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[en] This article examines the innovative techniques the participants in the Vidalia, Mississippi hydropower project used to overcome the numerous obstacles to the financing of the project. The topics of the article are early obstacles, funding and permitting, hydrology questions, matching income to debt, unorthodox provisions and a tough closing
[en] The Geologic Data Base for Richton Dome, Mississippi, was updated and expanded in FY 82 to support National Waste Terminal Storage characterization studies. The existing data base, consisting of references, maps, remote sensing data, and well-boring information, was inventoried to catalog the data acquired during previous studies. This catalog is maintained on Ertec's in-house computer. Bibliographies of selected documents were reviewed and commercial data bases were searched to identify additional references pertinent to future geologic characterization studies to be added to the data base. In addition to the references, selected preliminary safety analysis report sections and associated reports for nuclear generating stations, oil and gas well completion records, and US Geological Survey System 2000 hydrologic data were obtained for specific areas of Mississippi and Alabama. These additional data and references provide a comprehensive and current data base for Richton Dome
[en] The structure of a river network may be seen as a discrete set of nested subnetworks built out of individual stream segments. These network components are assigned an integral stream order via a hierarchical and discrete ordering method. Exponential relationships, known as Horton's laws, between stream order and ensemble-averaged quantities pertaining to network components are observed. We extend these observations to incorporate fluctuations and all higher moments by developing functional relationships between distributions. The relationships determined are drawn from a combination of theoretical analysis, analysis of real river networks including the Mississippi, Amazon, and Nile, and numerical simulations on a model of directed, random networks. Underlying distributions of stream segment lengths are identified as exponential. Combinations of these distributions form single-humped distributions with exponential tails, the sums of which are in turn shown to give power-law distributions of stream lengths. Distributions of basin area and stream segment frequency are also addressed. The calculations identify a single length scale as a measure of size fluctuations in network components. This article is the second in a series of three addressing the geometry of river networks
[en] Ertec, Inc. is conducting a potentiometric monitoring program in Mississippi and Louisiana for the Office of Nuclear Waste Isolation (ONWI) as part of the Regional Ground-Water Flow Activities for Richton and Vacherie domes. Ertec, Inc. assumed responsibility for this program from Law Engineering Company (LETCo) in February 1982. The results of Ertec's monitoring program have been periodically submitted to ONWI in two quarterly reports. This annual report contains monitoring data obtained during the 1982 Fiscal year, together with: a review of actions taken to ensure the quality of the monitoring program following the assumption of the monitoring program from LETCo, a summary of the problems encountered during the monitoring program, and recommendations for the monitoring program in the future
[en] The structure and stratigraphy over Richton Salt Dome, Mississippi, have been evaluated from 70 borings that were completed to various depths above the dome. Seven lithologic units have been identified and tentatively correlated with the regional Tertiary stratigraphy. Structure-contour and thickness maps of the units show the effects of dome growth from Eocene through early Pliocene time. Growth of the salt stock from late Oligocene through early Pliocene is estimated to have averaged 0.6 to 2.6 centimeters (0.2 to 1.1 inches) per 1000 years. No dome growth has occurred since the early Pliocene. The late Oligocene to early Pliocene strata over and adjacent to the dome reflect arching over the entire salt stock; some additional arching over individual centers may represent pre-Quaternary differential movement in the salt stock. The lithology and structure of the caprock at the Richton Salt Dome indicate that the caprock probably was completely formed by late Oligocene. In late Oligocene, the caprock was fractured by arching and altered by gypsum veining. Since late Oligocene, there are no indications of significant hydrologic connections through the caprock - that is, there are no indications of dissolution collapse or further anhydrite caprock accumulation. This structural and stratigraphic analysis provides insights on dome growth history, dome geometry, and neardome hydrostratigraphy that will aid in planning site characterization field activities, including an exploratory shaft, and in the conceptual design of a high-level waste (HLW) repository
[en] Highlights: • Archival OSL data from Mississippi Delta quartz sand samples (n = 42) inform age model selection and input. • Valid overdispersion (σb) inputs for age modeling are obtained from the dataset. • The bootstrapped Minimum Age Model yields robust ages for well- and heterogeneously-bleached samples herein. Optically stimulated luminescence (OSL) dating of heterogeneously-bleached sediment by means of a minimum age model requires the input of a 'sigmab' (σb) value describing the overdispersion of the single-aliquot De distribution expected for a well-bleached sample. We propose that σb and associated uncertainty can be accurately determined if a large dataset of De distributions is available and includes well-bleached samples. Our approach applies the bootstrapped Minimum Age Model (bootMAM) to a dataset of overdispersions in De distributions, to obtain quantitative estimates of σb. Corrections are made for constant-diameter aliquots of different grain sizes, based on the published dependency of overdispersion on the number of grains per aliquot. These adapted σb values are then input to bootMAM to obtain robust paleodoses for the samples. We test the sensitivity of paleodose to σb and we demonstrate that with correct σb, identical paleodoses are obtained using bootMAM and the Central Age Model on samples judged to be well-bleached. We conclude that for large datasets consisting of well- and heterogeneously-bleached samples, appropriate σb values can be obtained from the data, and that bootMAM can be applied to all samples within this dataset.
[en] The establishment of a standardized growth curve is desired for optical dating as it facilitates the dating procedures. Here, we analyzed the dose responses of 16 fine silt quartz samples from the Lower Mississippi Valley in order to identify common properties that would allow establishing a standardized OSL growth curve (SGC). The analysis confirms the dependence of the standardized dose response upon the size of test dose. This dependence was corrected by converting the standardized dose response to an equivalent standardized dose response obtained by a 1.8 Gy test dose. Equivalent SGCs were established for two different grain size ranges by combining the data of several samples and fitting the sum of a single saturating exponential function and a linear function to the equivalent standardized dose response of these data. Equivalent doses up to 500 Gy determined with an equivalent SGC agree well with those obtained with a conventional SAR protocol, suggesting that the equivalent SGCs established in this study are reliable.
[en] To provide information for the development of management strategies to reduce N loads and enhance N attenuation mechanisms, isotopic techniques have been used to investigate the sources and cycling of nutrients at a number of sites in the Mississippi Basin (which includes the Ohio and Missouri River Basins). About half of the POM in the Mississippi (and other big rivers in the USA) is composed of plankton and/or heterotrophic bacteria. This suggests that in-situ productivity may be a significant source of bioavailable organic matter contributing to the hypoxia in the Gulf of Mexico. Monthly samples from 19 river sites in the Basin sampled over 5 years showed that δ 15N and δ 13C were quite useful in discriminating among four major categories of POM: terrestrial soil, fresh terrestrial vegetation, aquatic macrophytes, and plankton/bacteria The isotopic data, along with ancillary chemical and hydrologic measurements, were also useful for documenting seasonal changes in in-situ processes. A pilot study in 2000-2001, designed to investigate the usefulness of isotopic techniques for determining nutrient sources in 24 medium and large watersheds in the Basin, found that nitrate and POM from basins with different land uses (e.g., row crops, animal farming, urban development, and undeveloped) had moderately distinctive isotopic compositions. The nitrate δ 18O and δ 15N values of the large rivers sites resembled the compositions seen in sites dominated by row crops. Sites with livestock tended to have high δ 15N values characteristic of manure, and urban and undeveloped sites tended to have higher δ 18O values characteristic of a significant fraction of atmospheric nitrate. The δ 18O data were critical in showing abrupt changes in nitrate sources with discharge. A more thorough study of nutrient sources in the Ohio River Basin was initiated in 2002. For this study, nitrate, POM, and water were collected 15-20 times each year at 6 small NAWQA-program watersheds in the White River- Miami River basins, and at the 7 large river NASQAN-program sites in the Ohio River Basin. Nitrate samples were analyzed for δ 15N and δ 18O, POM for δ 15N and δ 13C, and water for δ 18O and δ 2H. The δ 15N and δ 13C of fish were used as indicators of nutrient sources. Other studies have indicated that POM consists primarily of phytoplankton and is transported in the water column, particularly size fractions < 1-mm diameter, were the primary food source for food webs in the Ohio and Upper Mississippi Rivers