Army Yuma Proving Ground Research Articles

Photogrammetric Measurements of an EH-60L Brownout Cloud

There is a critical lack of quantitative data regarding the mechanism of brownout cloud formation. Recognizing this, tests were conducted during the Air Force Research Lab 3D-LZ Brownout Test at the US Army Yuma Proving Ground. Photogrammetry was utilized during two rounds of flight tests with an instrumented EH-60L Black Hawk to determine if this technique could quantitatively measure the formation and evolution of a brownout cloud. Specific areas of interest include the location, size, and average convective velocity of the cloud, along with the characteristics of any defined structures within it. Following the first flight test, photogrammetric data were validated through comparison with onboard vehicle data. Lessons learned from this test were applied to the development of an improved photogrammetry system. A second flight test, utilizing the improved system, demonstrated that obtaining quantitative measurements of the brownout cloud are possible. Results from these measurements are presented in the paper. Flow visualization with chalk dust seeding was also tested. It was observed that pickup forces of the brownout cloud appear to be very low. Overall, these tests demonstrate the viability of photogrammetry as a means for quantifying brownout cloud formation and evolution.

Landscape models of space use by desert bighorn sheep in the Sonoran Desert of southwestern Arizona

The desert bighorn sheep (Ovis canadensis mexicana) is one of the few ungulates native to North America capable of surviving in harsh desert environments and xeric conditions. However, the effects of an increasingly arid climate on this species and its habitat are unknown. We sought to identify important predictors of desert bighorn sheep diurnal space use to provide new insight into management and conservation opportunities. We evaluated home range size and relative intensity of space use for 41 collared individuals monitored between 2007 and 2010 across a 14,217-km2 extent of Arizona's Sonoran Desert, including the Kofa National Wildlife Refuge and the United States Army Yuma Proving Ground. Using linear mixed models and an information-theoretic approach, we developed seasonal models of intensity of space use for the summer (Jun–Aug) and non-summer (Sep–May) seasons. Models included environmental variables representing escape terrain and distance from developed waters, and Normalized Difference Vegetation Index metrics that represented forage and preformed water resources. We found intensity of space use to be greater for females (than for males) in the summer season and smaller home range sizes for both sexes in the summer season. Escape terrain was the dominant predictor of intensity of space use in both seasons, but forage and preformed water resources were strong predictors only in the non-summer season. These results likely reflected a seasonal trade-off between escape terrain (i.e., predator avoidance) and limited forage and water resources, particularly for more risk-averse females. Effective conservation and management strategies for desert bighorn sheep should consider the availability of both quality forage and water resources in areas of escape terrain. Although more research is needed on species-specific vulnerabilities to climate change and drought, our approach to integrating vegetation indices into estimates of space use is highly transferable to analyses of other wide-ranging species occupying dynamic arid environments. © 2014 The Wildlife Society.

A geomorphic classification of ephemeral channels in a mountainous, arid region, southwestern Arizona, USA

Despite the global abundance of arid-region ephemeral streams, hydrologic and geomorphic data for these systems are limited compared to their perennial counterparts. High spatial and temporal variability in flow makes hydrologic and geomorphic aspects of dryland ephemeral channels difficult to characterize. Perennial stream classifications have been extended to dryland ephemeral streams but do not adequately describe observed differences in channel geometry and characteristics of ephemeral channels in desert environments. We present a geomorphic classification for ephemeral streams in mountainous regions based on planform, degree of confinement, and composition of confining material. Five stream types were identified in the Sonoran desert of southwestern Arizona: (1) piedmont headwater, (2) bedrock, (3) bedrock with alluvium, (4) incised alluvium, and (5) braided channels. Nonparametric permutational multivariate analysis of variance for 101 surveyed reaches indicated differences (p<0.001) in channel geometry and hydraulics among the five stream types. Nonmetric multidimensional scaling ordination identified the strongest channel geometry and hydraulic variables capable of distinguishing the five channel types, and a classification tree determined relative importance of these variables in the following order: width-to-depth ratio (W/D), stream gradient (S), stream power (Ω), and shear stress (τ). A classification tree and discriminant analysis used W/D, S, Ω, and τ for 86 study reaches on the U.S. Army Yuma Proving Ground (77% and 77% internal validation hit rate, respectively) to predict stream type of 15 separate study reaches on Barry Goldwater Air Force Range with 67% and 73% external validation hit rates, respectively. Differences in channel geometry among the five stream types reflect likely differences in hydrology, hydraulics, and sediment transport with implications for disturbance regime, channel adjustment to disturbance, and ecological sensitivity.

Testing a Top-Down Strategy for Establishing a Sustainable Telemedicine Program in a Developing Country: The Arizona Telemedicine Program–U.S. Army–Republic of Panama Initiative

Many developing countries have shown interest in embracing telemedicine and incorporating it into their healthcare systems. In 2000, the U.S. Army Yuma Proving Ground (YPG) initiated a program to assist the Republic of Panama in establishing a demonstration Panamanian rural telemedicine program. YPG engaged the Arizona Telemedicine Program (ATP) to participate in the development and implementation of the program. The ATP recommended adoption of a "top-down" strategy for creating the program. Early buy-in of the Panamanian Ministry of Health and academic leaders was regarded as critical to the achievement of long-term success. High-level meetings with the Minister of Health and the Rectors (i.e., Presidents) of the national universities gained early program support. A telemedicine demonstration project was established on a mountainous Indian reservation 230 miles west of Panama City. Today, three rural telemedicine clinics are linked to a regional Ministry of Health hospital for teleconsultations. Real-time bidirectional videoconferencing utilizes videophones connected over Internet protocol networks at a data rate of 768 kilobits per second to the San Felix Hospital. Telepediatrics, tele-obstetrics, telepulmonology, teledermatology, and tele-emergency medicine services became available. Telemedicine services were provided to the three sites for a total of 1,013 cases, with numbers of cases increasing each year. These three demonstration sites remained in operation after discontinuation of the U.S. involvement in September 2009 and serve as a model program for other telemedicine initiatives in Panama. Access to the assets of a partner-nation was invaluable in the establishment of the first model telemedicine demonstration program in Panama. After 3 years, the Panamanian Telemedicine and Telehealth Program (PTTP) became self-sufficient. The successful achievement of sustainability of the PTTP after disengagement by the United States fits the Latifi-Weinstein model for establishing telemedicine programs in developing countries.

Desert terrain characterization of landforms and surface materials within vehicle test courses at U.S. Army Yuma Proving Ground, USA

The U.S. Army Yuma Proving Ground is the Department of Defense desert environment test center within the Sonoran Desert of Arizona. The Yuma Proving Ground has ∼320 km of unpaved vehicle test courses that cross a variety of landforms of diverse geologic age and characteristics. The surface materials of the courses ranges from bedrock to silt and their topography varies from steep and rolling to flat. Research presented here aims to provide a systematic characterization of the terrain of eight vehicle endurance and three dust courses so that their comparability with other desert areas of the World may be assessed. Landform and surface cover (upper 1 m) characterization was accomplished by geomorphic mapping based on 1-m resolution IKONOS satellite imagery, 10-m digital elevation models, field verification, and by assimilating pre-existing soil surveys and geologic maps, as well as site-specific investigations. Results provide an assessment of each test course, including information on the landform, geology, surface materials, soil type, degree of desert pavement development, dust content, and percent slope. Data is presented both on individual terrain property maps for each course and in the form of tabulated data for each official milepost marker along the courses. The results for one course area and an example of how they may be used to assess comparability with another desert of interest are presented here with the objective to improve the fidelity of desert testing during material research, development, testing and evaluation prior to deployment in the field.

Multivariate characterization of Sonoran Desert vegetation in southwest Arizona using US Army field data

This paper describes the classification and ordination of Sonoran Desert vegetation using systematically collected data from the US Army Yuma Proving Ground (USYPG). Two classifications were created, one based upon relative plant cover derived from 100 m line transect data and one based upon relative plant density derived from 6 m . × 100 m belt transect data, with the belt transect being a lateral extension of the line transect. Both cluster analysis using Ward’s Method and TWINSPAN were used for classifying the data while Principal Component Analysis, Correspondence Analysis, Detrended Correspondence Analysis, and Non-Metric Multidimensional Scaling were used as ordination methods. Cluster analysis was superior to TWINSPAN in creating logical classifications comparable to published descriptions of vegetation communities found in the Lower Colorado Subdivision of the Sonoran Desert. Together, the ordination methods served to accentuate different aspects of the data including main gradients of species composition, in particular a gradient separating plots with riparian-af-finities from the main data set, a Larrea tridentata-Ambrosia dumosa gradient, and a gradient separating Encelia farinosa from the main data set. The main difference between the relative cover and relative density classifications was that the former under-represented cacti such as Opuntia bigelovii and the latter under-represented such as Parkinsonia microphylla and Olneya tesota. The classification methodology used in this study is useful for evaluating resource sampling strategies on U.S. Army bases in sparsely vegetated areas and the classifications could be used as a baseline for monitoring changes in vegetation communities.

Using a probabilistic approach in an ecological risk assessment simulation tool: test case for depleted uranium (DU)

A probabilistic approach was applied in an ecological risk assessment (ERA) to characterize risk and address uncertainty employing Monte Carlo simulations for assessing parameter and risk probabilistic distributions. This simulation tool (ERA) includes a Window’s based interface, an interactive and modifiable database management system (DBMS) that addresses a food web at trophic levels, and a comprehensive evaluation of exposure pathways. To illustrate this model, ecological risks from depleted uranium (DU) exposure at the US Army Yuma Proving Ground (YPG) and Aberdeen Proving Ground (APG) were assessed and characterized. Probabilistic distributions showed that at YPG, a reduction in plant root weight is considered likely to occur (98% likelihood) from exposure to DU; for most terrestrial animals, likelihood for adverse reproduction effects ranges from 0.1% to 44%. However, for the lesser long-nosed bat, the effects are expected to occur (>99% likelihood) through the reduction in size and weight of offspring. Based on available DU data for the firing range at APG, DU uptake will not likely affect survival of aquatic plants and animals (<0.1% likelihood). Based on field and laboratory studies conducted at APG and YPG on pocket mice, kangaroo rat, white-throated woodrat, deer, and milfoil, body burden concentrations observed fall into the distributions simulated at both sites.

Soil and Plant Recovery After Historic Military Disturbances in the Sonoran Desert,USA

Military training exercises in desert areas have resulted in various types of disturbance through time. Camp Laguna, located on the U.S. Army Yuma Proving Ground in southwestern Arizona, served as a military base camp during World War II. The camp exhibits a variety of historic disturbances, including vehicle traffic (motor pool) and foot traffic (tent rows, commons, and footpaths). The extent of soil and plant recovery that has occurred at Camp Laguna in the 56 years since abandonment was assessed by comparing sites with historic disturbance to an apparently undisturbed control site. Vegetative recovery was determined by measuring perennial plant foliar cover and density. Soil was characterized by maximum penetration depth measurements and presence of biological soil crusts. Soil samples were collected and analyzed for inorganic and organic carbon and total nitrogen content. The tent city, disturbed primarily by foot traffic, did not show full recovery of vegetation and biological soil crust to predisturbance conditions. The slow recovery may be attributable to grading that removed topsoil and seed sources when the camp was established. In contrast, most plant species at the motor pool exhibited higher density and greater foliar cover than was found at the control site. This may be the result of a compacted soil layer that enhanced soil-water relations of the upper horizon of the sandy soil and provided fine plant roots with a greater amount of moisture.

Geomorphic Mapping Enhances Cultural Resource Management at the U.S. Army Yuma Proving Ground, Arizona, USA

Provisions of the National Historical Preservation Act of 1966, particularly Section 106 of that Act, require the Yuma Proving Ground (YPG) to conduct archaeological surveys and assess cultural resources to evaluate potential effects of planned military testing activities on those cultural resources considered eligible or potentially eligible for inclusion in the National Register of Historic Places. Landscape reconstruction was performed using aerial photography and satellite image interpretations, ground verification including detailed soils geomorphology descriptions, and archaeological surveys. Geographic Information System overlay analyses were used to determine the preferential distribution of cultural resources in the study area. A vast majority of the 40 mapped cultural sites are located on Pleistocene age geomorphic surfaces. Few sites occurred on Holocene age surfaces. Spatial relationships between geomorphology and archaeology were supported by chi-square statistical tests, rejecting the hypothesis that culture is evenly distributed across the landscape as a function of the size of geomorphic surfaces comprising it. Ninety-two percent of cultural resources designated eligible for the National Register of Historic Places occur on Pleistocene age geomorphic surfaces. Results of this interdisciplinary study suggest that both differential preservation of geomorphic surfaces and human behavior act together to explain the spatial distribution of cultural resources at YPG.

GUIDANCE AND CONTROL OF AFFORDABLE GUIDED AIRDROP SYSTEM

This paper addresses the development of an autonomous guidance, navigation and control system for a flat solid circular parachute. This effort is a part of the Affordable Guided Airdrop System (AGAS) that integrates a low-cost guidance and control system into fielded cargo air delivery systems. The paper describes the AGAS concept, its architecture and components. It further proceeds with the description of the control strategy based on Pontrjagin's principle of optimality. The paper ends with the results of the final AGAS demonstration performed at the U.S. Army Yuma Proving Ground in September, 2001.

Global Positioning System Differential Navigation Tests at the Yuma Proving Ground

The Global Positioning System (GPS) Joint Program Office has conducted the majority of user equipment testing at the U. S. Army Yuma Proving Ground (YPG), Yuma, Arizona. This paper briefly reviews the history of CPS testings at YPG, describes the major assets of the test range and presents the results of dynamic and static differential GPS tests conducted at YPG.