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Title: USING SPATIAL INFORMATION SYSTEM TECHNOLOGIES TO DETECT AND MAP WATERHYACINTH AND HYDRILLA INFESTATIONS IN THE RIO GRANDE RIVER

Author
item Everitt, James
item Davis, Michael

Submitted to: Journal of Aquatic Plant Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2002
Publication Date: 12/20/2003
Citation: Everitt, J.H., Davis, M.R. 2003. Using spatial information system technologies to detect and map waterhyacinth and hydrilla infestations in the Rio Grande river. Journal of Aquatic Plant Management. 41(2):93-98.

Interpretive Summary: Waterhyacinth and hydrilla are two invasive aquatic weeds that have infested the Rio Grande River in southern Texas. These weeds interfere with movement of water for drainage and irrigation purposes and artificially raise water levels and cause increased water loss through bank absorption. Aerial photography, airborne videography, geographic information system (GIS), and global positioning system (GPS) technologies were used in 2002 to detect and map waterhyacinth and hydrilla infestations in the Rio Grande. The integration of the GPS with the video imagery permitted the latitude-longitude coordinates of waterhyacinth and hydrilla infestations to be recorded on each image. The GPS coordinates were entered into a GIS, and a map was produced depicting the distribution of these weeds in the Rio Grande. This survey showed an increase in distribution of waterhyacinth and hydrilla in the river as compared to a 1998 survey. These results should be of interest to aquatic weed specialist and wetland resource managers.

Technical Abstract: This paper describes a study conducted in 2002 on the application of aerial photography and videography, global positioning system (GPS), and geographic information system (GIS) technologies for detecting and mapping waterhyacinth [Eichhornia crassipes (Mort.) Solms] and hydrilla [Hydrilla verticillata (L. F.) Royle] infestations in the Rio Grande in extreme southern Texas. Waterhyacinth and hydrilla could be readily distinguished in color-infrared photography, color-infrared videography, and normal color videography. The integration of the GPS with the video imagery permitted latitude-longitude coordinates of waterhyacinth and hydrilla infestations to be recorded on each image. The GPS latitude-longitude coordinates were entered into a GIS to map waterhyacinth and hydrilla infestations in the Rio Grande. This survey showed an increase in distribution of these weeds in the river as compared to a 1998 survey.