1Department of Computer Science, Loughborough University, Leicestershire LE11 3TU, UK
2School of Computing and Technology, University of Derby, Kedleston Road, Derby DE22 1GB, UK
3Department of Geography, King's College London, Strand, London WC2R 2LS,#N#UK
4Institute of Hydrology and Water Resources, Three Gorges University, Yichang, Hubei, China