Study On The Relationship Between Vegetation Index Of Remote Sensing Image And The Snail Distribution In JiangNing County

The schistosomiasis is the developing country's main public hygiene problem, which is a serious threaten to public health, and mainly distributes along Yangtse River and in 13 province, city, municipality in southern of Yangtse River in china. Schistosome and snail-the intermediate host distributed endemically, and the environmental factors are correlation with transmission of schistosomiasis, breeding and reproduction of snail. The study on the correlation between the environmental factors and snail distribution, the transmission of schistosomiasis is major matter in snail and schistosomiasis control programs. Remote Sensing can offer the environmental factors information timely, quickly, meanwhile vast study in many country indicated Remote Sensing can detect the distribution of the intermediate host or medium habitats more cost-effective, exacter than conventional epidemiology survey. So Remote Sensing supervising study for snail habitats is very important, promising epidemiological tool for the studieson schistosomiasis.By study on the correlation between the transmission of schistosomiasis and snail distribution in JiangNing, Nanjing city in 1991~1999,we found that new case load correlated positively with snail area, snail density and incidence of pixel with the alive snail whether on mountain or on marshland(P<0.05).the result indicate that the monitoring on snail distribution have important significance for schistosomiasis prevention.Based on study on the correlation in the NDVI extracted from NOAA-AVHRR satellite image and the snail density, incidence of pixel with the alive snail on mountain, we found that the snail density on mountain correlated positively with the maximum NDVI in May, the mean NDVI in June and the difference of extremity NDVI (P<0.05). and we establish the equation Y=0.625*V10+0.257*V, ,-0.226*V4-0.0588*S, (R2=0.888), Y is the nature logarithm of the snail density, V<^ V)(^ Vn is respectively the difference of extremity NDVI in April, October and November, Si is NDVI in the last ten-day of September. Otherwise incidence of pixel with the alive snail on mountain correlated positively with the maximum NDVI in April, May, the mean NDVI in June, the minimum NDVI in December and the difference of extremity NDVI in October, and we establish the equation Y=0.65*Vio-115*Sl+0.189* Apm-0.205*JLff0.125*UEmin (R2=0.776), (Vlo is the difference of extremity NDVI in October, S| is NDVI in the last ten-day of September. Apm is the middle ten-day of April, JLf is the first ten-day of July, UEmin is the minimum NDVI in non-epidemiology season.)Contemporarily we study on the correlation in the NDVI extracted from Terra-MODIS satellite image and the snail density, incidence of pixel with the5alive snail on mountain, and found that the snail density on marshland correlated positively with the mean NDVI in the first ten-day of May, the maximum NDVI (N20max) in the last ten-day of May. Otherwise incidence of pixel with the alive snail on marshland correlated positively with the mean NDVI (N2mean) in he first ten-day of May. Respectively we establish the equation Y=0.00947*N20m (R2=0.73), Y=0.0186*N2mean(R2=0.906).The research show that the NOAA-AVHRR and Terra- MODIS satellite images preferably reflect the status of the vegetation on mountain, and on marshland in JiangNing county. So they can be applied to the study on supervising the snail habitat, and enhance supervising efficiency by integrate other environment data.