Purpose

Soil erosion is one of the most significant environmental problems in the Ethiopian highlands. The study was conducted in the main Gumara-Maksegnit watershed and at the sub-catchment scale with and without soil and water conservation (SWC) measures to estimate event-based sediment yield and evaluate the effectiveness of level stone bunds on sediment reduction.

Materials and methods

The runoff volume and peak discharge were recorded manually with the help of a time series of pictures using the DOERR digital camera. The sediment concentration was determined from manual runoff samples and grid-based soil samples were collected at 162 points. The slope map and satellite image were obtained from the USGS Earth Explorer database with 30-m and 15-m spatial resolutions, respectively. Finally, all six-model factors were combined using the raster calculator in map algebra through the MUSLE framework. The paired t test parametric procedures were applied to test whether the means of event-based predicted and observed sediment yield values are different.

Result and discussion

The average event-based observed and estimated sediment yields were 0.5581 and 0.4031 Mg ha⁻¹ for the Gumara-Maksegnit watershed, 0.5125 and 0.4194 Mg ha⁻¹ for the treated (with SWC) sub-catchment, and 1.0694 and 1.0150 Mg ha⁻¹ for the untreated (without SWC) sub-catchment, respectively. The observed and estimated sediment losses within the main watershed and sub-catchments were not significantly different. However, comparing the treated and untreated sub-catchments, the sediment losses were highly significantly different and the stone bunds have a capacity for reducing sediment loss by 58.8%. In general, the MUSLE model performed well to estimate sediment yield in the study area with R² values of 0.62, 0.72, and 0.7 and NSE values of 0.53, 0.71, and 0.34 for treated, untreated, and the main Gumara-Maksegnit watershed, respectively.

Conclusion

The results showed that stone bunds have a capacity for reducing sediment loss by 58.8% as compared with untreated sub-catchment. Therefore, successful implementation of stone bunds in the study area, as well as similar agro-ecologies, has a great benefit to enhance land productivity. Meanwhile, the MUSLE model was well suited for reliable applications of sediment yield estimation in the study area.

中文翻译：

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埃塞俄比亚尼罗河流域古玛拉-马克斯格尼特流域的产沙量估算和水平石堤减少沙土流失的有效性

目的

土壤侵蚀是埃塞俄比亚高地最严重的环境问题之一。这项研究是在古玛拉-马克斯格尼特（Gumara-Maksegnit）主要流域以及有和没有水土保持（SWC）措施的集水规模下进行的，以估算基于事件的沉积物产量，并评估平整的石堤对减少沉积物的有效性。

材料和方法

径流量和峰值流量是使用DOERR数码相机在时间序列图片的帮助下手动记录的。从人工径流样品确定沉积物浓度，并在162个点收集基于网格的土壤样品。坡度图和卫星图像分别从USGS Earth Explorer数据库获得，其空间分辨率为30-m和15-m。最后，通过MUSLE框架在地图代数中使用栅格计算器将所有六个模型因子组合在一起。配对的t检验参数程序用于检验基于事件的预测和观察到的沉积物产率值的方法是否不同。

结果与讨论

平均基于事件观察和估计的沉淀产率分别为0.5581和0.4031镁公顷^-1为Gumara-Maksegnit分水岭，0.5125和0.4194镁公顷^-1的（与SWC）处理分集水，和1.0694 1.0150和镁公顷^{- 1}未处理（不SWC）分集水，分别。在主要流域和次流域内观察到的和估计的沉积物损失没有显着差异。然而，比较处理过的和未处理过的子汇水面积，沉积物的损失有很大的不同，石堤具有将沉积物损失减少58.8％的能力。通常，MUSLE模型在R ²的研究区域中能很好地估计沉积物产量 对于处理过的，未经处理的和主要的Gumara-Maksegnit分水岭，水的NSE值分别为0.62、0.72和0.7，NSE值分别为0.53、0.71和0.34。

结论

结果表明，与未经处理的集水区相比，石堤具有将泥沙流失减少58.8％的能力。因此，在研究区成功实施石滩以及类似的农业生态，对于提高土地生产力具有巨大的好处。同时，MUSLE模型非常适合研究区域泥沙产量估算的可靠应用。