Estimation of Evapotraspiration of Tamarisk using Energy Balance Models with High Resolution Airborne Imagery and LIDAR Data

The wide uncontrolled spread of the invasive species of Tamarisk (Salt Center) in the riparian areas of the southwest of the United States has become a source of concern to the water resource management community. This tree which was important for ornamental purposes and to control bank erosion during the 1800\u27s later became problematic and unwanted due to its biophysical properties: Its vigorous growth out-competes native species for moisture, lowering water tables, increasing the soil salinity and hence becomes the dominant riparian vegetation especially over arid to semi-arid floodplain environments. Most importantly they consume large amounts of water leading to reduction of river flows and lowering the groundwater table. We implemented this study in an effort to provide reliable estimates of the amount of water consumed or lost by such species through evapotranspiration (ET) as well as to a better understand of the related data quality made it possible to provide spatio-temporal estimates of ET at a considerably high resolution and reliable accuracy over a wide range of surface heterogeneity. We tested two different soil-vegetation atmosphere transfer models (SVAT) that are based on thermal remote sensing namely: the two source model (TSM) of Norman et al. (1995) with its recent modification and the Surface Energy balance algorithm (SEBAL) of Bastiaanssen et al. (1998) to estimate the different surface energy energy balance and longwave thermal airborne imagery acquired by the research aircraft at the Remote Sensing Services Lab at Utah State University (USU) and land use map classified from these images as well as a detailed vegetation height image acquired by the LASSI Lidar also developed at USU. We also compared estimates of ET from lower resolution Landsat TM imagery, at 30 meter pixel size, acquired on the same data of the airborne images. The study was conducted over the Cibola wildlife refuge in southern California which is populated with dense stands of tamarisk during the summer of 2007-2008 as part of a project funded by the USBR initiated for water resources management over the Palo Verdi Irrigation District (PVID) and Cibola area. The models results were compared to fluxes from eddy covariance and Bowen ratio towers deployed within the area. Both models were then applied in a different area over the 15 km of Mojave river floodplain near Barstow, California in a study that is aimed at estimating the amount of water that could be saved by controlling the Tamarisk