1. a Institute for Technology and Resources Management in the Tropics (ITT), Cologne University of Applied Sciences , Betzdorfer Straße 2, D-50679, Köln, Germany
2. b Institute of Geography, University of Leipzig , Johannisallee 19 a, D-04103, Leipzig, Germany
3. c Centre of Advanced Studies in Arid Zones (CEAZA) , University of La Serena , Casilla 599, La Serena, Chile
4. d Mines Engineering Department , University of La Serena , Benavente 980, La Serena, Chile