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Full-Text Articles in Engineering

Tidal Bed Stress Asymmetry And Sediment Transport In Estuaries, Austin Scott Hudson Nov 2023

Tidal Bed Stress Asymmetry And Sediment Transport In Estuaries, Austin Scott Hudson

Dissertations and Theses

Rivers and estuaries provide numerous ecological, economic, and cultural resources. The value of these resources is greatly influenced by sediment transport processes, which can be affected by human activities and climate variability. A key driver of sediment transport in tidal rivers and estuaries is tidal asymmetry of velocity and bed stress, which can manifest from both non-linear tidal interactions and linear interactions among astronomical tidal constituents.

In this study, an analytical framework is developed to examine and describe the dynamics of bed stress asymmetry in semidiurnal, diurnal, and mixed-tide estuaries (Chapter 1). While tidal velocity asymmetry has been previously analyzed, …


Hydraulic Redistribution Under Saline Conditions, Josh Gottlieb Dec 2022

Hydraulic Redistribution Under Saline Conditions, Josh Gottlieb

Civil and Environmental Engineering Undergraduate Honors Theses

Water scarcity and soil salinity are dual stressors for plants in arid, salt-affected ecosystems. Hydraulic redistribution, a hydraulic adaptation which moves water through plant roots into dry or saline soil regions along potential gradients, aids plant survival in stressful environments. Recent theory regarding hydraulic redistribution proposes limitations on the process within saline soils. This study applies a minimalist resistor-capacitor model of the soil-plant-atmosphere system to the experimental conditions of a 2010 study investigating hydraulic redistribution in a salt affected area. The effectiveness of the model is evaluated, and a sensitivity analysis is conducted to identify key dynamics affecting the moisture …


Cei Hub Failure Following A Cascadia Earthquake Event: Preliminary Modeling Of A Liquid Fuel Spill In The Lower Willamette And Columbia Rivers, Mike Du Bose Apr 2021

Cei Hub Failure Following A Cascadia Earthquake Event: Preliminary Modeling Of A Liquid Fuel Spill In The Lower Willamette And Columbia Rivers, Mike Du Bose

Civil and Environmental Engineering Undergraduate Honors Theses

The Critical Energy Infrastructure (CEI) Hub in Northwest Portland, OR spans a six-mile stretch of the Lower Willamette River and stores 90% of Oregon’s liquid fuel supply and 100% of the jet fuel for PDX. The CEI Hub is also built entirely on liquefiable soils which are likely to fail during a Cascadia earthquake event. The purpose of this project was to model a liquid fuel spill in the Lower Willamette and Columbia Rivers using the CE-QUAL-W2 model. Several scenarios were developed to account for different environmental conditions, (e.g., high and low discharge years) and varying spill durations (e.g., rapid …


Analytical And Field Verification Of A 3d Hydrodynamic And Water Quality Numerical Scheme Based On The 2d Formulation In Ce-Qual-W2, Hussein Ali Mahdi Al-Zubaidi, Scott A. Wells Jan 2020

Analytical And Field Verification Of A 3d Hydrodynamic And Water Quality Numerical Scheme Based On The 2d Formulation In Ce-Qual-W2, Hussein Ali Mahdi Al-Zubaidi, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

A new 3D hydrodynamic model was developed to simulate water quality transport in surface waterbodies. The governing equations are the continuity equation, free surface equation, momentum equation and transport equation. The 2D numerical scheme of CE-QUAL-W2 was expanded in three dimensions and modified to solve for the free surface elevation. A time splitting technique was employed to solve the momentum and transport equation. The numerical formulation of the 3D scheme used a novel solution, which resulted in a tri-diagonal matrix form for solving the free surface equation rather than a more computationally intensive penta-diagonal matrix solution. In addition, the hydrodynamic …


Global Observations Of Fine-Scale Ocean Surface Topography With The Surface Water And Ocean Topography (Swot) Mission, Rosemary Morrow, Lee-Lueng Fu, Fabrice Ardhuin, Mounir Benkiran, Bertrand Chapron, Emmanuel Cosme, Francesco D’Ovidio, J. Thomas Farrar, Sarah T. Gille, Guillaume Lapeyre, Pierre-Yves Le Traon, Ananda Pascual, Aurélien Ponte, Bo Qiu, Nicolas Rascle, Clement Ubelmann, Jinbo Wang, Edward Zaron May 2019

Global Observations Of Fine-Scale Ocean Surface Topography With The Surface Water And Ocean Topography (Swot) Mission, Rosemary Morrow, Lee-Lueng Fu, Fabrice Ardhuin, Mounir Benkiran, Bertrand Chapron, Emmanuel Cosme, Francesco D’Ovidio, J. Thomas Farrar, Sarah T. Gille, Guillaume Lapeyre, Pierre-Yves Le Traon, Ananda Pascual, Aurélien Ponte, Bo Qiu, Nicolas Rascle, Clement Ubelmann, Jinbo Wang, Edward Zaron

Civil and Environmental Engineering Faculty Publications and Presentations

The future international Surface Water and Ocean Topography (SWOT) Mission, planned for launch in 2021, will make high-resolution 2D observations of sea-surface height using SAR radar interferometric techniques. SWOT will map the global and coastal oceans up to 77.6 latitude every 21 days over a swath of 120 km (20 km nadir gap). Today’s 2D mapped altimeter data can resolve ocean scales of 150 km wavelength whereas the SWOT measurement will extend our 2D observations down to 15–30 km, depending on sea state. SWOT will offer new opportunities to observe the oceanic dynamic processes at scales that are important in …


The Quest For Model Uncertainty Quantification: A Hybrid Ensemble And Variational Data Assimilation Framework, Peyman Abbaszadeh, Hamid Moradkhani, Dacian Daescu Mar 2019

The Quest For Model Uncertainty Quantification: A Hybrid Ensemble And Variational Data Assimilation Framework, Peyman Abbaszadeh, Hamid Moradkhani, Dacian Daescu

Civil and Environmental Engineering Faculty Publications and Presentations

This article presents a novel approach to couple a deterministic four‐dimensional variational (4DVAR) assimilation method with the particle filter (PF) ensemble data assimilation system, to produce a robust approach for dual‐state‐parameter estimation. In our proposed method, the Hybrid Ensemble and Variational Data Assimilation framework for Environmental systems (HEAVEN), we characterize the model structural uncertainty in addition to model parameter and input uncertainties. The sequential PF is formulated within the 4DVAR system to design a computationally efficient feedback mechanism throughout the assimilation period. In this framework, the 4DVAR optimization produces the maximum a posteriori estimate of state variables at the beginning …


Hydro-Climatological Summer Trends In The Continental United States, Naya Mairena Flores Jan 2018

Hydro-Climatological Summer Trends In The Continental United States, Naya Mairena Flores

REU Final Reports

We investigated trends in air temperature, stream temperature and discharge for rivers across the continental United States from the summer months of 1996 to 2016. Using GAGES II from USGS and PRISM and programming language R we analyzed specific hydrological trends in Mann-Kendall’s tests. After collecting the slope values whether they were negative or positive and the P-Values, the significance of that slope, we mapped slopes of trends in GIS. Stream temperature increased 12% of stations across the summer, while air temperature increased 22% of stations, and discharge decreased 15% of stations, respectively. Seven day moving average of daily maximum …


Water Quality Factor Prediction Using Supervised Machine Learning, Kathleen Joslyn Jan 2018

Water Quality Factor Prediction Using Supervised Machine Learning, Kathleen Joslyn

REU Final Reports

The objective of this research is to explore prediction accuracy of water quality factors, with techniques and algorithms in machine learning consisting of a variation of support vector machines - Support Vector Regression (SVR) and the gradient boosting algorithm Extreme Gradient Boosting (XGBoost). Both the XGBoost and SVR algorithms were used to predict nine different factors with success rates ranging from 79% to 99%. Parameters of these algorithms were also explored to test the prediction accuracy levels of individual water quality factors. These parameters included normalizing the data, filling missing data points, and training and testing on a large set …


Archival Water-Level Measurements: Recovering Historical Data To Help Design For The Future, Stefan A. Talke, David A. Jay Aug 2017

Archival Water-Level Measurements: Recovering Historical Data To Help Design For The Future, Stefan A. Talke, David A. Jay

Civil and Environmental Engineering Faculty Publications and Presentations

Improving methods of assessing risk and designing structures to withstand extreme events and changing sea levels is a vital component of strategies for reducing risk to coastal resources and assets. An obvious approach to improving the statistical robustness of risk assessments is to increase the number, time span, and quality of available water-level data sets, and to assess trends and non-stationarity. In this report we discuss efforts to recover, digitize, and analyze hundreds of station-years of lost-and-forgotten tide data and other water-level measurements that extend back to the early 19th century. To date, more than 6,500 station-years of previously lost …


Remote Measurements Of Tides And River Slope Using An Airborne Lidar Instrument, Austin S. Hudson, Stefan A. Talke, Ruth Branch, Chris Chickadel, Gordon Farquharson, Andrew Jessup Apr 2017

Remote Measurements Of Tides And River Slope Using An Airborne Lidar Instrument, Austin S. Hudson, Stefan A. Talke, Ruth Branch, Chris Chickadel, Gordon Farquharson, Andrew Jessup

Civil and Environmental Engineering Faculty Publications and Presentations

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 …


Relative Sea-Level Trends In New York City During The Past 1500 Years, Andrew C. Kemp, Troy D. Hill, Christopher H. Vane, Niamh Cahill, Philip M. Orton, Stefan A. Talke, Andrew C. Parnell, Kelsey Sanborn, Ellen K. Hartig Jan 2017

Relative Sea-Level Trends In New York City During The Past 1500 Years, Andrew C. Kemp, Troy D. Hill, Christopher H. Vane, Niamh Cahill, Philip M. Orton, Stefan A. Talke, Andrew C. Parnell, Kelsey Sanborn, Ellen K. Hartig

Civil and Environmental Engineering Faculty Publications and Presentations

New York City (NYC) is threatened by 21st-century relative sea-level (RSL) rise because it will experience a trend that exceeds the global mean and has high concentrations of low-lying infrastructure and socioeconomic activity. To provide a long-term context for anticipated trends, we reconstructed RSL change during the past ~1500 years using a core of salt-marsh sediment from Pelham Bay in The Bronx. Foraminifera and bulk-sediment δ13C values were used as sea-level indicators. The history of sediment accumulation was established by radiocarbon dating and recognition of pollution and land-use trends of known age in down-core elemental, isotopic, and pollen …


A Validated Tropical-Extratropical Flood Hazard Assessment For New York Harbor, Philip M. Orton, T. M. Hall, Stefan A. Talke, Alan F. Blumberg, Nickitas Georgas, S. Vinogradov Dec 2016

A Validated Tropical-Extratropical Flood Hazard Assessment For New York Harbor, Philip M. Orton, T. M. Hall, Stefan A. Talke, Alan F. Blumberg, Nickitas Georgas, S. Vinogradov

Civil and Environmental Engineering Faculty Publications and Presentations

Recent studies of flood risk at New York Harbor (NYH) have shown disparate results for the 100 year storm tide, providing an uncertain foundation for the flood mitigation response after Hurricane Sandy. Here we present a flood hazard assessment that improves confidence in our understanding of the region's present-day potential for flooding, by separately including the contribution of tropical cyclones (TCs) and extratropical cyclones (ETCs), and validating our modeling study at multiple stages against historical observations. The TC assessment is based on a climatology of 606 synthetic storms developed from a statistical-stochastic model of North Atlantic TCs. The ETC assessment …


Larc: Local Agricultural Resource Conservation, Dash Justice, Josh Davis, Sid Crumble, Ashlie Kinney Apr 2016

Larc: Local Agricultural Resource Conservation, Dash Justice, Josh Davis, Sid Crumble, Ashlie Kinney

PSU High School Innovation Challenge

In America today, over 75% of the nation’s water is used in the irrigation of agriculture. The main users -- and abusers -- of water in the United States are farmers. In addition, many areas in the U.S. are facing drought conditions, especially in western states. Also, while the drought conditions in California are receding, water shortage as an issue demands a long term solution.


De La Salle Sensor, Shayla Adams, Geraldine Hernandez, Gloria Joseph, Elias Taylor, Elli Cooney Apr 2016

De La Salle Sensor, Shayla Adams, Geraldine Hernandez, Gloria Joseph, Elias Taylor, Elli Cooney

PSU High School Innovation Challenge

There is a huge amount of water being wasted and with climate change causing widespread water shortages, it is important that the people of Portland become more water conscious. With the our product, it will help you become aware of your water bill and the amount of water you use with a built in calculator.


Puddl: Gamifying Water Conservation, Quince Assenberg, Jack Chen, Denny Glenn, Jessica Lam Apr 2016

Puddl: Gamifying Water Conservation, Quince Assenberg, Jack Chen, Denny Glenn, Jessica Lam

PSU High School Innovation Challenge

As the global population surges, the demand for fresh water will only increase. With no technological breakthrough on the horizon, it is more important than ever to conserve water and not waste this precious resource. Water conservation is a serious issue, and will only become more severe as global warming worsens. As the global temperature increases, and rainfall becomes more sporadic, it will be important for communities to find new ways to save water. This push has already been made in certain areas in the united states, California, where they were forced to reduce their water consumption by 25%.

Through …


Small Scale Water Filtration Project, Elaine Yang, Lang Ming, Alex Tees, Lauren Galle, Tristan Coffey, Andria Tattersfield, Colin Brock Apr 2016

Small Scale Water Filtration Project, Elaine Yang, Lang Ming, Alex Tees, Lauren Galle, Tristan Coffey, Andria Tattersfield, Colin Brock

PSU High School Innovation Challenge

Access to clean drinking water is a large problem that our world is facing today. Consuming contaminated water can lead to the spread of water-borne illnesses. Populations without the security of water struggle to develop, as seen predominately in Africa. As Oregonians prepare for life after a major earthquake which could devastate the infrastructure that delivers clean water to our homes, a water filtration system should be part of a family’s emergency preparedness plan.

There are a large variety of processes for achieving fresh water. Combining all of the necessary components to lead to clean water is a complex process, …


A Genetic Approach To Designing A Novel Biological Sensor To Monitor Water Contamination, Cynthia Bui, Anissa Rosbaugh, Israel Gonzalez, Julie Lu, Colin Kuhns, Joel Crandall, Alyssa Faulk, Miriam Nguyen Apr 2016

A Genetic Approach To Designing A Novel Biological Sensor To Monitor Water Contamination, Cynthia Bui, Anissa Rosbaugh, Israel Gonzalez, Julie Lu, Colin Kuhns, Joel Crandall, Alyssa Faulk, Miriam Nguyen

PSU High School Innovation Challenge

Many cities across the country have experienced extreme water problems. The City of Portland has issued several water boiling advisories due to E. coli contamination. Additionally, there has been incidents of serious contaminants like lead leaching in water systems (Flint, Michigan). The Portland Water Bureau does not use a water treatment plant due to the quality of our water sources; a chlorination plant is used to chlorinate the water from the Bull Run Watershed (our main water source). Not having a water treatment plant makes Oregon more prone to a prolonged absence of potable water should the supply be contaminated. …


Residential Greywater Recycling System, Sophia Bui, Clare Clark, Anthony Hoang, Kim Le, Skyler Mishler, Janette Soler, Teresa Tran Apr 2016

Residential Greywater Recycling System, Sophia Bui, Clare Clark, Anthony Hoang, Kim Le, Skyler Mishler, Janette Soler, Teresa Tran

PSU High School Innovation Challenge

In a typical household, a majority of the fresh water is utilized by the shower, bathroom sinks and laundry. Water exiting from these fixtures is considered greywater. This is wasteful because the greywater is being combined with blackwater making it unusable. If greywater could be separated and captured, it can be reused for other purposes. We came to the conclusion that greywater is able to be recycled and reused for flushing excreta.


Isolated Water Circulation And Filtration System, Adrik Gurganus, Mellonie Mwawai, Wysteria Cedillo-Nielsen, Morgan Rekart, Zander Hoffman Apr 2016

Isolated Water Circulation And Filtration System, Adrik Gurganus, Mellonie Mwawai, Wysteria Cedillo-Nielsen, Morgan Rekart, Zander Hoffman

PSU High School Innovation Challenge

One big issue we are addressing is the large amount greywater produced by average households around the country. Still, the main problem is that, in areas affected by drought such as California, people have little available clean water, and this system will greatly benefit these people directly. The Isolated water system uses a filtration combined of organic materials, soaps, dirt, foods and sink to filter out the grey used water. Since the water system is not connected with the local water system if there were a natural disaster the owner would have free access to a water source while the …


Aqua Band, Jessica Peterson, Sam Behrens, Michael Desimone, Aiden Nelson, Alexandra Leamy Apr 2016

Aqua Band, Jessica Peterson, Sam Behrens, Michael Desimone, Aiden Nelson, Alexandra Leamy

PSU High School Innovation Challenge

People drown all of the time. Whether it's a young child playing in the river or a college student partying on a boat, there is always the danger of drowning. It is not always easy to tell if somebody is drowning. If you are a parent, you won’t always be watching your kids. When you look away and they start drowning, there is no safe way to be alerted of your child’s situation.


Estimating River Discharge Using Multiple-Tide Gauges Distributed Along A Channel, Hamed R. Moftakhari, David A. Jay, Stefan Talke Apr 2016

Estimating River Discharge Using Multiple-Tide Gauges Distributed Along A Channel, Hamed R. Moftakhari, David A. Jay, Stefan Talke

Civil and Environmental Engineering Faculty Publications and Presentations

Reliable estimation of freshwater inflow to the ocean from large tidal rivers is vital for water resources management and climate analyses. Discharge gauging stations are typically located beyond the tidal intrusion reach, such that inputs and losses occurring closer to the ocean are not included. Here, we develop a method of estimating river discharge using multiple gauges and time-dependent tidal statistics determined via wavelet analysis. The Multiple-gauge Tidal Discharge Estimate (MTDE) method is developed using data from the Columbia River and Fraser River estuaries and calibrated against river discharge. Next, we evaluate the general applicability of MTDE by testing an …


A Literature Review Of The Beneficial Use Of Dredged Material And Sediment Management Plans And Strategies, Portland State University. Hatfield School Of Government. Center For Public Service, Michelle Welch, Eric Thomas Mogren, Lauren Beeney Jan 2016

A Literature Review Of The Beneficial Use Of Dredged Material And Sediment Management Plans And Strategies, Portland State University. Hatfield School Of Government. Center For Public Service, Michelle Welch, Eric Thomas Mogren, Lauren Beeney

Center for Public Service Publications and Reports

This report identifies lessons learned from the body of existing literature on dredge sediment beneficial uses. It also examines the constructive role collaborative processes can play in development of sediment management plans. The authors reviewed approximately 100 documents and reports for this project. Seventeen of those were reviewed in detail based on their relevance in identifying sediment beneficial uses and/or the use of collaborative processes in the development of sediment management plans. A number of these documents were sediment management plans and strategies for specific projects and programs in other locations. The report presents findings and lessons for the consideration …


Multi-Criteria Evaluation Of Cmip5 Gcms For Climate Change Impact Analysis, Ali Ahmadalipour, Arun Rana, Hamid Moradkhani, Ashish Sharma Dec 2015

Multi-Criteria Evaluation Of Cmip5 Gcms For Climate Change Impact Analysis, Ali Ahmadalipour, Arun Rana, Hamid Moradkhani, Ashish Sharma

Civil and Environmental Engineering Faculty Publications and Presentations

Climate change is expected to have severe impacts on global hydrological cycle along with food-water-energy nexus. Currently, there are many climate models used in predicting important climatic variables. Though there have been advances in the field, there are still many problems to be resolved related to reliability, uncertainty, and computing needs, among many others. In the present work, we have analyzed performance of 20 different global climate models (GCMs) from Climate Model Intercomparison Project Phase 5 (CMIP5) dataset over the Columbia River Basin (CRB) in the Pacific Northwest USA. We demonstrate a statistical multicriteria approach, using univariate and multivariate techniques, …


Recent Progress In Performance Evaluations And Near Real-Time Assessment Of Operational Ocean Products, Fabrice Hernandez, Edward Blockley, Gary B. Brassington, Fraser Davidson, Prasanth Divakaran, Marie Drévillon, Shiro Ishizaki, Marcos Garcia-Sotillo, Patrick J. Hogan, Priidik Lagemaa, Bruno Levier, Matthew Martin, Avichal Mehra, Christopher Mooers, Nicolas Ferry, Andrew Ryan, Charly Regnier, Alistair Sellar, Gregory C. Smith, Sarantis Sofianos, Todd Spindler, Gianluca Volpe, John Wilkin, Edward Zaron, Aijun Zhang Oct 2015

Recent Progress In Performance Evaluations And Near Real-Time Assessment Of Operational Ocean Products, Fabrice Hernandez, Edward Blockley, Gary B. Brassington, Fraser Davidson, Prasanth Divakaran, Marie Drévillon, Shiro Ishizaki, Marcos Garcia-Sotillo, Patrick J. Hogan, Priidik Lagemaa, Bruno Levier, Matthew Martin, Avichal Mehra, Christopher Mooers, Nicolas Ferry, Andrew Ryan, Charly Regnier, Alistair Sellar, Gregory C. Smith, Sarantis Sofianos, Todd Spindler, Gianluca Volpe, John Wilkin, Edward Zaron, Aijun Zhang

Civil and Environmental Engineering Faculty Publications and Presentations

Operational ocean forecast systems provide routine marine products to an ever-widening community of users and stakeholders. The majority of users need information about the quality and reliability of the products to exploit them fully. Hence, forecast centres have been developing improved methods for evaluating and communicating the quality of their products. Global Ocean Data Assimilation Experiment (GODAE) OceanView, along with the Copernicus European Marine Core Service and other national and international programmes, has facilitated the development of coordinated validation activities among these centres. New metrics, assessing a wider range of ocean parameters, have been defined and implemented in real-time. An …


Estimation Of Historic Flows And Sediment Loads To San Francisco Bay, 1849 – 2011, Hamed Moftakhari Rostamkhani, David A. Jay, Stefan A. Talke, David H. Schoellhamer Aug 2015

Estimation Of Historic Flows And Sediment Loads To San Francisco Bay, 1849 – 2011, Hamed Moftakhari Rostamkhani, David A. Jay, Stefan A. Talke, David H. Schoellhamer

Civil and Environmental Engineering Faculty Publications and Presentations

River flow and sediment transport in estuaries influence morphological development over decadal and century time scales, but hydrological and sedimentological records are typically too short to adequately characterize long-term trends. In this study, we recover archival records and apply a rating curve approach to develop the first instrumental estimates of daily delta inflow and sediment loads to San Francisco Bay (1849 – 1929). The total sediment load is constrained using sedimentation/erosion estimated from bathymetric survey data to produce continuous daily sediment transport estimates from 1849 to 1955, the time period prior to sediment load measurements. We estimate that ~55% (45 …


Channel Shallowing As Mitigation Of Coastal Flooding, Philip M. Orton, Stefan A. Talke, David A. Jay, Larry Yin, Alan F. Blumberg, Nickitas Georgas, Haihong Zhao, Hugh J. Roberts, Kytt Macmanus Jul 2015

Channel Shallowing As Mitigation Of Coastal Flooding, Philip M. Orton, Stefan A. Talke, David A. Jay, Larry Yin, Alan F. Blumberg, Nickitas Georgas, Haihong Zhao, Hugh J. Roberts, Kytt Macmanus

Civil and Environmental Engineering Faculty Publications and Presentations

Here, we demonstrate that reductions in the depth of inlets or estuary channels can be used to reduce or prevent coastal flooding. A validated hydrodynamic model of Jamaica Bay, New York City (NYC), is used to test nature-based adaptation measures in ameliorating flooding for NYC’s two largest historical coastal flood events. In addition to control runs with modern bathymetry, three altered landscape scenarios are tested: (1) increasing the area of wetlands to their 1879 footprint and bathymetry, but leaving deep shipping channels unaltered; (2) shallowing all areas deeper than 2 m in the bay to be 2 m below Mean …


On The Assessment Of Reliability In Probabilistic Hydrometeorological Event Forecasting, Caleb Matthew Dechant, Hamid Moradkhani Jun 2015

On The Assessment Of Reliability In Probabilistic Hydrometeorological Event Forecasting, Caleb Matthew Dechant, Hamid Moradkhani

Civil and Environmental Engineering Faculty Publications and Presentations

Probabilistic forecasts are commonly used to communicate uncertainty in the occurrence of hydrometeorological events. Although probabilistic forecasting is common, conventional methods for assessing the reliability of these forecasts are approximate. Among the most common methods for assessing reliability, the decomposed Brier Score and Reliability Diagram treat an observed string of events as samples from multiple Binomial distributions, but this is an approximation of the forecast reliability, leading to unnecessary loss of information. This article suggests testing the hypothesis of reliability via the Poisson-Binomial distribution, which is a generalized solution to the Binomial distribution, providing a more accurate model of the …


Multimodal Internal Waves Generated Over A Subcritical Ridge: Impact Of The Upper-Ocean Stratification, Xie Jieshuo, Jiayi Pan, David A. Jay Mar 2015

Multimodal Internal Waves Generated Over A Subcritical Ridge: Impact Of The Upper-Ocean Stratification, Xie Jieshuo, Jiayi Pan, David A. Jay

Civil and Environmental Engineering Faculty Publications and Presentations

Interaction of barotropic tides with subsurface topography is vital to ocean mixing. Yet the behavior of large-amplitude, nonlinear, internal solitary waves (ISWs) that can cause strong mixing remains poorly understood, especially that of higher-mode and multimodal internal waves. Therefore, a 2.5-dimensional, nonhydrostatic model with adjustable vertical resolution was developed to investigate effects of upper-ocean stratification on tidally induced multimodal internal waves and to show how they are generated by the subcritical ridge where only upward-propagating internal wave beams (IWBs) are present. The effects of the stratification on properties and characteristics of the excited IWBs and on the energy partition of …


The Skill Of Seasonal Ensemble Low-Flow Forecasts In The Moselle River For Three Different Hydrological Models, Mehmet C. Demirel, Martijn Booij, Arjen Hoekstra Jan 2015

The Skill Of Seasonal Ensemble Low-Flow Forecasts In The Moselle River For Three Different Hydrological Models, Mehmet C. Demirel, Martijn Booij, Arjen Hoekstra

Civil and Environmental Engineering Faculty Publications and Presentations

This paper investigates the skill of 90-day low-flow forecasts using two conceptual hydrological models and one data-driven model based on Artificial Neural Networks (ANNs) for the Moselle River. The three models, i.e. HBV, GR4J and ANN-Ensemble (ANN-E), all use forecasted meteorological inputs (precipitation P and potential evapotranspiration PET), whereby we employ ensemble seasonal meteorological forecasts. We compared low-flow forecasts for five different cases of seasonal meteorological forcing: (1) ensemble P and PET forecasts; (2) ensemble P forecasts and observed climate mean PET; (3) observed climate mean P and ensemble PET forecasts; (4) observed climate mean P and PET and (5) …


Tides And The Swot Mission: Transition From Science Definition Team To Science Team, Brian K. Arbic, Florent Lyard, Aurelien Ponte, Richard D. Ray, James G. Richman, Jay F. Shriver, Edward Zaron, Zhongxiang Zhao Jan 2015

Tides And The Swot Mission: Transition From Science Definition Team To Science Team, Brian K. Arbic, Florent Lyard, Aurelien Ponte, Richard D. Ray, James G. Richman, Jay F. Shriver, Edward Zaron, Zhongxiang Zhao

Civil and Environmental Engineering Faculty Publications and Presentations

As the SWOT wide-swath satellite altimeter mission transitions from the Science Definition Team to the Science Team, it is an opportune time to review the progress that has been made with respect to tides, and the work remaining to be done. As with previous altimeter missions, tides present both an opportunity and a challenge for the SWOT mission. The TOPEX/Jason class of altimeters have allowed high-accuracy mapping of open-ocean barotropic tides over their coverage latitudes (66°S to 66°N), but the inter-track spacing of these missions (~150 km) has limited their ability to map smaller-scale features such as shelf tides, coastal …