Thesis (M.S.)--George Mason University, 2008. / Vita: p. 145. Thesis director: Susan A. Crate. Submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Science and Policy. Title from PDF t.p. (viewed Mar. 10, 2009). Includes bibliographical references (p. 134-144). Also issued in print.

Thesis (Ph. D.)--Southern Cross University, 2004. / Title from PDF title page (viewed on June 10, 2005). Includes bibliographical references.

Thesis (M. Sc.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 138-146).

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (M. Sc.)--University of Hong Kong, 2005.

<p> In this project we created a hydrodynamic model of the Lower Green Bay of Lake Michigan in Wisconsin, United States using the Visual Environmental Fluid Dynamics Code (EFDC). The model includes four tributary rivers to Lower Green Bay as well as the open boundary flow conditions at Chambers Island. This case study is used to: 1) compare the results obtained with a previous study of Lower Green Bay to validate the creation of the model 2) examine the hydrodynamics of the bay, and 3) create a framework for future studies at Lower Green Bay. The Geographic Information used to build the Grid was obtained from the NOAA web site. Meteorological and flow information was obtained from the National Weather Service and USGS web sites, respectively. It was necessary to create a new model grid as a platform for future studies of Lower Green Bay, and the Visual EFDC 1.2 code was a useful tool in the development of the grid. However, some limitations in the code made the creation of the grid a challenge. In this project, we summarize the process used to overcome challenges in creating a correct grid, and analyze the hydrodynamic results of the model simulation for the period between June and October 2011. Overall, we conclude that the model reproduces field data reasonably well, and a correct modeling framework for hydrodynamic modeling of Lower Green Bay was created. </p>

<p> During <i>in situ</i> remediation of contaminated groundwater, a treatment chemical is injected into the contaminated groundwater to degrade a contaminant through chemical reaction that occurs in the subsurface. Reactions and subsequent contaminant degradation occur only where the treatment chemical contacts the contaminant long enough to complete degradation reactions. Traditional <i> in situ</i> groundwater remediation relies on background groundwater flow to spread an injected treatment chemical into a plume of contaminated groundwater. </p><p> Engineered Injection and Extraction (EIE), in which time-varying induced flow fields are used to actively spread the treatment chemical into the contaminant plume, has been developed to increase contact between the contaminant and treatment chemical, thereby enhancing contaminant degradation. EIE has been investigated for contaminants degrading through irreversible, bimolecular reaction with a treatment chemical, but has not been investigated for a contaminant governed by complex biogeochemical processes. Uranium fate and transport in subsurface environments is governed by adsorption, oxidation reduction, solution, and solid-phase interactions with naturally occurring solution species, microbial communities, minerals and aquifer media. Uranium primarily occurs in aqueous, mobile U(VI) complexes in the environment but can be reduced to sparingly soluble, immobile U(IV) solid-phase complexes by native dissimilatory metal reducing bacteria. </p><p> This work investigates the ability of EIE to promote subsurface delivery of an acetate-amended treatment solution throughout a plume of uranium-contaminated groundwater to promote <i>in situ</i> growth of native microbial communities to immobilize uranium. Simulations in this investigation are conducted using a semi-synthetic flow and reactive transport model based on physical and biogeochemical conditions from two uranium contaminated sites: the Naturita Uranium Mill Tailings Remedial Action (UMTRA) Project site in southwestern Colorado and the Old Rifle UMTRA Project site in western Colorado.</p><p>

<p> Agricultural drought is a creeping disaster that overshadows the vegetative cover in general and cropland specifically in Iraq, a country that was well known for its agricultural production and fertile soil. In the recent years, the arable lands in Iraq experienced increasing land degradation that led to desertification, economic losses, food insecurity, and deteriorating environment. Remote sensing is employed in this study and four different indices are utilized, each of which is derived from MODIS satellite mission products. Agricultural drought maps are produced from 2003 to 2015 after masking the vegetation cover. Year 2008 was found the most severe drought year during the study period, where drought covered 37% of the vegetated land. This part of the study demonstrated the capability of remote sensing in fulfilling the need of an early warning system for agricultural drought over such a data-scarce region.</p><p> This study also aims to monitor hydrological drought. The Gravity Recovery and Climate Experiment (GRACE) satellite-derived monthly Terrestrial Water Storage (TWS) is the hydrological drought indicator, that is used to calculate the deficit. Severity of drought events are calculated by integrating monthly water deficit over the drought period. In addition, drought recovery time is assessed depending on the estimated deficit. Major drought events are classified into several levels of severity by applying a drought monograph approach. The results demonstrated that GRACE TWS is a reliable indicator for drought assessment over Iraq, and provides useful information for decision makers which can be utilized in developing drought adaptation and mitigation strategies. </p><p>

<p> The Salinas River Valley Watershed has endured the effects of seawater intrusion for decades caused by overpumping groundwater from the Salinas River Groundwater Basin. The Castroville Seawater Intrusion Project began delivering recycled water in 1998 with other water sources due to wells becoming too saline. One-on-one, in-person interviews with eighteen growers, who own or lease farmland within the Project&rsquo;s service area, were conducted during a severe, statewide drought. Interview questions explored grower attitudes and concerns regarding their water supply, and the impact of management strategies on the mitigation of seawater intrusion. Two research questions were posed, exploring factors that influence grower acceptance of alternative water supplies, and whether environmental impacts affect their attitudes. Four prominent factors were found that influence grower acceptance of alternative water supplies: perceived need for water supply, changes to cost and/or water quality, information/education, and level of trust. The study also revealed three motivations of growers for choosing water supplies that do not increase seawater intrusion or contribute to adverse environmental impacts: protecting harvest/land, managing associated cost of operations, and avoiding increased regulations and/or oversight. Growers with fewer numbers of farms and smaller acreage of farmland tended to have a greater perceived need to acquire sustainable water supplies, while being more reluctant to implement water sources of lesser quality.</p><p>

Water resources systems are designed to operate under a wide range of potential climate conditions. Traditionally, systems have been designed using stationarity-based methods. Stationarity is the assumption that the climate varies within an envelope of variability, implying that future variability will be similar to past variability. Due to anthropogenic climate change, the credibility of the stationarity-based assumptions has been reduced. In response, climate change assessments have been developed to quantify the potential impacts due to climatic change. While these methods quantify potential changes, they lack the probabilistic information that is needed for a risk-based approach to decision-analysis. This dissertation seeks to answer two crucial questions. First, what is the best way to evaluate water resource systems given uncertainty due to climate change? Second, what role should climate projections or scenarios play in water resources evaluation? A decision analytic approach is applied that begins by considering system decisions and proceeds to determine the information relevant to decision making. Climate based predictor variables are used to predict system hazards using a climate response function. The function is used with climate probability distributions to determine metrics of system robustness and risk. Climate projections and additional sources of climate information are used to develop conditional probability distributions for future climate conditions. The robustness and risk metrics are used to determine decision sensitivity to assumptions about future climate conditions. The methodology is applied within the context of the International Upper Great Lakes Study, which sought to determine a new regulation plan for the releases from Lake Superior that would perform better than the current regulation plan and be more robust to potential future climate change. The methodology clarifies the value of climate related assumptions and the value of GCM projections to the regulation plan decision. The approach presented in this dissertation represents a significant advancement in accounting for potential climate change in water resources decision making. The approach evaluates risk and robustness in a probabilistic context that is familiar to decision makers and evaluates the relevance of additional climate information to decisions.