USING REMOTE SENSING & MODELING FOR EVALUATING HYDROLOGIC FLUXES, STATES, & CONSTITUENT TRANSPORT PROCESSES WITHIN AGRICULTURAL LANDSCAPES
Title: Use of landsat thermal imagery in monitoring evapotranspiration and managing water resources
Submitted to: Remote Sensing of Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 1, 2011
Publication Date: July 1, 2012
Citation: Anderson, M.C., Allen, R.G., Morse, A., Kustas, W.P. 2012. Use of landsat thermal imagery in monitoring evapotranspiration and managing water resources. Remote Sensing of Environment. 122:50-65..
Interpretive Summary: Satellite data collected in the thermal infrared waveband give us information about land-surface temperature that is useful for mapping surface energy and water fluxes, including evapotranspiration (ET) - the water lost to the atmosphere though evaporation and plant transpiration. This paper explores the value of thermal imagery that has been collected by the Landsat series since 1982, with a spatial resolution of ~100m and a temporal revisit frequency of ~16 days. This spatial scale is able to resolve most agricultural fields, allowing us to map crop water use on a field-by-field basis. Applications for Landsat thermal data are described: in water rights monitoring and compact negotiations, assessing ecosystem health and water requirements, generating water use projections with changing land use, drought monitoring, and in monitoring food and water security. The moderate-resolution thermal image archive collected with the Landsat satellite provides an unequalled global view of changing water availability and consumption patterns at scales where humans are actively modifying the natural water cycle. Such information will be critical as we plan strategies for adapting to future changes in freshwater resources.
Freshwater resources are becoming increasingly limited in many parts of the world, and decision makers are demanding new tools for monitoring water availability and rates of consumption. Remotely sensed thermal-infrared imagery collected by Landsat provides estimates of land-surface temperature that allow mapping of evapotranspiration (ET) at the spatial scales at which water is being used. This paper explores the utility of moderate-resolution thermal satellite imagery in water resource management. General modeling techniques for using land-surface temperature in mapping the surface energy balance are described, including methods developed to safeguard ET estimates from expected errors in the remote sensing inputs. Examples are provided of how remotely sensed maps of ET derived from Landsat thermal imagery are being used operationally by water managers today: in monitoring water rights, negotiating interstate compacts, estimating water-use by invasive species, and in determining allocations for agriculture, urban use, and endangered species protection. Other applications include monitoring drought and food insecurity, and evaluation of large-scale land-surface and climate models. To better address user requirements for high-resolution, time-continuous ET data, novel techniques have been developed to improve the spatial resolution of Landsat thermal-band imagery and temporal resolution between Landsat overpasses by fusing information from other wavebands and satellites. Finally, a strategy for future modifications to the Landsat program is suggested, improving our ability to track changes in water use due to changing climate and growing population. The long archive of global, moderate resolution TIR imagery collected by the Landsat series is unmatched by any other satellite program, and will continue to be a invaluable asset for better management of our earth’s water resources.