Thesis (M.S.)--University of Wisconsin -- La Crosse, 1976. / Includes bibliographical references (leaves 72-76).

Published also as Thesis (Ph. D.)--University of Pennsylvania, 1906. / Includes bibliographical references (p. 153-160).

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1949. / Vita. The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed July 12, 2010) Includes bibliographical references (p. 50-51).

Thesis (M.S.)--University of Wisconsin -- La Crosse, 1985. / Includes bibliographical references (leaves 56-59).

The trends of degradation and aggradation are measured in this study for the Lower Mississippi River. Historical riverbed elevation and stage data from the past hundred years were used from six gages in order to measure changes in riverbed gradation. It was found that using stage data to measure gradation changes is a superior method to using riverbed elevations, due to stage data’s reliability, length of record and daily measurements. Degradation in the Lower Mississippi River was seen during the

In 1879 Congress created the Mississippi River Commission (MRC) to develop and coordinate federal flood control policy for the Lower Mississippi River. Through 1927, that Commission clung stubbornly to a "levees-only" policy that was based on the mistaken belief that levees alone could be effective in controlling the flood waters of the Mississippi River. When the levees failed--and they occasionally did--the MRC responded by raising and strengthening the system but refused to adopt a more comprehensive program, one which would include outlets and reservoirs. Finally, a disastrous flood in 1927 forced the abandonment of levees-only and the adoption of a comprehensive plan for the Lower Mississippi River. Predictably, the MRC faced heavy criticism following the failure of its highly-touted levee system in 1927. While certainly the Commission was culpable, there was plenty of fault to go around and a plethora of mitigating circumstances. Developing a plan for achieving adequate flood control along the lower Mississippi River constituted what was probably the most difficult and complex engineering problem ever undertaken by the U. S. Government. Additionally, there were innumerable political and financial constraints that worked to shape MRC policy. This study will endeavor to tell the story of the MRC from its earliest origins through the landmark 1928 Flood Control Act, and, in the process, give evidence to the reality that the Commission did not function independently. As an organization, it relied upon outside forces for its membership, for its jurisdiction, and for the appropriations necessary to carry out its policies. Significantly, these forces were politically driven and did not always, or even often, share the MRC's priorities for the Lower Mississippi River. Even so, the MRC accomplished a great deal in its efforts to protect the Valley from moderate floods, to improve the navigability of the Mississippi River, and to expand significantly the body of knowledge available on the "Father of Waters."

The habitat requirements of shovelnose sturgeon populations are unknown for the lower Mississippi River. Active acoustic telemetry was used to measure temporal variation in habitat use of shovelnose sturgeon and preference for depth, surface current velocity, and riverbed rugosity and slope by the population and within sandbar microhabitats. Shovelnose sturgeon occupied habitats differently throughout the year; and, within habitats, areas of moderate depth and surface current velocity and smooth riverbed were preferred. Within sandbars, environmental conditions did not differ from the surrounding environment, yet frequent aggregations of individuals in the lower portion of sandbars often in close proximity suggest habitat preference at a scale greater than the 5 ha measured. Results of this study provide information on seasonal habitat use patterns and methods that can be applied to a long-term dataset to identify the habitat requirements of shovelnose sturgeon.

Due to the flocculation process, suspended mud aggregates carried by rivers and streams can undergo changes in their size, shape, and settling velocity in response to environmental drivers such as turbulence, sediment concentration, organic matter (OM), and salinity. Some have assumed that salt is necessary for floc formation, and that mud, therefore, reaches the estuary unflocculated. Yet mud flocs exist in freshwater systems long before the estuarine zone, likely due to the presence of OM and ions in the water that facilitate binding and aggregation of mud particles. This research aimed to examine the flocculation state of mud over the fluvial as well as fluvial to marine transition (FtMT) zones of the Mississippi River basin and how salinity, or the ion concentration of water, and organic matter independently and together affect flocculation. Suspended mud was found to be mostly flocculated in the headwaters of the Mississippi River in southwest Virginia, USA. However, increasing the ion concentration of water samples to levels measured following winter storms changed the size distribution of suspended particles, led to more of the mud existing in large flocs, and resulted in an overall increase in average size by about 40%, thereby increasing the settling rate of the mud relative to the suspensions without salt. These results suggested that potential negative effects of road salts on mud deposition should be investigated further. Additional experiments were used to examine the flocculation of a natural mud sample with and without OM showed that the rate of floc growth and equilibrium size both increase with salinity regardless of the presence or absence of OM. However, the response of both to salinity was stronger when OM was present. In deionized water, natural sediment with OM was seen to produce large flocs. However, the size distribution of the suspension tended to be bimodal. With the addition of salt, increasing amounts of unflocculated material became bound within flocs, producing a more unimodal size distribution. Here, the enhancing effects of salt were noticeable at even 0.5 ppt, and increases in salinity past 3 to 5 ppt only marginally increased the floc growth rate and final size. A salinity-dependent model to account for changes in floc growth rate and equilibrium size was presented. Laboratory experiments on the sediment suspended in the lower reaches of the Mississippi River were used to provide further insight on the mud flocs behavior in the FtMT. Turbulence shear rate, a proxy for the river hydrodynamics, was found to be the most influential factor in mud floc size. While artificial increase in salinity by adding of salts did not lead to considerable increase in floc size, addition of water collected from the Gulf of Mexico enhanced the flocculation. These effects were speculated to originate from the biomatter composition of the Gulf water, particularly where the nutrient-rich Mississippi River water reaches the marine water. / Doctor of Philosophy / Rivers bring a substantial amount of mud to coastal regions. Where this mud deposits is important in shaping the coastal land and nutrient dynamics. Mud particles are different from sand and gravel in that they can form aggregates known as flocs that constantly change shape and size under different conditions. As they change size, they change how fast they sink, and this influences where they deposit. Due to their small size, mud particles are also considered a pollutant as they can clog up fish gills and destroy freshwater habitats. Findings of this dissertation showed that the roadway deicing salts that make their way to streams can enhance the aggregation of mud particles, causing them to sink faster. This can be harmful to the species that live on streambeds. While salts are known to enhance flocculation, there is ample evidence that flocs exist in rivers before reaching the sea. It is possible, therefore, that flocs in estuaries are due to biological matter acting as a glue to bind mud particles together and may not be influenced by salt. This dissertation looked at the effects of saltwater on mud flocculation when biological matter is present and when it is absent. Findings showed that salinity increased the size of mud flocs, even more so than when organic matter was absent. However, organic matter was needed for flocs to reach sizes often found in nature. An equation was also provided to aid in the prediction of floc size under different salinities. Observations on the lower Mississippi River flocs showed that the turbulence of water was the most influential factor in determining the size of flocs.

Note:

Shovelnose Sturgeon patterns of movement are unknown for the lower Mississippi River. Active acoustic telemetry was used to determine how Shovelnose Sturgeon moved throughout a section of river and what influenced those movements. Distance to habitat type, depth, surface current velocity, river stage, change in river stage, river bottom slope, and temperature were investigated. Shovelnose Sturgeon were found not to have random or goal-oriented movements using a straightness index. Movement rate was influenced by river stage and surface current velocity. Habitat suitability changed with river stage and distance to habitat type supported a suite of delineated river features that Shovelnose Sturgeon use at different river stages. Results of this study provide movement and selection methods that can be applied to a long-term dataset to identify movement characteristics of Shovelnose Sturgeon in the lower Mississippi River.