1. Dust Transport
In The Southwest
New Mexico State University
Elizabeth Smith
New Mexico State University
College of Agriculture, Consumer, and
Environmental Science
Corporative Extension Services- Plant
Science
Las Cruces, NM
http://www.weru.ksu.edu/new_weru/multimedia/2004storms/2004storms.html
Texas Tech Presentation
April 13, 2016
2. Definition:
• Soil erosion due to wind is initiated by
turbulent air movement across an open
surface, causing stable soil particles to
dislodge and to be suspended within the
moving air (Wild, 1993)
New Mexico State University
3. New Mexico State University
Regional Description
• Chihuahuan Desert ecosystem
is the most biologically diverse
desert in the world, The region’s
natural ecosystem has been
heavily degraded over time,
mainly due to grazing in the
past, river channelization for
agricultural activities, and urban
sprawl. Many native plant
species have been replaced
with invasive species such as
Creosote
4. • Southwest is considered an Arid
Environment
• Nearly 50% is precipitation falls
during summer monsoon(Nicholson,
2011)
• Drought conditions since 2001.
• Source pages:
• http://www.wrcc.dri.edu/ New Mexico
• http://www.srcc.lsu.edu/ Texas
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Regional Climate
6. Wind Science
• The United States is located within
the westerlies wind zone, where the
wind goes from west to east
normally, though local wind patterns
may vary.
• In the Las Cruces and El Paso, the
primary wind direction is west-
southwest.
• This wind is the primary cause of
erosion.
• The erodibility of a soil is dependent
on the diameter, density, and shape
of the particles.
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7. How Wind Erosion and Dust Storms
Start Part 1
• Creep: diameter above
0.5mm
– Rolls over soil surface
• Saltation: diameter 0.05-
0.5mm
– Primary cause of wind
erosion
• Suspension: smaller than
0.05mm
– Form dust storms and
Haboobs
New Mexico State University
8. Videos
• Saltation Transport:
• https://www.youtube.com/watch?v=xc4bbbwUnNE
• Local Videos- Lordsburg:
• https://www.youtube.com/watch?v=SwFyprF6a_g&nohtml5=
False
New Mexico State University
9. Haboob
New Mexico State Universityhttp://www.propertyinsurancecoveragelaw.com/uploads/image/Haboob.jpg
11. Sources of Wind Blown Dust
• Open land/ desert areas
• Public land used for recreation
• Private land for future development
• Residential Development projects
• Recreational areas with soil arenas or parking
lots
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12. • The carrying capacity of wind for soil particles
increases with wind speed and decreased
with particle and aggregate size
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𝑐 ∝ 𝑣3 ∗ 𝑑
1
2
𝑐 = quantity of soil removed
𝑣 = wind speed
𝑑 = particle diameter
2 m above surface
How Wind Erosion and Dust Storms
Start Part 2
13. Why is Wind Blown Dust an Issue?
• What is PM10?
– particulate matter with an aerodynamic diameter
less than or equal to a nominal ten micrometers
• Why is it a problem?
– Health
– Personal Property
– Environmental Problems
New Mexico State University
17. Homeowner Issues
• From Homeowners in Southwest area:
– Scours Roofing
– Destroys Landscape
– Sand Dune occurrence at fence line
– Reduction of indoor air quality
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18. Environmental Issues
• Loss of soil to support growth of plants (crops,
grasses, forests)
• Deposition of sediment loads into natural and man-
made waterways
• Water Pollution
– 1t contains 0.2% N/ 0.05% P = 2kg N/0.5 kg P
• Air Pollution
– Reduce solar radiation at the surface
– Change chemical processes in the atmosphere
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19. How Wind Erosion and Dust Storms
Start Part 1
• Creep: diameter above
0.5mm
– Rolls over soil surface
• Saltation: diameter 0.05-
0.5mm
– Primary cause of wind
erosion
• Suspension: smaller than
0.05mm
– Form dust storms and
Haboobs
New Mexico State University
20. Equipment
Passive
• BSNE
• Passive Marble Traps
Active
• High Volume, Continuous
air-flow sampler
• Dust-Track
– Sucks in samples
• Gravimetric Dust Sampler
– Provides time-weighted-
average respirable dust
concentration
New Mexico State Universityhttp://esp.cr.usgs.gov/projects/sw/swdust/marble_traps.html,
http://esp.cr.usgs.gov/projects/sw/swdust/tsp_sampler.html
21. What is a BSNE?
• Big Spring Number Eight
• As a Sample Collector:
– Stationary heights:
• 50 cm
– Rotating Control heights:
• 100 cm
• 50 cm
• 10 cm
New Mexico State University
22. Sampling
• Sampling occurs in an area when gusts
reached 25 mph with the National Weather
Service or local weather station
OR
• No high wind events have been registered for
a 1 month period
23. Lab Work!
• Opening the BSNE
– Collection equipment consisted of (A) screwdriver (B) Deionized
Water (DI water) (C) DI water distributer (D) funnel (E) individual
sampling containers (Numbered), one container per BSNE (F)
toothbrush.
• Preparing the Sample container
– sturdy plastic 16 ounce bottles, were washed with DI water and dried
before using in the field.
• Lab Process- Field Trip! (but first how it works)
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24. sample weight = beaker with sample - beaker
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Bake @ 105 °Centigrade
24-48 hours later
Chihuahuan Desert ecosystem, which includes the Mesilla Valley, is the most biologically diverse desert in the world, whether measured in the species richness or endemism. The region’s natural ecosystem has been heavily degraded over time, mainly due to grazing in the past, river channelization for agricultural activities, and urban sprawl. Many native plant species have been replaced with invasive species such as Creosote Bush (Larrea tridentate), Tamarisk (Tamarix), Russian thistle (Salsola), and many varieties of grasses (Brooks & Pyke, 2002).
The region’s climate is classified as an arid environment with a very dry spring season (Nicholson, 2011), followed by a wet monsoon and cool winter; nearly 50% of the precipitation falls during the summer monsoon. High wind events that cause dust storms are primarily during the spring months when Pacific and backdoor cold fronts move through the region. The numerous convective storms from the monsoon are also a very important event in defining the air quality in the study region. High winds from thunderstorm downdrafts and gust fronts lofting dust into the air have accounted for many dust storms in the study region. Average precipitation for the Las Cruces area is 9.74 inches based on the 1981 to 2010 climate normal (WRCC, 2014). Average monthly precipitation for the area is shown in Figure 1.3-1 over the period 1959 to 2013.
Figure 1.3‑1. Monthly precipitation measured at the NMSU Las Cruces weather station (WRCC, 2014)
Erosivity is promoted through two physical processes: atmospheric flow and surface roughness. Atmospheric flow is the rate of soil movement proportional to the cube of the wind velocity across a surface (Foken, 2008; Weinan, Zhibao, Zhenshan, & Zuotao, 1996). Surface roughness elements that influence the ability of soil particles to become suspended and transported fall into five (5) major categories: vegetation height and density, clods and non-erodible fractions, ridges, field shelter belts (wind breaks), and local changes in topography (Whitehouse, 2002).
Vegetation height and density determine the extent the wind contacts the soil surface. Clods and non-erodible fractions provide cover for smaller soil particles that could be picked up. Ridges shelter and trap suspended particles when the wind is perpendicular to them, but do not provide protection when the wind direction parallels them. A windbreak intercepts the suspended particles and slows down the initial velocity. As the particles slow, they are deposited in the leeward side of the barrier (Whitehouse, 2002). Soil particles are transported across an area by three primary processes: creep, saltation, and suspension.
Creep is a designation for soil particle movement with a diameter ranging from 1 millimeter to 0.5 millimeters. These particles have an upper limit of movement of 2 mm above a surface (Wild, 1993).
Movement of particles between 0.5 to 0.1 mm in diameter is the process of saltation. These particles are lightweight enough to be picked up by air moment but too large to be taken up into the atmosphere. These particles bounce, roll and dislodge additional particles across the ground surface and are considered to be the core process of erosion (Wild, 1993).
Suspension is a term used to describe particles smaller than 0.1 millimeters in diameter. Particles this size can be carried by air movement over a large distance and around the globe. These small particles make up the formation of dust storms, which have been found to increase during drought periods in semi-arid regions. Removal of these small particles from an area leaves coarse material behind; conditionally, this process is not ideal for plant growth. Once those particles come to settle within an area, it becomes and adds to the parent material considered to be top soil (Wild, 1993).
High wind events that cause dust storms are primarily during the spring months when Pacific and backdoor cold fronts move through the region. The numerous convective storms from the monsoon are also a very important event in defining the air quality in the study region. High winds from thunderstorm downdrafts and gust fronts lofting dust into the air have accounted for many dust storms in the study region
High wind events that cause dust storms are primarily during the spring months when Pacific and backdoor cold fronts move through the region. The numerous convective storms from the monsoon are also a very important event in defining the air quality in the study region. High winds from thunderstorm downdrafts and gust fronts lofting dust into the air have accounted for many dust storms in the study region
