Agroecology-based soil erosion assessment for better conservation planning in Ethiopian river basins

Ayele Almaw Fenta; Atsushi Tsunekawa; Nigussie Haregeweyn; Mitsuru Tsubo; Hiroshi Yasuda; Takayuki Kawai; Kindiye Ebabu; Mulatu Liyew Berihun; Ashebir Sewale Belay; Dagnenet Sultan

doi:10.1016/j.envres.2021.110786

Agroecology-based soil erosion assessment for better conservation planning in Ethiopian river basins

Environ Res. 2021 Apr:195:110786. doi: 10.1016/j.envres.2021.110786. Epub 2021 Jan 23.

Affiliations

¹ Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori, 680-0001, Japan; Department of Land Resources Management and Environmental Protection, Mekelle University, P.O. Box 231, Mekelle, Ethiopia. Electronic address: almawayele@yahoo.com.
² Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori, 680-0001, Japan.
³ International Platform for Dryland Research and Education, Tottori University, Tottori, 680-0001, Japan.
⁴ Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori, 680-0001, Japan; College of Agriculture and Environmental Sciences, Bahir Dar University, P.O. Box 1289, Bahir Dar, Ethiopia.
⁵ Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori, 680-0001, Japan; Faculty of Civil and Water Resource Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia.
⁶ Department of Earth Science, Bahir Dar University, P.O. Box 79, Bahir Dar, Ethiopia.
⁷ Faculty of Civil and Water Resource Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia.

PMID: 33497678
DOI: 10.1016/j.envres.2021.110786

Abstract

Soil erosion by water is one of the main environmental concerns in Ethiopia. Several studies have examined this at plot and watershed scales, but no systematic study of soil erosion severity and management solutions at national scale is available. This study investigated soil erosion and the potential of land-cover- and agroecology-specific land management practices in reducing soil loss through employing the Revised Universal Soil Loss Equation and the best available datasets. The mean rate of soil loss by water erosion in Ethiopia was estimated as 16.5 t ha^-1 yr^-1, with an annual gross soil loss of ca. 1.9 × 10⁹ t, of which the net soil loss was estimated as ca. 410 × 10⁶ t (22% of the gross soil loss). Soil loss varied across land cover types, 15 agroecological zones, and 10 river basins, with the main contributors in the respective analyses being cropland (ca. 23% of Ethiopia; 50% of the soil loss; mean soil loss rate of 36.5 t ha^-1 yr^-1), Moist Weyna Dega (ca. 10%; 20%; 33.3 t ha^-1 yr^-1), and the Abay basin (ca. 15%; 30%; 32.8 t ha^-1 yr^-1). Our results show that ca. 25% of Ethiopia (28 × 10⁶ ha) has soil loss rates above 10 t ha^-1 yr^-1, which is higher than the tolerable soil loss limits estimated for Ethiopia. Ex-ante analysis revealed that implementation of land-cover- and agroecology-specific land management practices (level bunds, graded bunds, trenches, and exclosures combined with trenches and/or bunds) in such areas could reduce the mean soil loss rate from 16.5 t ha^-1 yr^-1 to 5.3 t ha^-1 yr^-1 (mean, by ca. 68%; range, 65-70%). Suitable land management practices in the Abay and Tekeze basins and Dega and Weyna Dega agroecologies, which experience particularly severe erosion, would account for ca. 50 and 70% of the estimated soil loss reduction, respectively. This study can help raise awareness among policy makers and land managers of the extent and severity of soil loss by water erosion for better conservation planning in river basins to support sustainable use of land and water resources.

Keywords: Agroecology; Dryland; Land cover; Land degradation; Land management.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Agriculture
Conservation of Natural Resources*
Environmental Monitoring
Geographic Information Systems
Rivers*
Soil
Soil Erosion

Substances

Soil