1. a School of Geography, University of Nottingham , Nottingham, NG7 2RD, UK
2. b Department of Computer Science , Loughborough University , Loughborough, LE11 3TU, UK
3. c School of Geography, University of Leeds , Leeds, LS2 9JT, UK
4. d Department of Civil and Environmental Engineering , University of Auckland, Private Bag , 92019, Auckland, New Zealand