[Relationship between environmental remote sensing alternate indexes and Oncomelania snail distribution in hilly and mountainous areas].

OBJECTIVE

To analyze the relationship between Oncomelania snail distribution and environmental remote sensing indexes in hilly and mountainous areas.

METHOD

The normalized different vegetation index (NDVI), land surface temperature (LST), humidity index (Wetness) of 85 snail spots in Dali City were extracted for statistical analysis by TM image, and the land-use types were classified. LST, NDVI, Wetness, snail density and land-use types were overlaid and analyzed by using a weight of suitability model of ArcGIS 9.2, and snail appropriate distribution range in Dali City was calculated.

RESULTS

The distribution of LST, NDVI, Wetness values of the investigated snail points were approximately normal, and most of the snail points distributed nearby the average values of the remote sensing alternate indexes, then gradually reduced to the ends. More than 90% of the snail spots were distributed in the land type with crops and grassland. The environments in Dali City were divided into unsuitable snail environment (0-14 points), suitable snail environment (15-21 points), and optimum snail environment (22-26 points) by the weight suitability mode.

CONCLUSIONS

Environmental remote sensing indicators can reflect the environmental factors affecting snail distribution directly. Combining remote sensing with GIS and field survey can describe, judge and forecast the distribution of snails.