国家自然科学基金项目41171108;中国科学院地理科学与资源研究所“一三五”战略科技计划项目2012QY004;中国科学院重点部署项目KZZD-EW-06-02;National Natural Science Foundation of China,No.41171108;Project of Institute of Geographic Sciences and Natural Resources Research,CAS,No.2012QY004;Key Program of the Chinese Academy of Sciences,No.KZZD-EW-06-02