Submitted to: International Conference on Tropical and Subtropical Plant Diseases
Publication Type: Abstract Only
Publication Acceptance Date: 1/11/2010
Publication Date: 1/25/2010
Citation: Gowda, P., Goolsby, J., Howell, T.A., Yang, C., Basu, S. 2012. Application of scintillometry to estimate water use by giant reed (Arndo Donax L.)- A perennial invasive weed along the Rio Grande River near Laredo, Texas. International Conference on Tropical and Subtropical Plant Diseases, January 25, 2010, Weslaco, Texas. 2010 CDROM.
Technical Abstract: Giant reed (Arundo donax L.) is a bamboo-like perennial invasive weed from Eurasia presenting a severe threat to agroecosystems and riparian areas in Texas and Mexican portions of the Rio Grande River Basin. It is spreading rapidly by displacing native vegetation. Giant reeds are expected to consume excessive amount of water to support its incredible vegetative growth rate. However, very limited information is available on its water usage in the United States. The objective of this study was to estimate daily water use by the giant reed using a Large Aperture Scintillometer (LAS) along the Rio Grande River near Laredo, Texas. On March 20, 2009, a LAS was deployed 1 m above the giant reed canopy (5.3 m above the ground level). The path distance between the transmitter and receiver of the LAS was 230 m. Scintillometer measurements were made at 1 minute intervals and averaged to 15 minutes, synchronized with weather station measurements. In addition, net radiation (Rn) and soil heat fluxes (G) were measured. Latent heat fluxes (LE) and evapotranspiration (ET) rates were derived using LAS-estimated sensible heat flux (H) as a residual from the energy balance equation (LE=Rn-G-H) and hourly ET values were summed to obtain a daily ET value. Analysis of the data for a day with clear skies (March 20, 2009) indicated that the daily water demand for giant reed was 5.1 mm. A long term monitoring of the giant reed canopy is required to accurately quantify the variations in water demand at different growth stages and meteorological conditions. Scintillometer-based water use data can be used as a ground truth to validate remote sensing based regional scale daily/monthly/seasonal water use maps covering giant reed areas in the Rio Grande River Basin.