title: [Further study on possibility of diffusion of Oncomelania hupensis with water in river channels of the east route of South-to-North Water Diversion Project].
abstract: OBJECTIVE
  To study the drifting law of floats and potential risks of Oncomelania hupensis diffusion in the water diversion rivers of the east route of South-to-North Water Diversion Project.
  
  
  METHODS
  The O. hupensis snails in the river channels were monitored by the salvage method and snail luring method with rice straw curtains, and the diffusion possibility of snails along with water was assessed through the drift test of floats with GPS.
  
  
  RESULTS
  In the flood seasons from 2006 to 2013, totally 8 338.0 kg of floats were salvaged, and 2 100 rice straw curtains were put into water in the Li Canal and Jinbao shipping channel, but no Oncomelania snails were found. The drift test of floats with GPS before water diversion showed that the flow velocity on water surface (northbound) was 0.45 m/s, the average drift velocity of the floats was 0.56 - 0.60 m/s, and the average drift distances each time were 999.70 - 1 995.50 m in the Gaoshui River section, while there were no obvious drift in Jinbao shipping channel section. During the water diversion period, the flow velocity on water surface (northbound) was 0.45 m/s, the average drift velocity of the floats was 0.35 - 0.41m/s, and the average drift distances each time were 1 248.06 -1 289.44 m in the Gaoshui River, while in Jinbao shipping channel section, the flow velocity on water surface was 0.28 m/s, the average drift velocity of the floats was 0.25 - 0.27 m/s, and the average drift distances each time were 477.76 - 496.38 m. The drift test showed that the floats gradually closed to the river bank as affected by water flow, wind direction and ship waves, when blocked by the reeds, water plants or other obstacles, and they would stopped and could not continue to drift without outside help.
  
  
  CONCLUSIONS
  There are no Oncomelania snails found in the river channels of the east route of South-to-North Water Diversion Project. The drifting distance of the floating debris along with the water is restricted by the flow rate and shore environment.
authors: Yi-Xin
authors: YX
authors: Huang
authors: De-Rong
authors: DR
authors: Hang
authors: Hong-Ping
authors: HP
authors: Tang
authors: Dao-Kuan
authors: DK
authors: Sun
authors: Can-Hua
authors: CH
authors: Zhou
authors: Jin-Bin
authors: JB
authors: Gao
authors: Bo
authors: B
authors: Zheng
authors: Gui-Quan
authors: GQ
authors: Hu
authors: Qian
authors: Q
authors: Li
authors: Yong-Jun
authors: YJ
authors: Huang
authors: Guang-Song
authors: GS
authors: She
authors: Zhi-Yuan
authors: ZY
authors: Ren
mesh_terms: D000818:Animals; D002681:China; D004197:Disease Reservoirs / Q000145:classification / Q000706:statistics & numerical data; D011157:Population Dynamics; D045483:Rivers / Q000737:chemistry / Q000469:parasitology*; D012908:Snails / Q000145:classification / Q000254:growth & development*