title: [Spatial analysis of Oncomelania snail information based on grid data-driven].
abstract: OBJECTIVE
  To explore the relationship between the Oncomelania snail situation and the distance to the water source, soil humidity, vegetation and water level in flood seasons in the islets of Changsha Section of the Xiang River.
  
  
  METHODS
  Combined with the NDVI and soil humidity of islets, the GIS spatial analysis based on grid data-driven was used to analyze the snail situation in Changsha Section of the Xiang River from 2005 to 2009. The relationship between the snail density and the water level in blood seasons was analyzed.
  
  
  RESULTS
  In 2005, the snails in Zengpi Islet were mainly distributed at the range of 40-240 m far away from the nearest water source, and the number at the spots with a distance of 60 m was the largest. There was an obvious positive correlation between the snail density and water level in flood seasons. The ranges of the Normalized Difference Vegetation Index and soil humidity of Zengpi Islet in 2005 were 0-0.982 and 0-0.298, respectively and the main vegetation in Changsha Section of the Xiang River were weed and sedge. The map of snail situation by year was drawn according to the standard water level, which reflected the snail situation intuitionistically.
  
  
  CONCLUSIONS
  By using spatial analysis based on grid data-driven, the situation of vegetation, soil humidity and snail accurately can be reflected, which can help us to understand the endemic situation timely. Even under the circumstance of human intervention, the water level in flood seasons is still an important factor influencing the change of snail situation.
authors.affiliation: Mathematics and Computer Science College, Hunan Normal University, Changsha 410081, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Qiong-Yao
authors.initials: QY
authors.lastname: Huang
authors.forename: Yun-Ziang
authors.initials: YZ
authors.lastname: Liu
authors.forename: Jiang-Tao
authors.initials: JT
authors.lastname: Wang
authors.forename: Fei
authors.initials: F
authors.lastname: Peng
authors.forename: Nian-Meng
authors.initials: NM
authors.lastname: Liu
mesh_terms: D000818:Animals; D004197:Disease Reservoirs / Q000469:parasitology*; D017753:Ecosystem; D040362:Geographic Information Systems / Q000295:instrumentation*; D006801:Humans; D006813:Humidity; D045483:Rivers / Q000469:parasitology; D012547:Schistosoma / Q000502:physiology; D012552:Schistosomiasis / Q000453:epidemiology / Q000517:prevention & control*; D012908:Snails / Q000254:growth & development*; D012987:Soil / Q000032:analysis / Q000469:parasitology
chemical_list: D012987:Soil