Rapid In Situ Characterization of Soil Erodibility With a Field Deployable Robot. Issue 5 (23rd May 2019)

• Record Type: Journal Article
• Authors: Qian, Feifei; Lee, Dylan; Nikolich, George; Koditschek, Daniel; Jerolmack, Douglas
• Is Part Of: Journal of geophysical research. Volume 124:Issue 5(2019)
• Page Start: 1261
• Page End: 1280
• Publication Date: 2019-05-23
• Subjects: erodibility -- legged robot -- shear strength; Geomorphology -- Periodicals; 551.3
• DOI: 10.1029/2018JF004887
• Languages: English
• ISSNs: 2169-9003

Abstract

Abstract : 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 ( τ r ) 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 τ r, 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. Key Points: A novel field method is presented that uses a robot's mechanical probing of soil to provide measurements of a soil's erodibility Lab measurements are performed and compared to the field results to begin understanding the controls on erodibility in the dune field Initial field results lead us to develop other tests of soil erodibility that can provide an estimate of threshold wind‐erosion stress