Fig. 1
![Fig. 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12887-020-02281-9/MediaObjects/12887_2020_2281_Fig1_HTML.png)
The geographical location of Hunan Province in China.(GIS10.2, The URL is https://user.qzone.qq.com/327532957/infocenter)
The geographical location of Hunan Province in China.(GIS10.2, The URL is https://user.qzone.qq.com/327532957/infocenter)