The Windermere turbidite system, exposed in the southern Canadian Cordillera, east-central British Columbia, is a continental scale, passive margin, submarine fan system, part of which is well exposed in the Castle Creek study area. Here millimetre- to decametre-scale sedimentological and stratigraphic observations identified five facies in interchannel strata: very thin- to medium-bedded turbidite (F1), thick-bedded turbidite (F2) coarse-tail graded structureless sandstone (F3), mudstone clast breccia (F4) and carbonaceous mudstone (F5) and four architectural elements: channel (AE1), distal levee (AE2), overbank splays (AE3) and crevasse splays (AE4). These elements are assembled into a predictive depositional model that describes the initiation and evolution of sandy splay elements developed in distal levee strata of deep-marine slope channels. These data can be used in hydrocarbon exploration to identify and differentiate splay deposits in core and on seismic, and thereby improve the accuracy of subsurface reservoir models.

The Windermere turbidite system, exposed in the southern Canadian Cordillera, east-central British Columbia, is a continental scale, passive margin, submarine fan system, part of which is well exposed in the Castle Creek study area. Here millimetre- to decametre-scale sedimentological and stratigraphic observations identified five facies in interchannel strata: very thin- to medium-bedded turbidite (F1), thick-bedded turbidite (F2) coarse-tail graded structureless sandstone (F3), mudstone clast breccia (F4) and carbonaceous mudstone (F5) and four architectural elements: channel (AE1), distal levee (AE2), overbank splays (AE3) and crevasse splays (AE4). These elements are assembled into a predictive depositional model that describes the initiation and evolution of sandy splay elements developed in distal levee strata of deep-marine slope channels. These data can be used in hydrocarbon exploration to identify and differentiate splay deposits in core and on seismic, and thereby improve the accuracy of subsurface reservoir models.

Understanding the internal organization of the Lower Pleistocene 8 Sand reservoir in the Green Canyon 18 field, Gulf of Mexico, helps to increase knowledge of the geology and the petrophysical properties, and hence contribute to production management in the area. Interpretation of log data from 29 wells, core and production data served to detail as much as possible a geological model destined for a future reservoir simulation. Core data showed that the main facies resulting from fine-grained turbidity currents is composed of alternating sand and shale layers, whose extension is assumed to be large. They correspond to levee and overbank deposits that are usually associated to channel systems. The high porosity values, coming from unconsolidated sediment, were associated to high horizontal permeability but generally low kv/kh ratio. The location of channel deposits was not obvious but thickness maps suggested that two main systems, with a northwest-southeast direction, contributed to the 8 Sand formation deposition. These two systems were not active at the same time and one of them was probably eroded by overlying formations. Spatial relationships between them remained unclear. Shingled stacking of the channel deposits resulted from lateral migration of narrow, meandering leveed channels in the mid part of the turbidite system. Then salt tectonics tilted turbidite deposits and led to the actual structure of the reservoir. The sedimentary analysis allowed the discrimination of three facies A, B and E, with given porosity and permeability values, that corresponded to channel, levee and overbank deposits. They were used to populate the reservoir model. Well correlation helped figure out the extension of these facies.

The Windermere turbidite system, exposed in the southern Canadian Cordillera, east-central British Columbia, is a continental scale, passive margin, submarine fan system, part of which is well exposed in the Castle Creek study area. Here millimetre- to decametre-scale sedimentological and stratigraphic observations identified five facies in interchannel strata: very thin- to medium-bedded turbidite (F1), thick-bedded turbidite (F2) coarse-tail graded structureless sandstone (F3), mudstone clast breccia (F4) and carbonaceous mudstone (F5) and four architectural elements: channel (AE1), distal levee (AE2), overbank splays (AE3) and crevasse splays (AE4). These elements are assembled into a predictive depositional model that describes the initiation and evolution of sandy splay elements developed in distal levee strata of deep-marine slope channels. These data can be used in hydrocarbon exploration to identify and differentiate splay deposits in core and on seismic, and thereby improve the accuracy of subsurface reservoir models.

This study combined flood-frequency analysis, 1-D (one-dimensional) hydraulic modeling using HEC-RAS, and flood-loss modeling using FEMA's Hazus-MH (Hazards U.S. Multi-Hazard) in order to: 1) quantify how different flood-frequency methodologies affect flood-risk assessments, and 2) quantify the impacts of different floodplain-management scenarios along the Middle Mississippi River (MMR). The nine scenarios tested here included various combinations of flood-frequency methodology, buyouts, and levee configurations. The levee configurations analyzed included: 1) current levee configuration, 2) no levees, 3) a 1500 m levee setback, 4) a 1000 m levee setback, and 5) a customized levee setback designed to maximize protection around existing infrastructure. Two study reaches were chosen: (1) an Urban Study Reach within St. Clair and northern Monroe Counties, IL, with levees designed to withstand the 500-year flood and (2) an Agricultural Study Reach within Union and Jackson Counties, IL, with <100-year levees. A flood-frequency analysis was completed for the St. Louis, MO gauging station, and detailed building inventories were used to estimate flood losses on a structure-by-structure basis (Hazus-MH UDF analysis) for an array of floods ranging from the 2- to the 500-year events. These flood-loss estimates were combined with a stochastic levee-failure model. Finally, estimated flood damages from Hazus-MH were integrated across the full range of flood recurrences in order to calculate expected annual damage (EAD). This study's flood-frequency analysis and corresponding flood-loss assessment demonstrate how differences in flood-frequency methodology can significantly impact flood-risk assessments. EAD based on the UMRSFFS (Upper Mississippi River System Flow Frequency Study) flood frequencies was 68% ($45.4 million) lower than EAD based on this study's flood frequencies. This decrease in EAD demonstrates that the UMRSFFS flood frequencies and corresponding stages may significantly underestimate flood risk within the Urban Study Reach. The 100-year discharge in the UMRSFFS appears to be underestimated by an estimated 17% (187,000 cfs), resulting in a 10% (1.6 m) underestimation of the 100-year flood level. Given the magnitude of the EAD, discharge, and stage differences documented here, a reanalysis of the MMR flood frequencies, flood profiles, and flood maps should be considered. The hydraulic modeling completed here showed that levee setbacks and levee removal successfully reduce stages for all recurrence intervals. For the 100-year flood, average reductions ranged from 0.20 m for a 1000 m levee setback to 1.61 m with levees removed. In general, stage reductions increased with increasing discharge and with increasing setback distance. The flood-level reductions are attributed to increased floodwater storage and conveyance across the reconnected floodplain. Compared to the current conditions, the levee setback and levee removal scenarios tested here reduced flood losses for large, infrequent flooding events but increased flood losses for smaller, more frequent flood events. When combined with buyouts of unprotected structures, levee setbacks reduced flood losses for all recurrence intervals. The 1000 m and 1500 m levee setbacks required buyouts in order to reduce EAD; however, a levee setback carefully planned around existing high-value structures reduced EAD with or without buyouts. The planned levee setback configuration combined with buyouts resulted in the largest decreases in EAD: a $16.8 million (55%) decrease in the Urban Study Reach and an $8.3 million (93%) decrease in the Agricultural Study Reach. Overall, this project showed that levee setbacks in combination with buyouts are an economically viable approach for flood-risk reduction along the study reaches and likely elsewhere where levees are widely employed for flood control. Designing a levee setback around existing high-value infrastructure can maximize the benefit of the setback while simultaneously minimizing the costs. Potentially, this type of planned levee configuration could be used as a template for the replacement of aging or failing levee systems.

This study utilized a new database of levee failures along 685 km of the Middle and Lower Mississippi River from St. Louis, MO to Memphis, TN during the past 120 years. The goals of this investigation were to: 1) identify the relative importance of geologic and geomorphic factors that have led to levee failures through the past century along the Mississippi River and 2) measure levee crest elevations to determine if they have increased or decreased between 1998 and 2007 and if they are built to the proper design grade elevation. Logistic regression analysis was utilized to examine selected site characteristics at each levee failure location. These site characteristics (levee failure parameters) included: 1) levee underlain by previous channel fill, 2) presence/absence of borrow pit, 3) location of failure on a meander bend, 4) width of channel, 5) width of floodway, 6) constriction-over-time factor, 7) land-cover type, 8) width of vegetative buffer, 9) sinuosity of channel, 10) intensity of dredging, and 11) presence/absence of bank revetment. Each of these parameters was evaluated using geologic maps, soil survey data, Digital Elevation Models (DEMs), historic river maps, and dredging reports (Winkley, 1977; Pinter et al., 2004). Two models were created for each river reach. The first model for both reaches used a 95% significance threshold, while the second model for the MMR used a 80% significance threshold, and the second model for the LMR used a 90% significance threshold. The first model for the Middle Mississippi River (MMR) identified only the presence/absence of channel fills to predict levee failure as significant, had an R² value of 0.178, a p-value of 0.002, and a percentage accuracy of 68.6%. The second model for the MMR identified the following variables as significant: presence/absence of channel fills to predict levee failure, location of failure on a meander bend, channel width, land-cover type, and intensity of dredging. This model had an R2 value of 0.408, p-value of 0.002, and a percentage accuracy of 74.3%. The 95% model for the Lower Mississippi River (LMR) identified location of failure on a meander bend, land-cover type, constriction-over-time factor, and sinuosity of the channel as significant. This model had an R2 value of 0.326, p-value of 0.003, and a percentage accuracy of 69.5%. The 90% LMR model identified the following variables as significant: the presence/absence of borrow pits, location of failure on meander bend, channel width, land-cover type, constriction-over-time factor, vegetative buffer width, channel sinuosity, and presence/absence of bank revetment. This model had an R2 value of 0.385, p-value of 0.006, and a percentage accuracy of 72.0%. The MMR and LMR models with the 95% significance threshold had no predictors in common because of differences between the two river reaches or possibly because of the small sample size. However, the expanded MMR and LMR models shared three predictors (i.e., meander location, channel width, and land cover type). The second portion of this project used post-processed dual-frequency GPS surveying to measure levee elevations between St. Louis, MO and Cairo, IL. These elevations were compared to the 50-year design flood grade elevations and to a 1998 DEM to identify areas of levee heightening, levee degradation and/or subsidence, and locations of past levee crevasses. This surveying revealed areas that, between 1998 and 2007, were raised up to ~1.5 meters and other areas that degraded or subsided up to ~1.0 meter. Also, the locations of five recent levee crevasses were investigated, showing local increases or decreases at those points. The importance of levee road construction type was identified through many sharp increases or decreases at the transition between road types. Overall, this project showed promising implications for the determination of levee failure susceptibility and proper levee elevation heights using logistic regression analysis and kinematic GPS surveying. The logistic regression models predicted the potential for levee failure based on local site characteristics of levees between St. Louis, MO and Memphis, TN. The high-precision kinematic GPS surveying illustrated levee elevations along the MMR to a high degree of accuracy, allowing for the rapid and efficient identification of areas that do not correspond to the proper design flood grade elevation.

The Windermere turbidite system, exposed in the southern Canadian Cordillera, east-central British Columbia, is a continental scale, passive margin, submarine fan system, part of which is well exposed in the Castle Creek study area. Here millimetre- to decametre-scale sedimentological and stratigraphic observations identified five facies in interchannel strata: very thin- to medium-bedded turbidite (F1), thick-bedded turbidite (F2) coarse-tail graded structureless sandstone (F3), mudstone clast breccia (F4) and carbonaceous mudstone (F5) and four architectural elements: channel (AE1), distal levee (AE2), overbank splays (AE3) and crevasse splays (AE4). These elements are assembled into a predictive depositional model that describes the initiation and evolution of sandy splay elements developed in distal levee strata of deep-marine slope channels. These data can be used in hydrocarbon exploration to identify and differentiate splay deposits in core and on seismic, and thereby improve the accuracy of subsurface reservoir models.

The main goal of this research is to investigate vulnerability of levees to future slump slides. In the first part, polarimetric synthetic aperture radar (PolSAR) imagery is used as input in an automated classification system for characterizing areas on the levee having anomalies. In addition, a set of in-situ soil data is collected to provide detailed soil properties over the study area. In-situ soil properties of different classes characterized by the classifier are analyzed to determine how similarities between different areas. The second part, a database including of 34 slump slides that occurred in the lower Mississippi River levee system over a period of two years is used. The impacts of rainfall as well as several spatial geometrical and geomorphological variables (including channel width, river sinuosity index, riverbank erosion, channel shape condition and distance to river) are analyzed and tested for significance and used for developing a logistic regression model.

Levees are a significant part of the United States flood protection infrastructure. It is estimated that over 100,000 miles of levees exist in the United States. Most of these levees were designed many years ago to protect farmland and rural areas. As growth continues in the United States, many of these levees are now protecting homes and other important structures. The American Society of Civil Engineers gave the levees in the United States a grade of D- in 2009. To bring flood protection up to modern standards there requires adequate methods of evaluating levees with respect to seepage, erosion, piping and slope instability. Transient seepage analyses provide an effective method of evaluating seepage through levees and its potentially destabilizing effects. Floods against levees usually last for days or weeks. In response to a flood, pore pressures within the levee will change from negative (suction) to positive as the phreatic surface progresses through the levee. These changes can be calculated by finite element transient seepage analyses. In order for the transient seepage analysis to be valid, appropriate soil properties and initial conditions must be used. The research investigation described here provides simple and practical methods for estimating the initial conditions and soil properties required for transient seepage analyses, and illustrates their use through a number of examples. / Ph. D.

Submarine channel-levee systems represent one of the most significant features of sediment transfer on Earth and one of the final segments in source-to-sink routing systems. As such, they serve as conduits as well as intermediate or final storage for large volumes of sediment, paleoenvironmental signals, and pollutants on their way to the deep ocean. Over the years, these systems have been studied through a variety of methods, including: (i) outcropping analogs; (ii) seismic data, occasionally integrated with core analysis; (iii) numerical modeling and physical experiments, and more recently; (iv) repeated multibeam bathymetry and (v) direct measurement of sediment gravity flows. However, as we are able to show in this study, there are still questions about the inherent evolution of these systems that need to be addressed. In this study, we focus on the sedimentary processes and depositional products of submarine channel-levee systems through the characterization, analysis and interpretation at different scales of outcropping analog systems of the Upper Cretaceous Tres Pasos and Cerro Toro Formations in the Magallanes-Austral Basin. In the first research-chapter, Chapter 2, we analyze the transition between laterally offset and vertically stacked channels on a previously undocumented, seismic-scale outcrop of the Tres Pasos Formation. This change in stacking pattern has been widely recognized in submarine channel systems, however, the stratigraphic and sedimentologic details and implications to general conceptual models have not been addressed in the past. Our observations indicate that in between these two depositional architecture styles there is a significant phase of erosion and bypass at a complex-scale (or larger) and that the relief achieved via this deep incision of one or multiple simultaneously active conduits was the necessary condition to promote flow stripping processes and associated overbank deposition. In addition, we discuss the presence of an unusual intra-channel lithofacies association observed directly overlying one of these incisions, which we interpret to represent the along-strike expression of bedforms associated with supercritical flow processes that are found in modern channels and some ancient channel-fill successions. In the next research chapter, Chapter 3, we characterize a 500 m thick fine-grained dominated sedimentary succession interpreted as overbank deposits of the Cerro Toro Formation that have been affected by synsedimentary faulting and crosscut by an extensive injectite network. The scale of this outcrop allows us to resolve the relationship between sedimentary packages and structural features that are commonly overlooked or beyond the resolution of datasets derived from other sources by using high-resolution measurements and quantitative analysis at a cm scale. The orientation of synsedimentary normal faults, paleocurrent directions, and characteristics of 10-36 m thick sandstone-prone intervals suggest a model of overspilling turbidity currents (from the main axial channel belt to the west) on a large levee-slope that might share deformational mechanisms with other depositional slopes. Finally, in Chapter 4, we use detrital zircon U-Pb geochronology to determine maximum depositional ages of seven sandstone samples attributed to the axial channel-belt of the Cerro Toro Formation and shallow-marine deposits of the Dorotea Formation, which extend the chronostratigraphic framework for Ultima Esperanza 55 km southward to help reduce the gap between field sites in the Ultima Esperanza and Magallanes provinces. Based on these new data, we hypothesize that the conglomeratic-rich deposits at this location, which have generally similar lithofacies and large-scale stratigraphic architecture to the Cerro Toro Formation, are unlikely to represent the southward extension of the well-studied axial channel belt deposits to the north, and therefore they potentially represent their own sediment routing system emanating from erosional catchments in the fold-thrust belt to the west. This chapter highlights the value of establishing a chronostratigraphic framework to reconstruct ancient paleogeography in addition to interpretation based purely on observable sedimentary parameters. / Doctor of Philosophy / Turbidity currents are one of the most common processes in in deep-marine environments, they are sediment-laden flows that move downslope due to an excess of density caused by the sediment they carry. They occur under a wide range of geomorphologic configurations, one of such are submarine channel-levees systems. A submarine channel-levee system is a composite geomorphologic feature in the ocean floor consisting of a concave, long-lived sedimentary conduit flanked by parallel depositional highs that is orders of magnitude longer in its downslope longitude than its width. These systems have a worldwide distribution and can be found in every tectonic setting. They represent one of the final segments in sedimentary routing systems and their study is of great importance for numerous reasons, including (i) as hydrocarbon reservoirs, (ii) to mitigate submarine geological hazards that might affect human infrastructure, (iii) their role in the carbon cycle as they transport and bury organic carbon, (iv) their impact to the marine environment as they disperse human-sourced pollutants, and (v) their capacity to preserve geochemical proxies that record past climate and tectonic history. This dissertation is divided in three research chapters focused on different aspects of the processes and depositional products of submarine channel-levee systems through the characterization, analysis and interpretation at different scales of analog ancient systems now exposed in the mountains of Southern Chile. The use of outcropping sedimentary successions is a common practice to characterize and understand modern environments, as they provide an accessible record of their evolution through temporal scales of hundreds of thousands or even millions of years. From a geologic point of view, this study is located in the Chilean part of the Magallanes-Austral Basin, which in the past was an ocean that reached paleowater depths of ~2,000 m during the Late Cretaceous and that was subsequently filled with sediments that form the different geologic units of the area. Here, we focus on two geologic units that represent deep-marine sedimentation in this ancient ocean, known as the Tres Pasos and the Cerro Toro formations. Our study ranges from the detailed stratigraphic characterization of the transition between two different styles of stacking patterns widely recognized in submarine channel systems and its implications, to the influence of sedimentary structures on hundreds of meters of fine-grained sediments deposited in a large levee subjected to failure, and the use of tiny minerals known as zircons to constrain the depositional age and paleogeography associated to coarse-grained deposits historically attributed to a >150 km long axial channel-belt. The results presented here do not only serve to better understand the configuration of ancient deep-marine deposits in this part of the world, but also have implications to improve our understanding of the fundamental sedimentary processes and the depositional products in deep-marine environments worldwide.