Satellite-derived digital elevation model accuracy: hydrogeomorphological analysis requirements

✍ Scribed by T. A. Endreny; E. F. Wood; D. P. Lettenmaier

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 719 KB
• Volume: 14
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/(sici)1099-1085(200001)14:1<1::aid-hyp918>3.0.co;2-#

✦ Synopsis

Digital elevation models (DEMs) are currently generated using satellite imagery, but little is known about how errors in satellite-derived DEMs aect hydrogeomorphological products such as relief, elevation contours, basin boundaries and stream networks. This study identi®ed and minimized vertical errors for a SPOT-derived DEM of the 532 km 2 Little Washita River, OK, watershed and then assessed how elevation inaccuracies aected hydrogeomorphological analyses. SPOT-derived DEM errors were identi®ed using a set of ground control points (GCPs) and by comparing the 600 000 pixels comprising the SPOT image of the study area to high and low accuracy US Geological Survey (USGS) 7 . 5-minute airborne-derived DEMs. The comparative analysis identi®ed a basin-wide error structure in the SPOT product that post-processing of the SPOT image then reduced from an RMSE of 8 . 7 to 4 . 5 m. Although SPOT-and USGS-derived topographic relief images had a poor correlation at small spatial scales, at larger hillslope scales nearly 90% of the image pixels overlapped. For basin-scale descriptors, such as catchment area, stream length, stream density and Horton ratios, SPOT-and USGS-derived estimates diered by no more than 3%. At smaller spatial scales, however, an overlay of SPOT-derived vector images of basin boundaries and stream networks with equivalent higher accuracy products revealed that the products were incongruent on average at 100 m and at most up to distances of 1 km. In summary, the accuracy of the SPOT-derived DEM was adequate for deriving estimates of basin average hydrogeomorphology but was unable to match equivalent products derived from USGS 7 . 5-minute DEMs at scales ®ner than 100 m.