High-accuracy coastal flood mapping for Norway using lidar data

Abstract

Abstract. Using new high-accuracy light detection and ranging (lidar) elevation data we generate coastal flooding maps for Norway. Thus far, we have mapped ∼80 % of the coast, for which we currently have data of sufficient accuracy to perform our analysis. Although Norway is generally at low risk from sea level rise largely owing to its steep topography and land uplift due to glacial isostatic adjustment, the maps presented here show that, on local scales, many parts of the coast are potentially vulnerable to flooding. There is a considerable amount of infrastructure at risk along the relatively long and complicated coastline. Nationwide we identify a total area of 400 km2, 105 000 buildings, and 510 km of roads that are at risk of flooding from a 200-year storm surge event at present. These numbers will increase to 610 km2, 137 000, and 1340 km with projected sea level rise to 2090 (95th percentile of RCP8.5 as recommended in planning). We find that some of our results are likely biased high owing to erroneous mapping (at least for lower water levels close to the tidal datum which delineates the coastline). A comparison of control points from different terrain types indicates that the elevation model has a root-mean-square error of 0.26 m and is the largest source of uncertainty in our mapping method. The coastal flooding maps and associated statistics are freely available, and alongside the development of coastal climate services, will help communicate the risks of sea level rise and storm surge to stakeholders. This will in turn aid coastal management and climate adaptation work in Norway.

Insight into real-world complexities is required to enable effective response from the aquaculture sector to climate change

“…But in low-lying coastal areas, storm surges have caused considerable damage to buildings and transport infrastructure in the past [41]. In the future there could be increased incidences, as model projections for Norway show an increase in storm surges and extreme water levels [35,37,38].…”

“…Damage to infrastructure had 'Documented links' to 4 climate stressors (Sea level rise and extreme water levels, Storms, Extreme temperatures and heatwaves, Precipitation/runoff). Breeding and hatchery facilities are located close to the coast (Fig 1 ), and studies have shown that many Norwegian coastal areas are susceptible to flooding from storm surges due to sea level rise [40,41], which may cause damage to buildings and wider infrastructure. Storms are also known to cause destruction within affected areas, e.g.…”

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“…The terminology of "coastal climate services" has just evolved throughout the last few years, with only a few studies referring to the specific term (Le Cozannet et al 2017, Hinkel et al 2019, Breili et al 2020, Khan et al 2020, Stephens et al 2020. All of those studies relate to adaptation to sea-level rise and predominantly address the physical aspect from a social perspective.…”

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“…Webster et al [211] used topographic LiDAR to map the flood hazard from storm-surge events for Charlottetown on Prince Edward Island in Canada. Moreover, numerous research papers have been based on the use of high-density LiDAR data, often in combination with 2D streamflow hydraulic modelling using high-density LiDAR for mapping high accuracy urban, river or coastal flood risks [212][213][214][215]. Morrissey et al [216] used LiDAR data for modelling groundwater flooding in a lowland karst catchment.…”