Optimal spatial resolution for collection of ground data and multi-sensor image mapping of a soil erosion cover factor

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2007.05.014 Byline: Guangxing Wang (a), George Gertner (a), Heidi Howard (b), Alan Anderson (b) Keywords: Cost-efficiency; Mapping; Optimal spatial resolution; Remote sensing; Sampling; Soil erosion; Spatial variability Abstract: Military training activities disturb ground and vegetation cover of landscapes and increases potential soil erosion. To monitor the dynamics of soil erosion, there is an important need for an optimal sampling design in which determining the optimal spatial resolutions in terms of size of sample plots used for the collection of ground data and the size of pixels for mapping. Given a sample size, an optimal spatial resolution should be cost-efficient in both sampling costs and map accuracy. This study presents a spatial variability-based method for that purpose and compared it with the traditional methods in a study area in which a soil erosion cover factor was sampled and mapped with multiple plot sizes and multi-sensor images. The results showed that the optimal spatial resolutions obtained using the spatial variability-based method were 12 and 20m for years 1999 and 2000, respectively, and were consistent with those using the traditional methods. Moreover, the most appropriate spatial resolutions using the high-resolution images were also consistent with those using ground sample data, which provides a potential to use the high-resolution images instead of ground data to determine the optimal spatial resolutions before sampling. The most appropriate spatial resolutions above were then verified in terms of cost-efficiency which was defined as the product of sampling cost and map error using ordinary kriging without images and sequential Gaussian co-simulation with images to generate maps. Author Affiliation: (a) Department of Natural Resources and Environmental Sciences, University of Illinois, W503 Turner Hall, 1102 S. Goodwin Avenue, Urbana, IL, USA (b) U.S. Army Corps of Engineers, Construction Engineering Research Laboratory, P.O. Box 9005, Champaign, IL, USA Article History: Received 31 August 2006; Revised 30 March 2007; Accepted 25 May 2007