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- All Subjects: Water Quality
- Creators: Camhi, Ashley L
- Status: Published
Description
Safe, readily available, and reliable sources of water are an essential component of any municipality’s infrastructure. Phoenix, Arizona, a southwestern city, has among the highest per capita water use in the United States, making it essential to carefully manage its reservoirs. Generally, municipal water bodies are monitored through field sampling. However, this approach is limited spatially and temporally in addition to being costly. In this study, the application of remotely sensed reflectance data from Landsat 7’s Enhanced Thematic Mapper Plus (ETM+) and Landsat 8’s Operational Land Imager (OLI) along with data generated through field-sampling is used to gain a better understanding of the seasonal development of algal communities and levels of suspended particulates in the three main terminal reservoirs supplying water to the Phoenix metro area: Bartlett Lake, Lake Pleasant, and Saguaro Lake. Algal abundances, particularly the abundance of filamentous cyanobacteria, increased with warmer temperatures in all three reservoirs and reached the highest comparative abundance in Bartlett Lake. Prymnesiophytes (the class of algae to which the toxin-producing golden algae belong) tended to peak between June and August, with one notable peak occurring in Saguaro Lake in August 2017 during which time a fish-kill was observed. In the cooler months algal abundance was comparatively lower in all three lakes, with a more even distribution of abundance across algae classes. In-situ data from March 2017 to March 2018 were compared with algal communities sampled approximately ten years ago in each reservoir to understand any possible long-term changes. The findings show that the algal communities in the reservoirs are relatively stable, particularly those of the filamentous cyanobacteria, chlorophytes, and prymnesiophytes with some notable exceptions, such as the abundance of diatoms, which increased in Bartlett Lake and Lake Pleasant. When in-situ data were compared with Landsat-derived reflectance data, two-band combinations were found to be the best-estimators of chlorophyll-a concentration (as a proxy for algal biomass) and total suspended sediment concentration. The ratio of the reflectance value of the red band and the blue band produced reasonable estimates for the in-situ parameters in Bartlett Lake. The ratio of the reflectance value of the green band and the blue band produced reasonable estimates for the in-situ parameters in Saguaro Lake. However, even the best performing two-band algorithm did not produce any significant correlation between reflectance and in-situ data in Lake Pleasant. Overall, remotely-sensed observations can significantly improve our understanding of the water quality as measured by algae abundance and particulate loading in Arizona Reservoirs, especially when applied over long timescales.
ContributorsRussell, Jazmine Barkley (Author) / Neuer, Susanne (Thesis advisor) / Fox, Peter (Committee member) / Myint, Soe (Committee member) / Arizona State University (Publisher)
Created2018
Description
Payments for ecosystem services (PES) are transactions between landholders and the beneficiaries of the services their land provides. PES schemes are growing worldwide with annual transactions over ten billion dollars (Salzman et al., 2018). Much can be learned from looking at oldest and best funded PES schemes on working agricultural land. Initiated in 1985, the USDA’s Conservation Reserve Program (CRP) is the oldest private conservation PES program in the United States. CRP incentivizes farmers to put their land into conservation through an annual payment. In Iowa, CRP has been a source of extra income and a way for farmers to buffer the fluctuating costs of cash crops, such as corn and soy. The dominance of agriculture in Iowa poses many challenges for water quality. A potential solution to the problem, implemented through CRP, is the use of conservation practices to mitigate the negative effects of agricultural run-off.
This dissertation considers three aspects of the problem:
1. the relationship between changes in land cover due to CRP enrollment and changes in water quality, controlling for a range of factors known to have an effect on the filtering role of different land covers;
2. the inter-annual variability in water quality measures and enrollment in different CRP conservation practices to examine the cost-effectiveness of specific conservation practices in mitigating lake sedimentation and eutrophication;
3. discrete choice models to identify what characteristics drive the enrollment by farmers into specific conservation practices.
Results indicate that land cover and CRP have different impacts on different indicators of lake water quality. In addition, conservation practices that were cost-effective for one water quality variable tended to be cost-effective for the other water quality variables. Farmers are making decisions to enroll in CRP based on the opportunity cost of the land. Therefore, it is necessary to alter financial incentives to promote productive land being putting into CRP through continuous sign-up. The United States Department of Agriculture (USDA) needs a more effective way to calculate the payment level for practices in order to be competitive with the predicted value of major crops.
This dissertation considers three aspects of the problem:
1. the relationship between changes in land cover due to CRP enrollment and changes in water quality, controlling for a range of factors known to have an effect on the filtering role of different land covers;
2. the inter-annual variability in water quality measures and enrollment in different CRP conservation practices to examine the cost-effectiveness of specific conservation practices in mitigating lake sedimentation and eutrophication;
3. discrete choice models to identify what characteristics drive the enrollment by farmers into specific conservation practices.
Results indicate that land cover and CRP have different impacts on different indicators of lake water quality. In addition, conservation practices that were cost-effective for one water quality variable tended to be cost-effective for the other water quality variables. Farmers are making decisions to enroll in CRP based on the opportunity cost of the land. Therefore, it is necessary to alter financial incentives to promote productive land being putting into CRP through continuous sign-up. The United States Department of Agriculture (USDA) needs a more effective way to calculate the payment level for practices in order to be competitive with the predicted value of major crops.
ContributorsCamhi, Ashley L (Author) / Perrings, Charles (Thesis advisor) / Abbott, Joshua K (Thesis advisor) / Englin, Jeffrey (Committee member) / Sala, Osvaldo (Committee member) / Iovanna, Rich (Committee member) / Arizona State University (Publisher)
Created2019