1. a Department of Land Resources Management and Environmental Protection , Mekelle University , P.O. Box 231, Mekelle , Ethiopia
2. b Department of Earth and Environmental Sciences , Katholieke Universiteit Leuven , Leuven , Belgium
3. c Georges Lemaitre Center for Earth and Climate Research, Earth and Life Institute Universite Catholique de Louvain , Louvain-la-Neuve , Belgium
4. d Research Foundation Flanders , Brussels , Belgium
5. e Department of Geography , Ghent University , Ghent , Belgium
6. f Department of Geology , University of Namur , Namur , Belgium
7. g Arid Land Research Center, Tottori University , Tottori , Japan