Soil erosion remains one of the principal environmental problems in arid regions. This study aims to assess and quantify the variability of soil erosion in the Koutine catchment using the RUSLE (Revised Universal Soil Loss Equation) model. The Koutine catchment is located in an arid area in southeastern Tunisia and is characterized by an annual mean precipitation of less than 200 mm. The model was used to examine the influence of topography, extreme rainstorm intensity and soil texture on soil loss. The data used for model validation were obtained from field measurements by monitoring deposited sediment in settlement basins of 25 cisterns (a traditional water harvesting and storage technique) over 4 years, from 2015 to 2018. Results showed that slope is the most controlling factor of soil loss. The average annual soil loss in monitoring sites varies between 0.01 and 12.5 t/ha/y. The storm events inducing the largest soil losses occurred in the upstream part of the Koutine catchment with a maximum value of 7.3 t/ha per event. Soil erosion is highly affected by initial and preceding soil conditions. The RUSLE model reasonably reproduced (R² = 0.81) the spatiotemporal variability of measured soil losses in the study catchment during the observation period. This study revealed the importance of using the cisterns in the data-scarce dry areas as a substitute for the classic soil erosion monitoring fields. Besides, combining modeling of outputs and field measurements could improve our physical understanding of soil erosion processes and their controlling factors in an arid catchment. The study results are beneficial for decision-makers to evaluate the existing soil conservation and water management plans, which can be further adjusted using appropriate soil erosion mitigation options based on scientific evidence.

中文翻译：

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干旱地区土壤侵蚀估算：突尼斯东南部 Koutine 流域的案例研究

土壤侵蚀仍然是干旱地区的主要环境问题之一。本研究旨在使用 RUSLE（修订后的通用土壤流失方程）模型评估和量化 Koutine 流域土壤侵蚀的可变性。Koutine 流域位于突尼斯东南部的干旱地区，年平均降水量不足 200 毫米。该模型用于检验地形、极端暴雨强度和土壤质地对土壤流失的影响。用于模型验证的数据是从 2015 年到 2018 年 4 年间通过监测 25 个蓄水池（一种传统的集水和蓄水技术）沉降盆地中沉积物的现场测量获得的。 结果表明，坡度是土壤的最大控制因素损失。监测点的年平均土壤流失量在 0.01 至 12.5 吨/公顷/年之间变化。导致最大土壤流失的风暴事件发生在 Koutine 流域的上游部分，每次事件的最大值为 7.3 吨/公顷。土壤侵蚀受初始和先前土壤条件的影响很大。合理再现的 RUSLE 模型（R² = 0.81) 观测期间研究流域实测土壤流失的时空变异性。这项研究揭示了在数据稀缺的干旱地区使用蓄水池替代经典土壤侵蚀监测领域的重要性。此外，结合输出建模和现场测量可以提高我们对干旱集水区土壤侵蚀过程及其控制因素的物理理解。研究结果有利于决策者评估现有的水土保持和水管理计划，可以根据科学证据使用适当的土壤侵蚀缓解方案进一步调整。