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Research Projects Master Environmental Reference Site (MERS): Deformation and recovery of desert pavements, U.S. Army Yuma Proving Ground PI: Eric McDonald Co-PI: Steve Bacon and Todd Caldwell Collaborators: Daniel A. Gilewitch (USMA), Mark Sweeney (USD) Funded by: U.S. Army Yuma Proving Ground, Natural Environments Test Office Right: Soil disturbance resulting from roughly 20 passes of a 60-ton Stryker. The deep soil rutting is a combination of both soil compaction and depletion by wind erosion. |
 Click image above to view Quicktime video (3.32 mb) |
Keywords: Soil disturbance, Yuma Proving Ground, Sonora desert, desert pavement, military vehicles, dust Project Description The Yuma Proving Ground (YPG) is a multi-purpose test facility within the U.S. Army Test and Evaluation Command covering more than 3,000 km2. It is located in 40 km north of Yuma, Arizona in the southwestern extent of the Sonoran Desert. Extensive areas of desert piedmonts (bajadas) at YPG have a nearly ubiquitous cover of well developed desert pavements that have formed on early Holocene to Pleistocene age alluvial deposits. Pavements consist of a single layer of surface stones that largely range in size from 1 to 5 cm and that form an armor of closely packed stones. The clasts have a well developed layer of rock varnish (patina) that forms the characteristic dark surface of these alluvial surfaces. Underlying the pavement is a gravel-poor and fine-textured vesicular (v) A horizon. This Av horizon is essentially an accretionary layer of dust that has accumulated below the surface layer of stones. Desert pavements are prominent features in arid and semi-arid environments and can be found on a variety of landforms. These types of stone covered soils are also commonly referred to as reg, hamada, gobi, and gibber plains. Specifically, the NRCS soil series is Cristobal-Gunsight, a loamy-skeletal, mixed, superactive, hyperthermic Typic Calciargids with a prismatic structure Av horizon from 0 to 8 cm, a fine granular Bw horizon from 8 to 15 cm, underlain by a gravel rich Ck horizon. Under the auspices of the Army Research Office, the Natural Environment Testing Office at Yuma Proving Ground, in cooperation with the Desert Research Institute and the United States Military Academy, conducted research to expand the Army’s understanding of desert environments to better meet the needs of military equipment testing, soldier training, and unit operations (King et al., 2004). The study concluded that desert regions vary extensively in parameters important to the military mission, and that desert areas currently available for military testing, training and operations in the United States do not provide all the environmental conditions that troops and their equipment may encounter in potential conflict areas worldwide. In some cases, the physical training environment has been severely degraded to the extent that it no longer accurately represents the desired desert setting for testing and training. The study recommends, in part, that further analysis be conducted using desert Master Environmental Reference Sites (MERS) set aside to allow detailed data collection and analysis of desert environments over long periods of time. Analyses of MERS data can significantly enhance understanding of the long term sustainability of desert surfaces for military use. To that end, the first MERS site was developed at YPG in June of 2006 to assess the degradation and recovery of a desert pavement following impacts from both tracked and wheeled military vehicles. Detailed measurements of soil compaction, hydraulic properties and dust emissivity were taken and will continue to be measured annually in an attempt to quantify both disturbance and recovery of these unique and ubiquitous desert soils.
Above: Oblique aerial view of the MERS at the Yuma Proving Ground. Soil disturbance was evaluated for a HMV, M1A2, Stryker, and a T72 Russian tank. Each vehicle followed a marked course design to capture impacts from 1, 5, 10, and 40 vehicle passes. Each vehicle also conducted 40 additional passes along a single track to determine impacts related to large military convoys (CON in figure. A similar study design is proposed for VPG.
Above: Hydraulic conductivity and pore size distribution measurements taken along the single pass of a M1A2 tank.
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