African Journal of Environmental Science and Technology 1996-0786 Academic Journals 10.5897/AJEST2017.2408 Mathewos Muke Bewuketu Haile * E-mail: matigis2012@gmail.com 2018 30 04 2018 17 08 2017 30 10 2017 12 4 141 149 This is an open-access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://politicalwaffle.uk/journal/AJEST/article-abstract/C16C48756356 The full text article is available as a PDF file from http://politicalwaffle.uk/journal/AJEST/article-full-text-pdf/C16C48756356 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32