Spatial variability in aeolian abrasion
Abstract
Wind-driven sediment transport dominates arid landscape evolution. In particular, wind-blown sand forms vast dune fields and erodes exposed surfaces through abrasion. Abrasion requires that sand is entrained by the wind, and aeolian dunes often serve as a sand source for abrasion. However, the relationship between the magnitude of abrasion and distance from a sand source remains poorly constrained. Previous work on aeolian abrasion has focused on ventifacts, wind-carved cobbles and boulders that record the direction of erosive winds in their pattern of surface erosion. These geologic indicators provide robust evidence that wind-abrasion has occurred, but without more information provide little information about the magnitude or rate of surface erosion. At the moment, sources of sand are easy to identify (e.g., dune fields, sand sheets), but the expected erosion rate on materials places some distance away is unknown. Aeolian abrasion can cause significant damage to both natural and engineered materials, but sometimes proximity to sand sources is unavoidable. A quantitative understanding of how aeolian erosion rates vary with material type and distance from a dune field would facilitate better-informed decision making in arid regions, and provide an expected rates of degradation from aeolian abrasion that could be used in planning and risk management. The proposed work aims to address this gap in knowledge. Objective: Quantify the magnitude of aeolian abrasion as a function of distance away from a sand dune source. Technical approach: To determine quantitatively how abrasion varies distally away from a dune field, we propose a 12- month field experiment in which we monitor the wind conditions in the field, capture saltating sand causing abrasion, and measure progressive abrasion-related mass loss on a variety of natural and synthetic materials at increasing distance from the dune field. The proposed work is divided into three major tasks completed over a total of 18 months. Preparatory assembly of sampling devices and initial deployment of those devices in the field (Task 1a) will be conducted at the beginning of the proposal period. Ventifacts in the area will also be mapped as a proxy for geologically recent winds (Task 1b). For the next 12 months, the field area will be visited regularly to track progressive abrasion and monitor the winds and sediment flux (Task 2). Data analysis (Task 3) will be conducted after the 12 months of monitoring. We hypothesize that abrasion decreases linearly away from a sand source. This hypothesis can be directly tested with the proposed field measurements and geologic interpretation. The patterns and magnitude of abrasion at each sample site will provide data to quantify the relationship between distance from the sand source and abrasion date. Additional contextual information will refine the scientific interpretation of these results.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 04, 2021
- Source ID
- W911NF2110063
Entities
People
- Mackenzie Day
Organizations
- Army Contracting Command
- United States Army
- University of California, Los Angeles