Quantifying Basalt Rock Outcrops in NRCS Soil Map Units Using Landsat-5 Data

Rock outcrop places many limitations on land use. For this reason, identifying its presence in a soil map unit is as important as identifying major soils. Presently the most accurate way to determine the percentage of rock outcrop in any one soil map unit involves transecting, which is time-consuming and not practical for large areas. Remote sensing can provide more accurate data for the surveys and a tremendous time saving. Endmembers, which are spectrally unique materials selected within the scene, were chosen for rock outcrop by analyzing National Aerial Photography Program (NAPP) photography under a stereoscope. Spectral Angle Mapper (SAM) classifications were performed on Landsat data of the study area to classify vegetation and rock outcrop. Global Positioning Satellite (GPS) ground-truth data with 30-meter buffers were used to validate the rock classifications. Although it is likely the amount of rock outcrop is overestimated in the final image, additional methods could ultimately produce a successful methodology to accurately map and quantify rock outcrop.