The effect of vertical accuracy of digital elevation models (DEMs) on hydrologic prediction accuracy was evaluated by comparing three DEMs and associated stream-flow simulations for the 7.2 km2 USDA-ARS watershed at Mahantango Creek, PA. The DEMs were the standard 30 m USGS 7.5′ DEM, a 5 m product derived from low altitude aerial photography, and a 30 m product derived from interferometric processing of Spaceborne Imaging Radar-C (SIR-C). Statistical analysis of the DEMs showed that the USGS DEM had the typical stipling errors resulting from processing of the source digital contour maps, and a vertical error structure related to the topographic attributes of the watershed. The SIR-C DEM had a vertical offset of about 50 m from the high resolution and USGS DEMs, as well as error features that were somewhat related to topographic features. Inaccuracies in both the USGS and SIR-C DEMs were apparent in the drainage network, as well as in spatial images of elevation, slope; and contributing area. Comparisons of runoff predicted using a hydrologic model based on the three DEMs showed that mean annual predicted runoff volumes were 0.3% and 7.0% larger for the USGS and SIR-C DEMs, respectively, as compared to the reference DEM. Much larger differences were apparent in individual hydrographs; and the USGS and SIR-C DEMs predicted lower peaks, and higher base flows, than did the reference.
All Science Journal Classification (ASJC) codes
- Soil Science
- Computers in Earth Sciences