[1] Open Univ, Fac Math Comp & Technol, Gateshead NE8 3DF, England
[2] Univ Newcastle, IRES, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
[3] Univ Durham, Dept Geog, Durham DH1 3LE, England
[4] Indian Inst Technol, Engn Geosci Grp, Kanpur 208018, Uttar Pradesh, India
[5] Harran Univ, Dept Geog, TR-63300 Sanliurfa, Turkey