AIRBORNE LASER ALTIMETER MEASUREMENTS OF LANDSCAPE TOPOGRAPHY

Measurements of topography can provide a wealth of information on land scape properties for managing hydrologic and geologic systems and cons erving natural and agricultural resources. This article discusses the application of an airborne laser altimeter to measure topography and o ther landscape surface properties. The airborne laser altimeter makes 4000 measurements per second with a vertical recording resolution of 5 cm. Data are collected digitally with a personal computer. A video ca mera, borehole sighted with the laser, records an image for locating f light lines. CPS data are used to locate flight line positions on the landscape. Laser data were used to measure vegetation canopy topograph y, height, cover and distribution and to measure microtopography of th e land surface and gullies with depths of 15-20 cm. Macrotopography of landscape profiles for segments up to 4 km were in agreement with ava ilable topographic maps but provided more detail. Larger gullies with and without vegetation, and stream channel cross sections and their as sociated floodplains have also been measured and reported in other pub lications. Landscape segments for any length could be measured for eit her micro- or macrotopography. Airborne laser altimeter measurements o f landscape profiles can provide detailed information on landscape pro perties or specific needs that will allow better decisions on the desi gn and location of structures (i.e., roads, pipe, and power lines) and for improving the management and conservation of natural and agricult ural landscapes.