Global ETD Search

1	Spatial and Seasonal Variations of Pollen in the Mississippi and Atchafalaya Rivers, U.S.A. Smirnov, Alexei January 1995 (has links) Note: Pollen -- Mississippi River.
2	The kinematics of distributary channels on the Wax Lake Delta, coastal Louisiana, USA Shaw, John Burnham 17 July 2014 (has links) The Wax Lake Delta (WLD) is a sandy, modern river delta prograding rapidly into Atchafalaya Bay. This dissertation uses field data to improve the understanding of channel kinematics that dictate river delta geometry and stratigraphy, while providing a framework for coastal restoration efforts. The studies presented here show that the distributary channel network of the WLD is erosional. In the first study, analyses of the feeder channel to the WLD and the channel network within the sub-aerially emergent delta show that the channel bed has incised into the consolidated muds that act as bedrock. The large (>62%) fraction of bedrock exposure found in multi-beam surveys is related to the under-saturation of suspended sand measured during the flood of 2009. The second study concerns the delta front beyond the emergent delta Distributary channels extend 2 – 6 km into the delta front. Four bathymetric surveys of one bifurcating distributary channel – Gadwall Pass – show that the majority of bed aggradation occurs during floods, but the majority of channel extension of each bifurcate channel occurs during low river discharge. In the third study, field measurements of fluid flow during a tidal cycle indicate that tidal augmentation of during periods of low river discharge is responsible for channel extension during low river discharges. Flow direction measured from streaklines present in aerial photomosaics is combined with bathymetric evolution data to quantify spatial velocity changes on the delta front. These data show that flow spreading is insufficient to prevent acceleration at channel margins, providing an explanation for observed erosion. Flow divergence is limited on the delta front by the proximity of neighboring channels, even though they are separated by 10-30 channel widths. The associated convergence of flow in inter-distributary bays occurs along “drainage troughs”. These channel-forms collect flow that has been dispensed from distributary channel network. Finally, ambient currents in Atchafalaya Bay (0.06 – 0.2 m/s) caused by tides and the proximity to the neighboring Atchafalaya Delta appear to alter flow patterns on the delta foreset, and are responsible for channel curvature on the delta front. / text River delta Sediment Distributary channels Progradation Kinematics Wax Lake Delta Louisiana Atchafalaya Bay
3	Coastal marsh formation and its relation to sediment exchange along the Chenier Plain in southwest Louisiana January 2013 (has links) It is well recognized that rivers are the primary pathway that delivers sediment to the ocean. However, the fate of these sediments is poorly understood, and is complicated by relative sea level rise and meteorological forcings. One coastal system to examine these issues is the Atchafalaya River-Chenier Plain (ARCP) of southwest Louisiana, which relies on Mississippi River sediment supply and is vulnerable to coastal erosion and land loss. Despite regional coastal degradation, some land gain and marsh growth have been observed here. Land gain in south Louisiana is generally observed at the mouths of the rivers â€“ the Birdâ€™s Foot, and the Atchafalaya and Wax Lake deltas. However, satellite imagery and sedimentological analyses indicate that coastal lakes in southwest Louisiana have also filled in and converted into salt marshes in the last 40 years. To understand sediment delivery in these marshes, multiple short cores were collected in a central Chenier Plain tidal creek system, and analyzed for 210Pb, 137Cs, 7Be, Î´13C, and grain size distribution. We propose that Chenier Plain reactivation processes are triggered by the increase in Atchafalaya River flow that began in the early 1900s. Fluvial sediments delivered through westward longshore transport and resuspended during energetic events become available to the sediment-starved Chenier coast, leading to deposition, infilling, mudflat progradation, and marsh growth. / acase@tulane.edu Atchafalaya Marsh Sediment School of Science & Engineering Earth and Environmental Sciences Masters
4	Estimating population parameters of the Louisiana black bear in the Upper Atchafalaya River Basin Lowe, Carrie Lynne 01 May 2011 (has links) In 1992, the Louisiana black bear (Ursus americanus luteolus) was granted threatened status under the Endangered Species Act primarily because of extensive habitat loss and fragmentation. Currently, the Louisiana black bear is restricted to 3 relatively small, disjunct breeding subpopulations located in the Tensas River Basin of northeast Louisiana, the upper Atchafalaya River Basin (ARB) of south-central Louisiana, and coastal Louisiana. The 1995 Recovery Plan mandates research to determine the viability of the remaining subpopulations. I conducted a capture-mark-recapture study during 2007–2009 to estimate population parameters for the ARB bear subpopulation by collecting hair samples (n = 2,977) from 115 barbed-wire hair traps during 8 1-week periods each summer. DNA was extracted from those hair samples and microsatellite genotypes were used to identify individuals. I analyzed encounter histories using the Huggins full heterogeneity estimator in a robust design framework in Program MARK. I compared candidate models incorporating heterogeneity, behavior, and time effects on capture using information-theoretic methods. I directly estimated apparent survival, temporary emigration, probability of capture and recapture, and probability of belonging to 1 of 2 mixtures; population abundance was a derived parameter. Apparent survival was 0.91 (SE = 0.06) and did not vary by gender or year. There was some evidence of temporary emigration for males only (0.10, 95% CI = 0.001–0.900). I modeled capture probabilities with a 2-mixture distribution for both male and females. Overall mean weekly capture probability was 0.12 (SE = 0.03) and 0.25 (SE = 0.04) for males and females, respectively. Recapture rates indicated a positive behavioral response to capture. Model-averaged mean annual abundance was 56 (SE = 4.5, 95% CI = 49–68). I calculated population density using spatially-explicit maximum-likelihood methods; model-averaged density was 0.15 bears/km2 (SE = 0.03). My results updated previous abundance estimates for the ARB bear subpopulation and will be used in a population viability analysis to determine if recovery criteria for the Louisiana black bear have been met. abundance black bear robust design Atchafalaya Ursus americanus luteolus DNA Other Life Sciences Population Biology
5	A Multidisciplinary Approach for Determining the Extents of the Beds of Complex Natural Lakes in Louisiana Willis, Frank Levins 06 August 2009 (has links) In Louisiana, the beds of natural lakes are owned by the state. The locations of property boundary lines separating state property from private lands have usually been set by determining the levels of natural monuments known as ordinary high water marks. The term is confusing and subjective, leading to controversy in reference to its determination. Catahoula Lake in central Louisiana was chosen as a study site because of its large size, its 20-foot variation in water levels, and its low-relief perimeter. Geology, geomorphology, hydrology, archaeology, vegetation, dendrochronology and dendrohydrology of the ancient cypress fringe, nineteenth century land survey records, historical records, and time-series statistics were applied to determine the elevation range of ordinary high water. Research suggests that the level of the ordinary high water natural monument used universally in Louisiana to define lake boundaries is not the correct natural monument. This research suggests that, for example, the natural monument that defines the Catahoula Lake boundary is not a vertical monument, but rather an areal monument that was originally recognized by nineteenth century U.S. government surveyors and embedded in the evidence extracted from their original field notes. The solution coincides with the boundaries of regional land patents and offers a consistent solution to determining the boundaries of thousands of acres of disputed lands. The procedure is applicable to other lake and swamp boundaries in Louisiana and other states. Lake lake boundary lake shore bed shore bank survey river stream geomorphology geology tree rings cross dating dendrohydrology dendrochronology dendrosedimentology pollenology baldcypress ordinary high water ordinary high water mark Swamplands Act areal cypress fringe alluvial ridge natural monuments cypress knee Great Red River Raft Atchafalaya River raft US General Land Office land survey patent oil and gas litigation

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