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.

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.

The Calvin-Benson-Bassham (CBB) pathway is the primary pathway for the entry of inorganic carbon in the biosphere. Autotrophic organisms use this cycle to ultimately convert CO2 into carbohydrates using a key enzyme known as ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). The gene that encodes for the large subunit of RubisCO is rbcL and detection of its expression can be used to determine the autotrophic organisms present in the environment. Recently, microarrays have been used to study functional gene expression from environmental samples such as those obtained from sediments and soil. The purpose of this thesis is to combine microarray technology and rbcL expression analysis to investigate phytoplankton populations in the Mississippi River Plume (MRP). Initially, a macroarray was constructed to determine its capabilities of quantifying gene expression in MRP. PCR amplicons were spotted onto a nylon membrane and labeled transcript RNA was hybridized to each array. Due to the large amount of cross hybridization that was observed, a microarray was used. Microarray analysis revealed large amounts of Synechococcus, pelagophyte and prymnesiophyte expression in the surface waters. Furthermore, there was no chlorophte or Prochlorococcus expression observed in the surface waters. Subsurface microarray data showed high levels of pelagophytes and other Form ID organisms. A significant chlorophyte signal was also observed in the subsurface. This study provides a third level of specificity at which phylogenetic diversity has been sampled in the MRP. Although a limited number of samples were analyzed by microarrays, this technology shows promise and this study was viewed as a pilot for their application. The rbcL probes designed were based upon published sequences from 2003 and we now have a much greater understanding of the diversity of rbcL-containing phytoplanktonic phylotypes. Future studies should employ this knowledge for judicious probe selection.

Optically stimulated luminescence (OSL) dating beach ridge sediments is one method for resolving barrier island growth at intermediate scales (decades-centuries), information that is lacking for Louisiana. This research combines OSL, GPR, aerial imagery, and cores to document temporal and spatial evolution of a Louisiana barrier island. Grand Isle is composed of beach ridges organized in distinct, unconformable sets that began forming 0.75 ka until 0.575 ka when deposition ceased, the ridges were partially eroded, and deposition resumed in a more eastward direction. The central ridges formed between 370±30 and 170±10 years ago at a rate of one ridge every 11.6 years with sand from the eroding Caminada headland that, with flanking barriers, forms the Bayou Lafourche transgressive depositional system. Grand Isle’s lithosome (92,600,000 cubic meters) requires an annual longshore transport of 128,625 cubic meters. The lithosome thickness (10 meters) and steady sediment supply stabilize the island relative to other Louisiana barriers.

This thesis details the work completed in order to develop a hydrodynamic and nitrate transport and reaction model for Round Lake, a backwater on UMR Pool 8. This work begins with investigating the fundamentals of nitrogen removal in aquatic ecosystems and reviewing other combined hydrodynamic and nutrient modeling efforts. Field data were gathered to determine model boundary conditions and provide a basis for calibration and validation. Using this data, the flow regime in Round Lake was simulated. CFD applications to model particle residence times and species transport and reaction were used to analyze the effects local hydraulics have on nitrogen removal in the lake. Results demonstrated an ability for CFD to predict spatial variation of nitrate with this ecosystem.

The Upper Mississippi River System (UMRS) is a diverse and dynamic ecosystem that includes the main stem river channel, side channels, backwater floodplains and lakes, islands, wetlands, grasslands, and floodplain forests. The hydrology of this rich ecosystem is one of the key drivers for physical, chemical and biological processes. However, the hydrology and hydraulics of the UMRS has been drastically altered from its natural state as a result of the construction of the locks and dams in the 1930s. Beginning with the Water Resources Development Act of 1986, biologists, ecologists, and engineers have been working to restore the river to a more natural state within the current constraints imposed by the lock and dam system. In an effort to restore rivers to a more natural state, the determination of a hydraulic reference condition is essential to understanding the "why and how" of historical river system function. Understanding the fundamental processes of historical conditions will help prioritize resources and better quantify possible outcomes for riverine restoration. The main goal of this study was to construct a hydrodynamic reference condition for Pool 8 of the Upper Mississippi River System using hydrodynamic computational fluid dynamic (CFD) modeling. The CFD model will provide a better understanding of pre-impoundment flow conditions as compared to post-impoundment conditions today. The numerical model was constructed and developed primarily from a pre-impoundment 1890s topographic map with bathymetric cross-sections in the channels. The 1890s map and other sources from the U.S. Army Corps of Engineers provided historic elevation and hydraulic reference data for model calibration. The calibrated historic model was then compared with a current model of similar scale representing post-impoundment conditions, allowing for quantitative analysis of the differences between the two conditions. Model results indicated large changes in average depth and average velocity between historic and current conditions in certain parts of the pool, while others remained relatively unchanged. For example, velocities decreased in main channel aquatic areas in the lower part of Pool 8 from an average of 0.6 m/s (2.0 ft/s) under historic conditions to 0.1 m/s (0.3 ft/s) under current conditions. In the same part of the pool, however, velocities in contiguous backwater areas remained relatively constant, with most remaining less than 0.25 m/s (0.82 ft/s). Additionally, in the lower part of the pool, discharge distribution between the floodplain areas and the main channel was historically much more dynamic, with flow concentrated in the main and secondary channels at discharges less than 2265 m3/s and in the floodplains at greater than 2265 m3/s. Under current conditions, discharge distribution is much less dynamic, with approximately 2/3 of the total discharge conveyed on the floodplain for all discharges modeled (283 m3/s to 2832 m3/s or 10,000 ft3/s to 100,000 ft3/s).