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Global Positioning System Sampling Intensity and Pattern Effects on Computed Topographic Attributes
Author(s) -
Wilson John P.,
Spangrud Damian J.,
Nielsen Gerald A.,
Jacobsen Jeffrey S.,
Tyler David A.
Publication year - 1998
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1998.03615995006200050038x
Subject(s) - digital elevation model , terrain , topographic wetness index , sampling (signal processing) , elevation (ballistics) , global positioning system , geology , contour line , traverse , intensity (physics) , remote sensing , topographic map (neuroanatomy) , sample (material) , physical geography , geodesy , hydrology (agriculture) , cartography , geography , mathematics , geometry , computer science , filter (signal processing) , quantum mechanics , computer vision , physics , cognitive psychology , chemistry , posterior parietal cortex , psychology , telecommunications , chromatography , geotechnical engineering
Global positioning system (GPS) and digital elevation model (DEM) technologies can provide measurements of terrain attributes that influence soil processes, soil properties, and site‐specific management. We hypothesized that the intensity and pattern of sampling points affects the computed contour maps and topographic attributes. The intensity and pattern of sampling points, selected from 6284 GPS‐derived x, y, z values, were varied to test this hypothesis on estimated elevations and topographic attributes in a 20‐ha Montana farm field. Variations of 0.05% in mean elevation between the sample and reference grids generated ≤25% differences in slope gradients, ≤38% in specific catchment area, and ≤22% in steady‐state topographic wetness index. Errors diminished as sample size (resolution) and distribution (spread) increased. Overall, the results demonstrate how relatively small differences in elevations at individual points (locations) in a landscape may mask large variations in the resultant shapes and hydrologically important topographic attributes calculated from DEMs. The intensive sampling may be practical where vehiclemounted GPS can traverse cultivated fields, but impractical in trees and rough terrain.