GIS Analyst

Miami, FL, United States

GIS Analyst

Miami, FL, United States

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Thistle H.W.,U.S. Department of Agriculture | White J.A.,U.S. Department of Agriculture | Backer D.M.,National Park Service | Ghent J.H.,U.S. Department of Agriculture | And 4 more authors.
Applied Engineering in Agriculture | Year: 2014

A pilot project was conducted to evaluate the feasibility of aerially spraying buffelgrass (Cenchrus ciliaris) with glyphosate in the Sonoran Desert of Arizona. Buffelgrass is an invasive grass that is spreading rapidly and has catastrophic ecological impacts. Spraying was conducted using a helicopter and extremely coarse drops. Blue dye was used as a deposition tracer. This work indicates that it is possible to aerially spray buffelgrass in this setting though it is difficult to get herbicide to deposit in hot, dry, unstable, midday conditions. The extremely complex, broken terrain and the small spray blocks targeted in this project are a challenge to precision application. © 2014 American Society of Agricultural and Biological Engineers.


Sohl T.L.,Eros | Sohl L.B.,GIS analyst
Geographical Review | Year: 2012

Information on the rates, characteristics, and drivers of land-use change are vital for addressing the impacts and feedbacks of change on environmental processes. The U.S. Geological Survey's Land Cover Trends project is conducting a consistent, national analysis of the rates, causes, and consequences of land-use change. In this article we assess change in the Atlantic Coastal Pine Barrens ecoregion from 1973 to 2000. Urban lands expanded by more than 900 square kilometers during the study period. Land-use change in the ecoregion followed the tenets of "Forest Transition Theory" (ftt) prior to the study period, but forest lands experienced consistent declines from 1973 to 2000. Increasing government regulation during the study period, consistent with concept of the "Quiet Revolution" (qr), mitigated forest loss during the latter half of the study period. Generalized theories, including ftt and the qr, are valuable, but local and regional determinants of comparative land rents ultimately drive land-use change at this scale. © 2012 by the American Geographical Society of New York.


Schilling K.E.,Research Geologist | Isenhart T.M.,Iowa State University | Palmer J.A.,Natural Resource Biologist | Wolter C.F.,GIS Analyst | Spooner J.,North Carolina State University
Journal of the American Water Resources Association | Year: 2011

Suspended sediment is a major water quality problem, yet few monitoring studies have been of sufficient scale and duration to assess the effectiveness of land-use change or conservation practice implementation at a watershed scale. Daily discharge and suspended sediment export from two 5,000-ha watersheds in central Iowa were monitored over a 10-year period (water years 1996-2005). In Walnut Creek watershed, a large portion of land was converted from row crop to native prairie, whereas in Squaw Creek land use remained predominantly row crop agriculture. Suspended sediment loads were similar in both watersheds, exhibiting flashy behavior typical of incised channels. Modeling suggested that expected total soil erosion in Walnut Creek should have been reduced 46% relative to Squaw Creek due to changes in land use, yet measured suspended sediment loads showed no significant differences. Stream mapping indicated that Walnut Creek had three times more eroding streambank lengths than did Squaw Creek suggesting that streambank erosion dominated sediment sources in Walnut Creek and sheet and rill sources dominated sediment sources in Squaw Creek. Our results demonstrate that an accounting of all sources of sediment erosion and delivery is needed to characterize sediment reductions in watershed projects combined with long-term, intensive monitoring and modeling to account for possible lag times in the manifestation of the benefits of conservation practices on water quality. © 2011 American Water Resources Association.


Imbach P.,Tropical Agriculture Research and Higher Education Center | Manrow M.,Tropical Agriculture Research and Higher Education Center | Barona E.,GIS Analyst | Barretto A.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | And 2 more authors.
Global Biogeochemical Cycles | Year: 2015

Amazonia holds the largest continuous area of tropical forests with intense land use change dynamics inducing water, carbon, and energy feedbacks with regional and global impacts. Much of our knowledge of land use change in Amazonia comes from studies of the Brazilian Amazon, which accounts for two thirds of the region. Amazonia outside of Brazil has received less attention because of the difficulty of acquiring consistent data across countries. We present here an agricultural statistics database of the entire Amazonia region, with a harmonized description of crops and pastures in geospatial format, based on administrative boundary data at the municipality level. The spatial coverage includes countries within Amazonia and spans censuses and surveys from 1950 to 2012. Harmonized crop and pasture types are explored by grouping annual and perennial cropping systems, C3 and C4 photosynthetic pathways, planted and natural pastures, and main crops. Our analysis examined the spatial pattern of ratios between classes of the groups and their correlation with the agricultural extent of crops and pastures within administrative units of the Amazon, by country, and census/survey dates. Significant correlations were found between all ratios and the fraction of agricultural lands of each administrative unit, with the exception of planted to natural pastures ratio and pasture lands extent. Brazil and Peru in most cases have significant correlations for all ratios analyzed even for specific census and survey dates. Results suggested improvements, and potential applications of the database for carbon, water, climate, and land use change studies are discussed. The database presented here provides an Amazon-wide improved data set on agricultural dynamics with expanded temporal and spatial coverage. © 2015. The Authors.

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