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Title: USING SPATIAL INFORMATION TECHNOLOGIES FOR MAPPING FOUR INVASIVE WEEDS IN THE RIO GRANDE RIVER SYSTEM OF TEXAS

Author
item Everitt, James
item YANG, CHENGHAI - TEXAS A&M, WESLACO
item Davis, Michael
item Deloach Jr, Culver
item NIBLING, F.L. - US DEP'T. OF INTERIOR

Submitted to: Biannual Workshop in Color Photography and Videography in Resource
Publication Type: Proceedings
Publication Acceptance Date: 11/15/2003
Publication Date: 12/12/2004
Citation: Everitt, J.H., Yang, C., Davis, M.R., Deloach Jr, C.J., Nibling, F. 2004. Using spatial information technologies for mapping four invasive weeds in the Rio Grande river system of Texas. Proceedings of 19th Biennial Workshop on Color Photography, Videography, and Airborne Imaging for Resource Assessment, Bethesda, Maryland. 2004 CD-ROM.

Interpretive Summary: The Rio Grande is the effective border between Texas and Mexico and is a major source of water for agricultural and municipal uses in Texas and northern Mexico. The area has been impacted by severe drought over the past decade which has led to water shortages in the entire region. Water shortages in the Rio Grande system have been contributed to by the invasion and spread of four invasive weeds: water hyacinth, hydrilla, giant reed, and saltcedar. Improved methods are needed to determine the distribution and density of these weeds in the Rio Grande system. A study was conducted using airborne remote sensing (aerial photography and videography) techniques integrated with global positioning system (GPS) and geographic information system (GIS) technologies for detecting and mapping waterhyacinth, hydrilla, giant reed, and saltcedar infestations in the Rio Grande from near Brownsville in south Texas to near El Paso in west Texas. Integration of the GPS with the video imagery permitted latitude-longitude coordinates of weed infestations to be recorded on each image. The GPS coordinates on imagery depicting where infestations of the weeds occurred were entered into the GIS. Distribution maps were developed of essentially the entire Rio Grande in Texas denoting the locations of infestations of the four weed species. This information should be useful to irrigation district personnel and natural resource managers interested in locating and controlling these noxious weeds.

Technical Abstract: The Rio Grande is a major source of water for agricultural and municipal uses in Texas and northern Mexico. Water shortages in the Rio Grande have been significantly impacted by the invasion and spread of four invasive weed species: waterhyacinth [Eichhornia crassipes (Mart.) Shohms], hydrilla [Hydrilla verticillata (L.F.) Royle], giant reed (Arundo donax L.) and saltcedar (Tamarix chinensis Lour.). Waterhyacinth and hydrilla are aquatic species that occur in the river, whereas giant reed and saltcedar are wetland species that grow adjacent to the river. This paper reports the results of an aerial remote sensing survey conducted in 2002 on the Rio Grande from its mouth near Brownsville in south Texas to near El Paso in west Texas. Aerial photography and videography were acquired simultaneously of the Rio Grande. Conventional color videography was used to detect waterhyacinth and hydrilla. Color-infrared photography and videography were used to detect giant reed, whereas conventional color photography and videography were used to distinguish saltcedar. The videography was integrated with global positioning system (GPS) and geographic information system (GIS) technologies for detecting and mapping the distribution of the four weed species. Integration of the GPS with the video imagery permitted latitude-longitude coordinates of weed infestations to be recorded on each image. The GPS coordinates on the video scenes depicting waterhyacinth, hydrilla, giant reed, and saltcedar infestations were entered into a GIS. Distribution maps were developed denoting the locations of infestations of these four weeds in or along the Rio Grande.