
High-Tech Surveillance Nabs Water WeedsBy Ben Hardin May 24, 1999The thickest patches of exotic weeds
clogging the lower Rio Grande River cant hide any longer and could get
their comeuppance, thanks to high-tech aerial mapping technology developed by
Agricultural Research Servicescientists. Beginning last year, the technology helped the
Texas Natural Resource Conservation
Commission (TNRCC) and the
Texas
Parks and Wildlife Department detect tons of hydrilla and water hyacinth
growing on the river so they could be removed. During last years drought,
these weeds were sucking up scarce water and obstructing the flow of irrigation
water. Hydrilla, native to Asia, and water hyacinth, native to South America, share
a notoriety for clogging marinas, snarling fishing lines and interfering with
flood control and hydroelectric power generation. The weeds grow so
competitively with other aquatic plants that biological diversity may be
threatened in many lakes and streams through southern parts of North America. ARS and TNRCC researchers used aircraft to acquire color-infrared video
imagery that pinpointed locations where the alien vegetation had infested the
Rio Grande. The imagery makes water hyacinth appear orange-red and hydrilla
appear reddish-brown. The scientists measured the area of infestations by
computer analysis of the imagery. Verification of the data by boat helped advance other research thats
aimed at conducting wider-scale surveys of weed infestations using additional
remote sensing, global positioning system and geographic information system
technologies. These technologies may help scientists make timely assessments of
experimental weed control measures. ARS is the chief scientific arm of the U.S.
Department of Agriculture. Scientific contact: James H. Everitt, ARS
Subtropical Agricultural Research Center,
Weslaco, Texas; phone (956) 969-4824, fax (956) 969-4893,
[email protected]. U.S. Department of Agriculture | |