Skip to main content
U.S. flag

An official website of the United States government

Colorado River Project: A compilation of vegetation indices, phenology assessment metrics, estimates of evapotranspiration and change maps for five reaches between Hoover and Morelos Dams on the Lower Colorado River, for nearly the last two decades

September 24, 2021

These raster and tabular data were compiled to develop time series data of the lower Colorado River (LCR) vegetation greenness, water use, and phenology since the year 2000. An objective of our study was to evaluate short and long-term effects of drought and biocontrol on LCR riparian and aquatic ecosystems south of Hoover Dam. These data represent spatially explicit average Enhanced Vegetation Index (EVI2) derived evapotranspiration (ET) difference, and scaled normalized difference vegetation index (NDVI*) difference maps between two decades (2000 to 2010 and 2011 to 2020) and two 5 year periods (2000 to 2005 and 2016 to 2020). The time-series period statistics data provide estimates of the riparian woodland area ecosystem health and its water use for the Lower Colorado River between Hoover and Morelos dams over the past 21 years. These data were compiled by the U.S. Geological Survey (USGS) and University of Arizona, to monitor riparian zone trends and changes in the Lower Colorado, and document riparian ecosystem health and its water use. The growing season ET and EVI2 difference maps were created using both EVI and ET from-Landsat-OLI, and the NDVI* difference maps were created using Landsat OLI 30m data only. These data were processed over time and space along to capture different land cover, management conditions, general geospatial and hydrological conditions (ET-EVI), and areas where riparian plant communities greened or browned over these time frames (NDVI*). The spatial extent of the raster data includes five Reaches (R3..R7) along the LCR riparian corridor between Hoover Dam and Morelos Dam on the Northern International Border (NIB) near Yuma, Arizona. This extent allowed for the evaluation of short and long-term effects on the river's vegetation of drought and hydrological processes in this dryland region. All data associated with this project were acquired from the LP-DAAC and pre-processed to remove and capture issues prior to further analyses. Preprocessing involved projection to a common coordinate system, masking to only retain the area of interest, quality analysis to discard poor data, and then value addition to generate the growing season ET and EVI2 difference maps, as well as water use difference maps produced with ET-from-Landsat-EVI, and the NDVI* difference maps. Data acquisition and analysis were performed at the University of Arizona VIP lab (vip.arizona.edu) using their large Linux cluster of computing and storage resources. A mix of off the shelf software and specialized in-house tools were used to process the data and analyses. These data depict a Landsat time series from three sensors over the 21-year period from the derived ET-EVI2 and NDVI* time-series data. These data can be used to monitor spatial and temporal riparian zone trends and changes, and the impact of both drought, fire, land clearing and/or non-native species biocontrol on riparian habitat, in the LCR from Hoover Dam and Morelos Dam in the United States and document riparian ecosystem health and its water use.