MULTI SCALE TERRAIN RUGGEDNESS ANALYSIS USING MULTI SOURCE DIGITAL ELEVATION MODEL: A CASE STUDY OF MANALI AREA OF (NW) HIMALAYA
Surface ruggedness is an important parameter to determine the quality of the landscape and morphological features. This study evaluates widely used ruggedness algorithms (Area ratio, vector ruggedness model (VRM), Terrain Ruggedness Index (TRI), Standard Deviation of residual topography (SD restopo), Standard Deviation of Slope (SD slope), Standard Deviation of profile curvature (SD profile Curvature), Standard Deviation of elevation (SD elevation)) in complex mountainous terrain for deriving the surface. The high resolution (1m) photogrammetric DEM, coarser resolution (30m) Global DEM, and 30m Survey of India topographic sheet DEM were used for this study. The 1m DEM had been resampled at 5, 10, 25 and 50m and coarser DEM resampled at 50 and 100m spatial resolution. These DEMs at different spatial resolutions were used for extracting surface ruggedness at different window size (3x3, 5x5, 9x9, and 11x11). Rapid changes in the variation of ruggedness were observed with the varying cell sizes for SD slope, SD elevation, and VRM and TRI methods. On the other hand Area ratio and SD profile curvature methods witnessed medium changes in the ruggedness with the change of window size. All the 184 layers (4cell size, 4 Window Size and 7 methods), (3cell size, 4 Widow Size and 2 methods were selected). The output results were normalized in the scale range of 0-1.The ruggedness value in Area ratio; SD profile curvature and VRM were slightly increased with the increase in spatial resolution and window size. Comparing with the ruggedness derived from the reference, SD slope and VRM provides best results with minimum errors in all resolution and window size. These two methods were applied at the multi sources DEMs in coarser spatial resolutions and variety of ruggedness results were found out.
Morphological features, Digital Elevation Model (DEM), Digital terrain analysis, photogrammetric, Spatial Resolution.
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