Delta islands make up the majority of coastal delta area. However, the groundwater hydrology of young, prograding delta systems and its relationship to surrounding surface water dynamics are poorly understood. Deltas in coastal environments are assumed to function as chemical “buffers”, filtering nutrient-rich terrestrial runoff through the island structures and surface water ecosystems as it travels to the sea, but the magnitude of this effect cannot be accurately quantified without understanding the physical relationships between the surface water and groundwater. This study developed the first conceptual model of the hydrology of prograding delta island groundwater systems. The study was based on field data collected at Pintail Island, a 2 km2 island within the Wax Lake Delta in Louisiana. Hydraulic properties and processes were quantified at multiple depths at locations spanning the island elevation gradient. Groundwater and surface water levels were monitored. A weather station recorded precipitation, air, and wind conditions. The groundwater within Pintail Island was both spatially and temporally dynamic throughout the study period of Sept/9/2013 to Feb/4/2014. The aquifer within the distal limbs of the island responded as a connected, saturated unconfined aquifer. The portions of Pintail Island within the older, proximal, higher elevation apex were found to be a two-layer system with fine sediments and organic matter overlying sandy deposits. The aquifer within this section of the island responded differently during times of elevated surface water (storm events) and times of normal surface water (calm periods) and differently from the distal-island unconfined system. The fine, shallow (roughly 0-60cm depth) sediments capping this older, higher portion of the island appeared to inhibit vertical flow between the surface and subsurface, creating semi-confined conditions within the sands in the deeper island subsurface. High water levels led to overpressurization of the apical aquifer, which was maintained between storms due to the low hydraulic gradient and the low permeability of the porous medium. During inundating storm events, groundwater potentials mimicked surrounding surface water levels. This conceptual model of a prograding coastal delta island now provides a foundation for further, hydrologically-realistic study of delta ecology and nutrient exchange. / text

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Having constructed a plantation economy in the Yazoo Mississippi Delta, white Delta planters struggled to retain control of African-American labor after the start of the Civil War. In their effort, the planters manipulated the Freedmen's Bureau; passed the Black Code; sought out foreign labor; and condoned extralegal intimidation. The Civil War disrupted the plantation economy of the Yazoo Delta, prompting the planters to pursue innovative means to preserve the status quo. To achieve this end, they fought with the Confederate government for control of the militia, attempting to stabilize an economy rocked by military incursions, deserters, and outbreaks of lawlessness. Emancipation, the ultimate disruption to the plantation, precipitated a struggle between these former masters and African-Americans seeking to find the meaning of their freedom. The United States government also attempted to restructure the plantation economy of the Delta after the Civil War, but planters often manipulated federal authority to their advantage. Charged with protecting the interests of the freedmen, the Freedmen's Bureau, for example, frequently accommodated the labor needs of Delta planters, even transporting labor to the plantations when necessary. Similarly, Union military commanders frequently supported the planters in their attempt to control black labor. Delta planters, however, wished themselves entirely free of outside governance. Thus, in 1865, they helped formulate the Black Code, seeking to limit the labor options of the freedmen. When Congress negated this code, the planters sought foreign laborers to force African-Americans into economic desperation. Under congressional patronage, moderate Republicans, led by Delta planter James L. Alcorn, attempted to build a party led by white men and supported by African-American votes. When this moderate "Alcorn Republican" system failed in 1873, the planters aligned themselves with the "straight out" Democratic party, rather than support the pro-black Republicans led by Adelbert Ames. Using a system of fraud and brute violence, the white planters ultimately seized power from the Republican party in 1875. This "Mississippi Plan" allowed the planters to remove labor from politics, free the state from authority inimical to their interests, and ensure continuation of the plantation economy.

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The rate of data growth outpaces the decline of hardware costs, and there has been an ever-increasing demand in reducing the storage and network overhead for online database management systems (DBMSs). The most widely used approach for data reduction in DBMSs is blocklevel compression. Although this method is simple and effective, it fails to address redundancy across blocks and therefore leaves significant room for improvement for many applications. This dissertation proposes a systematic approach, termed similaritybased deduplication, which reduces the amount of data stored on disk and transmitted over the network beyond the benefits provided by traditional compression schemes. To demonstrate the approach, we designed and implemented dbDedup, a lightweight record-level similaritybased deduplication engine for online DBMSs. The design of dbDedup exploits key observations we find in database workloads, including small item sizes, temporal locality, and the incremental nature of record updates. The proposed approach differs from traditional chunk-based deduplication approaches in that, instead of finding identical chunks anywhere else in the data corpus, similarity-based deduplication identifies a single similar data-item and performs differential compression to remove the redundant parts for greater savings. To achieve high efficiency, dbDedup introduces novel encoding, caching and similarity selection techniques that significantly mitigate the deduplication overhead with minimal loss of compression ratio. For evaluation, we integrated dbDedup into the storage and replication components of a distributed NoSQL DBMS and analyzed its properties using four real datasets. Our results show that dbDedup achieves up to 37⇥ reduction in the storage size and replication traffic of the database on its own and up to 61⇥ reduction when paired with the DBMS’s block-level compression. dbDedup provides both benefits with negligible effect on DBMS throughput or client latency (average and tail).

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A barrier to creating the platform-independent services envisioned by middleware-based development infrastructures is the level of performance robustness of the distributed applications created with them, in lieu of unpredictable variations in application behavior or in the resources available for satisfying user requests. Our goal is to improve the behavior locality of distributed applications and to prevent performance (mis-)behaviors from spilling across certain boundaries, since such spillage weakens behavior diagnoses and/or weakens or disables the effects of locally applied control or management methods. Toward these ends, we develop a novel software abstraction, termed {em isolation points} (I-points), which can be used to isolate application components or subsystems from each other. The main contributions of this work are Isolation Points, which are software abstractions for monitoring and understanding dynamic runtime behaviors to better isolation application components hence creating more robust distributed applications. Two concrete artifacts using I-points also developed in this thesis are: I(solation)-RMI and I(solatoin)-Queue. I-RMI demonstrates the utility of isolation points in J2EE's RMI-IIOP domain. I(solation)-Queue applies isolation points to message passing systems.

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Deposits of Robertkiri field, in the central offshore area of Niger Delta, comprise a 4 km thick succession of Pliocene to Miocene non-marine and shallow marine deposits. A sequence stratigraphic framework for Robertkiri field strata was constructed by combining data from 20 well logs and a seismic volume spanning 1400 km2. Major sequences, hundreds of meters thick, define layers of reservoir and sealing strata formed during episodic progradation and retrogradation of deltaic shorelines. These deposits progress upward from fine-grained prodelta and deep water shales of the Akata Formation through paralic sandstone-shale units of the Agbada Formation and finally to sandy non-marine deposits of the Benin Formation. The Agbada Formation is divided into six third-order sequences starting at the first seismic reflection that can be mapped across the seismic volume. The Agbada Formation under Robertkiri field is complexly deformed across a succession of major, cuspate, offshore-dipping, normal faults, and associated antithetic faults and rollover anticlines within down-dropped blocks. Thickening of intervals between some reflections across major faults and away from the crests of adjacent rollover anticlines suggest syndepositional displacement. Relationships between major faults and the thickness of transparent seismic facies that comprise lower parts of the seismic record suggest faulting was associated with movement of undercompacted shales within the Akata and lower Agbada Formations. Robertkiri field is located along the proximal margin of the Coastal Swamp I depobelt, a subbasin within the Niger Delta clastic wedge formed by margin collapse into underlying undercompacted shale. Accommodation and sequence development in this setting is controlled by both structural faulting and sea level fluctuations. Upsection, sequences become thinner, more laterally uniform in thickness, less structurally deformed and contain less growth strata. Erosion along sequence boundaries becomes progressively shallower and broader, as accommodation under Robertkiri field declined and more sediment was bypassed basinward. Incisions along the base of older sequences (>100 m) is greater than 3rd order sea level falls reported to occur during the Miocene, which suggests that there were local areas of tectonic uplift within this dominantly extensional setting.