Raster modelling of coastal flooding from sea-level rise

As rates of sea-level rise continue to increase due to climate change, land planners
require accurate spatial analyses on the extent and timing of coastal flooding and
associated hazards. Digital elevation data used to evaluate coastal vulnerability
to flooding are available at various horizontal and vertical resolutions. However,
the quality of digital elevation models (DEM) used in environmental assessment
can significantly affect the detection of topographic features and the magnitude
of hydrological processes. We used lidar elevation data in coastal North
Carolina, USA to investigate the effects of horizontal resolution and connectivity
on the extent and timing of flooding from sea-level rise. We found that the rate
and extent of inundation were dependent on horizontal resolution and
assumptions made on hydrological connectivity. The variation in flood extent
was much larger (760km2) at low sea-level projections (,0.4 m) than at high sealevel
projections (.,0.9 m, 114km2) due to the effect of hydrological corrections
on the coarse-scale DEM and topographic complexity at low elevations. Lidar
elevation data provide a significant advance in mapping potential coastal
flooding, but the extent and timing of inundation are sensitive to horizontal
resolution and the modelling of hydrological connectivity.