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.
Department of Land Resources Management and Environmental Protection, Mekele University, P.O. Box 231, Mekele, Ethiopia.
J Environ Manage. 2023 Jan 15;326(Pt A):116707. doi: 10.1016/j.jenvman.2022.116707. Epub 2022 Nov 12.
Soil erosion by water is a major cause of land degradation in the highlands of Ethiopia and anywhere else in the world, but its magnitude and variability are rarely documented across land uses and climatological conditions. The purpose of this study was to examine runoff and soil loss responses under cropland (CL) and grazing land (GL) management practices in three climatic regions of the Ethiopian highlands: semi-arid (Mayleba), dry sub-humid (Gumara), and humid (Guder). We measured runoff and soil loss using runoff plots with and without soil and water conservation (SWC) measures (trenches, stone/soil bunds [embankments] with trenches on the upslope side, and exclosure) during the rainy season (July-September). The results revealed significant variation in runoff and soil loss amounts across land uses, SWC measures, and climatic regions. At Mayleba, seasonal runoff and soil loss in control plot were far higher from GL (280 mm, 26.5 t ha) than from CL (108 mm, 7.0 t ha) largely due to lack of protective vegetation cover and soil disruption because of intense grazing. In contrast, at Gumara and Guder, seasonal soil loss values were much higher from CL (21.4-71.2 t ha) than from GL (0.6-24.2 t ha) irrespective of runoff values. This was attributed to the excessive tillage/weeding operations involved in cultivation of teff (cereal crop) at Gumara and potato at Guder. Although SWC measures (practices) substantially reduced runoff and soil loss (decreased by 23%-86%) relative to control plot, seasonal soil loss under GL uses with trenches at Mayleba (12.6 t ha), CL with soil bunds and trenches at Gumara (22.1 t ha), and Guder (21.4 t ha) remained higher than the average tolerable soil loss rate (10 t ha year) proposed for the Ethiopian highlands. This suggests that SWC measures should be carefully designed and evaluated specific to land use and climatic conditions. Overall, the results of this study can help improve SWC planning in regions where land use and climate impact on soil erosion vary across geographical areas, as they do in Ethiopia and anywhere else. However, further investigation is crucial with replication of measurements over years and locations to provide more accurate information on land use, management and climate controls on hydrological and soil erosion processes.
水蚀是埃塞俄比亚高地和世界其他任何地方土地退化的主要原因，但在土地利用和气候条件下，其规模和变异性很少有记录。本研究的目的是在埃塞俄比亚高地的三个气候区（半干旱的 Mayleba、干旱亚湿润的 Gumara 和湿润的 Guder）研究耕地（CL）和放牧地（GL）管理实践下的径流量和土壤流失响应。我们在雨季（7 月至 9 月）使用带有和不带有水土保持（SWC）措施（沟渠、具有坡上沟渠的土石堤岸[堤岸]和围栏）的径流场测量径流量和土壤流失。结果表明，土地利用、SWC 措施和气候区之间的径流量和土壤流失量存在显著差异。在 Mayleba，由于缺乏保护植被覆盖和由于强烈放牧导致的土壤破坏，对照小区的季节性径流量和土壤流失量远高于 GL（280mm，26.5t ha）。相比之下，在 Gumara 和 Guder，无论径流量如何，CL 的季节性土壤流失值（21.4-71.2t ha）远高于 GL（0.6-24.2t ha）。这归因于 Gumara 种植 teff（谷物作物）和 Guder 种植马铃薯时过度的耕作/除草作业。尽管与对照小区相比，SWC 措施（做法）大大减少了径流量和土壤流失（减少了 23%-86%），但在 Mayleba 有沟渠的 GL 用途、Gumara 有土壤堤岸和沟渠的 CL 用途和 Guder（12.6t ha）的土壤流失仍然高于埃塞俄比亚高地提出的平均可容忍土壤流失率（10t ha 年）。这表明 SWC 措施应根据土地利用和气候条件进行精心设计和评估。总的来说，本研究的结果可以帮助改善土地利用和气候对土壤侵蚀影响在地理区域内变化的地区的 SWC 规划，就像在埃塞俄比亚和其他任何地方一样。然而，需要进一步调查，以多年和多个地点的测量结果为基础，提供有关土地利用、管理和气候对水文和土壤侵蚀过程的控制的更准确信息。
