|Davis, Michael Rene|
Submitted to: Geocarto International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2006
Publication Date: 3/1/2007
Citation: Everitt, J.H., Davis, M.R., Nibling, F.L. 2007. Using spatial information technologies for detecting and mapping Eurasian watermilfoil. Geocarto International. 22(1):49-61. Interpretive Summary: Invasive plant species are an extremely big problem in the United States and Canada. Eurasian watermilfoil is an exotic, aquatic weed that has invaded many lakes and other waterways throughout the United States and southern Canada. A study was conducted to determine the potential of using remote sensing techniques to detect Eurasian watermilfoil infestations in Texas waterways. Field reflectance measurements showed that Eurasian watermilfoil had distinct spectral characteristics. Aerial color-infrared photography and videography were used successfully to distinguish Eurasian watermilfoil infestations. A global positioning system (GPS) was integrated with the video imagery permitting latitude-longitude coordinates of Eurasian watermilfoil infestations to be recorded on each image. A portion of the Rio Grande River in southwest Texas was flown with the video system to detect Eurasian watermilfoil infestations. The GPS coordinates on the color-infrared video scenes depicting Eurasian watermilfoil infestations were entered into a geographic information system (GIS) to map the distribution of this invasive weed in the Rio Grande. These findings should be of interest to wetland resource managers who are interested in locating infestations and controlling this aquatic weed.
Technical Abstract: This paper describes the spectral light reflectance characteristics of Eurasian watermilfoil (Myriophyllum spicatum L.) and the application of aerial color-infrared photography and videography for distinguishing infestations of this invasive, exotic, submerced aquatic weed in Texas waterways. Airborne videography was integrated with global positioning system (GPS) and geographic information system (GIS) technologies for mapping the distribution of Eurasian watermilfoil. Field reflectance measurements showed that Eurasian watermilfoil could be spectrally distinguished from other associated plant species in either the visible green, visible red, or near-infrared regions of the electromagnetic spectrum. Eurasian watermilfoil submerged at depths greater than 5 cm below the water surface had similar visible reflectance to water. Surfaced Eurasian watermilfoil could be distinguished on color-infrared (CIR) aerial photography and videography where it had a grayish-pink or faint pink image response. Integration of the GPS with the video imagery permitted latitude-longitude coordinates of Eurasian watermilfoil infestations to be recorded on each image. A stretch of the Rio Grande River in southwest Texas was flown with the photographic and video systems to detect Eurasian watermilfoil infestations. The GPS coordinates on the color-infrared video scenes depicting Eurasian watermilfoil infestations were entered into a GIS to map the distribution of this invasive weed in the Rio Grande. .