Wind Erosion and Dust Emissions on the Colorado Plateau
Science Center Objects
Wind erosion of soils and dust emissions are a significant resource management challenge on the Colorado Plateau. Loss of topsoil and associated aeolian sediment (wind-driven sediment) movement can lead to reduced soil fertility as well as abrasion and burial of vegetation. Dust in the atmosphere poses a threat to human health, visual resources, and regional water supplies (due to interactions with mountain snowpack). Erosion of surface soils and subsequent emissions of dust are greatly influenced by land-use practices and climate, especially drought. In this project, the U.S. Geological Survey and collaborators are monitoring aeolian sediment movement, atmospheric dust concentrations, and related erosion and dust properties to better understand the relationship between land use (grazing by domestic livestock, unpaved roads, off highway vehicles, and oil and gas development), climate variability, and aeolian processes. Results show that dust emissions increase during drought, but these increases in erosion processes are exacerbated with common land use types, especially off-road vehicle activity.
Background & Importance
The American Dust Bowl of the 1930s produced hard-learned lessons about how misguided land use and climate variation can trigger extreme wind erosion and land degradation. During the Dust Bowl, plowing in semi-arid regions coincident with drought caused extreme wind erosion and general economic devastation. Although many lessons were learned from the Dust Bowl, we now face similar challenges but with much more varied land use demands, a larger population base, and risks of intensifying drought. Although considerable uncertainty exists, current land use and drought trends have the potential to cause destabilization of sediments that increases wind erosion, sand dune mobilization, sand storms, dust emissions, productivity loss, and desertification.
The processes controlling wind erosion and dust emissions operate at scales ranging from microns to global. Vegetation height, orientation and size of vegetation gaps, soil type, soil cover, surface roughness, wind speed, and antecedent moisture all can influence dust dynamics. The Colorado Plateau in the southwestern United States is an active aeolian system that has co-occurring land-use types which vary at fine scales over a large area, each with the potential to generate large quantities of dust due to soil surface disturbance. Land uses of concern include energy and mineral extraction, unpaved road and trail development, and livestock grazing. Many of the regional shale formations (e.g. Mancos, Chinle, and Morrison Formations) have a variety of metals and other potentially hazardous constituents that could be mobilized as dust. Although this region is only a minor contributor to global dust loads currently, it represents one area of many semi-arid regions in the world that, if destabilized by drought and land use, could become a much larger dust source. The general objective of this work is to understand how land use and climate separately and synergistically affect wind erosion and dust emissions on the Colorado Plateau.
We are employing a variety of measurement approaches to understand the controls on dust emissions and how those processes vary across time, land-use, and among vegetation and soil types. This includes a distributed network of passive dust traps in grazing lands, in off-highway vehicle use areas, in national parks with limited land disturbance, on oil and gas pads, and along unpaved roadways. We have active samplers that are measuring atmospheric concentrations of dust located in Canyonlands National Park. Additionally, we have a network of automated cameras that document visibility that are being used to quantify how dust impacts visual resources. We also maintain a highly instrumented monitoring site that is part of the National Wind Erosion Network. Data from this site are being used to develop wind erosion models applicable to all land types.
Results from this work suggest dust emissions regionally are strongly impacted by the interaction of land use and drought. Some of the largest dust sources are associated with off-highway vehicle use and overgrazing by domestic livestock. In our distributed network, we have observed dust production increasing with temperatures and decreasing precipitation. However, the strength of these climate-dust relationships vary with land use. In general, our results suggest that roads and other highly disturbed areas are producing several time more dust per unit area than general grazing lands; however, due to the relatively small area occupied by roads, grazing lands still produce the vast majority of dust regionally.
Next steps from this work will include 1) understanding how dust is impacting visual resources regionally, 2) incorporating process-based wind erosion modelling to understand how management scenarios might impact dust processes, and 3) provide decision support tools to assess dust risk based on land use and restoration practices.