Table 1. Candidate topographical and ecological characters of Oncomelania h. hupensis used for the SESR modeling.

Parameter	Source/data transformation	Original resolution	Relevance
Elevation	SRTM3 90 m Digital Elevation Model	90 m	Main snail distribution parameter
Slope	SRTM3 90 m Digital Elevation Model	90 m	Main snail distribution parameter
Bioclimatic variable bio6 (minimum temperature of coldest month)	Global Climate database at www.worldclim.org [82]	1000 m	Lethal temperature for O. hupensis is −2.7°C [71]
Bioclimatic variable bio11 (mean temperature of coldest quarter)	Global Climate database at www.worldclim.org [82]	1000 m	The development of both snails and parasite larvae requires a minimum temperature [72], [83], [84]
Bioclimatic variable bio12 (annual precipitation)	Global Climate database at www.worldclim.org [82]	1000 m	Proxy for suitable snail habitat [84]
Bioclimatic variable bio16 (precipitation of wettest quarter)	Global Climate database at www.worldclim.org [82]	1000 m	Proxy for flooding, transporting and/or potentially drowning of snails
Euclidean distances to water bodies	Calculated in ArcMap 9.3 based on water body data in www.diva-gis.org	90 m	Proxy for suitable snail habitat and/or flooding
Normalized Difference Vegetation Index (NDVI)	Moderate Resolution Imaging Spectroradiometer (MODIS) data for 2000–2010, United States Geological Survey. Clouds were masked and the ten year average was calculated by using the raster 2.0–12 package [85] for R 2.15	250 m	Proxy for soil moisture [8] and therefore suitable snail habitat (wetlands)

All original resolutions were re-sampled to 500 m.