GIS Modelling of Intertidal Wetland Exposure Characteristics

CROWELL, N.; WEBSTER, T., and O'Driscoll, N.J., 2011. GIS modelling of intertidal wetland exposure characteristics. Journal of Coastal Research, 27(6A), 44-51. West Palm Beach (Florida), ISSN 0749-0208. Exposure to solar radiation and tidal inundation are important factors for a wide variety of chemical and ecological processes in coastal ecosystems. Accurate quantification of these factors is often difficult on a local scale. To address this research gap, a remote-sensing approach was developed to model inundation and radiation characteristics within an intertidal zone located in the Minas Basin (Bay of Fundy, Nova Scotia, Canada). A light detection and ranging (LIDAR) derived elevation model was subjected to tidal modelling based on hourly sea level predictions and solar modelling based on sunrise and sunset times for 2009. Model results indicated an intertidal zone of 145.8 km(2) with an elevation between 6.9 m and 6.8 m. The intertidal zone was determined to contain three unique wetland classes: (1) 4.4 km(2) of high salt marsh, dominated by Spartina patens; (2) 5.0 km(2) of low salt marsh, dominated by Spartina alterniflora; and (3) 63.1 km(2) of nonvegetated marine flat (73.3 km(2) unclassified intertidal). Detailed exposure characteristics were calculated for each of the classes within the intertidal zone at 10-cm vertical intervals. Exposure calculations for 2009 showed that an average of 4.2 km(2) of salt marsh were exposed to solar radiation and 8.4 km(2) were exposed to the atmosphere each hour. Similarly, 11.7 km(2) of marine flat were exposed to solar radiation and 22.9 km(2) were exposed to the atmosphere each hour. The developed remote-sensing techniques successfully established intertidal zones, uniquely identified wetland classes, and modelled inundation and solar exposure characteristics within the study area.