Remote Measurements of Tides and River Slope Using an Airborne Lidar Instrument

Tides and river slope are fundamental characteristics of estuaries, but they are usually undersampled due to deficiencies in the spatial coverage of water level measurements. This study aims to address this issue by investigating the use of airborne lidar measurements to study tidal statistics and river slope in the Columbia River estuary. Eight plane transects over a 12-h period yield at least eight independent measurements of water level at 2.5-km increments over a 65-km stretch of the estuary. These data are fit to a sinusoidal curve and the results are compared to seven in situ gauges. In situ– and lidar-based tide curves agree to within a root-mean-square error of 0.21 m, and the lidar-based river slope estimate of 1.8 × 10−5 agrees well with the in situ–based estimate of 1.4 × 10−5 (4 mm km−1 difference). Lidar-based amplitude and phase estimates are within 10% and 8°, respectively, of their in situ counterparts throughout most of the estuary. Error analysis suggests that increased measurement accuracy and more transects are required to reduce the errors in estimates of tidal amplitude and phase. However, the results validate the use of airborne remote sensing to measure tides and suggest this approach can be used to systematically study water levels at a spatial density not possible with in situ gauges

Seasonal and spatial variability of major organic contaminants in solution and suspension of the Pomeranian Bight

Studies of hexachlorocyclohexane-isomers (HCHs) and selected triazine herbicides in solution and suspension were carried out in the Pomeranian Bight in 1995. The concentrations of HCHs and triazines were determined by gas-liquid chromatography (GC) or by GC in connection with quadrupole mass spectrometry(GC/MS). Particulate and dissolved material were separated by means of an in-situ filtration/extraction system. The seasonal variability and regional distribution of the various components were investigated in January, April, July and September 1995. Their distribution in the western Pomeranian Bight is described. The concentrations of individual hexachlorocyclohexane-isomers were in the range of 100–1 000 pg l–1 in solution and 20 to 60 pg l–1 in suspension. The levels of the triazines in solution showed pronounced differences between the individual components (atrazine (2–20 ng l–1), simazine (5–30 ng l–1), terbuthylazine (< 5 ng l–1)), but they were one order of magnitude higher compared with the hexachlorocyclohexane-isomers. The concentration of triazines in suspension was low, often below the limit of detection (25 pg l–1)

Assessing hydrokinetic tidal energy extraction for Rose Dhu Island, Georgia: A case study for tidal rivers with marsh environs

Hydrokinetic tidal power is a novel and emergent technology undergoing continuous advancement with much of the progress focused on large utility scale projects. This resource is potentially underutilized because much of the coastal United States, despite having substantial tidal currents, do not have the deep and wide environments required by most of the developing turbine technology. This dissertation includes a detailed characterization of the tidal hydrodynamics for Rose Dhu Island, Georgia used for a tidal energy resource assessment as well as a general feasibility study for tidal estuaries with extensive wetlands. For predictions and evaluation of the estuarine hydrodynamics, data from an existing numerical model of the estuary encompassing the island is utilized. Field measurements in close proximity to the island are used to calibrate the model as well as characterize local hydrodynamic features. After the model calibration, the simulation data is used to evaluate the hydrodynamics. Wetland dominated estuaries commonly have a high degree of non-linear distortion which govern the relative durations and strengths of the tidal stages and thus the overall hydrodynamics and incoming hydrokinetic energy. The Ogeechee Estuary is characterized as ebb dominant with peak ebb and flood volume fluxes near high tide as a result of the increased storage capacity of the wetlands. Lowering the average wetland elevation in the model decreased ebb dominance and quickened the transition from flood to ebb tide. Increased domain friction in the model removed energy from the system and reduced ebb dominance. Enhanced model marsh friction reduced lateral flooding of the wetlands as well as ebb dominance. Localized measurements surrounding the island are analyzed to determine a location near the southwest coast of the island as a hydrokinetic energy hotspot. A kinematic and dynamic analysis is performed using channel transect measurements to identify key physical processes behind the hotspot formation. The hotspot forms due to sub-critical flow acceleration over a singular bump in the topography. High streamwise momentum is further concentrated at the hotspot due to secondary circulation cells across the channel. Flood tide circulation is characterized by two co-rotating cells induced by channel curvature and delineated by the bump. Ebb circulation consists of two counter-rotating cells from flow confluence of two upstream channels. Once the hydrodynamics are understood, the theoretical and technical resource assessment of the island is completed. A sensitivity analysis of hydrokinetic energy and tidal distortion is performed on synthetic data. For a principle constituent and its first harmonic, distortion greatly changes as does the distribution of velocities and energy as the relative phase varies. While the theoretical energy remains consistent, the technical energy can greatly vary. This effect is reduced with the addition semi-lunar variation. Using a simplified analytical method, the maximum average channel power is estimated as 8.80 MW. For the hotspot it is estimated that there is 30.3 MWh available to capture yearly with an average power of 3.46 kW for a turbine with an area of 10 square meters. For the same turbine area with conservative efficiencies, the hotspot could provide a yearly technical energy of 10.9 MWh with an average power of 1.25kW for the island. Due to the complex localized hydrodynamics, both the theoretical and technical resource varies greatly across and along the channel. These considerations are more pertinent when performing a hydrokinetic energy resource assessment in a marsh estuary than for large scale bay-ocean exchange environments, the present industry focus.Ph.D

Structural analysis and 3D modeling of a potential analogue of hydrocarbon reservoir: The Jurassic synsedimentary structure of Monte Testo (Southern Alps, Italy)

Structural traps created by synsedimentary extensional tectonics events can hold very interesting hydrocarbon accumulation and for this reason, they are a main target for the hydrocarbon exploration. Furthermore, the faults generated during extensional events can favour the circulation of dolomitaizing fluids, leading to the formation of fault related dolomitized bodies that can strongly improve the porosity framework. In the last few years, this type of bodies received particularly attention by the hydrocarbon industry, due to the decrease of conventional reservoir discoveries. However, structural network, porosity distribution, shape and geometry of the fault related dolomitized bodies and the porosity evolution of these types of reservoirs are difficult to predict only on the bases of well-logs and seismic information. The study of outcrop analogues can help to solve these issues. In this work I focused my attention to the carbonate platform of the Calcari Grigi group (formed by Monte Zugna, Loppio and Rotzo Formations), located on the Trento platform in the Southern Alps, which was extensively affected by synsedymentary extensional tectonic during the Early Jurassic. This tectonic event led to the tilting of the Loppio Formation and caused abruptly change of thickness in the Rotzo Formation. The extension ceased during the deposition of the upper part of the Rotzo Formation, which seals the Jurassic faults. During the late Paleocene-early Eocene, the Alpine tectonics reactivated, with a strike slip movement, the Jurassic faults allowing the circulation of dolomitizing fluids and leading to the formation of secondary fault-related dolomitized bodies. A Jurassic synsedimenatry structure affected by secondary dolomitization is spectacularly exposed near the Monte Testo on the Asiago Plateau. In this work a geological map, structural studies, porosity analysis, 3D photogrammetric model and 3D geomodel were realized in order to reconstruct the tectonic evolution, porosity distribution and reservoir potential of M.Testo structure and better understand geometry, shape and porosity of the fault-related dolomititized bodies. Moreover, this multi-approaching analysis allows to reconstruct the complex porosity evolution of the potential reservoirs. The final results have shown that during the Jurassic, the early cemented tilted and high porous (8%) blocks of the Loppio Formation were put in contact laterally and above with the low porous (0%) Rotzo Formation, creating important potential hydrocarbon traps on the upper part of the tilted blocks. At that time the Zugna Formation likely had a porosity given only by fracturing (1%), hence fluids might have circulated from depth up to potential Loppio reservoir following the extensional fault network. Starting from this moment onwards the porosity of the Loppio Formation began to decrease due to cementation. During Late Paleocene-Early Eocene, the formation of the fault-related dolomitized bodies within reactivated fault zones gave a new chance to the reservoir potential of the M. Testo structure. Indeed, these bodies have a porosity ranging from 0% to 10,6% with a mean of 4,7%. The higher porosity values are concentrated along the breccia fault zones enclosed within low porous and low permeable formations, confirming the strong relationship between late dolomitization and the structural network as well as the great potential of these bodies for hydrocarbon accumulation

Proceedings of the Fourth Workshop on the Okhotsk Sea and Adjacent Areas

This report is the outcome of the fourth PICES Workshop on “The Okhotsk Sea and Adjacent Waters” held August 27–29, 2008, in Abashiri, Japan. (PDF contains 319 pages

Updates in Volcanology

Updates in Volcanology - From Volcano Modeling to Volcano Geology is a new book that is based on book chapters offered by various authors to provide a snapshot of current trends in volcanological researches. Following a short Introduction, the book consists of three sections, namely, ''Understanding the Volcano System from Petrology, Geophysics to Large Scale Experiments,'' ''Volcanic Eruptions and Their Impact to the Environment,' and ''Volcanism in the Geological Record.'' These sections collect a total of 13 book chapters demonstrating clearly the research activity in volcanology from geophysical aspects of volcanic systems to their geological framework. Each chapter provides a comprehensive summary of their subject's current research directions. This book hence can equally be useful for students and researchers