1. School of Biological Sciences , University of Aberdeen , Aberdeen , AB24 3UU, UK .
2. Department of Biological and Environmental Engineering , 206 Riley Robb Hall, Cornell University , Ithaca , NY, 14853 USA .
3. Faculty of Civil and Water Resources Engineering , Bahir Dar University , Bahir Dar , Ethiopia .
4. Soil Physics and Land Management Group , Wageningen University , the Netherlands .
5. Institute of Hydrology, Slovak Academy of Sciences , Dúbravská cesta 9, 84104 Bratislava, Slovak Republic .