1. Professor, College of Urban and Environmental Sciences, Northwest Univ., Xi’an 710127, China; Key Laboratory of Earth Surface System and Environmental Carrying Capacity of Shaanxi Province, Northwest Univ., Xi’an 710127, China (corresponding author).
2. Master Student, College of Urban and Environmental Sciences, Northwest Univ., Xi’an 710127, China.
3. Professor, Dept. of City and Regional Planning, Univ. of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3140.
4. Associate Professor, School of Public Security, Northwest Univ. of Political Science and Law, Xi’an 710122, China.