune plants. To track recovery, we conducted physical and biological surveys of the restoration site and an adjacent control site (groomed beach) using metrics including sand accretion, elevation, foredune and hummock formation, vegetation recovery, and wildlife use. Sediment accretion, elevation, and geomorphic complexity increased over time in the restoration site, largely in association with sand fencing and dune vegetation. A foredune ridge (maximum elevation increase of 0.9 m) and vegetated hummocks developed, along with a general increase in elevation across the restoration site (0.3 m). After six years, an estimated total volume of approximately 1,730 m ³ of sand had accreted in the restoration site and 540 m ³ of sand had accreted in the foredune ridge. Over the same period, more than a meter of sediment (vertical elevation change) accumulated along the perimeter sand fencing. Groomed control areas remained flat and uniform. The total cover of vegetation in the restoration site increased over time to a maximum of approximately 7% cover by the sixth year. No vegetation was observed on the groomed control site. Native plant species formed distinct zones across the restoration site beginning by the second year and increasing over time, with dune forming species aggregating closest to the ocean in association with the incipient foredune ridge. Ecological functions observed in the restoration area included presence of dune invertebrates, shorebird roosting, and use by a breeding federally threatened shorebird, the western snowy plover ( Charadrius nivosus nivosus ). Our findings on geomorphic and ecological responses of a pilot dune restoration on a heavily groomed urban beach provide new insights on the opportunities and expectations for restoring dunes as nature-based solutions for climate adaptation on urban shorelines.
... Nevertheless, retreat generally evokes feelings of a sudden movement of people, provoking negative reactions. Several authors emphasize that managed retreat is a long-term strategy and denotes planned and successive movements of infrastructure and people from hazardous locations in a manner that is purposeful and coordinated (Griggs & Patsch, 2019;Hino et al., 2017;Lovett, 2017;Neal et al., 2017;Siders, 2019a;Siders, 2019b). In UK, the term realignment began to be used as a replacement for managed retreat or setback to put emphasis on habitat recreation on earlier reclaimed land (Esteves, 2014). ...
As the sea level rises and the frequency of intense rains increase, so does the need for climate adaptation. Planning for a successive development of society away from current and future flood prone areas to give room for water is not seen as an alternative in Sweden today, although it could be a strategy that creates long-term security.In this study, we investigated Swedish public authorities' perceptions of planned retreat and flexible land use. This was done through an online survey and interviews directed to officials directly involved in climate adaptation work, at municipalities, County Administration Boards (CABs), Regions, national authorities (NAs), and industry organizations (IOs). The responses were analyzed through the lens of a windows of opportunity approach. The study indicates that the extent to which climate scenarios are used and how far into the future the planning horizon extends in the practical work, varies between governance level which also have impact on the perspectives on planned retreat. The openness for planned retreat and flexible strategies seemed to differ slightly between governance levels in an ascending scale from regions, IOs / NAs, municipalities, to CABs. The survey has generated insights from a large number of respondents at different governance levels sharing their perceptions of retreat and adaptation in Sweden as a main contribution of this work.Difficulties to deal with uncertainties in climate scenarios and considering long-term perspectives were identified as some reasons that close the window for planned retreat. Enabling a flexible use of the land that will gradually become more exposed to flooding and sea level rise could be an intermediate step towards retreat. This would be a way to reframe a closed window of opportunity and begin the process of turning it into something transformative. It could be where the short- and long-term planning meet and a way to reframe our way of thinking about how we live and reside in dynamic waterfront areas, and perhaps lead to a more transformative, safe, and sustainable society for future generations.
... The Southern California Bight is the most developed of the four West Coast ecoregions, with dense population centers along the coast. Shoreline armoring is especially pronounced in this region, encompassing 38% of the coastline (Griggs and Patsch 2019). Beach nourishment is also pronounced in this region and may bury shallow nearshore reefs and degrade beach habitat quality (Wooldridge et al. 2016). ...
... Engineered structures such as seawalls, embankments, and dikes are typical coastal defenses built to protect at-risk assets and people. However, this "gray" infrastructure can be expensive to construct and maintain, is often not aesthetically pleasing, and can adversely impact adjacent ecological communities (Griggs and Patsch, 2019;Kochnower et al., 2015). Due to the cost and limitations of traditional engineered flood defenses, nature-based features such as coastal dunes, coastal wetlands (i.e., salt marsh, mangroves), and oyster and coral reefs are increasingly considered viable options to mitigate flood risk. ...
Coastal wetlands are an effective natural and nature-based feature to mitigate coastal flood hazards. While the sheltering and attenuation offered by wetlands are recognized, the protection level varies based on wetland and storm characteristics. Here we focus on the effects of the spatial scales of the coastal wetlands (i.e., channel geometry, marsh elevation-gradient) and the temporal scales of storm forcing (i.e., storm surge amplitude and duration) on peak water level attenuation. The study was conducted by performing hydrodynamic simulations on an idealized marsh geometry. One hundred seventy-one hydrodynamic simulations were conducted by varying wetland features under variable hydrodynamic forcing. Increased tidal channel area enhances water flow across marshes by reducing the capacity of vegetated platforms to resist propagation of a storm surge. The level of surge attenuation and channel area shows a non-linear relationship. Storm scales also affect surge attenuation for a given channel geometry. Higher amplitudes and lower surge durations provide greater attenuation of peak water levels. The level of attenuation and surge scales also show a non-linear correlation. A multivariate scaling relationship was developed that successfully integrates the combined effects of channel geometry and surge scales on water level attenuation by salt marsh. This research provides guidance to engineers and coastal managers on salt marsh's flood hazard reduction benefits.
... More broadly, what is known about managed retreat based on experiences in California? Are there examples of the ''the planned, purposeful, coordinated movement of people and assets away from risk'' (Siders, 2019, p. 216; see also Anderson et al., 2020;Griggs and Patsch, 2019)-a common definition of managed retreat-on California's coast? What about examples of movement away from the coast, intentional or not? ...
... The Surfers Point Managed Shoreline Retreat project was a partnership of the City of Ventura, the Ventura County Fairgrounds, the California Coastal Conservancy, California State Parks, the CCC, and the Surfrider Foundation. The City of Ventura had historically taken the traditional approach to coastal protection in the 1980s and 1990s by hardening its shoreline in places, which it eventually realized produced negative effects (Griggs and Patsch, 2019;Griggs, Patsch, and Savoy, 2005;Patsch and Griggs, 2008;Runyan and Griggs, 2003). The 1980-era local coastal plan designated this area as a recreational corridor that did not allow shoreline protection. ...
Lester, C.; Griggs, G.; Patsch, K., and Anderson, R., 0000. Shoreline retreat in California: Taking a step back. Journal of Coastal Research, 00(0), 000-000. Coconut Creek (Florida), ISSN 0749-0208. Adapting to long-term sea-level rise has emerged as perhaps the most significant coastal management challenge of the 21st century. But this challenge has become fraught with controversy in California, especially around the idea of managed retreat. This article reframes the current adversarial and highly politicized dichotomous controversy about managed retreat with an overview of California's actual experience managing coastal shoreline hazards over the last half-century. The review shows that managed retreat in California is more than an either-or fight about private beachfront residential property. The article reviews a range of cases in which development or development potential has been moved back from the shoreline. The cases stand in contrast to the overly simplified debate about managed retreat and show that retreat has been happening on California's coast for decades. The discussion identifies the complexity and multiple dimensions of shoreline adaptation over long periods and concludes with some observations in hopes of shedding light on and opening more reasonable discussion of pathways to shoreline retreat and resilient communities. ADDITIONAL INDEX WORDS: Sea-level rise, coastal adaptation, managed retreat, California coastal management.
... Literature suggests both positive and negative impacts of applying the revetment [10]. Griggs and Patsch [11] reported that only 2.5% of California's entire 1,760-km shoreline was armored in 1971, and increased to 13.9% in 2018. The revetment has been applied along the California coast for nearly a century. ...
Coastal revetment has a main function to protect eroding shorelines. Sometimes, the revetment is considered ineffective and harmful to the environment. This article presents 3 case studies in Thailand where stepped concrete revetments were successfully implemented. If theoretically accurately designed, the revetments will not only protect the coastlines but also enhance community’s well-being. The case studies at the Suan-Son beach, the Pra-Ae beach, and the Laem-Sadet beach advocate such a claim. When the incoming waves break on the steps, the revetment crest is accurately configured, the front slope is well-designed, the wave reflection will be minimized. The sand will climb and deposit on the steps. The beach berm will be wide. People can walk either on the beach or the revetment crest. Tourism will be promoted. Livelihoods of coastal communities will be enhanced. Sustainable coastal development can follow. None of these can happen if the coast is still being eroded. The revetment is not a bad thing. What is bad is an engineer who poorly designs the revetment. The misleading belief that the revetment will do more harm than good must be adjusted.
... The Southern California Bight is the most developed of the four West Coast ecoregions, with dense population centers along the coast. Shoreline armoring is especially pronounced in this region, encompassing 38% of the coastline (Griggs and Patsch 2019). Beach nourishment is also pronounced in this region and may bury shallow nearshore reefs and degrade beach habitat quality (Wooldridge et al. 2016). ...
