Abstract The development of adaptation and mitigation strategies to tackle anthropic and climate changes impacts is becoming a priority in drought-prone areas. This study examines the capabilities of indigenous rainwater harvesting techniques (RWHT) to be used as a viable solution for flood mitigation. The study analyses the hydraulic performance of the most used micro-catchment RWHT in sub-Saharan regions, in terms of flow peak reduction (FPR) and volume reduction (VR) at the field and basin scale. Parametrized hyetographs were built to replicate the extreme precipitations that strike Sahelian countries during rainy seasons. 2D hydrodynamic simulations showed that half-moons placed with a staggered configuration (S-HM) have the best performances in reducing runoff. At the field scale, S-HM showed a remarkable FPR of 77% and a VR of 70% in case of extreme rainfall. Instead at the basin scale, in which only 5% of the surface was treated, 13% and 8% respectively for FPR and VR were obtained. In addition, the reduction of the runoff coefficient (Rc) between the different configuration was analyzed. The study critically evaluates hydraulic performances of the different techniques and shows how pitting practices cannot guarantee high performance in case of extreme precipitations. These results will enrich the knowledge of the hydraulic behavior of RWHT; aspect marginally investigated in the scientific literature. Moreover, this study presents the first scientific application of HEC-RAS as a rainfall-runoff model. Despite some limitations, this model has the effective feature of using very high-resolution topography as input for hydraulic simulations. The results presented in this study should encourage stakeholders to upscale the use of RWHT in order to lessen the flood hazard and land degradation that oppresses arid and semi-arid areas.

中文翻译：

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雨水收集技术作为缓解洪水的适应策略

摘要 制定适应和减缓战略以应对人为和气候变化的影响正成为干旱多发地区的优先事项。本研究考察了将本土雨水收集技术 (RWHT) 用作缓解洪水的可行解决方案的能力。该研究分析了撒哈拉以南地区最常用的微流域 RWHT 的水力性能，包括田间和盆地规模的流量峰值减少 (FPR) 和体积减少 (VR)。参数化的hyetographs 用于复制在雨季袭击萨赫勒国家的极端降水。二维流体动力学模拟表明，以交错配置 (S-HM) 放置的半月在减少径流方面具有最佳性能。在田间尺度上，在极端降雨的情况下，S-HM 的 FPR 为 77%，VR 为 70%。相反，在盆地尺度上，其中仅 5% 的表面被处理，FPR 和 VR 分别获得了 13% 和 8%。此外，分析了不同配置之间径流系数（Rc）的降低。该研究批判性地评估了不同技术的水力性能，并展示了在极端降水情况下点蚀实践如何无法保证高性能。这些结果将丰富对 RWHT 水力行为的认识；方面在科学文献中略有研究。此外，这项研究首次将 HEC-RAS 作为降雨-径流模型的科学应用。尽管有一些限制，该模型具有使用高分辨率地形作为水力模拟输入的有效特征。本研究中提出的结果应鼓励利益相关者扩大 RWHT 的使用，以减轻压迫干旱和半干旱地区的洪水灾害和土地退化。