Matching Items (2)
Description
Droughts are a common phenomenon of the arid South-west USA climate. Despite water limitations, the region has been substantially transformed by agriculture and urbanization. The water requirements to support these human activities along with the projected increase in droughts intensity and frequency challenge long term sustainability and water security, thus the need to spatially and temporally characterize land use/land cover response to drought and quantify water consumption is crucial. This dissertation evaluates changes in `undisturbed' desert vegetation in response to water availability to characterize climate-driven variability. A new model coupling phenology and spectral unmixing was applied to Landsat time series (1987-2010) in order to derive fractional cover (FC) maps of annuals, perennials, and evergreen vegetation. Results show that annuals FC is controlled by short term water availability and antecedent soil moisture. Perennials FC follow wet-dry multi-year regime shifts, while evergreen is completely decoupled from short term changes in water availability. Trend analysis suggests that different processes operate at the local scale. Regionally, evergreen cover increased while perennials and annuals cover decreased. Subsequently, urban land cover was compared with its surrounding desert. A distinct signal of rain use efficiency and aridity index was documented from remote sensing and a soil-water-balance model. It was estimated that a total of 295 mm of water input is needed to sustain current greenness. Finally, an energy balance model was developed to spatio-temporally estimate evapotranspiration (ET) as a proxy for water consumption, and evaluate land use/land cover types in response to drought. Agricultural fields show an average ET of 9.3 mm/day with no significant difference between drought and wet conditions, implying similar level of water usage regardless of climatic conditions. Xeric neighborhoods show significant variability between dry and wet conditions, while mesic neighborhoods retain high ET of 400-500 mm during drought due to irrigation. Considering the potentially limited water availability, land use/land cover changes due to population increases, and the threat of a warming and drying climate, maintaining large water-consuming, irrigated landscapes challenges sustainable practices of water conservation and the need to provide amenities of this desert area for enhancing quality of life.
ContributorsKaplan, Shai (Author) / Myint, Soe Win (Thesis advisor) / Brazel, Anthony J. (Committee member) / Georgescu, Matei (Committee member) / Arizona State University (Publisher)
Created2014
Description
Global water consumption is at record levels, prompting concerns about sources, treatment, shortages, accessibility, and environmental impacts. While residential use is high due to population growth, industrial activities, particularly in sectors like textiles, are major contributors to overconsumption and pollution. The textile industry's emphasis on high-volume production, driven by capitalist economies and fueled by trends and social media, has led to increased consumption and waste, notably in the cotton sector, which has one of the highest water consumption rates. By investigating the three (3) top cotton-producing countries, an inference regarding global cotton production practices, water usage, and pollutant discharge was able to be made. These countries included India, China, and the United States. It was determined that the agricultural and post-harvest production conjointly sum to a water usage of about 10,000 m3 per ton. This includes water use for irrigation, various purification processes, serial dilutions for pollutants, cleansing, dyeing, and printing processes. In addition to high water consumption, the cotton industry is also a major source for pollution. These pollutants are due to many processes within the complete production process. The contaminants of concern within this investigation are azo dyes. These dyes are able to degrade into toxic byproducts called aromatic amines which are known to be carcinogenic, mutagenic, and irritating. They also reduce sunlight transmittance and increase the BOD and COD within aquatic ecosystems. Popular remediation methods include reverse osmosis, electrolysis, and biological decoloration – through fungi and prokaryotes – are used due to their high degradation efficiency of around 90%. Although this efficiency rate is quite high, a newer remediation method for azo dyes was found that has a 99.8% efficiency rate along with reusable materials. This process utilized silver nanoparticle-intercalated cotton fibers to completely remove the dyes from the tested waters. Through the investigation, inefficiencies and possible sustainability initiatives were determined that will hopefully become globally implemented in order to reduce the large impact of the cotton textile industry.
ContributorsMiller, Natalie (Author) / Boyer, Treavor (Thesis director) / Boyer, Mackenzie (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainable Engineering & Built Envirnmt (Contributor)
Created2024-05