Plan Curvature derived from 1" SRTM DEM-S

Plan (or contour) curvature is the rate of change of aspect (orthogonal to the slope) and represents topographic convergence or divergence. It is significant for water movement across the landscape, i.e., the accumulation or dispersion of water.\n\nThe plan curvature products were derived from the Smoothed Digital Elevation Model (DEM-S; ANZCW0703014016), which was derived from the 1 second resolution SRTM data acquired by NASA in February 2000. The calculation of plan curvature from DEM-S accounted for the varying spacing between grid points in the geographic projection. \n\nThe plan curvature data are available at 1 arc-second (approx. 30 m) and 3 arc-second (approx. 90 m) resolutions.\n\nThe 3 arc-second resolution product was generated from the 1 arc-second plan curvature product and masked by the 3” water and ocean mask datasets.\nLineage: Source data\n1.\t1 arc-second SRTM-derived Smoothed Digital Elevation Model (DEM-S; ANZCW0703014016).\n2.\t1 arc-second plan curvature product\n3.\t3 arc-second resolution SRTM water body and ocean mask datasets\n\nPlan Curvature calculation\nPlan curvature was calculated from DEM-S using the finite difference method (Gallant and Wilson, 2000). The different spacing in the E-W and N-S directions due to the geographic projection of the data was accounted for by using the actual spacing in metres of the grid points calculated from the latitude.\n\nThe plan curvature calculation was performed on 1° x 1° tiles, with overlaps to ensure correct values at tile edges.\n\nThe 3 arc-second resolution version was generated from the 1 arc-second plan curvature product. This was done by aggregating the 1” data over a 3 x 3 grid cell window and taking the mean of the nine values that contributed to each 3” output grid cell. The 3” plan curvature data were then masked using the SRTM 3” ocean and water body datasets.\n\n\nReferences\nGallant, J.C. and Wilson, J.P. (2000) Primary topographic attributes, chapter 3 in Wilson, J.P. and Gallant, J.C. Terrain Analysis: Principles and Applications, John Wiley and Sons, New York.