Optimization of aeolian soil erosion control with sand fences

这个项目的动机是需要一个可靠的数值工具来优化保护沉积物土壤免受风蚀的措施。控制风蚀土壤往往需要设置不同排列的沙栅，可与植被种植结合使用，以减少风力和诱导沉积。然而，仅基于实验来评估它们对大规模风成景观的保护效果是困难的，这不仅是因为床层演化涉及的长期过程，还因为土壤形态动力学在很大程度上取决于当地地形和风的行为。因此，需要一个数值工具来设计保护土壤免受风蚀的优化策略，并应在本项目中开发。该数值工具将计算流体动力学（CFD）模拟土壤和围栏上的平均湍流风场与最先进的泥沙景观形态动力学模拟相结合。为了验证模拟结果，在巴西东北部Jericoacoara沙丘场进行了平均基底剪应力、高度积分泥沙通量和河床剖面演化的野外实测，并与数值预测结果进行了比较。随后，该数值工具将应用于在不同风况和沙粒可用性条件下，使用不同孔隙度、间距和高度的栅栏阵列来推导最佳土壤保护策略。为了研究沙栅对植被覆盖发展的影响，模拟应扩展到包括风、跃迁颗粒和植被之间相互作用的模型。这对于制定更好的防沙措施和解决长期存在的沙丘固定问题是重要的。

This project is motivated by the need for a reliable numerical tool to optimize measures for protecting sediment soil from wind erosion. Control of soil erosion by wind often requires the erection of different arrays of sand fences, which may be applied in combination with vegetation cultivation to reduce wind power and induce deposition. However, evaluating their efficacy to protect large-scale aeolian landscapes based on experiments alone is difficult both due to the long-term processes involved in the bed evolution and because soil morphodynamics depends strongly on local topography and wind behavior. Therefore, a numerical tool for designing optimized strategies to protect soils against wind erosion is required and shall be developed in the present project. The numerical tool couples Computational Fluid Dynamic (CFD) modeling of the average turbulent wind field over the soil and the erected fences with state-of-the-art morphodynamic modeling of sediment landscapes. To validate the simulations, field measurements of the average basal shear stress, height-integrated sediment flux and bed profile evolution shall be performed in the dune field of Jericoacoara, Northeastern Brazil, and the results compared with numerical predictions. Subsequently, the numerical tool shall be applied to derive strategies for optimal soil protection using arrays of fences of different porosity, spacing and height, and under different wind regimes and conditions of sand availability. To investigate the effect of sand fences on the development of vegetation cover, the simulations shall be then extended to include a model for the interaction between wind, particles in saltation and vegetation. This is important to develop improved anti-desertification measures and to address the long-standing problem of dune immobilization.