Using GRASS GIS to Calculate Potential Global Solar Irradiation Using Canopy Heights as a Base Elevation Layer to Assist in the Landscape Scale Characterization of Aquatic Habitats

Session Type: 
Academic Session
Doug Newcomb, Department of Interior- U.S. Fish and Wildlife Service

Water temperature variation  can have a significant impact on freshwater aquatic communities.  Elevated temperatures can lead to differences in predator/prey relationships and mortality in relatively non-mobile classes of aquatic species such as mussels.  Using native 64-bit GRASS 6.5 on 64-bit Centos Linux, a previously generated 18.2 m (60 foot) forest canopy height grid for the State of North Carolina ( 17237 Rows and 45102 columns )  was used as a base elevation layer for calculation of  18.2 m total irradiance ( Watt hours/square meter/day) grids generated for all 365 days of the year using the GRASS r.sun command.  Daily data was aggregated by month and for the year using r.series.  Output annual and monthly irradiation data was overlaid on rasterized 1:24000 scale USGS Quadrangle hydrology line work to quantize solar irradiation input to streams and rivers in North Carolina.  


An existing 6.1m (20ft) bare earth elevation grid for North Carolina was generalized  to 18.2 m (60 foot) and used as a base layer for calculation of statewide 18.2 .m total solar irradiation grids using  r.sun for 12 days (1st day of each month) to compare to daily irradiation totals calculated using the canopy height layer as a base layer.

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