Water Resources Research Act Program

Details for Project ID 2019AZ019B

Detecting Colorado River Tamarix phenology using publicly available satellite images

Institute: Arizona
Year Established: 2019 Start Date: 2019-06-01 End Date: 2020-05-31
Total Federal Funds: $9,152 Total Non-Federal Funds: $34,275

Principal Investigators: Temuulen Sankey

Abstract: An invasive Eurasian shrub known as tamarisk (Tamarix spp.) is now commonly found along the Colorado River in the southwestern USA, which provides drinking water and hydroelectric power to millions of people in Central Arizona and Southern California. Tamarisk is characterized by its deep tap root, and excessive water consumption and evapotranspiration, which lower water tables in arid riparian habitats, including the Colorado River Basin in Grand Canyon National Park. Scientists and land managers from the US Geological Survey (USGS), National Park Service (NPS), and Bureau of Reclamation (BOR) are working to understand its population dynamics and phenology, and to map its distribution to guide control treatment efforts. One notable effort was the recent release of the tamarisk beetle (D. carinulata), a specialized herbivore of tamarisk, as a biocontrol agent. The vast area inhabited by tamarisk, combined with its locally-variable phenologic interactions with the beetle, make remote sensing tools invaluable for quantifying the leaf defoliation and mortality events at a landscape scale. Previous studies have used expensive, high-resolution, airborne imagery to study these interactions in topographically-complex regions like Grand Canyon, but have not successfully used free, publicly available satellite imagery such as Landsat (30 m) or MODIS (250 m). We propose to assess Landsat imagery in quantifying tamarisk leaf defoliation and mortality by the beetle. If Landsat images are determined inadequate for detecting defoliation events, we will use higher resolution, commercial satellite data known as Worldview-2, provided by the USGS for this project, to test this image source in detecting these events. The results will be used to produce a MS thesis, a peer-reviewed manuscript, and a data product, which will be published and hosted by the USGS. We will also present our results to the Glen Canyon Dam Adaptive Management Program stakeholders’ meeting. Our results will help other scientists use the freely available image source for surveying landscape processes such as phenology, hydrologic cycling, and evapotranspiration.