Wakulla Springs, located in the Woodville Karst Plain (WKP) of Florida’s Big Bend, is a complex phreatic cave system characterized by convoluted, irregular, conduit geometry—reaching depths between 45 meters to 90 meters (Werner, 2001). The depth and expanse of the underground conduit system makes the calculation of volumetric flow a challenging phenomenon to interpret. However, despite the challenges the Wakulla system presents to researchers, it poses as a unique system for study in that at least 60 kilometers of the system have been mapped to date—providing an extensive amount of well documented information about the conduits that is unavailable in other systems (Xu et al., 2015). Wakulla demonstrates distinct flashy spring characteristics, where there is a temporary high volume discharge in the springs. The dynamic nature of a flashy spring is of interest because of their inherent complex flow behavior compared to that of a static (near constant flow) spring. Early studies by Darcy (1865), Nikuradse (1933), Colebrook (1939), and Moody (1944) provide valuable phenomenological equations for describing flow behavior in pipe systems where a high degree of relative roughness (/D) is minimal. However, their studies lack detailed data pertaining to flow where the relative roughness was greater than five percent, which is common in natural karst conduit systems like Wakulla (Kandlikar et al., 2006). This study utilized a laboratory model to investigate the nature of flow through conduits with relative roughness greater than five percent as it pertains to karstic conduit systems, and determines the type of flow regimes that are achieved under various relative roughness. Parameters utilized in the experiment are categorized as having either a major or minor loss effect to the overall flow of the system. The minor loss parameters of hydraulic diameter, constriction and expansion, flow path modification, sinuosity, and major loss parameter of relative roughness were proven to have significant impacts on the flow velocity through a conduit. While each parameter had a major impact on fluid flow, the roughened pipes proved to have the greatest effect. The roughened pipes (/D of 0.00015 - 0.236) utilized in the experiment demonstrated similar behavior to pipes with relative roughness’ less than five percent and had reductions in flow up to 80 percent. The minor loss factor of hydraulic diameter also proved to be the most effective at reducing flow velocity, with velocities 70 percent less than those produced by unaltered pipe of the same hydraulic diameter. Minor loss parameters of expansion and contraction of the pipe diameter, and sinuosity also demonstrated a significant impact on flow velocity with reductions in flow upwards of 50 percent. The effects demonstrated by the parameters of the study contribute to the general understanding of the influence morphodynamics has on flow through Wakulla Springs conduit system and phreatic conduit systems, globally. / A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2018. / April 16, 2018. / Includes bibliographical references. / Stephen Kish, Professor Directing Thesis; James Tull, Committee Member; Leroy Odom, Committee Member.

The development of accurate carbon budgets, as well as global climate models with predictive capabilities, requires an understanding of the delivery and fate of terrigenous carbon in the environment. Understanding the extent to which estuarine and continental shelf processes alter carbon transfer between marine and terrestrial systems, including estimates of organic matter accumulation in coastal sediments, is poorly known. Organic carbon and nutrients exported to the adjacent Gulf of Mexico by the Mississippi River are influenced by biological and physical processes including remineralization, hydrodynamic sorting, seabed mixing and bioturbation, and burial. These complex processes make it difficult to know the fate of this organic matter (OM). The objective for this study was to examine the sources and fate of OM along its dispersal pathway from the Mississippi River mouth to the adjacent shelf and canyon. Changes in OM composition (C/N, δ13C, and lipid biomarker compounds) in surface sediment (0-1 cm) were examined along two transects. Using Factor Analysis, biomarkers representing allochthonous (plant) and autochthonous (algal) sources distinguished regional differences between the sites. The river, South West Pass (SW Pass), and marsh sites had greater contributions from higher plant sources. However, sources of OM delivered to these regions differed as evidenced by δ13C stable isotope signatures and C/N ratios. The river sites received inputs from soil organic matter and C3 terrestrial plants while the marsh region received inputs from marsh macrophytes. Despite offshore decreases in biomarkers representing terrigenous sources, signatures of terrigenous OM were present in surface sediments of the distal sites along each transect. The shelf sites had the greatest input of algal material, with biomarkers for diatoms dominating. Down-core analysis of sediment cores collected from three sites (SW Pass, 50 m Proximal, and canyon) further supported the surface sediment results. Plant / terrigenous materials were a major source of OM at the SW Pass site. The box cores from the 50 m Proximal and canyon sites received inputs from both autochthonous and allochthonous sources, with proportionately greater contributions from autochthonous OM. The downcore profiles were influenced by diagenesis as indicated by differences in the ratio of terrestrial to aquatic fatty acids resulting from preferential losses of short-chained fatty acids. This study provides information about sources of OM within the Mississippi River / Gulf of Mexico, and builds upon previous studies in this region. Results from this study illustrate that complex processes influence the fate of terrestrial OM. Hydrodynamic sorting which delivers fine-grained organic rich material further offshore and dilution of terrigenous material by productive shelf sites affect distribution and fate of terrigenous OM. This study also provides baseline information about carbon sources, important for understanding the influence of recent events such as Hurricanes Katrina and Rita, and further management / restoration efforts.

To estimate delivery to the coastal ocean, a global river database was assembled. An estimated 35,000 km3 of freshwater, 4 * 10 6 tonnes of dissolved solids and 18.6 * 106 tonnes of suspended sediment are delivered annually. The global delivery of fluvial water and sediment, both suspended and dissolved, is dominated by Southeast Asia, due to the unique climatic, geologic and geomorphic character of the rivers in this region. Over 30% of the global freshwater and dissolved solid discharge, and an astounding 70% of the suspended sediment originate in this region. The Salinas River, central California, was the focus of an in-depth study on the controls on sediment delivery from a small, semi-arid watershed. This river discharges into the Monterey Bay an average of 0.4 km3 of water and 3.3 tonnes of sediment annually. Basin-scale control on the discharge of the river is dominated by the underlying geology as well as the anthropogenic changes to the watershed. Despite the altered nature of the Salinas River, the fluvial discharge is dominated by short-lived meteorological events. Large flood events on the Salinas River almost entirely correlate with El Nino events. However, not all El Nino years produce flood events. It was shown that the probability of a large flood on the Salinas River is determined not only by the presence of El Nino conditions, but also by the interaction between the Pacific Decadal Oscillation and the ENSO. The coinciding of warm phases of both of these large-scale phenomena produces significantly higher annual discharges than any other combination of the climatic phenomena. The Monterey Bay is bisected by a submarine canyon, restricting the shelf space and creating 2 separate sedimentary environments. The southern shelf bypasses most modern fluvial sediment to the canyon, whereas the northern shelf stores most of the sediment delivered. The estimate of Holocene sediment discharge from the rivers and creeks of the bay indicate that >60% of fluvially delivered sediment is lost to the canyon and deep ocean. The transport pathways of this removal are currently unknown, but hyperpycnal flow from the mouth of the Salinas River is hypothesized.

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No description available.

Thesis (M.S.)--Ohio State University, 1984. / Includes bibliographical references (leaves 48-53). Available online via OhioLINK's ETD Center

Investigation of infiltration provides insights about the flow of water and transport of contaminants through the vadose zone. Infiltration is governed by prevailing environmental conditions like soil characteristics, plant cover and geologic settings. The main objective was to study preferential flow dominated infiltration at two contrasting hydrologic settings in Texas. For the first study, artificial rainfall was simulated within a plot covered with juniper trees at a karst region of the Edwards Plateau and sub-surface flow was monitored using TDR probes. Sub-surface flow was simulated using HYDRUS-2D. Results demonstrated that sub-surface flow occurred in a tri-modal manner, consisting of flow in karst conduits, planar fractures in the limestone, and soil matrix. Both fracture and matrix flow responses increased with increase in rainfall intensity. During large rainfall events, water exchange was observed between the fractures and matrix. Dye studies indicated that fractures and juniper roots were primary pathways for preferential flow occurring within the plot. The model simulated flow characteristics like exchange processes and differentiated between preferential and conduit flow besides determining approximate van Genuchten parameters for each geologic unit.For the second study, tension infiltrometers were used to conduct infiltration experiments at six soil water pressures (?? = -0.2 to 0 m) in an agricultural field near College Station over a 21 month period. The aim was to determine steady infiltration rate, if, saturated hydraulic conductivity, Ksat, unsaturated hydraulic conductivity, K(??) and unsaturated flux density ??(??). Moreover, the effect of varying disc diameters on steady state infiltration rates (if) was also studied. Results demonstrated that infiltration occurred in a bi-modal fashion consisting of preferential flow and matrix flow. Macropores and roots present in the soil resulted in gravity dominated flow at ?? = -0.05 to 0 m for all experiments. Statistical analysis suggested that the soil did not exhibit spatial variability within the plot and the five different disc diameters had no effect on if. Statistically significant differences in if were observed between 0.2 and 0.24 m disc diameters at saturation over the 21 month period. The if values illustrated strong temporal variations based on natural conditions over the 21 month period.

The following research describes the collection and evaluation of geochemical data from the Logsdon River, an open-flow conduit that drains a portion of the Turnhole Spring drainage basin within the Mammoth Cave karst aquifer of south-central Kentucky. This spatial survey of nearly 10 km of continuous base-level conduit included seasonal sampling of carbon dioxide partial pressures (Pco2)> dissolved ions, and saturation indices for calcite (SIcal). The highest PC02 values are found at the upstream site, closest to the Sinkhole Plain recharge area, which creates under-saturated conditions. Rapid outgassing of C02 into the cave atmosphere creates oversaturated conditions for several thousand meters. This change in chemistry results in the accumulation of rimstone in these areas. A boost in PC02 roughly half-way through the flow path returns the water to slightly under-saturated conditions. The most likely source for additional C02 is in-cave organic decay, as the boost also occurs during winter, when microbial activity in the soil is at a minimum. A general decline in Ca2+ , Mg2+, and HC03 concentrations occurred over the distance through the Logsdon River conduit. This decline may reflect a diluting of water by localized inputs from the plateau and precipitation of travertine along the flow path. Although values for all parameters are greater in summer than winter, the trend in evolution is similar for both seasonal extremes. The nature of the transition from summer to winter conditions in the aquifer was investigated by way of an intensive study of the geochemistry at the Logsdon River monitoring well. The relationship between conductivity (spC) and pH was evaluated during both seasons in an attempt to predict the activity of hydrogen for any given water sample based on continuous spC measurements at the well. Data collected during the 1997-98 seasonal transition supported a single, nonlinear regression equation that may represent two distinct seasonal regimes.

This thesis summarizes my research in which I investigated differences and characteristics in hydrologic, nutrient and geochemical cycling between karst versus nonkarst basins within the Interior Low Plateau Province. Field data including stream discharge, evapotranspiration, and dissolved major ion concentrations were collected for a period of one year for two basins within Mammoth Cave National Park. Twelve percent carbonate rocks underlie one basin, while the other consists of 48 percent carbonate rocks. The carbonate rock exposures within both basins exhibit karstification. The hydrologic and geochemical differences between these basins were compared to determine to what extent that cycles are modified or altered within karst terrains. The characteristics of these cycles within both basins were also compared. I found that there were noticeable hydro geochemical effects from the presence of karst within a basin. These effects were either the result of the presence of carbonate rocks within the basin or due to the presence of morphological karst features within the carbonate rocks. The presence of karst serves as a buffer by moderating temperature extremes, lessens the effect of acid precipitation, moderates discharges during storm surges, moderates/lessens a basin's evaporative losses, and affects available moisture and nutrients to surface biological processes. These hydrologic effects in turn, also continue to affect the basin's geochemistry in noticeable ways. Findings included that it only takes a small percentage of carbonate rocks within a basin to produce an output stream with a calcium/bicarbonate geochemical signature. In these situations, the quantity of karst is perhaps not as important as spatial distribution. Therefore, the quantity of karst within a basin may be more critical to accurately assess when conducting geochemical modeling. Many global geochemical models do not factor in karst affects (Holmen, 1992). Considering the extent of carbonate rocks globally and their potential ability to affect hydrogeochemical cycles, future model modifications may need to factor in karst affects in order to more accurately represent actual real-world field conditions.

Numerous quantitative relationships have been formulated to describe the nature of surface-drainage networks. These parameters have been used in various studies of geomorphology and surface-water hydrology, such as flood characteristics, sediment yield, and evolution of basin morphology. Little progress has been made in applying these quantitative descriptors to karst flow systems due to the lack of sufficiently complete data and inadequate technology for processing the large, complex data sets. However, as a result of four decades of investigation, an abundance of data now exists for the Mammoth Cave Watershed providing the opportunity for broader quantitative research in the organization of a large, highly-developed, karst-drainage network. Developing Geographic Information System (GIS) technology has provided tools to 1) book-keep the karst system's large, complex spatial data sets, 2) analyze and quantitatively model karst processes, and 3) visualize spatially and temporally complex data. Karst aquifers display drainage characteristics that in many ways appear similar to surface networks. The purpose of my research was to explore techniques by which quantitative methods of drainage- network analysis can be applied to the organization and flow patterns in the Turnhole Bend Groundwater Basin of the Mammoth Cave Watershed. Morphometric analysis of mapped active base-flow, stream-drainage density within the Turnhole Bend Groundwater Basin resulted in values ranging from 0.24 km/km2 to 1.13 km/km2. A nearby, climatologically similar, nonkarst surface drainage system yielded a drainage density value of 1.36 km/km2. Since the mapped cave streams necessarily represent only a fraction of the total of underground streams within the study area, the actual subsurface values are likely to be much higher. A potential upper limit on perennial drainage density for the Turnhole Bend Groundwater Basin was calculated by making the assumption that each sinkhole drains at least one first-order stream. Using Anhert and Williams' (1998) average of 74 sinkholes per km2 for the Turnhole Bend Groundwater Basin, the minimum flow-length draining one km2 is 6.25-7.22 km (stated as drainage density, 6.25-7.22 km/km2). Stream ordering of cave streams and their catchments generally follow Hortonian relationships observed for surface-stream networks. Subsurface streams within the Mammoth Cave Watershed generally exhibit a converging, dendritic pattern and possess drainage basins proportionately large for their order. However, even at base-flow conditions, the Turnhole Bend drainage system continues to possess confounding characteristics. These include at least one leakage to an adjacent groundwater basin (Meiman et al., 2001), diverging streams sharing the same surface catchment (Glennon and Groves, 1997), and highly complex, three-dimensional basin boundaries (Meiman et al, 2001). In spite of the incomplete data set available for the Mammoth Cave Watershed, study of initial values suggests an orderly subsurface flow network with numerical results that allow for comparison of the karst-flow network to surface fluvial systems.