Abstract Recurrent storms, floods, landslides, earthquakes and tsunamis challenge the development of resilient infrastructure and communities in coastal northwestern British Columbia. Vulnerability assessment first requires extended and improved understanding of geohazards in the Pacific Basin to constrain modelling of future events. An investigation of soils and bedrock structures in the Douglas Channel provides insight into the distribution of deposits attributed to geohazards in the region. Newly discovered marine inundation deposits corroborate numerical models and suggest that Pacific-sourced storms and earthquake-triggered tsunamis expend much of their energy in the outer coast and rarely reach far up the mainland fjords. Small-volume Folisolic slides and rockfalls do not generate tsunamis of any consequence. In contrast, marine sediments deposited beyond storm berms at the fjord head are a record of local tsunamis generated by large-volume marine slumps. Deep-fractured bedrock mapped upslope from relict submarine features would trigger damaging tsunami waves if rapid failure into the fjord were to occur. The observations above suggest only great earthquakes, large landslides and seasonal storms above a certain threshold volume and impulse energy produce geomorphically significant inundation events. However, even small submarine landslides have tsunamigenic potential in Douglas Channel since they occur in shallow water.

Westhampton Beach is located between two stabilized inlets (Shinnecock and Moriches Inlets) on a barrier island on the south shore of Long Island, New York. Increasing beach erosion in the 1970s prompted a request for construction of a groin field to trap sand and restore the beach. The U.S. Army Corps of Engineers developed a plan for the groin field, and their recommendation was to sequentially build the groins up drift (eastward toward Shinnecock Inlet) using standard project design. However, in the late 1970s, local community pressure forced the U.S. Army Corps of Engineers, contrary to project design, to construct the groins down drift (westward) toward Moriches Inlet. The aim was to restore the eastern, more commercial, part of Westhampton Beach first. Financial limitations in 1972 suspended the project before its completion. Unfortunately, this set the stage for serious problems because the groin field was meant to operate as a completed project, and major problems developed soon after project termination. As a result, severe erosion and multiple washovers occurred west of the last groin. The major nor'easter of 1992 breached the island and destroyed many homes. The U.S. Army Corps of Engineers, in an emergency operation, dredged offshore sand and filled the breaches before they widened too much for effective closure. The subsequent litigation among the homeowners, the county, and the state spread over a number of years. A final settlement was reached on 31 October 1994. However, in a time of sea-level rise on a developed barrier island between two stabilized inlets, more people and bigger structures have now been put in peril.

Pea Island, Oregon Inlet, and Bodie Island, North Carolina, are severely human-modified barrier-island segments that are central to an age-old controversy pitting natural barrier-island dynamics against the economic development of coastal North Carolina. Bodie Island extends for 15 km from the Nags Head–Kitty Hawk urban area to the north shore of Oregon Inlet and is part of Cape Hatteras National Seashore. Pea Island extends 19.3 km from the southern shore of Oregon Inlet to Rodanthe Village and is the Pea Island National Wildlife Refuge. Bodie and Pea Islands evolved as classic inlet- and overwash-dominated (transgressive) simple barrier islands that are now separated by Oregon Inlet. The inlet was opened in 1846 by a hurricane and subsequently migrated 3.95 km past its present location by 1989. With construction of coastal Highway 12 on Bodie and Pea Islands (1952) and the Oregon Inlet bridge (1962–1963), this coastal segment has become a critical link for the Outer Banks economy and eight beach communities that occur from Rodanthe to Ocracoke. The ongoing natural processes have escalated efforts to stabilize these dynamic islands and associated inlet in time and space by utilizing massive rock jetties and revetments, kilometers of sand bags and constructed dune ridges, and extensive beach nourishment projects. As the coastal system responds to ongoing processes of rising sea level and storm dynamics, efforts to engineer fixes are increasing and now constitute a “human hurricane” that pits conventional utilization of the barriers against the natural coastal system dynamics that maintain barrier-island integrity over the long term.

As a result of the natural setting plus poor development and management decisions, the town of North Topsail Beach on Topsail Island, North Carolina, is the state's most vulnerable barrier-island community. It is our view that this very narrow, low, and duneless island community is the most hazardous on the U.S. East Coast. Although most of North Topsail Beach was designated a CoBRA unit under the Coastal Barrier Resources Act of 1982, the area has been developed extensively (mostly post-1980), starting with “mom and pop” beach cottages, and evolving into large single-family rental houses, duplexes, and several medium- and high-rise hotels and condos. Over the years, North Topsail Beach has experienced property losses from storm surge, overwash, flooding, inlet migration, new inlet formation, and chronic shoreline erosion. The single evacuation road crosses seven swash channels and is flooded early in every significant storm. A political cauldron has evolved, often featuring the front-row property owners versus those behind the front row, in which this middle-class town seeks to solve its problems. Debate centers on beach erosion problems, including proposed beach nourishment; exemptions to banned shore hardening; and construction of a proposed terminal groin and inlet channel realignment.

Southeast Florida's beaches, which are heavily developed and imperiled by rising sea level, continue to be seriously mismanaged and uneconomically maintained and to generate increasing environmental stress for adjacent marine habitats. Broward County heads the list of counties that stretch from St. Lucie southward to Miami-Dade. Five serious problems plague the stability of these barrier-island shorelines: inlet disruption of littoral drift; beach management that enhances shore erosion (lack of shore vegetation, inappropriate vehicular traffic, and structural protections that enhance erosion); historically very poor-quality renourishment sediment (in size and durability); strong resistance by coastal engineering and dredging firms and counties to embrace an understanding of sandy shore dynamics; and a philosophy that renourishment projects are a solve-all management approach to maintaining beaches and protecting infrastructure. This has led to seriously destabilized beaches, overly aggressive beachfront development, major economic waste, and severe environmental degradation to adjacent marine waters and associated valuable sandy bottom and hard-bottom communities. Many of these sandy shorelines may well not survive this global warming century of rapidly rising sea level. It is economically and environmentally critical for both the future risks to be understood and for lessons from the repeated failed history of beach management to be learned. Continued mismanagement will shorten the inhabitable lifetime of this developed sandy coast by decades and at great economic and environmental cost.