[Snail habitats detection in the marshland of Eastern Dongting Lake Area, based on China-Brazil Earth Resources Satellite-02B CCD data].

Objective: To detect the snail habitats from the marshland of Eastern Dongting Lake Area, using the Remote Sensing (RS) and Geographic Information System (GIS) technology based on the China-Brazil Earth Resources Satellite-02B (CBERS-02B) CCD images.

Methods: According to the two typical traits of snail habitats in marshland including "water in summer and land in winter" and "no grass, no snails", the "water in summer and land in winter" region and the vegetation coverage region were calculated by RS image processing respectively. The two regions mentioned above were then overlapped to confirm the snail habitats through comparing with the data from field survey under spatial overlapping of Arcgis as the last step.

Results: In Eastern Dongting Lake area, the "water in summer and land in winter" region and vegetation coverage region were predicted based on the formula normalized difference water index (NDWI) > 0.01 and normalized difference vegetation index (NDVI) > 0.36, respectively. The snail habitat was determined by theme overlay of the two regions said above. The agreement rate between the prediction and the geospatial data of field survey was 93.55%, which demonstrated the final results were credible and reliable.

Conclusion: CBERS-02B image could be used to detect the snail habitats and to monitor the changes of them, so as to find out the characteristics of distribution and the trends of diffusion. The snail index (discriminant 1 and 2) seemed to be suitable for the detection of snail habitats in the marshland of Lake area and used for the programs of snail control.