Fellowship
Michael George
Biography
Mr. George is a geological engineer specializing in scour and erosion. Since receiving his BS degree from the Colorado School of Mines in 2004, he has worked as a consulting engineer on projects around the United States and abroad. Specifically, his work has focused on dam foundation erosion, plunge pool scour and design, scour protection design, rock cover design, hydrologic analysis, and drainage channel design. He has also conducted numerous field investigations in support of such analyses. Mr. George is currently enrolled in the MS/PhD program in the Civil and Environmental Engineering Department at the University of California – Berkeley. His proposed research will focus on rock scour evaluation using block theory and the critical key block concept. Mr. George is currently registered as a Professional Engineer in the State of Colorado.
Research- Rock scour evaluation using block theory and the critical key block concept
Excessive erosion of a dam’s foundation, abutments, or spillway can compromise dam stability and result in high remediation costs, property damage or even loss of life. To facilitate improvements in dam safety, it is necessary to comprehend the underlying physics of the scour process. Current state-of-the-art scour models by Bollaert (2002) and Annandale (1995, 2006) fail to adequately quantify the removal of individual rock blocks from dam abutments or unlined rock spillways where block removal is the major mechanism driving scour.
The roots of understanding block removal stem from theory in rock mechanics and hydraulics. Although advances have been made in both fields, blending of the two disciplines has been limited in regard to scour. Typically, the 3D orientation of rock discontinuities are ignored and block geometry is assumed to be rectangular, promoting a more generalized and unreliable assessment of scour. Block theory yields promise for application to scour assessment as the 3D orientation of the rock discontinuities can readily be incorporated. Based on discontinuity orientations within a rock mass, a finite number of block shapes exist. Exposure of discontinuities on a free rock face (such as a spillway cut) can liberate individual blocks of rock when acted upon by outside forces (e.g., flowing water). Evaluation of the susceptibility of various block shapes to removal (by sliding, lifting, or rotating) forms the basis of block theory. Blocks that are the most readily removed are termed “key blocks” (Goodman & Shi 1985).
The proposed research will have three key components: 1) literature review and initial concept development, 2) field study 3) refinement and application of scour analysis techniques.
First, an in-depth review of the application of rock mechanics and hydraulic engineering principles to scour processes will be made with emphasis on the applications of block theory. Based upon existing laboratory and field data, initial concepts would be developed to quantify the hydrodynamic pressures that are applied to individual rock blocks subject to overtopping or spillway discharges.
Second, field investigations will be conducted for selected dam sites to collect pertinent geologic information for scour assessment. State-of-the-art methodologies for rock mass classification (e.g., laser scanning, photogrammetry) will be used in conjunction with in-depth field mapping to obtain rock discontinuity information including orientation, roughness, alteration/filling, and spacing.
Third, field data coupled with known discharge data for the selected dam sites will be used to determine rock resistance to erosion and flow erosive capacity. The initial concepts developed for scour assessment using block theory will be applied and refined to evaluate scour potential at the dam sites. The final concepts would be presented as methodologies that can be practically applied to real world evaluations.
The research will be performed at the University of California – Berkeley as a 2 year Master’s thesis project under the direction of Prof. Nicholas Sitar with outside consultation provided by Dr. Richard Goodman (Prof. Emeritus at UC – Berkeley) and Dr. George Annandale (scour expert). UC – Berkeley has a world-renowned reputation as a leader in civil engineering and geoscience research and is widely known for the development and use of block theory in the engineering of rock masses.
There is a significant benefit to society to be able to critically understand the scour process. This research would improve safety for infrastructure that serve as key resources for society. The use of block theory would promote more site specific assessments of scour ultimately improving prediction reliability and allowing for more efficient, cost-effective remediation designs.
Justin Hannon
Biography
Justin Hannon grew up in Council Bluffs, IA and began attending The University of Iowa after graduating high school. While an undergraduate, Justin worked at IIHR – Hydroscience and Engineering for two years, working on computational fluid dynamics simulations of large waterways and fish passage facilities. After receiving a BSE in civil engineering from The University of Iowa in the fall of 2009, h e began working toward an MS in civil engineering while continuing his work at IIHR.
Research-Computational Fluid Dynamics Study to Examine the Affect of a
Kármán Gait on Fish Locomotion
Fish passage through hydraulic structures, such as the turbines in hydropower dams, is an important issue due to the inherent risk of injury or death to the fish. The design of fish passage facilities requires knowledge of how fish respond under given situations. Models have been developed in an attempt to predict fish locomotion patterns in large rivers and waterways. Such methods are typically used for large-scale systems and are useful for capturing the general motion of fish. However, much is to be learned from how and why fish move the way they do given different environmental and flow field conditions. A thorough understanding of fish motion requires knowledge of the neuro-biology, cognitive ecology, and hydrology involved in the system. This proposal focuses on studying the hydraulics of fish locomotion under prescribed fluid conditions.
The research to be undertaken in this proposal is a study of the drag, propulsion and other flow features (such as vorticity) of a single fish swimming in an unsteady, but controlled, flow field. What sets the proposed research apart is the incorporation of image analysis techniques to quantify actual fish motion from digital videos, and to use these digital videos as inputs to the computational fluid dynamics (CFD) simulations. The research videos of fish locomotion were provided by Professor George Lauder at Harvard University. Professor Lauder’s research group has provided several videos of trout moving under controlled conditions for various fluid flows (i.e. free stream and behind a D-section cylinder). The videos were segmented into individual frames by an electrical engineering professor (Dr. Mona Garvin) at the University of Iowa, and were translated into a form usable for CFD analysis.
The video frames of the swimming fish will be used to generate a dynamically moving boundary which will follow the exact motion of the fish that was filmed. This moving boundary will impart forces on the fluid being simulated, providing insight on the details of fish locomotion. The simulation scenario of the most interest is that of a fish slaloming between the vortices shed behind a D-section cylinder in a Kármán gait pattern. Determining the drag and pressure distribution for this type of fish locomotion will help in the understanding of aquatic biological propulsion and also will provide information on the formation of fish schools due to the complex vortex structure that would inevitably be present during schooling. A series of CFD simulations will also be conducted to determine which set of solution parameters (i.e. turbulence model and numerical schemes) are most appropriate for this type of problem. This information will be used to achieve the most accurate results possible and will be also useful as a guide for future researchers seeking to perform CFD studies in this area.
Jordan Kern
Biography
Jordan Kern grew up in the Piedmont of North Carolina. As an undergraduate, he attended the University of North Carolina at Chapel Hill (UNC-CH), where he studied physical geography, GIS and remote sensing while working as a research assistant on a project studying the ecological effects of dam removal. Jordan earned a B.S. in Environmental Science in May 2007 and received a Phillips Scholarship in summer 2007 to study geothermal resources and regional effects of global warming in Iceland. Upon his return, Jordan worked for a consulting firm in the Washington, DC area, where he provided technical and administrative support to the US Department of Energy’s Hydrogen and Fuel Cells program. In spring 2009 Jordan enrolled in the UNC-CH Department of Environmental Science and Engineering as a M.S. student, where he is a Progress Energy Fellow. He currently works with Professors Greg Characklis (Environmental Sciences and Engineering) and Martin Doyle (Geography) on economic and environmental trade-offs between water resource management and the energy industry in the Roanoke River basin of North Carolina and Virginia. After receiving his M.S. degree in July 2010, Jordan will continue work at UNC-CH towards a Ph.D. with the support of the Hydropower Research Foundation.
Research- Dynamic hydrologic-economic modeling of tradeoffs in hydroelectric systems
In the Southeastern U.S., competition for water is becoming increasingly contentious due to rapid growth in demand. As state and regional managers seek to balance the water needs of humans and the environment, the timing of steamflows—in addition to their quality and quantity—is an important concern, and one that can be significantly impacted by hydropower generation. In de-regulated electricity markets, where the price of energy and grid reliability services change throughout the day, generators may have financial incentives to alter generation schedules, sometimes on a real-time basis, in order to increase revenues. Hydroelectric dams’ ability to respond to changes in electricity demand more rapidly and at lower cost than thermal generators (i.e., coal, nuclear and natural gas) makes them well suited to take advantage of short-term changes in market prices. However, the hydropower release schedules that result may lead to flow regimes that differ significantly from natural patterns.
My M.S. research at the University of North Carolina at Chapel Hill began to explore the potential for electricity market dynamics to impact flow regimes downstream from hydroelectric dams. Three dam sites in the Roanoke River Basin (North Carolina and Virginia) were modeled under several different operating scenarios. Flow regime statistics that reflect five environmentally critical components of river flow (magnitude, timing, frequency, rate-of-change and duration) were used to quantify the impact of different operational scenarios on downstream flows. Results yielded some insight into the complicated relationship between hydropower revenues and downstream deviation from the ‘natural flow regime’.
The Hydropower Research Foundation fellowship will be vital to my continued investigation of the relationship between electricity markets and flow regime downstream from hydroelectric dams. My Ph.D. project proposal involves the generation of stochastic hydrologic and market inputs, coupled with a probabilistic decision making algorithm on the part of the modeled hydropower utility, in order to set up a true revenue maximization problem. This enhanced model will also allow me to incorporate potential future impacts of climate change, increased reliance on more intermittent renewable energy sources (wind and solar), and changes in regional water demand from municipalities, industry and agricultural users. In order to gauge downstream environmental quality, a new set of flow regime statistics, ones that reflect potential hourly flow regime changes resulting from participation in dynamic electricity markets, will be developed and incorporated in our method for identifying a robust, Pareto-optimal solution for managing the hydrological assets of an entire river basin.
Marina Kopytkovskiy
Biography
Marina Kopytkovskiy was born in Minsk, Belarus and moved to Salt Lake City, Utah at the age of 8. Growing up in Utah she learned to appreciate and love the natural beauty, especially snow. First attending the University of Utah, she then transferred to the University of Washington in Seattle, WA. Entering the workforce after graduation from UW, she gained valuable experience, which led her to return to the academic sphere and pursue a graduate degree. In her spare time, Marina loves to be active, travel and explore her surroundings. She is very thankful for this amazing Fellowship and looks forward to starting her studies!
Research-The Effects of Climate Change on the Water Resources and Hydropower Production Capacity of the Upper Colorado River
The Upper Colorado River head is regulated by 8 major reservoirs to provide water supply, flood control, and hydropower. It is the prime water source for much of the western United States, as well as key wildlife and fish habitat. Climate change is a concern on the Upper Colorado River basin due to the sensitivity of snow accumulation processes that dominate runoff generation within the basin (Loaiciga, 1996). Climate models project Colorado will warm by 2.5°F by 2025, relative to the 1950–99 baseline, and 4°F by 2050. The projections show an increase in temperatures and a decline in snowpack (Christensen and Lettenmaier 2006). This is expected to cause a decline in runoff by the mid-to-late 21st century. Although most studies disagree on the numerical changes in precipitation, there is general consensus that precipitation increases will be offset by increased evapotranspiration, reducing overall runoff.
Potential impacts of climate change on the hydrology and water resources of the Upper Colorado River basin will be assessed. This will be accomplished through a comparison of simulated stream flow, reservoir volumes and levels, and hydropower production capacity under future climate conditions derived from current climate models and scenarios, and from historical climate data. A climate model will be used to generate future climate scenarios for the Upper Colorado River basin which will be utilized to drive a hydrologic model for the basin. A Watershed Analysis Risk Management Framework (WARMF) will be used for hydrologic analysis. WARMF performs daily simulations of snow and soil hydrology to calculate surface runoff and groundwater accretion to river segments, lakes or reservoirs. A reservoir analysis will be performed within the WARMF framework to determine if management strategy could be developed to mitigate climate change. The result of this research is expected to assist water management in adapting to longer-term climate change impacting water supply, flood management, and hydropower potential.
Thus, the objectives of this research are to: 1) provide water resource planners (e.g. utility designers, reservoir operators, and managers) with a better understanding of anticipated climate change impacts for the long-term decision-making process, 2) predict changes in stream flow (magnitude and timing) due to climate change, 3) predict reservoir storage, water deliveries, hydropower production, and probability of uncontrolled spills, 4) assess impact of climate change on ensuring delivery of the required flow to the Lower basin according to the water rights allocation agreements.
The proposed research will be completed at the Colorado School of Mines (CSM). The Environmental Science and Engineering (ESE) division and its’ Hydrologic Science and Engineering (HSE) program have expertise in climate change, watershed scale surface, and ground water modeling. The Geology department advises watershed scale groundwater modeling. Currently, ESE has a climate-related project on carbon sequestration with plans for extensive research on climate change’s impact on surface and groundwater resources, complementing the proposed project. Additionally, CSM’s Colorado Energy Research Institute (CERI) and the International Ground Water Modeling Centre (IGWMC) provide facilities for research. CERI engages in climate research while the IGWMC advises on ground-water modeling problems. The proposed research will benefit from the expertise and services of these departments and centers and experts, to meet the research objectives.
Jonathon Lamontagne
Biography
Jonathan Richard Lamontagne was born on November 11, 1986 in Nashua, NH to parents Marc and Pam and has a younger brother and sister. He was raised primarily in Deerfield, a small town in the southeast region of the state. Throughout his childhood Jonathan was active in Scouting, eventually achieving the rank of Eagle Scout in 2004. He graduated from Pembroke Academy in 2005, where he was captain of the Track and Cross Country teams and also a member of the National Honors Society. After graduation, Jonathan began studies at the University of New Hampshire, initially studying political science before switching to civil engineering in his second year. During the spring of 2008 Jonathan studied at Heriot Watt University in Edinburgh, Scotland, during which time he traveled extensively both in the UK and across Europe. Upon graduating suma cum laude from UNH in May 2009, Jonathan began MS/PhD studies at Cornell University in the School of Civil and Environmental Engineering with a concentration in Environmental and Water Resources Systems Engineering. Jonathan is engaged to marry Katelyn Louise Trexler in June 2011 upon completion of her graduate studies. After completing his PhD studies, Jonathan plans move back to New England and seek a faculty position at one of the various universities there.
Research- Real-time forecasting and hydropower optimization
The proposed research will address real-time forecasting and hydropower optimization. Of particular interest is hydropower operation of reservoirs in the Northeast, whose hydrology is often complicated and highly variable and whose storages are typically much smaller than Western reservoirs. These factors combined make short-term management decisions of great importance, but also very difficult. Frequent hydrologic variability in small watersheds can cause dramatic changes in reservoir storage, which can in turn lead to frequent suboptimal hydropower operation. My research seeks to build on previous works in stochastic dynamic programming (SDP) and recent developments in NEXRAD and other forecasting technologies which more accurately represent the spatial distribution of potential precipitation. The potential value of such analysis of such real-time reservoir optimization using forecasts has been demonstrated by previous studies.
SDP seeks to find the release Rt at time t which maximizes the sum of the present benefit Bt and expected future benefit. Inflow at the present time, Rt, is usually assumed to be known. In this time study time steps might range from 1-6 hours, depending on the system in question.
SSDP is an improvement on the traditional SDP scheme. The main advantage of SSDP is that it chooses Rt based on sampling from future flow scenarios which could employ the best available forecast information to explicitly consider uncertainty in future flows. This double-tiered methodology makes the best immediate decision using the best forecasting information available, including forecast uncertainty. Furthermore, SSDP generates an empirical distribution of future scenarios, allowing computation of statistics of interest about the system, and avoids the chronic over estimation of the benefits of optimal management policies which plague SDP models by separating the calculation of future flows from the calculation of an optimal policy.
SDP and SSDP algorithms can become computationally untenable for multi-reservoir systems and as such have largely been ignored for real-time optimization applications. To address this, we propose to use cubic piecewise polynomials (splines) rather than linear tensor product interpolates to approximate the value function of dynamic programs of various dimensionalities. For multi-dimensional cases similar to those proposed in this study, these methods have been shown to significantly reduce computational burden. Furthermore, a probability thinning procedure in which the density of sampling in the tails of the future scenario distributions is greater than in the center will be utilized. Since values in the extremes contribute more to uncertainty, values in the center of the distribution can be combined without loss of resolution. Studies have also successfully implemented SSDP re-optimization schemes which use single-stage forward moving SDP to choose the release for each stage instead of interpolating between predetermined policies, with great computational savings. Between utilization of such efficient algorithms and advances in the speed and affordability of computational power, this study hopes to show SSDP to be an ideal and feasible tool for real-time forecasting reservoir optimization.
In conversations with New England utilities, several reservoir systems have emerged as promising case studies. The first is the Upper Androscoggin Lakes of northeastern Maine, which consist of six connected reservoirs and several associated hydro generation units. This system is ideal because the local geology and topography make it especially prone to rapid influxes of water during storm events, and because downstream structures, ecology, and run-of-river hydro greatly restrict the allowable discharges, making optimal release decisions of great importance. The second candidate reservoir is the Kennebec River Storage System of north central Maine, which encompasses three reservoirs (including Maine’s biggest lake, Moosehead Lake) and ten hydrogenation units. This system is ideal for initial development candidate because of its relative simplicity. This study proposes to use two systems utilized by two utilities to explore the benefits of new and evolving streamflow forecasting products to improve hydropower operations. The findings of this study should be applicable to modest-sized systems across the country.
Ann Marie Larquier
Biography
Ann Marie is a graduate student at Alaska Pacific University pursuing her master’s degree in Environmental Sciences with an emphasis in hydrology and water resources. Her thesis research is focused on the diminishing role of glacier runoff to Eklutna Lake and the potential impacts on hydropower and drinking water supply for the Municipality of Anchorage.
Ann Marie was raised in the high desert of northern Nevada where she witnessed the importance of water in an arid climate. She took this interested to Southern Oregon University where she graduated Cum Laude with a bachelor’s degree in Environmental Studies, with an emphasis in Geology and a minor in Land Use Planning. During this time she gained experience in watershed sciences though a position as a Water Quality Technician for a local government agency as well as a Hydrologic Technician for the Bureau of Land Management conducting riparian surveying. Additionally, she spent the summer of 2007 studying watershed sciences Lake Baikal in Russia. She took a brief hiatus from Oregon during the first half of her sophomore year to study at the University of Alaska Fairbanks through the National Student Exchange program.
Unable to wash her hands of the grandeur of Alaska, Ann Marie followed her passion north where she worked as a research technician on Prince of Wales Island participating in a study focused on the impacts of timber harvest on the geomorphology of salmon spawning streams in southeast Alaska. Now in the second year of her graduate program, her research has taken her on a 24 day research traverse of glaciers in the Chugach Mountain Range which provide drinking water and hydropower for Alaska’s largest city, as well as countless opportunities for mountain biking to remote river sites to gage runoff and sediment transport.
Outside of the university, she works as a Hydrologic Technician for the U.S. Geological Survey as well as a Biological Science Technican for the U.S. Fish and Wildlife Service. Ann Marie’s extracurricular activities highlight her desire to work toward holistic watershed management through interdisciplinary approaches. She volunteers with the Anchorage Waterways Council, Alaska Center for the Environment, and the Tahoe-Baikal Institute as well as participates in the Alaska Women’s Environmental Network mentorship program. Other activities include yoga and any outdoor activity that Alaska has to offer.
Research-Glacial Influences on Water Resources of the Eklutna Basin, Alaska
The purpose of this research is to analyze the influence of glacial meltwater contributions to the seasonal availability of water in the Eklutna basin for municipal water use and hydropower generation. The information from this study will be used to create scenarios under which to model the influence of climate-mediated glacier volume reduction on the water storage capacity of Eklutna Glacier and Eklutna Lake, and determine the proportion of total discharge (water and suspended sediment) into Eklutna Lake that is provided by the lake’s two primary tributaries: East Fork Eklutna River (predominantly precipitation and groundwater fed) and West Fork Eklutna River (predominantly glacier fed). This data will be used examine the quantity, timing, and distribution of these inputs to Eklutna Lake to determine potential changes in storage capacity of Eklutna Lake and affects to drinking water quality.
Objectives: The outcome from this research will be used to answer the following:
- Under future modifications to Eklutna Basin hydrology, will domestic water resource and hydropower demand exceed water supply availability?
To assess how water supplies may evolve, I will derive seasonal monthly estimates of streamflow and suspended sediment inputs under a variety of scenarios:
- Current situation (reflecting average conditions during the 2009-2010 field seasons)
- With the Eklutna Glacier at its larger 1957 volume
- With the Eklutna Glacier at 50% of its current ice volume
- With no Eklutna Glacier
These seasonal monthly estimates of water availability (supply) will be compared to possible future water quantity demands by the water and power utilities at:
- Current water resource demand
- Doubling of drinking water demand
- Doubling of hydropower demand
Eklutna Lake has been providing water for the generation of power since 1929 when a small hydroelectric power plant was established on the Eklutna River. The city of Anchorage acquired this project in 1943 and in 1955 the Eklutna Project was constructed to provide electricity to the Anchorage-Palmer area. The Eklutna Project developed infrastructure by which to extract water from the lake by means of a penstock approximately 24,000 feet long which is buried through Goat Mountain to Knick Arm where the Eklutna Power Plant is located. The current dam structure, which impounds 100% of Eklutna Lake outflow and has no outlet works, has been in place since 1965 replacing other outflow barriers that were damaged in the 1964 Good Friday Earthquake. Outflows from Eklutna Lake are diverted through an intake tunnel at 814 feet in elevation for drinking water or hydroelectric use. In 1996, Anchorage Municipal Light and Power (ML&P), Chugach Electric Association, and Matanuska Electric Association jointly took over the Eklutna Hydroelectric Power Plant (Municipal Light & Power, 2010). This power plant provides electricity for roughly 30,000 residential and commercial customers in the northern part of the Municipality of Anchorage including military bases and the downtown central business district and has 380 megawatts of installed generation capacity.
Minal Parekh
Biography
Ms. Parekh is a geotechnical engineer with over 15 years of experience in civil, geotechnical, and environmental engineering. She is currently pursuing a Ph.D. in Engineering at Colorado School of Mines, with research focusing on evaluating the integrity of existing earthen dams and levees using nondestructive methods. Ms. Parekh has served as a project manager, staff manager and mentor to junior engineers. Her practical experience includes design in support of water and wastewater infrastructure, shallow and deep foundation design, retaining wall and slurry wall design, soil and rock slope stabilization, specification and contract document preparation, construction submittal review, construction inspection, and construction management. Ms. Parekh has field engineering experience in projects that have involved geotechnical investigation, slurry wall construction, soil nail wall construction, rock slope stability, tunneling and trenchless technology, and pipeline construction. In addition to engineering consulting, she has worked in the public sector in environmental compliance, engineering design, and construction management.
Research-Valuating internal erosion in earth dams, using non-destructive methods
This research will advance methods for evaluating hydropower infrastructure using real time, continuous, and non‐destructive techniques. This research investigates earthen embankments (dams and levees) subject to water flow by exploring internal erosion initiation and propagation in heterogeneous earth materials and in zoned embankments. Internal erosion is a primary failure mode of dams and levees. There is limited understanding regarding characterization of the inception and early progression of internal erosion in earthen structures– both in terms of geometry of erosion features, properties within the seepage paths, and changes that occur with time progression. Research is needed to explore the accuracy and resolution required to capture changes in subsurface conditions using multi‐sensor, non‐destructive geophysical techniques deployed at the ground surface and/or in situ. Research is also needed to explore what parameters can be measured, how they can be used to diagnose where internal erosion susceptibility is high, how the parameters change with the initiation and progression of internal erosion over time and space, what scale of change in parameter can be measured, what the confidence of the measurements is in a probabilistic framework. The proposed research will motivate solutions to a significant challenge presented by earth dams which are susceptible to internal erosion as infrastructure ages. Colorado School of Mines is uniquely positioned to develop this research by working with local representatives from the U.S. Bureau of Reclamation (USBR) and U.S. Army Corps of Engineers, from within the SmartGeo Intelligent Geosystems program framework. (http://smartgeo.mines.edu) As a member of the program’s Intelligent Earth Dam research group, I am working to develop dam and levee systems that can sense changes in environment and performance and provide decision support for improving performance.
This research will focus on the geotechnical behavior observed at the initiation and early progress of internal erosion using continuous monitoring techniques (geophysical and imaging). Research will be conducted by experiment, analysis of results, and evaluation of dam and levee management policy related to advancing monitoring methods by addressing the following questions:
1. What does internal erosion look like as it initiates and progresses? Size, shape of erosion feature, surface deformations? Changes with time? Movement of particles? How do the material and hydraulic properties (porosity, density, permeability, flow rate) change as erosion initiates and progresses to form a continuous “pipe”? Experiment
2. Determine if we can detect the initiation/early stages of internal erosion using state of the art geophysical electrical/acoustic techniques? What size anomalies can geophysical techniques (electrical, acoustic) discern? What testing variables (sampling interval, electrode spacing) influence what we can see? Experiment
3. Using non invasive continuous monitoring, can we predict the location of susceptible soils, and probability of progression of the initiation of an internal erosion anomaly to a pipe? To a failure? Analysis
4. How does the ability to predict the occurrence of internal erosion dovetail into the risk assessment methods used by dam safety managers? How can we reduce uncertainties in the existing failure mode analyses and event tree models? Analysis/Policy
5. What are the implications of continuous monitoring to levee and dam management policy (and vice versa)? Policy
John Petrie
Biography
John Petrie is a candidate for the degree of Doctor of Philosophy in civil and environmental engineering at Virginia Tech. John’s areas of interest include river morphology, field measurements of river velocity, and computational hydraulics. His dissertation work focuses on the relationship between variations in discharge patterns due to hydropower operations and downstream riverbank erosion and stability. Prior to doctoral studies at Virginia Tech, John served as assistant professor of physics and mathematics at the Virginia Commonwealth University in Qatar (VCUQ) for three years. His professional activities include publications in journals such as Water Resources Research and Environmental Science and Technology and reviewing manuscripts for Earth Surface Processes and Landforms. In addition to his work in engineering, John received a Bachelor of Music in jazz performance from the New England Conservatory. John has performed on string bass across the globe from the Vancouver International Jazz Festival in Canada to Dunestock in Qatar.
Research- Modifying hydropower releases to reduce riverbank erosion
Through a combination of field surveys, numerical modeling, and analytical work, this study investigates the effects of hydropower peaking operations on erosion of the downstream riverbank and seeks to identify appropriate reservoir release adjustments to minimize these effects. Peaking operations, designed to generate electricity, result in dramatic changes in discharge often on a daily basis. For example, an almost ten-fold increase in discharge over two hours is typical on the lower Roanoke River. Erosion rates and conditions for stream ecology depend on the characteristics of hydropower peaking operations. Proper adjustments in the release patterns could mitigate adverse effects, further enhancing the appeal of hydropower as a renewable, sustainable energy source.
To predict erosion, three quantities must be specified: (i) the resistive capacity of the soil, (ii) the erosive force of the flowing water, and (iii) a threshold condition after which erosion occurs. To determine these quantities, this study uses a new approach to combine advanced field measurement techniques with computational fluid dynamics (CFD) models. Actual field conditions and flow releases on the lower Roanoke River, a regulated river in eastern North Carolina, serve as the basis for the study.
The resistive capacity and threshold condition of cohesive soils, such as those found on the lower Roanoke River, depend on the composition of the bank soil as well as chemical properties of the river and pore water. The complexity of interparticle forces has prevented the development of a general theoretical model to predict cohesive soil erosion. This study uses the in situ jet erosion test to determine the soil erodibility. The jet test uses a submerged water jet to erode the soil. The resulting scour depth is monitored over time to estimate the soil’s threshold shear stress and resistance to erosion.
To characterize the river flow and channel topography, extensive measurements have been carried out with an acoustic Doppler current profiler (ADCP) throughout the study reach. The ADCP provides direct measurements of three dimensional flow velocities and flow depth which may be used to determine discharge and bathymetry. The field data collected with the ADCP will be used to build CFD models representative of a straight reach and meander bend in the lower Roanoke River.
The erosive force applied by flowing water can be represented by the shear stress applied to the bank, known as the boundary shear stress. Boundary shear stress is influenced by the near- bank flow conditions, including the presence of secondary currents and turbulence. Direct measurements of boundary shear stress in natural rivers are not possible and techniques to estimate shear stress have been shown to provide significantly different results. CFD models are used in this study to calculate the distribution of boundary shear stress on the riverbank. CFD involves the numerical solution of the governing equations of fluid flows and can describe the entire three dimensional flow field. These models directly calculate the boundary shear stress based on local flow conditions. In addition to the shear stress, the models will allow a detailed study of the flow processes that generate the applied stress.
While this study focuses on the lower Roanoke River, the results will provide an improved understanding of the relationship between flow releases for hydropower generation and adjustments in the downstream river channel. Through numerical simulations of existing and alternative flow scenarios, recommendations can be made to minimize riverbank erosion. By reducing associated erosion, hydropower can continue as an important renewable energy source while minimizing the effects on the surrounding river and ecosystem.
Adam Witt
Biography
Adam Witt was born in Minnesota and raised throughout the country - Florida, Colorado and Missouri before returning to Minnesota in 1996. He graduated cum laude from Carleton College, Northfield, MN in 2006 with a BA in Physics and a concentration in French and Francophone Studies. Shortly after graduation, Adam took a job with The Travelers Companies in St. Paul, MN as a management liability underwriter trainee. In July 2007 he accepted a transfer to the San Francisco, CA office. In 2008, Adam was promoted to National Technology Analyst, and in 2009 he earned the underwriting professional designation and became a CPCU (Certified Property and Casualty Underwriter). In September 2010 he will begin graduate studies in Water Resources at the University of Minnesota.
Research-Developing a technology which can predict gas transfer at low head and high head structures
Low levels of dissolved oxygen will disrupt aquatic ecosystems. At low head hydraulic structures, such as the many locks and dams on navigable rivers, entrained air from increased turbulence and flow variation leads to a substantial increase in dissolved oxygen concentration, and is a benefit to the aquatic biota. At high head structures, due to increased water velocity and deeper plunge pools, dissolved nitrogen and oxygen (total dissolved gas) can reach high levels as further exchange occurs between compressed bubbles and the water (Urban et. al 2008). Total dissolved gas (TDG) concentration thus becomes higher than equilibrium with the atmosphere (supersaturated) and fish exposed to these concentrations will often develop gas bubble disease (Urban et. al 2001). Gas transfer at spillways can thus have a positive or a negative effect on the aquatic biota. The physical process by which these two phenomena occur, however, is similar.
My proposed research involves developing a technology, which can predict gas transfer at low head and high head structures. The goal is a unified theory and computer code that will function to predict oxygen transfer at low head structures, and oxygen and nitrogen transfer at high head structures. If the physics and chemistry of gas transfer at spillways can be accurately analyzed, the science of the process should not change with scale. The resulting equations can be used to solve gas transfer problems at multiple structures: locks, dams, spillways and hydropower facilities. Detailed analysis using traditional computational fluid dynamic (CFD) modeling would be implemented with field verification from existing measurements. Subroutines to a commercial code such as FLUENT will be developed at first to see if these codes are capable of performing to the task. If not, a St. Anthony Falls Laboratory in-house code, CENTAUR3D, developed by the group of Professor Sotiropoulos for bubble dynamics at hydro-turbines will be utilized. If necessary, selective experiments will be developed and run to estimate the importance of particular physical processes.
The overall objective of the research will be to develop a CFD code that can be used to predict gas transfer at any spillway, without the currently required calibration to field data. The field data would then be used for true verification. Eventually, the requirement for expensive field measurements will be reduced or even eliminated.
Gas transfer at spillways is an important consideration when developing and relicensing hydropower facilities. The benefits of hydropower may be offset by declinations in river wildlife, causing negative public relations with the community and irreversible destruction of local ecosystems. Through understanding and controlling gas transfer at hydropower facilities, these adverse environmental impacts can be mitigated.
Existing and proposed hydropower facilities need to be cognizant of the transfer of oxygen and total dissolved gas that occurs at their spillways. A low head facility in the Midwestern or Eastern USA may require the installation of energy–intensive aeration facilities because the water that will not travel over the spillway (travel through the powerhouse) will have a lower dissolved oxygen concentration (Gulliver et. al 1998). It is important to make sure that the correct oxygen transfer is applied to the spillway, because regulators have a tendency to error on the side of protecting the environment. This code will help hydro plants reduce or eliminate energy expenditures for aeration.
Many high-head hydropower dams are going through the relicensing process. The spillways for these dams were designed without consideration for total dissolved gas concentrations downstream. Since that time, strict TDG regulation (110%) has been imposed upon the water resources the hydro-plant uses, and owners are struggling to meet these regulations. These dams generate the majority of hydropower in the USA, and the inability to meet regulations could have serious consequences for the energy potential of these facilities. A unified CFD code to predict gas transfer at both low head and high head spillways without calibration to field data is currently needed and desired by the industry.
Hydropower generates enough electricity to meet the needs of about 35 million residential customers.