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Title: Actual evapotranspiration (water use) assessment of the Colorado River Basin at the Landsat resolution using the operational Simplified Surface Energy Balance Model

Author
item SINGH, R.K. - Us Geological Survey (USGS)
item SENEY, G.B. - Us Geological Survey (USGS)
item VELPURI, N.M. - Us Geological Survey (USGS)
item BOHMS, STEFANIE - Us Geological Survey (USGS)
item Scott, Russell - Russ
item VERDIN, J.P. - Us Geological Survey (USGS)

Submitted to: Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2013
Publication Date: 12/20/2013
Citation: Singh, R., Seney, G., Velpuri, N., Bohms, S., Scott, R.L., Verdin, J. 2013. Actual evapotranspiration (water use) assessment of the Colorado River Basin at the Landsat resolution using the operational Simplified Surface Energy Balance Model. Remote Sensing. 6:223-256. https://doi.org/10.3390/rs6010233.
DOI: https://doi.org/10.3390/rs6010233

Interpretive Summary: Accurately estimating the amount of water lost to evaporation in the Colorado River Basin (CRB) is important for assessing and managing limited water resources in the basin. We have developed a detailed, field-level, map of evaporation for the CRB for water use assessment. To do this, a computer model was developed that incorporated meteorological and satellite measurements for the year 2010. Our results show that cropland had the highest evaporation among all land cover classes except for open lake or river water. Comparisons of the model estimates with actual evaporation measurements and basin water budget measurements indicated a good agreement. Likewise, our model estimates agreed well with coarser-scale model estimates, but our map is more suitable for water use assessments at the agricultural field level.

Technical Abstract: Accurately estimating consumptive water use in the Colorado River Basin (CRB) is important for assessing and managing limited water resources in the basin. Increasing water demand from various sectors may threaten long-term sustainability of the water supply in the arid southwestern United States. Landsat is the world’s longest operating earth observation mission in human history. We have developed a first ever basin-wide evapotranspiration (ET) map of the Colorado River Basin at the Landsat scale for water use assessment at the field level. We used the operational Simplified Surface Energy Balance (SSEBop) model for estimating evapotranspiration using more than 300 cloud-free Landsat images acquired during 2010. Our results show that cropland had the highest ET among all land cover classes except for water. Validation using eddy covariance measured ET showed that SSEBop estimated annual ET was within 4% of the measured ET. Comparison with water balance-based ET showed good agreement (R2 = 0.85) between Landsat-based ET and water balance-based ET at the sub-basin level (Hydrologic Unit Code, HUC8) for HUCs having annual ET less than annual precipitation.. Comparison at the HUC8 level has also shown that there was good correlation (R2 = 0.79) between Moderate Resolution Imaging Spectroradiometer (MODIS)-based ET and Landsat-based ET. However, spatial distribution of MODIS-based ET was not suitable for water use assessment at the field level. In contrast, Landsat-based ET has a good potential to be used at the field level for water use assessment, planning, and management.