Dynamics of Soil Erosion as Influenced by Watershed Management Practices: A Case Study of the Agula Watershed in the Semi-Arid Highlands of Northern Ethiopia.
Since the past two decades, watershed management practices such as construction of stone bunds and establishment of exclosures have been widely implemented in the semi-arid highlands of northern Ethiopia to curb land degradation by soil erosion. This study assessed changes in soil erosion for the years 1990, 2000 and 2012 as a result of such watershed management practices in Agula watershed using the Revised Universal Soil Loss Equation. The Revised Universal Soil Loss Equation factors were computed in a geographic information system for 30 × 30 m raster layers using spatial data obtained from different sources. The results revealed significant reduction in soil loss rates by about 55 % from about 28 to 12 t ha-1per year in 1990-2000 and an overall 64 % reduction from 28 to 10 t ha-1per year in 1990-2012. This change in soil loss is attributed to improvement in surface cover and stone bund practices, which resulted in the decrease in mean C and P-factors, respectively, by about 19 % and 34 % in 1990-2000 and an overall decrease in C-factor by 29 % in 1990-2012. Considerable reductions in soil loss were observed from bare land (89 %), followed by cultivated land (56 %) and shrub land (49 %). Furthermore, the reduction in soil loss was more pronounced in steeper slopes where very steep slope and steep slope classes experienced over 70 % reduction. Validation of soil erosion estimations using field observed points showed an overall accuracy of 69 %, which is fairly satisfactory. This study demonstrated the potential of watershed management efforts to bring remarkable restoration of degraded semi-arid lands that could serve as a basis for sustainable planning of future developments of areas experiencing severe land degradation due to water erosion.
Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori , 680-0001, Japan. almawayele@yahoo.com.|Department of Land Resources Management and Environmental Protection, Mekelle University, P.O. Box 231, Mekelle, Ethiopia. almawayele@yahoo.com.
Ayele Almaw
0000-0002-8228-4048
AA
Fenta
Arid Land Research Center, Tottori University, 1390 Hamasaka, Tottori , 680-0001, Japan.
Hiroshi
H
Yasuda
Faculty of Agriculture, Tottori University, 4-101 Koyama-cho Minami, Tottori , 680-8553, Japan.
Katsuyuki
K
Shimizu
International Platform for Dryland Research and Education, Tottori University, 1390 Hamasaka, Tottori , 680-0001, Japan.
Nigussie
N
Haregeweyn
World Agroforestry Centre (ICRAF), P.O. Box 5689, Addis Ababa, Ethiopia.
Aklilu
A
Negussie
D003247:Conservation of Natural Resources / Q000379:methods* / Q000639:trends; D003889:Desert Climate; D004784:Environmental Monitoring / Q000379:methods*; D005002:Ethiopia; D005544:Forecasting; D040362:Geographic Information Systems; D008962:Models, Theoretical; D012987:Soil / Q000737:chemistry*; D062066:Water Resources / Q000600:supply & distribution*
D012987:Soil
Ethiopia; RUSLE model; Semi-arid; Soil erosion; Watershed management