CREATION OF A DIGITAL ELEVATION MODEL FROM 1:12,000 SCALE AERIAL PHOTOGRAPHS FOR USE IN SEDIMENT STUDIES IN THE SPRING CREEK WATERSHED, COLORADO

The Buffalo Creek wildfire burned approximately 4900 hectares in the Rocky Mountain foothills of Colorado during May 18-20, 1996. One of the most heavily impacted watersheds was Spring Creek, in which nearly 79% was burned. The geology of the watershed is characterized by bedrock of Pikes Peak granite, a highly erodable coarse-grained rock that produces shallow soils that support vegetation which is predominately Ponderosa Pine on south-facing slopes and Douglas Fir on north-facing slopes. On July 12, 1996, a thunderstorm occurred over the burned area, producing up to 7.5 cm of rain in about an hour covering an area of 15 sq. km. Flooding ensued, causing two deaths and extensive property damage. The flood severely altered the morphology of the watershed, causing erosion and depositing up to 2 m of sediment in the larger channels. The USGS Water Resources Division is conducting a multi-year study in the burned area to understand the hydrologic and erosional response after a wildfire and the downstream effects of this flood and subsequent floods. To aid this study, a 5m digital elevation model (DEM) of the Spring Creek Watershed was created from 1:12,000 scale aerial photographs using soft-copy stereo-photogrammetry. Data derived from the DEM include slope percent, slope aspect, and curvature grid layers, watershed, and sub-basin boundaries and a channel network layer, all in Arc/Info format. Seven 1:12,000 scale maps, and 16 statistical tables were also produced to aid research.