Day: January 29, 2010

Spatial Analysis of Melioidosis Distribution in a Suburban Area

/ Matt Artz

Epidemiology and Infection,22 Jan 2010

M. L. CORKERON, R. NORTON and P. N. NELSON

“Burkholderia pseudomallei, the causative agent of melioidosis is associated with soil. This study used a geographic information system (GIS) to determine the spatial distribution of clinical cases of melioidosis in the endemic suburban region of Townsville in Australia. A total of 65 cases over the period 1996–2008 were plotted using residential address. Two distinct groupings were found. One was around the base of a hill in the city centre and the other followed the old course of a major waterway in the region. Both groups (accounting for 43 of the 65 cases examined) are in areas expected to have particularly wet topsoils following intense rainfall, due to soil type or landscape position.”

Surveillance of Mother-to-child HIV Transmission: Socioeconomic and Health Care Coverage Indicators

/ Matt Artz

Revista de Saúde Pública, Dececember 2009; 43(6):1006-14.

Barcellos C, Acosta LM, Lisboa E, Bastos FI. 

“OBJECTIVE: To identify clustering areas of infants exposed to HIV during pregnancy and their association with indicators of primary care coverage and socioeconomic condition.

“METHODS: Ecological study where the unit of analysis was primary care coverage areas in the city of Porto Alegre, Southern Brazil, in 2003. Geographical Information System and spatial analysis tools were used to describe indicators of primary care coverage areas and socioeconomic condition, and estimate the prevalence of liveborn infants exposed to HIV during pregnancy and delivery. Data was obtained from Brazilian national databases. The association between different indicators was assessed using Spearman’s nonparametric test.

“RESULTS: There was found an association between HIV infection and high birth rates (r=0.22, p<0.01) and lack of prenatal care (r=0.15, p<0.05). The highest HIV infection rates were seen in areas with poor socioeconomic conditions and difficult access to health services (r=0.28, p<0.01). The association found between higher rate of prenatal care among HIV-infected women and adequate immunization coverage (r=0.35, p<0.01) indicates that early detection of HIV infection is effective in those areas with better primary care services.

“CONCLUSIONS: Urban poverty is a strong determinant of mother-to-child HIV transmission but this trend can be fought with health surveillance at the primary care level.”

Mohonk Preserve Offers Two Paid Summer Internships in Land Management and Scientific Research

/ Matt Artz

…from the Poughkeepsie Journal…

“To help college students preparing for conservation work, Mohonk Preserve will offer two paid summer internships in land management and scientific research. Each internship runs for 10 weeks (June to mid-August) and provides a stipend of $3,200. Housing is available. The application deadline is March 15.

“The Scheuer Land Management Internship is open to college juniors and seniors majoring in geography, planning, natural resource management, environmental studies, or a related field (GIS experience is helpful).”

U.S. National Agricultural Statistics Service Releases New Geospatial Data Products

/ Matt Artz

New Satellite Images Show Ag Land Cover for 2009 Crop Year

The U.S. Department of Agriculture’s National Agricultural Statistics Service (NASS) today announced the release of new satellite images depicting agricultural land cover across most of the nation for the 2009 crop year. The images, referred to as cropland data layers (CDL), are a useful tool for monitoring crop rotation patterns, land use changes, water resources and carbon emissions.

These crop-specific, digital data layers are suitable for use in geographic information systems (GIS) applications. They can be used by agribusinesses, farmers, government agencies, researchers and academic institutions to study pesticide risk, epidemiology, transportation, fertilizer usage, carbon dioxide flux and other topics.

NASS produced the CDLs using satellite images observed at 56-meter (0.775 acres per pixel) resolution and collected from the Resourcesat-1 Advanced Wide Field Sensor (AWiFS), Landsat Thematic Mapper and Moderate Resolution Imaging Spectroradiometer (MODIS). The collection of images was then categorized using on-the-ground farm information including field location, crop type, land cover, elevation, tree canopy and urban infrastructure.

For the first time, the CDL images are available for 47 of the 48 contiguous states. Data for the final state, Florida, will be available this spring pending the availability of certified farm data required to produce the images. NASS is also making available, for the first time, the New Mexico CDL for 2008.

The entire inventory of CDL products, including metadata and accuracy assessments, is available online at the USDA Natural Resources Conservation Service’s Geospatial Data Gateway: http://datagateway.nrcs.usda.gov and at this NASS website: http://www.nass.usda.gov/research/Cropland/SARS1a.htm.

[Source: NASS press release]

Animals Populated Madagascar by Rafting There

/ Matt Artz / 1 Comment

…from Purdue University News Service…

“How did the lemurs, flying foxes and narrow-striped mongooses get to the large, isolated island of Madagascar sometime after 65 million years ago?

“A pair of scientists say their research confirms the longstanding idea that the animals hitched rides on natural rafts blown out to sea.

“The raft hypothesis has always been the most plausible, says Anne Yoder, director of the Duke University Lemur Center. She specializes in using molecular biogenetic techniques and geospatial analysis to examine the evolutionary history of Madagascar. But Ali and Huber’s study now puts hard data behind it, says the Duke professor of biology, biological anthropology and anatomy.”

Reforestation Planning using Bayesian Networks

/ Matt Artz

Environmental Modelling & Software, Volume 24, Issue 11, November 2009, Pages 1285-1292

C. Ordóñez Galán, J.M. Matías, T. Rivas, and F.G. Bastante

“The aim of this research was to construct a reforestation model for woodland located in the basin of the river Liébana (NW Spain). This is essentially a pattern recognition problem: the class labels are types of woodland, and the variables for each point are environmental coordinates (referring to altitude, slope, rainfall, lithology, etc.). The model trained using data for existing wooded areas will serve as a guideline for the reforestation of deforested areas. Nonetheless, with a view to tackling reforestation from a more informed perspective, of interest is an interpretable model of relationships existing not just between woodland type and environmental variables but also between and among the environmental variables themselves. For this reason we used Bayesian networks, as a tool that is capable of constructing a causal model of the relationships existing between all the variables represented in the model. The prediction results obtained were compared with those for classical linear techniques, neural networks and support vector machines.”

GIS for Renewable Energy: New GIS Best Practices e-Book

/ Matt Artz / 3 Comments

“Faced with grim predictions of energy supply and consumption, humankind is responding with tremendous efforts to capture and cultivate renewable resources. We are looking to help sustain ourselves using wind, solar, geothermal, and biomass energy. We are also searching for cleaner, smarter, and more conscientious methods of energy production, transmission, and distribution.

“GIS technology is supporting and underlying the progress of this monumental change. GIS is not only improving the way we produce and deliver energy, it is changing the way we view our earth’s resources.”

Groundwater Rights in Mexican Agriculture: Spatial Distribution and Demographic Determinants

/ Matt Artz

The Professional Geographer, Volume 62, Issue 1 February 2010 , pages 1 – 15

Christopher A. Scott;  Sandy Dall’erba; Rolando Diacuteaz Caravantes

“Groundwater use intensity and aquifer depletion increase from south to north with decreasing rainfall and increasing economic activity in Mexico. To heighten scholarly understanding and offer new insights that strengthen policy responses to aquifer depletion, we analyze the spatial distribution of agricultural groundwater use from irrigation well titles in 2,429 municipalities and its relation to agricultural surface water and population employed in agriculture. Exploratory spatial data analysis reveals spatial dependence among all three variables implying that policy initiatives to address intensive groundwater use must be targeted at clusters of aquifers and municipalities.”

Darkness on the Edge of Town: Mapping Urban and Peri-Urban Australia Using Nighttime Satellite Imagery

/ Matt Artz / 1 Comment

The Professional Geographer, Volume 62, Issue 1 February 2010 , pages 119 – 133

Paul C. Sutton; Andrew R. Goetz; Stephen Fildes; Clive Forster; Tilottama Ghosh

“This article explores the use of nighttime satellite imagery for mapping urban and peri-urban areas of Australia. A population-weighted measure of urban sprawl is used to characterize relative levels of sprawl for Australia’s urban areas. In addition, the expansive areas of low light surrounding most major metropolitan areas are used to map the urban-bush interface of exurban land use. Our findings suggest that 82 percent of the Australian population lives in urban areas, 15 percent live in peri-urban or exurban areas, and 3 percent live in rural areas. This represents a significantly more concentrated human settlement pattern than presently exists in the United States.”

Comparison of Interpolation Methods for Depth to Groundwater and its Temporal and Spatial Variations in the Minqin Oasis of Northwest China

/ Matt Artz / 1 Comment

Environmental Modelling & Software, Volume 24, Issue 10, October 2009, Pages 1163-1170

Yue Sun, Shaozhong Kang, Fusheng Li, and Lu Zhang

“Severe water shortages and dramatic declines in groundwater levels have resulted in environmental deterioration in the Minqin oasis, an arid region of northwest China. Understanding temporal and spatial variations in the depth to groundwater in the region is important for developing management strategies. Depth to groundwater records for 48 observation wells in the Minqin oasis were available for 22 years from 1981 to 2003, allowing us to compare three different interpolation methods based on three selected years (1981, 1990, 2002) as starting points. The three methods were inverse distance weighting (IDW), radial basis function (RBF), and kriging (including ordinary kriging (OK), simple kriging (SK), and universal kriging (UK)). Cross-validation was applied to evaluate the accuracy of the various methods, and two indices – the correlation coefficient (R2) and the root mean squared error (RMSE) – were used to compare the interpolation methods. Another two indices – deviation of estimation errors (σ) and 95% prediction interval (95 PPI) – were used to assess prediction errors. Comparison of interpolated values with observed values indicates that simple kriging is the optimal method for interpolating depth to groundwater in this region: it had the lowest standard deviation of estimation errors and smallest 95% prediction interval (95 PPI). By using the simple kriging method and an autoregressive model for depth to groundwater based on the data from 1981 to 2003, this work revealed systematic temporal and spatial variations in the depth to groundwater in the Minqin oasis. The water table has declined rapidly over the past 22 years, with the average depth to groundwater increasing from 4.95 m in 1981 to 14.07 m in 2002. We attribute the decline in the water table to excessive extraction and to decreases in irrigation channel leakage.”