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William G. McDougal

Other affiliations: University of Florida
Bio: William G. McDougal is an academic researcher from Oregon State University. The author has contributed to research in topics: Longshore drift & Coastal erosion. The author has an hindex of 16, co-authored 62 publications receiving 1575 citations. Previous affiliations of William G. McDougal include University of Florida.


Papers
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Journal Article
TL;DR: In this article, a model was developed to evaluate the susceptibility of coastal properties to wave induced erosion, including analyses of the probabilities of extreme water levels due to tides affected by various oceanographic and atmospheric processes, and the runup elevations of storm waves on beaches.
Abstract: A model has been developed to evaluate the susceptibility of coastal properties to wave induced erosion. The model includes analyses of the probabilities of extreme water levels due to tides affected by various oceanographic and atmospheric processes, and the runup elevations of storm waves on beaches. The application is to the Oregon coast where measured tides often exceed predicted astronomical tides by tens of centimeters, especially during the occurrence of an EI Nino. The measurements of wave runup on dissipative beaches typical of the Oregon coast depend primarily on the deep-water significant wave height, but when combined with other data sets show some dependence on the wave period and beach slope. Predicted extreme water elevations due to the combined processes are compared with measured elevations of the junctions between the beach face and the toe of foredunes or sea cliffs. The objective is to evaluate the frequency with which water can reach the property, providing an evaluation of the susceptibility to potential erosion. Application is made to a number of sites along the Oregon coast, revealing differences between the various littoral cells depending on the quantity of sand on the beach and its capacity to act as a buffer from wave attack. A more detailed application is made to the Newport Littoral Cell, demonstrating how this type of analysis can aid in making coastal management decisions. Although the application here is to the Oregon coast, the model can be used on other coastlines with evaluations of extreme tides and storm-wave runup specific to those locations.

357 citations

Book
01 Dec 1998
TL;DR: In this paper, the authors present a method for dynamic analysis of a single-degree-of-freedom (SDOF) system, based on the principle of virtual displacements, which is used to distinguish features of a dynamic problem.
Abstract: 1. Basic Concepts. Introduction to Structural Dynamics. Types of Dynamic Loads. Sources of Dynamic Loads. Distinguishing Features of a Dynamic Problem. Methodology for Dynamic Analysis. Types of Structural Vibration. Organization of the Text. Systems of Units. References. I. SINGLE-DEGREE-OF-FREEDOM (SDOF) SYSTEMS. 2. Equation of Motion and Natural Frequency. Fundamental Components of a Vibrating System. D'Alembert's Principle of Dynamic Equilibrium. The Energy Method. The Principle of Virtual Displacements. References. Notation. Problems. 3. Undamped Free Vibration. Simple Harmonic Motion. Interpretation of the Solution. Equivalent Stiffness. Rayleigh Method. References. Notation. Problems. 4. Damped Free Vibration. Free Vibration with Viscous Damping. Logarithmic Decrement. Hysteresis Damping. Coulomb Damping. References. Notation. Problems. 5. Response to Harmonic Excitation. Forced Harmonic Response of Undamped Systems. Beating and Resonance. Forced Harmonic Vibrations with Viscous Damping. Effect of Damping Factor on Steady-State Response and Phase Angle. Harmonic Excitation Caused by Rotating Unbalance. Base Excitation. Vibration Isolation and Transmissibility. References. Notation. Problems. 6. Response to Periodic and Arbitrary Dynamic Excitation. Response to Periodic Excitation. Response to Unit Impulse. Duhamel Integral. Response to Arbitrary Dynamic Excitation. Response Spectrum. References. Notation. Problems. 7. Numerical Evaluation of Dynamic Response. Interpolation of the Excitation. Direct Integration of the Equation of Motion. Central Difference Method. Runge-Kutta Methods. Average Acceleration Method. Linear Acceleration Method. Response to Base Excitation. Response Spectra by Numerical Integration. References. Notation. Problems. 8. Frequency Domain Analysis. Alternative Forms of the Fourier Series. Discrete Fourier Transform. Fast Fourier Transform. Discrete Fourier Transform Implementation Considerations. Fourier Integral. References. Notation. Problems. II. MULTI-DEGREE-OF-FREEDOM (MDOF) SYSTEMS. 9. General Property Matrices for Vibrating Systems. Flexibility Matrix. Stiffness Matrix. Inertia Properties: Mass Matrix. The Eigenproblem in Vibration Analysis. Static Condensation of the Stiffness Matrix. References. Notation. Problems. 10. Equations of Motion and Undamped Free Vibration. Hamilton's Principle and the Lagrange Equations. Natural Vibration Frequencies. Natural Vibration Modes. Orthogonality of Natural Modes. Systems Admitting Rigid-Body Modes. Generalized Mass and Stiffness Matrices. Free Vibration Response to Initial Conditions. Approximate Methods for Estimating the Fundamental Frequency. References. Notation. Problems. 11. Numerical Solution Methods for Natural Frequencies and Mode Shapes. General Solution Methods for Eigenproblems. Inverse Vector Iteration. Forward Vector Iteration. Generalized Jacobi Method. Solution Methods for Large Eigenproblems References. Notation. Problems. 12. Analysis of Dynamic Response by Mode Superposition. Mode Displacement Method for Undamped Systems. Modal Participation Factor. Mode Superposition Solution for Systems with Classical Damping. Numerical Evaluation of Modal Response. Normal Mode Response to Support Motions. Response Spectrum Analysis. Mode Acceleration Method. References. Notation. Problems. 13. Analysis of Dynamic Response by Direct Integration. Basic Concepts of Direct Integration Methods. The Central Difference Method. The Wilson-u Method. The Newmark Method. Practical Considerations for Damping. Stability and Accuracy of Direct Integration Methods. Direct Integration versus Mode Superposition. References. Notation. Problems. III. CONTINUOUS SYSTEMS. 14. Vibrations of Continuous Systems. Longitudinal Vibration of a Uniform Rod. Transverse Vibration of a Pretensioned Cable. Free Transverse Vibration of Uniform Beams. Orthogonality of Normal Modes. Undamped Forced Vibration of Beams by Mode Superposition. Approximate Methods. References. Notation. Problems. IV. NONLINEAR DYNAMIC RESPONSE. 15. Analysis of Nonlinear Response. Classification of Nonlinear Analyses. Systems with Nonlinear Characteristics. Formulation of Incremental Equations of Equilibrium. Numerical Solution of Nonlinear Equilibrium Equations. Response of Elastoplastic SDOF Systems. Response of Elastoplastic MDOF Systems. References. Notation. Problems. V. PRACTICAL APPLICATIONS. 16. Elastic Wave Propagation in Solids. Stress and Strain at a Point. Constitutive Relations. Equations of Motion. Stress Wave Propagation. Applications. References. Notation. Problems. 17. Earthquakes and Earthquake Ground Motion. Causes of Earthquakes. Faults. Seismic Waves. Earthquake Intensity. Earthquake Magnitude. Seismicity. Earthquake Ground Motion. Earthquake Damage Mechanisms. References. Notation. 18. Earthquake Response of Structures. Time-History Analysis: Basic Concepts. Earthquake Response Spectra. Earthquake Design Spectra. Response of MDOF Systems. Generalized SDOF Systems. In-Building Response Spectrum. Inelastic Response. Seismic Design Codes. References. Notation. Problems. 19. Blast Loads on Structures. Sources of Blast Loads. Shock Waves. Determination of Blast Loads. Strain-Rate Effects. Approximate Solution Technique for SDOF Systems. References. Problems. Notations. 20. Basic Concepts of Wind Waves. Linear Wave Theory. Nonlinear Waves. Wave Transformations. Wave Statistics. Wave Information Damping. References. Notation. Problems. 21. Response of Structures to Waves. Morison Equation. Force Coefficients. Linearized Morison Equation. Inclined Cylinders. Transverse Lift Forces. Froude-Krylov Theory. Diffraction Theory: The Scattering Problem. Diffraction Theory: The Radiation Problem. References. Notation. Problems. Appendix A. Appendix B. Index.

263 citations

Journal Article
TL;DR: A recent review by the first author of the literature on the effects of seawalls on the beach is extended to cover the period 1988 to the present as mentioned in this paper, which synthesizes knowledge on beach profile change, longshore sand transport, and scour in the vicinity of the seawalls.
Abstract: A previous review by the first author of the literature on the effects of seawalls on the beach is extended to cover the period 1988 to the present. The review synthesizes knowledge on beach profile change, longshore sand transport, and scour in the vicinity of seawalls. Remarkable progress has been made since 1988 with new phenomena and observations reported such as on longshore transport processes at walls. Some previous results and conclusions of the 1988 review have been cast into doubt, with example now results being that (1) wave reflection at walls may not be a significant contributor to profile change, and 121 scour at seawalls in the field may be more a product of longshore transport and return of overtopping water than a result of direct cross-shore wave action. The validity or usefulness of small-scale physical model tests is questioned. Conclusions and recommendations for future work are given. This paper is the first of a companion set of papers that investigate the effects of seawalls on the beach. The second paper presents a numerical model of cross-shore transport and beach profile change at seawalls that includes wave reflection, and it compares predictions to measurements made at the SUPERTANK project and to recent results found in the literature on scour at walls.

158 citations

01 Jan 1983
TL;DR: The Journal of Waterway, Port, Coastal, and Ocean Engineering presents information regarding the engineering aspects of dredging, floods, ice, pollution, sediment transport, and tidal wave action that affect shorelines, waterways, and harbors as mentioned in this paper.
Abstract: The Journal of Waterway, Port, Coastal, and Ocean Engineering presents information regarding the engineering aspects of dredging, floods, ice, pollution, sediment transport, and tidal wave action that affect shorelines, waterways, and harbors. The development and operation of ports, harbors, and offshore facilities, as well as deep ocean engineering and shore protection and enhancement, are also covered. Other topics include the regulation and stabilization of rivers and the economics of beach nourishment.

95 citations

DOI
05 Aug 1997
TL;DR: In this paper, a probabilistic model has been developed to analyze the susceptibilities of coastal properties to wave attack, using an empirical model for wave runup, long term data of measured tides and waves are combined with beach morphology characteristics to determine the frequency of occurrence of sea cliff and dune erosion along the Oregon coast.
Abstract: A probabilistic model has been developed to analyze the susceptibilities of coastal properties to wave attack. Using an empirical model for wave runup, long term data of measured tides and waves are combined with beach morphology characteristics to determine the frequency of occurrence of sea cliff and dune erosion along the Oregon coast. Extreme runup statistics have been characterized for the high energy dissipative conditions common in Oregon, and have been found to depend simply on the deep-water significant wave height. Utilizing this relationship, an extreme-value probability distribution has been constructed for a 15 year total water elevation time series, and recurrence intervals of potential erosion events are calculated. The model has been applied to several sites along the Oregon coast, and the results compare well with observations of erosional impacts.

89 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, an empirical parameterization for extreme runup, defined by the 2% exceedence value, has been developed for use on natural beaches over a wide range of conditions.

1,058 citations

Journal ArticleDOI
TL;DR: In this paper, the authors provide a brief synopsis of the unique physical and ecological attributes of sandy beach ecosystems and review the main anthropogenic pressures acting on the world's single largest type of open shoreline.
Abstract: We provide a brief synopsis of the unique physical and ecological attributes of sandy beach ecosystems and review the main anthropogenic pressures acting on the world's single largest type of open shoreline. Threats to beaches arise from a range of stressors which span a spectrum of impact scales from localised effects (e.g. trampling) to a truly global reach (e.g. sea-level rise). These pressures act at multiple temporal and spatial scales, translating into ecological impacts that are manifested across several dimensions in time and space so that today almost every beach on every coastline is threatened by human activities. Press disturbances (whatever the impact source involved) are becoming increasingly common, operating on time scales of years to decades. However, long-term data sets that describe either the natural dynamics of beach systems or the human impacts on beaches are scarce and fragmentary. A top priority is to implement long-term field experiments and monitoring programmes that quantify the dynamics of key ecological attributes on sandy beaches. Because of the inertia associated with global climate change and human population growth, no realistic management scenario will alleviate these threats in the short term. The immediate priority is to avoid further development of coastal areas likely to be directly impacted by retreating shorelines. There is also scope for improvement in experimental design to better distinguish natural variability from anthropogenic impacts. Sea-level rise and other effects of global warming are expected to intensify other anthropogenic pressures, and could cause unprecedented ecological impacts. The definition of the relevant scales of analysis, which will vary according to the magnitude of the impact and the organisational level under analysis, and the recognition of a physical–biological coupling at different scales, should be included in approaches to quantify impacts. Zoning strategies and marine reserves, which have not been widely implemented in sandy beaches, could be a key tool for biodiversity conservation and should also facilitate spillover effects into adjacent beach habitats. Setback and zoning strategies need to be enforced through legislation, and all relevant stakeholders should be included in the design, implementation and institutionalisation of these initiatives. New perspectives for rational management of sandy beaches require paradigm shifts, by including not only basic ecosystem principles, but also incentives for effective governance and sharing of management roles between government and local stakeholders.

992 citations

Journal Article
TL;DR: In this paper, a new scale is proposed that categorizes impacts to natural barrier islands resulting from tropical and extra-tropical storms, and the proposed scale is fundamentally different than existing storm-related scales in that the coupling between forcing processes and the geometry of the coast is explicitly included.
Abstract: A new scale is proposed that categorizes impacts to natural barrier islands resulting from tropical and extra-tropical storms The proposed scale is fundamentally different than existing storm-related scales in that the coupling between forcing processes and the geometry of the coast is explicitly included Four regimes, representing different levels of impact, are defined Within each regime, patterns and relative magnitudes of net erosion and accretion are argued to be unique The borders between regimes represent thresholds defining where processes and magnitudes of impacts change dramatically Impact level 1 is the 'swash' regime describing a storm where runup is confined to the foreshore The foreshore typically erodes during the storm and recovers following the storm; hence, there is no net change Impact level 2 is the 'collision' regime describing a storm where the wave runup exceeds the threshold of the base of the foredune ridge Swash impacts the dune forcing net erosion Impact level 3 is the 'overwash' regime describing a storm where wave runup overtops the berm or, if present, the foredune ridge The associated net landward sand transport contributes to net migration of the barrier landward Impact level 4 is the 'inundation' regime describing a storm where the storm surge is sufficient to completely and continuously submerge the barrier island Sand undergoes net landward transport over the barrier island; limited evidence suggests the quantities and distance of transport are much greater than what occurs during the 'overwash' regime

817 citations

Journal ArticleDOI
TL;DR: In this article, the author's version of the work is posted here by permission of Annual Reviews for personal use, not for redistribution, and the definitive version was published in Annual Review of Earth and Planetary Sciences 36 (2008): 601-647, doi:10.1146/annurev.35.031306.140139.
Abstract: Author Posting. © Annual Reviews, 2007. This is the author's version of the work. It is posted here by permission of Annual Reviews for personal use, not for redistribution. The definitive version was published in Annual Review of Earth and Planetary Sciences 36 (2008): 601-647, doi:10.1146/annurev.earth.35.031306.140139.

729 citations

Book
01 Jan 2012
TL;DR: The Flood Risk Management Guide as mentioned in this paper is a state-of-the-art guide for decision and policy makers, technical specialists, central, regional and local government officials and concerned stakeholders in the community sector, civil society and non-governmental organizations, and the private sector.
Abstract: The guide serves as a primer for decision and policy makers, technical specialists, central, regional and local government officials, and concerned stakeholders in the community sector, civil society and non-governmental organizations, and the private sector. The Guide embodies the state-of-the art on integrated urban flood risk management. The Guide starts with a summary for policy makers which outlines and describes the key areas which policy makers need to be knowledgeable about to create policy directions and an integrated strategic approach for urban flood risk management. The core of the Guide consists of seven chapters, organized as: understanding flood hazard; understanding flood impacts; integrated flood risk management (structural measures and non-structural measures); evaluating alternative flood risk management options: tools for decision makers; implementing integrated flood risk management; and conclusion. Each chapter starts with a full contents list and a summary of the chapter for quick reference.

614 citations