Rapid In Situ Characterization of Soil Erodibility With a Field Deployable Robot
Rapid In Situ Characterization of Soil Erodibility With a Field Deployable Robot
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DOI：
10.1029/2018jf004887
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发表时间：
2019-05
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影响因子：
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通讯作者：
Feifei Qian;Dylan B. Lee;G. Nikolich;D. Koditschek;D. Jerolmack
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作者：
Feifei Qian;Dylan B. Lee;G. Nikolich;D. Koditschek;D. Jerolmack
预测土壤对风蚀的敏感性很困难，因为它是粒度、土壤湿度、压实度和生物生长的多变量函数。犁耕和放牧等侵蚀剂在机制上也与流体剪切的夹带不同。目前还不清楚每个过程的侵蚀阈值是否以及如何相关。在这里，我们展示了快速组装可蚀性经验图的潜力，同时还使用半自主机器人进行的表面土壤抗剪力（τr）的新型“犁耕”测试来检查控制它的因素。美国新墨西哥州白沙国家纪念碑的实地工作检查了两个尺度的可蚀性梯度：（i）土壤湿度从干燥沙丘顶部到潮湿沙丘间的变化（数十米）和（ii）与植物、盐和生物结皮生长相关的顺风沙丘稳定性增加（公里）。我们发现，土壤湿度的百分之几的变化对应于 τr 的加倍，这一结果已得到实验室实验的证实，并且土壤结皮所赋予的稳定性与湿度的影响相当。然后，我们在受控实验室环境中比较了不同的机械扰动机制。一种新的“踢出”测试确定表层土壤的峰值抗剪力作为屈服强度的代表。抗踢出性与土壤湿度存在关系，与耕作试验不同，并且与独立测量的风蚀阈值流体应力相关。结果表明，我们的新方法绘制了干旱环境中的土壤侵蚀性，并提供了对土壤侵蚀性变化的环境控制的理解。
Predicting the susceptibility of soil to wind erosion is difficult because it is a multivariate function of grain size, soil moisture, compaction, and biological growth. Erosive agents like plowing and grazing also differ in mechanism from entrainment by fluid shear; it is unclear if and how erosion thresholds for each process are related. Here we demonstrate the potential to rapidly assemble empirical maps of erodibility while also examining what controls it, using a novel “plowing” test of surface‐soil shear resistance (τr) performed by a semi‐autonomous robot. Field work at White Sands National Monument, New Mexico, United States, examined gradients in erodibility at two scales: (i) soil moisture changes from dry dune crest to wet interdune (tens of meters) and (ii) downwind‐increasing dune stabilization associated with growth of plants and salt and biological crusts (kilometers). We found that soil moisture changes of a few percent corresponded to a doubling of τr, a result confirmed by laboratory experiments, and that soil crusts conferred stability that was comparable to moisture effects. We then compared different mechanisms of mechanical perturbation in a controlled laboratory setting. A new “kick‐out” test determines peak shear resistance of the surface soil as a proxy for yield strength. Kick‐out resistance exhibited a relation with soil moisture that was distinct from the plowing test and that was correlated with the independently measured threshold‐fluid stress for wind erosion. Results show that our new method maps soil erodibility in arid environments and provides an understanding of environmental controls on variations in soil erodibility.