Submitted to: Remote Sensing in Hydrology Symposium
Publication Type: Proceedings
Publication Acceptance Date: 4/7/2000
Publication Date: N/A
Technical Abstract: Airborne remote sensing is a useful tool for obtaining high resolution, multi-spectral imagery of riparian vegetation in western river systems, due to the scale of variability and smaller size of these riparian systems in semi-arid climates. A multi-faceted study is presently being conducted along the Rio Grande in New Mexico to determine the evapotranspiration rates of a riparian ecosystem dominated by Salt Cedar (Tamarisk spp) and Cottonwood. The field study comprises the acquisition of energy balance flux data using eddy correlation techniques and other micrometerological instrumentation, some plant biophysical variables, transpiration rates from Lidar measurements as well as airborne remote sensing in the visible, near-infrared and thermal infrared portions of the spectrum. The USU airborne digital system was used to acquire the high-resolution imagery (0.5 meter pixels) over the site during a field campaign in June, 1999. The system acquires narrow-band digital images centered in the green (0.57 um), red (0.65 um), and near-infrared (0.80 um), as well as thermal-infrared imagery at 8-12 um. Throughout the course of the field experiment, imagery was acquired over the Tamarisk groves at different times of the day and through multiple overpasses. The paper will describe how the calibrated imagery from the USU systems was used to estimate spatial variations in the energy balance fluxes over the site. Comparisons of instantaneous spatially distributed upwind fluxes with values of ground-based measured fluxes were conducted for two different dates. Results show considerable differences between the fluxes that can be attributed to advection, canopy heat storage and wind variability.