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Understanding the relationship between climate change and concentration-discharge discharge: Agricutural Nitrate in the clear creek watershed.
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Dorley, Jancoba K
Master of Science
Date of Defense:
July 01, 2018
Li Li, Thesis Advisor
Christopher Duffy, Thesis Advisor
Cibin Raj, Committee Member
Time series analysis
The use of agricultural nitrate sources is a growing concern in Midwestern United States. Since the late 1980s, studies have shown that seasonal hypoxic zone formations at the Gulf of Mexico is mostly the result of high levels of nutrients being exported from Midwestern streams. The main source of nutrients in Midwestern streams is due to increases use in agricultural fertilizers. This study examines the concentration-discharge (C-Q) signature in streams draining agricultural lands using Time series analysis, frequency analysis and model simulation for nitrate-Nitrogen. The study uses the Soil and Water Assessment tool (SWAT), a watershed scale model to predict the impact of land practices on an agricultural watershed using historical observations and future projection data. These include five years observational field data and the Inter- Governmental Panel for Climate Change (IPCC) model 3 analysis data for a fifty-year climate projection. Time series (Spectral and Frequency) analysis and Multivariate (Principal Component Analysis) analysis suggests seasonal stream discharge is a dominant driver of nitrate concentration at the watershed outlet. Analysis of the trends in the concentration-discharge phase plain show a seasonal increase in nitrate during the wet season and nitrate utilization during the growing or dry season (late May through August). The major sources/sinks of nitrate include plant nutrient uptake and seasonal fertilizer application
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