ARS | Publication request: MONITORING RANGELAND WATERSHEDS WITH VERY-LARGE SCALE AERIAL IMAGERY

Submitted to: First Interagency Conference on Research in the Watersheds
Publication Type: Proceedings
Publication Acceptance Date: December 6, 2002
Publication Date: October 27, 2003
Citation: Booth, D.T., Glenn, D., Keating, B., Cox, S.E., Nance, J., Barriere, J. 2003. Monitoring rangeland watersheds with very-large scale aerial imagery. pp. 212-215. In: First Interagency Conference on Research in the Watersheds Proceedings.

Technical Abstract: Rangeland management has depended more on judgement than science for monitoring vast landscapes. The result is a crisis of confidence and recognition that we need objective information based on standardized indicators. We recognize the complex, multivariate nature of rangeland ecosystems; we also recognize that information-collection costs require that we define key indicators -- those that lend themselves to detection of ecological important change with minimal expense. Therefore we are testing bare ground as a potential key indicator and we are investigating very-large scale aerial (VLSA) imagery as a means for inexpensive acquisition of statistically adequate, unbiased, high-resolution (high detail), samples (images) from which to make accurate ground-cover measurements. Our remote-sensing tools include an ultra-light-type, 3-axis airplane capable of straight and level flight at 73 km/hr, 100 m above 1520-m elevational rangelands; a laser altimeter for precise, instantaneous measurements of platform altitude above ground level (AGL); and high-shutter-speed film and digital cameras automatically triggered by computer using pre-programed coordinates with an interfaced geographic positioning system. The system provides the pilot with navigational information including ground speed, a critical parameter in close-to-the-earth photography. Our methods for making bare-ground measurements from the imagery include manual photogrammetry and digital methods (color density slicing image analysis). Ground truth is being collected using both laser-bar point frames and image analysis of 2-m AGL digital photographs from a stationary platform.