![]() Marina development, breakwater or jetty construction to protect marinas and harbors, and the addition of highways, bridges, and pipelines have all been major public projects, along with the development of deep-water ports with dredged shipping lanes ( Pilkey and Dixon 1996). In the second half of the 20th century, new residential and recreational land uses have been the primary drivers of investment in engineering projects at local and regional scales in coastal areas in the US ( Beach 2003 Hill 2011). ![]() The US Army Corps of Engineers (USACE) has developed guidelines for what they call “natural and nature-based features” (NNBFs) that are now considered by federal agencies as functional components of coastal infrastructure designs ( Bridges et al. Coastal wetlands, sand dunes, beaches, and freshwater ponds are treated as supporting structures for flood management, co-existing in hybrid systems with levees, breakwaters, seawalls, floodwalls, tide gates, storm-surge barriers, pumps, and pipes. Several new terms have emerged to serve this new definition of infrastructure for instance, “landscape infrastructure” alludes to the capacity of topography, soils, and entire ecosystems to support human needs ( Beach 2003 Hill 2011), whereas “green infrastructure” typically relates to the use of plants and soils to provide ecosystem services (eg Arcadis 2014). In past centuries, the term “infrastructure” referred primarily to masonry and metal constructions, but more recently it has come to signify any structures (eg power-lines, floodwalls, wetlands) that support or alter the spatial and temporal distribution of resources and risks for human benefit. Investment may need to be in phases to accommodate higher rates of sea-level rise over time (ie investing in a new seawall or floodwall structure that may require replacement or relocation in the future) Some regions have limited experience with these new approaches and may benefit from using decision-support tools that identify such ecosystem-based strategies Many coastal regions have begun to plan for adaptation to sea-level rise, and are in need of a clear overview of options that can be discussed with policy makers, advocacy organizations, and the publicĪ mix of adaptation strategies often provides the broadest suite of benefits, including newer approaches that involve living system components such as wetlands, sandy beaches, sandbars, or living breakwaters Typologies are useful when many examples of alternative infrastructure design strategies exist, and a high-level categorization allows planners to perceive the pattern of alternatives under consideration The initial driver for mound construction in sandy tidal areas was access to small-scale fishing and trade, while the main driver of later dike construction was urban growth, which led to more land being dedicated to intensive food production ( Charlier et al. In 79 CE, Pliny the Elder reported encountering people on the northern coasts of present-day Germany and the Netherlands who built artificial mounds that enabled them to live in a tidally flooded environment ( Henry 1855). Artificial harbors shaped by rock walls were also an early invention, often contained within early cities by gates built both for protection from attacking navies and to control the passage of goods and travelers ( Blackman 1982). The first coastal structures that appear in the archaeological record were rock breakwaters, built to protect harbor entrances from wave energy. Humans have altered coastal areas by introducing artificial structures dating back to at least 2580 BCE, on the shores of the Red Sea in modern Egypt ( Tallet and Marouard 2014). The San Francisco Bay region provides an example of how this typology can be applied to help policy makers choose more successful strategies as coastal areas plan for sea-level rise. Key factors in a geomorphological, ecological, and land-use context must be taken into account when selecting various infrastructure strategies, to ensure that they function as intended. Such structures can be optimized for different phases of coastal adaptation and can provide multiple benefits (eg supporting ecosystems as well as minimizing flooding in coastal cities). ![]() Although similar approaches have been described elsewhere in different policy contexts, this article focuses on evaluating physical infrastructure types – including hybrid structures that combine landforms with concrete and steel elements –based on historical differences in engineering practices. Categorizing the choices in coastal infrastructure that are available to policy makers will allow for comparisons of their potential impacts on ecosystems and of their value in preparation for long-term sea-level rise. ![]()
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