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Biofuel production-driven land-use change in agricultural land can have impacts on ecosystem services. Since there is no planned mandate after the Renewable Fuel Standard, there are questions about what implications will future land-use changes have on water quality and how do water quality changes, resulting from potential bioenergy scenarios, affect changes in people's well-being? To answer these questions, I will estimate the value of the predicted changes in water quality under biofuel policy scenarios in counties inside the Mississippi River Basin. From this study, I found that as the percent of land-use changes increase across each county, water quality decreased. I also found that for every unit increase for the change in water quality index, the percentage of individuals' willingness to pay for a change in water quality would increase. The predicted willingness to pay for a change in water quality for a given household varied from -$72 to $143.

This study was undertaken to assess the effectiveness of implanted substrates in sampling aquatic macroinvertebrate assemblages associated with stone dikes on the Lower Mississippi River and to obtain basic information on assemblage composition, structure, and patterns of distribution over a dike. For study purposes, stone-filled baskets were implanted into a dike near Vicksburg, Mississippi, in February 1979, and retrieved four months later. The resulting data indicated the presence of a diverse and productive assemblage (38 taxa; average of 101,968 organisms/m²), characterized by net-spinning caddisflies, tube-building chironomids, isopods, and clinging mayflies. The caddisfly, Hydropsyche spp., accounted for over 60 percent of the total organisms collected. A comparison of assemblage data obtained from the surface stones of the implanted substrates with data obtained from adjacent surface stones of the dike indicated close agreement in estimates of both assemblage composition and structure. However, on an average basis, over seventy percent of the total organisms collected in the substrate implants were found below the surface layer of substrate. The importance of this finding to future sampling efforts is discussed. Statistically significant differences in assemblage estimates were encountered over both the length and width of the structure sampled. These findings are discussed both in terms of their potential ecological significance and in terms of future sampling design considerations. / Master of Science

Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Timothy D. Keane / Many small Midwestern towns established near a river thrived on industry and the transport of goods up and down the waterway. Unfortunately, industrial riverfronts that have acted as the heart of their communities have seen tremendous flux as time has progressed. In the past half century the economic activity of industrial riverfronts declined as more goods can be shipped via interstate highways and as factories are closed and relocated. These vacant factories leave behind contaminated brownfield sites which discourage reinvestment and promote greenfield development on a city’s periphery in agricultural lands. Citizens have turned their backs on a history and heritage from which the first cornerstones of their communities were laid. A void results as industry begins to fade from the riverfront and a town loses its connection to the river. Put simply, we have lost our riverfronts. The Riverfront Found Master Plan for Quincy, Illinois integrates the different uses of the riverfront, weaving together the existing industrial, recreational, and natural fabrics that line the Mississippi River. Design concepts strive to create a dynamic atmosphere to encourage a healthy lifestyle environment and destinations with year-round interest. Enjoyable and memorable experiences of Quincy’s riverfront encourage users to return as the negative community perceptions of the Mississippi River are reversed. Planning is inwardly focused to combat sprawl of the urban fabric. Decision-making remains sensitive to floodplain ecology and mindful of flood occurrence. Conservation is an important design response concerning riverfronts and requires understanding an intricate system regionally and locally. Education ties both conservation and site experience together as users remember how their city and culture are embedded in ecology. Three case studies identify key concepts to inform the project at later stages. A site inventory and analysis spanning three scales, regional, city, and site uncovers history and processes. The programming phase addresses proposed elements to address the concepts, ideas, and problems identified in previous steps. A final master plan presents the proposed program elements within context of the site to create a functional and dynamic riverfront for the citizens of Quincy.

In this study we assessed growth laws of sub-delta crevasses in the Mississippi River delta plain, experimental laboratory deltas, and compared them to previously studied river dominated large deltas worldwide. Metrics for channel and delta geometry for each system were obtained using a combination of geospatial tools, bathymetric datasets, sediment size, and hydrodynamic observations. Most crevasses and experimental deltas appear to obey delta growth laws suggesting that they exhibit planform metrics similar to larger deltas. However, some channels within each system, exhibit outlier behavior (e.g. asymmetric growth) where channel length is much larger than channel width. Hydrodynamic observations and morphodynamic modeling results, support the role of confinement in governing this response, through direct lateral confinement of the receiving basin width and depth thus guiding channels, and indirect confinement caused by sediment cohesion, whereby natural levees guide the systems asymmetric channel growth.

Every thousand years or so, when the Mississippi River's sediment load lengthened and blocked the River’s route to the Gulf of Mexico, the mother stream changed course completely, finding a shorter route to the sea. Then, it built a new delta, thus spreading the gift of land creation along a wide coastline and creating the bayou region of Louisiana. However, this ancient, natural process was gradually halted by the arrival of man who settled across the River's natural floodplain (delta) and constructed levees and other structures to control the great Mississippi River. Since the 1930s, the Mississippi River Delta Basin and the coast of Louisiana have been literally losing ground. The decline of this environment is now affecting, and will continue to affect, our nation's economy, infrastructure, culture, and safety. Moreover, efforts to fix this problem are not working. My research and this thesis will address the issue of how plans without action have appeased Louisianans while the nation looses vital wetlands daily.

Alterations along the Mississippi River, such as dams and levees, have greatly reduced the amount of freshwater and sediment that reaches the Louisiana coastal area. Several freshwater and sediment diversions have been proposed to combat the associated land loss problem. To aid in this restoration effort a 1-D numerical model was calibrated, validated, and used to predict the response of the river to certain stimuli, such as proposed diversions, channel closures, channel modifications, and relative sea level rise. This study utilized HEC-RAS 4.0, a 1-D mobile-bed numerical model, which was calibrated using a discharge hydrograph at Tarbert Landing and a stage hydrograph at the Gulf of Mexico, to calculate the hydrodynamics of the river. The model showed that RSLR will decrease the capacity of the Lower Mississippi River to carry bed material. The stage at Carrollton Gage is not significantly impacted by large scale diversions

The purpose of this research is to develop a 3-D numerical model on the Lower Mississippi River to simulate hydrodynamics and non-cohesive sediment transport. The study reach extends from Bonnet Carré Spillway (RM 127) to Head of Passes (RM 0). Delft3D with sigma coordinates was selected as the river modeling tool. This model River domain is characterized by a complex distributary system that connects the Mississippi River to the Gulf of Mexico. The boundary conditions were: water levels in the Gulf and Head of Passes; and discharges upstream. For the calibration, there are observed data for both types of boundary conditions. Several periods of high discharge were simulated to compare water level, discharge, velocity profiles and sediment transport with measurements and accomplish calibration and validation of the model. A calibrated 3-D model has been developed with the following %RMSE: 5% for stage; 6% for discharge; and 5% for sand load.

The stratified flow of the lower Mississippi River due to density gradients is a well documented phenomenon. This stratification of fresh and saline water manifests itself as a heavier wedge of saline water that extends upriver and a buoyant fresh water plume extending into the Gulf of Mexico past the Southwest Pass jetties. The maximum absolute distance of saltwater intrusion observed anywhere in the world occurred on the Mississippi River in 1939 and 1940 when saltwater was observed approximately 225 km upstream from the mouth of Southwest Pass. The U. S. Army Corps of Engineers now prevents the wedge from migrating upstream by constructing a subaqueous barrier in the river channel. A curvilinear grid was constructed representative of the modern Mississippi River delta. Boundary conditions were developed for the drought year of 2012 and the grid was tested in order to evaluate the salinity intrusion and sediment transport abilities of the Cartesian Z-coordinate Delft3D code. The Z-model proved to have the ability to propagate the saline density current as observed in the prototype. The effect of salinity on fine sediment transport is evaluated by manipulation of the settling velocity through a cosine function provided in the model code. Manipulation of the fine sediment fall velocity through the cosine function was an effective means to simulate the re-circulation of flocculated sediments in the saline wedge turbidity maxima. In addition, the Z-model capably reproduced the fine sediment concentration profiles in a fully turbulent shear flow environment. With the ability to reproduce the seasonal saline density current and its effect on sedimentation within the turbidity maxima as well as sedimentation characteristics in a fully turbulent shear flow, a model capable of analyzing all of the major processes affecting fine sediment transport within the Mississippi River salt wedge estuary has been developed.

Late Holocene climate variability includes the Little Ice Age (LIA, 450-150 BP) and the Medieval Warm Period (MWP, 1100-700 BP) that are characterized by contrasting hydrologic and thermal regimes. The degree of interaction between the North American continent and the ocean during these two abrupt climate events is not well known. Marine sedimentary records from basins proximal to major rivers integrate climate signals across large spatial scales and can provide a coherent, high-resolution assessment of the oceanic and continental responses to changing climate and hydrologic conditions. The Pigmy Basin in the northern Gulf of Mexico is ideally situated to record inputs from the Mississippi River and to relate these inputs to changing hydrologic conditions over North America during the LIA and MWP. Hydrologic variability recorded over the North America continent is directly dependent on the moisture balance (E/P) over the sub-tropical Gulf of Mexico (a major source of moisture to the North America continent). Warm, moist air masses from the south interact with cold/dry air masses from the north over the North American continent to produce storm fronts. Increased evaporation over the Gulf of Mexico leads to enhanced precipitation over the North American continent, due to the intensification of atmospheric circulation, which influences meridional moisture flux from the Gulf of Mexico to the North American continent. This study focuses on the sedimentary record spanning the last 1400 years and utilizes a multi-proxy approach incorporating organic and inorganic geochemical analyses to define intervals of varying continental inputs and to assess changes in the moisture balance (E-P) within the Gulf of Mexico.