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Droughts are a recurrent part of our climate, and are still considered to be one of the most complex and least understood of all natural hazards in terms of their impact on the environment. In recent years drought has become more common and more severe across the world. For more than a decade, the US southwest has faced extensive and persistent drought conditions that have impacted vegetation communities and local water resources. The focus of this work is achieving a better understanding of the impact of drought on the lands of the Hopi Tribe and Navajo Nation, situated in the Northeastern corner of Arizona. This research explores the application of remote sensing data and geospatial tools in two studies to monitor drought impacts on vegetation productivity. In both studies we used land surface phenometrics as the data tool. In a third related study, I have compared satellite-derived land surface phenology (LSP) to field observations of crop stages at the Maricopa Agricultural Center to achieve a better understanding of the temporal sensitivity of satellite derived phenology of vegetation and understand their accuracy as a tool for monitoring change. The first study explores long-term vegetation productivity responses to drought. The paper develops a framework for drought monitoring and assessment by integrating land cover, climate, and topographical data with LSP. The objective of the framework is to detect long-term vegetation changes and trends in the Normalized Difference Vegetation Index (NDVI) related productivity. The second study examines the major driving forces of vegetation dynamics in order to provide valuable spatial information related to inter-annual variability in vegetation productivity for mitigating drought impacts. The third study tests the accuracy of remote sensing-derived LSP by comparing them to the actual seasonal phases of crop growth. This provides a way to compare and validate the various LSP algorithms, and more crucially, helps to characterize the remote sensing-based metrics that contrast with the actual biological phenophases of the crops. These studies demonstrate how remote sensing data and simple statistical tools can be used to assess drought effects on vegetation productivity and to inform about land conditions, as well as to better understand the accuracy of satellite derived LSP.

Arsenic-based pesticide residues have been detected on Arizona State Museum’s (ASM) Diné (Navajo) textile collection using a handheld portable X-ray (pXRF) spectrometer. The removal of this toxic pesticide from historic textiles in museums and collections is necessary to reduce potential health risks to Native American communities, museum professionals, and visitors to these cultural institutions. A leader in engineering innovative pesticide removal methods, ASM received federal funding support to continue essential research in removing heavy metal pesticides from cultural property. The research objective was divided into three interconnected stages: (1) calibrate the pXRF instrument for arsenic contaminated cotton and wool textiles; (2) engineer a textile conservation aqueous washing treatment to remove arsenic from wool textiles; (3) demonstrate the aqueous washing treatment method on actual Navajo textiles known to have arsenic-based pesticide residues. The calibration process consisted of a dipping method to produce known homogenous arsenic cotton and wool test samples saturated with solutions of 100, 500, 1000, 2500, and 5000 parts per million (ppm). A linear correlation between observed pXRF test readings and formulated arsenic solutions corroborated the instruments range of detection for arsenic on specific textile materials. The calibration confirms that the pXRF is suitable instrument to measure the removal of arsenic from wool textiles. Wool test samples treated with solutions of an arsenic concentration of 1000ppm were used to develop an optimal aqueous washing treatment exploring the effects of time, temperature, agitation, and pH conditions to efficiently remove arsenic while minimizing damage to the structure and properties of the textile. Each conditional effect removed a certain percentage of arsenic, although the most efficient aqueous washing treatment consisted of submerging a wool textile in deionized water at room temperature for ten minutes with the greatest level of agitation within reason to minimize damage the textile. The final stage of the research applied the aqueous washing guidelines formulated from experimental research on three historic ASM Navajo textiles. Two textiles contained low arsenic concentrations (<100ppm), and one tested with a high arsenic concentration (~1000ppm). The aqueous washing treatment resulted in minimal change for low arsenic concentration textiles, and a 96% removal of arsenic on a high arsenic concentration textile. The preliminary success of removing arsenic-based pesticide residues from historic Navajo textiles greatly impacts the future management of historic textile collections, and also raises questions to further refine the research methodology or pursue alternative related research such as engineering a closed circulating arsenic removal system to limit the quantity of toxic water.

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Project report (D. Min.)--George W. Truett Theological Seminary, Baylor University, 2006. / Includes bibliographical references (leaves 95-99).

Thesis (Ph. D. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 128-133).

Thesis (M.S.- Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references (leaves 245-249).