Browsing by Author "Thornton, Christopher, advisor"
Now showing 1 - 10 of 10
Results Per Page
Sort Options
Item Open Access Air concentration and bulked flow along a curved, converging stepped chute(Colorado State University. Libraries, 2020) Biethman, Blake W., author; Ettema, Robert, advisor; Thornton, Christopher, advisor; Wohl, Ellen, committee memberThis thesis focuses on the air-entrainment performance of a stepped spillway of unique form. The performance was determined using a hydraulic model constructed at a length scale (prototype length/model length) of 24. The new stepped spillway is part of the Gross Reservoir Expansion (GRE) project, which by 2025 is expected to raise the existing Gross Dam about a third of its current height. The stepped spillway will be the tallest stepped spillway in the United States. The model spillway consisted of a chute whose step dimensions, vertical to horizontal, were 0.051 m by 0.025 m, resulting in a chute slope (V:H) of 2.0 and a chute angle of 63.4°. Additionally, the chute conformed, in planform, to the curved planform of raised Gross Dam. At the spillway's crest, that radius of curvature, at model scale, was 22.2 m. The chute width converged by about 20% from the top of the chute to the stilling basin at the base of the chute. The chute's steepness, height, curvature and convergence made the chute's geometry unique among existing stepped spillways. The evaluation involved measurements of air entrainment and flow velocity along the stepped chute, for which the skimming flow regime prevailed for discharge larger than about 9% of the spillway's design discharge. To date, the effect on water flow and air entrainment of chute curvature in stepped spillways had not been investigated. The investigation was facilitated from measurements obtained using a dual-tip conductivity probe, which detected the instantaneous void fraction of the air-water mixture. The probe also enabled measurement of the velocity of the bulked flow along the chute. The study showed that, when the chute conveyed the design discharge (at model scale, 0.347 m3/s), streamwise values of air concentration and flow depth (bulked with entrained air) were basically constant near the bottom of the chute. Additionally, the chute's planform curvature resulted in non-uniform flow across the chute. At the design discharge, and near the bottom of the chute, the flow depth along the chute's centerline was nominally about 30% greater than the flow depth at the sidewall. When the chute's curvature was accounted for, the water surface along the centerline of the chute was approximately level with the water surface near the sidewall. Further, the depth-averaged concentration of entrained air near the bottom of the chute decreased with increasing water discharge. The chute's converging sidewalls mildly affected the flow near the sidewalls, causing slight increases in flow depth and reductions in flow velocity. These changes, though noticeable, were negligible in terms of spillway performance because of their magnitude.Item Open Access Analysis of riprap design methods using predictive equations for maximum and average velocities at the tips of transverse in-stream structures(Colorado State University. Libraries, 2014) Parker, Thomas Richard, author; Thornton, Christopher, advisor; Abt, Steven, advisor; Williams, John, committee memberTransverse in-stream structures are used to enhance navigation, improve flood control, and reduce stream bank erosion. These structures are defined as elongated obstructions having one end along the bank of a channel and the other projecting into the channel center and offer protection of erodible banks by deflecting flow from the bank to the channel center. Redirection of the flow moves erosive forces away from the bank, which enhances bank stability. The design, effectiveness, and performance of transverse in-stream structures have not been well documented, but recent efforts have begun to study the flow fields and profiles around and over transverse in-stream structures. It is essential for channel flow characteristics to be quantified and correlated to geometric structure parameters in order for proposed in-stream structure designs to perform effectively. Areas adjacent to the tips of in-stream transverse structures are particularly susceptible to strong approach flows, and an increase in shear stress can cause instability in the in-stream structure. As a result, the tips of the structures are a major focus in design and must be protected. Riprap size is a significant component of the design and stability of transverse in-stream structures, and guidance is needed to select the appropriate size such that the structure remains stable throughout its design life. The U.S. Bureau of Reclamation contracted the Engineering Research Center at Colorado State University to construct an undistorted 1:12 Froude scale, fixed bed, physical model of two channel bend geometries that are characteristic of a reach of the Rio Grande River south of the Cochiti Dam in central New Mexico. A series of factors including the construction of the Cochiti Dam and control levees has caused the historically braided river to meander and become more sinuous. Bank erosion threatens farmlands, irrigation systems, levee function, aquatic habitat, and riparian vegetation. The purpose of the model was to determine the effectiveness of in-stream structures in diffusing the magnitude of forces related to bank erosion. Multiple configurations of transverse in-stream structures with varying x, y, and z parameters were installed in the model, and velocity and shear stress data were collected. A series of twenty-two different configurations of transverse in-stream structures were tested. An analysis of the average and maximum velocities at the tips of the transverse in-stream structures was performed. Utilizing a channel bend approach velocity, average and maximum velocity ratios were calculated using physical model data. A set of dimensionless parameters consisting of influential structure design parameters was organized and arranged for regression analysis. Predictive equations were developed that describe the ratios of maximum and average velocity at the tips of the in-stream structures to bend-averaged velocities. The predictive equations for maximum and average velocity ratios function as a first approximation of in-stream structure riprap design for configurations that are within the range of tested data. Velocity data were used to assess the suitability of current riprap sizing techniques for transverse in-stream structures. Bank revetment design methodologies were found to be dependable methods for in-stream structure riprap design. Methodologies developed by the United States Army Corps (USACE) and the United States Bureau of Reclamation (USBR) were recommended for the sizing of riprap for in-stream structures. Velocity adjustment procedures were created for use in the USACE and USBR methods. The velocity adjustment procedures include a velocity factor for the determination of a riprap sizing design velocity. The riprap sizing design velocity produces a conservative riprap size for bank revetment, but an appropriate riprap size for in-stream transverse structures. Two velocity factors are provided: one for natural channels and the one for uniform, trapezoidal channels. Limitations and recommendations of the proposed tip velocity ratios and riprap sizing techniques are provided.Item Open Access Baffle-post structures for flow control in open channels(Colorado State University. Libraries, 2015) Ubing, Caroline, author; Thornton, Christopher, advisor; Ettema, Robert, advisor; Bledsoe, Brian, committee member; Wohl, Ellen, committee memberThis thesis presents theory and laboratory findings regarding the hydraulic performance of baffle-post structures used as a means for controlling flow in open channels. Such structures comprise one to two parallel rows of posts that extend slightly higher than the anticipated depth of flow, and offer a useful means for retarding flow in various channel situations where there is a need to reduce flow energy, possibly to reduce flow capacity to transport bed sediment and manage channel morphology. Observations and data regarding headloss and discharge coefficients and backwater flow profiles associated with varying structure geometry were obtained so as to determine the extent to which a baffle-post structure will retard an approach flow and reduces its capacity to convey bed sediment. The creation of a M₁ gradually varied flow profile in the upstream reach complicates the use of headloss to characterize hydraulic performance of the baffle-post structures. Instead, the parameter, y₁/y₀, offers a practical means for describing such performance; y₁= flow depth at the upstream face of the structure, and y₀= the depth of uniform flow prior to use of a structure. The most influential geometric variable was influencing structure performance was the lateral spacing between posts, s; it is expressed non-dimensionally as s/D, where D = post diameter. Qualitative results regarding sediment transport confirm a reduction in bed-sediment transport rate upstream of the structure. However, the turbulent flow structures at the baffle-post structures promote local scour at the base of such structures. Due to the flow acceleration between posts, baffle-posts structures could potentially obstruct fish and other aquatic life passage along the channel.Item Open Access Estimating interstitial discharge and velocity in flow in riprap and gabion engineering applications(Colorado State University. Libraries, 2019) Keene, Anthony, author; Thornton, Christopher, advisor; Scalia, Joseph, advisor; Williams, John, committee memberInterstitial flow is a difficult hydraulic process to measure and predict. Interstitial flow does not follow the same laws as seepage flow in small-grain media (i.e. Darcy's Law), because flow regimes in aggregate rock are often transitional or turbulent at a mild slope. Flow paths and local velocities in open cavities of a rock layer are dynamic, and instrumentation is difficult to place in rock for physical measurement. Due to the dynamic and complicated nature of interstitial flow, limited tools are available for engineering flow through aggregate rock. Flow in aggregate rock is relevant to many hydraulic engineering applications, including riprap and gabions used in designs for drainage, earth retention, and rockfill structures. Riprap and gabion published design guidelines are derived from external flow conditions and often neglect interstitial flow. Discharge in rock directly influences internal forces that can transport loose rock or strain a gabion mattress structure, interstitial velocity also directly influences bed shear stress. However, despite the importance of interstitial velocity and discharge for design, riprap and gabion design guidelines are developed primarily for rock stability. There is a need for interstitial discharge as design criteria; estimating the discharge capacity of aggregate rock can be useful in applications where drainage for a design flow is relevant. Data from laboratory prototype gabion mattress tests are used in tandem with data collected in a previous study on riprap to develop two simple design equations to predict interstitial velocity and interstitial discharge per unit area of a rock layer. A multivariate nonlinear regression was performed as a function of the following key parameters in a rock system: rock size for which 50% of rock is finer than, D₅₀, rock size for which 10% of rock is finer than, D₁₀, coefficient of uniformity (D₆₀/D₁₀), acceleration due to gravity, and bed slope. The regressions yield a coefficient of determination of 0.97 for both interstitial velocity and interstitial discharge predictive equations. Equations are suited for use in rock layers with nominal sizes from ¼-in to 5-in on bed slopes up to 0.15 ft/ft.Item Open Access Flow resistance corrections for physical models using unit flowrates(Colorado State University. Libraries, 2024) Cote, Cassidy B., author; Thornton, Christopher, advisor; Ettema, Robert, committee member; Rathburn, Sara, committee memberFlow resistance is an essential aspect of evaluating flow behavior in open-channel hydraulic models. Flow resistance in open channels is commonly characterized by Manning's resistance equation, where a value of Manning's roughness coefficient n, indicates the magnitude of flow resistance. Physical hydraulic models are one method to estimate Manning's n values for prototype channel reaches. A physical hydraulic model evaluates prototype channel characteristics at the model scale. The scale for a given physical model may be characterized by length-scale factor, given by the relationship of prototype to model geometry. Models that have a large length-scale factor are known to introduce errors associated with instrumentation, measurement, and scale effects, therefore minimization of the length-scale factor is an important consideration in the development of hydraulic models. Evaluating physical models using a scaled unit flowrate provides a method by which the length-scale factor may be minimized. In this way, a scaled design discharge per unit width of channel is applied to a channel that is less wide than the prototype design. Using this approach greatly improves the ability of laboratories to utilize available facilities, without being constrained by prototype design width, which can otherwise be a driving factor increasing the length-scale factor for a given model. This thesis documents the construction and analysis of two physical models of a proposed rectangular canal along Rio Puerto Nuevo in San Juan, Puerto Rico. One model used a scaled unit flowrate and a reduced channel width at a lesser length-scale factor, and the other model accommodated the total scaled design flowrate and design channel width at a larger-scale factor. Tests were conducted for three sidewall conditions to identify the impact associated with applying a unit flowrate physical modeling approach for models with different Manning's n values specific to the sidewalls. The unit flowrate approach was found to result in larger estimates of flow depth and composite Manning's n compared to the model that accommodated the full prototype channel width. Insights regarding the variability of Manning's n as a function of channel width for each sidewall condition were identified by comparing results from the two models. A correction method was proposed for improving estimates of Manning's n derived from scaled unit flowrate models. Correction factors were identified as a function of two dimensionless parameters, relative prototype channel width (defined as the ratio of the width evaluated using a unit flowrate model to the design width of the channel), and relative flow resistance exerted by the individual boundary elements as determined from the unit flow rate model (defined as the ratio of Manning's n values between the sidewall and channel bed boundary elements). Findings indicate that it becomes increasingly important to apply correction factors to flow resistance estimates on unit flowrate models when wall boundary elements exert a larger contribution to flow resistance than that of the channel bed (large relative roughness), and when the scaled unit flowrate approach results in a prototype channel width that is significantly smaller than the proposed design channel width (small relative channel width). Correction factors were developed for a range of relative channel width values from approximately 0.4 to 1.0, and a range of relative roughness values from approximately 0.5 to 3.0. Future physical models using unit flowrates with relative channel widths and relative flow resistance within the range evaluated may use the presented correction methods to improve estimates of flow resistance.Item Open Access Frequency of pressure fluctuations in the stilling basin for the spillway of raised Gross Dam, Colorado(Colorado State University. Libraries, 2021) Tasdelen, Selina, author; Ettema, Robert, advisor; Thornton, Christopher, advisor; Little, Ann M., committee memberGross Dam, Colorado, was constructed in 1954 to provide potable water to the city of Denver, Colorado. The location of Gross Dam is in Boulder County, Colorado. The dam itself is a high, curved concrete gravity-arch dam that retains Gross Reservoir, a reservoir capacity that of volume 51,573, 109.1 cubic meter. The Gross Reservoir Expansion (GRE) Project will increase the height of the Gross Dam from 39.93 m to an ultimate height of 143.56 m by 2025, thereby creating more storage behind the Gross Dam. The new stepped spillway required for GRE will be the highest stepped spillway in the U.S. Besides the height of the spillway, the steepness, the length, and the curved form of the chute will make the spillway stand out. This study focused on (1) determining how roller-rotation frequency varied with water discharge for the full range of the discharges expected for the spillway, (2) determining the main frequencies in the pressure fluctuations at selected locations along the stilling basin, and (3) relating frequency fluctuations of measured pressure to frequencies of features evident in the flow field too and through the stilling basin. This effort involved assessing the influence of flow discharge on the rotation frequency of a major roller formed immediately upstream of the row of baffle blocks for each discharge. The experimental investigation carried out at the Hydraulics Laboratory of Colorado State University, Engineering Research Center, for the current Gross Dam. The frequency of the rotation of the roller formed immediately upstream of the row of the baffle blocks determined approximately from the observation for every flow rate. The mean value of the rotation frequency of the roller formed for the PMF-equivalent discharge down the hydraulic model of the spillway (0.348 m3/s) was 2.45 Hz or 0.5 Hz at prototype scale. The plot of the roller-rotation frequency versus discharge showed that there was a proportional relationship between the rotation frequency and the discharge. The dynamic pressures were measured with the use of four pressure sensors which were positioned in front of the floor, behind the floor, at the face of the baffle block, and the behind the baffle block. The sampling rate of these sensors was 2,500 Hz. The maximum pressure (prototype scale) recorded at the front face of the baffle block when the model-scale flowrate was equivalent to the 1.0 PMF was 59.78 kPa. Low-pass filter applied to the original signal of pressures, and the pressure signal was filtered out at frequencies above 200 Hz (model scale). The cut off frequency of the filtered signal was chosen 200 Hz, as flow oscillations would not occur at this frequency. Then, Fast Fourier Transform (FFT) method was applied to both original and filtered signal. The result showed that filtered FFT gave about the same result as the FFT from the unfiltered data and there was no continuous low frequency or continuous high frequency pattern, indicating that the pressure signals oscillated irregularly, as did the roller formed in the front of the stilling basin. Therefore, FFT could not find the dominant frequency in the signal. The largest peak frequencies at prototype scale for the upstream floor, front face of the baffle block, downstream face of the baffle block, and downstream floor of the stilling basin were 0.496, 1.15, 1.396, and 1.544 Hz, respectively.Item Open Access Hydraulic efficiency of grate and curb inlets for urban storm drainage(Colorado State University. Libraries, 2010) Comport, Brendan, author; Thornton, Christopher, advisor; Kampf, Stephanie, committee member; Roesner, Larry, committee memberStormwater runoff from an urban landscape is typically conveyed through networks comprised of streets, gutters, inlets, storm sewer pipes, and treatment facilities. Objectives of this research program included evaluating the hydraulic efficiency of three storm-drain inlet types and developing design methodology. Denver Type 13 and 16 grate inlets and Colorado Department of Transportation Type R curb inlet were evaluated during the course of testing. Grate inlets were tested in a grate-only and combination inlet configuration. A one-third Froude scale model was constructed to permit testing longitudinal slopes from 0.5 to 4 %, cross slopes from 1 to 2 %, prototype depths from 0.333 to 1 ft, and prototype inlet lengths from 3.3 to 15 ft. A total of 318 tests were performed for the various configurations. Inlets tested are currently used by the Urban Drainage and Flood Control District (UDFCD), and have never been tested or studied in a manner such that an efficiency relationship is known. Efficiency is defined in this study as the percentage of total street flow removed by an inlet design. Current design practices are typically based upon “Hydraulic Engineering Circular 22” (HEC 22), which addresses the use of other inlet types, but it does not provide guidance specific to the three inlets tested. Need for this study arose from general uncertainty in matching inlets used by the UDFCD to methods presented in HEC 22. This uncertainty in design relates to sizing inlets and in determining the level of flood protection afforded by their use. After examining the collected test data, dimensional analysis was conducted on influencing variables and regression techniques were used to develop new equations for prediction of inlet efficiency. In addition, HEC 22 methods were modified to include the three inlets tested. Street flow was observed to be often supercritical and non-uniform, with efficiency highly dependent upon flow velocity and inlet length. For a given inlet length, the combination inlets were found to perform most efficiently. Inlet efficiencies computed from the developed empirical equations and modified HEC 22 methods were compared to the collected test data and current HEC 22 methods. When compared to prototype data for typical design flow depths of 0.5 to 1 ft, the empirical equations showed accuracy to within 9% efficiency error for the combination inlets which is a 30% improvement over current HEC 22 methods. All methods for the type R inlet showed similar results at 0.5 and 1 ft depths, with differences up to 15 % occurring at the lowest depth of 0.333 ft. Furthermore, details of the testing and analysis were presented and suggestions for further research were made.Item Open Access Live-bed failure modes of bendway weirs and rock vanes in alluvial channels(Colorado State University. Libraries, 2022) Maddocks, Parker, author; Ettema, Robert, advisor; Thornton, Christopher, advisor; Wohl, Ellen, committee memberBendway weirs and rock vanes have been used and refined for decades to control thalweg location and alignment along alluvial channel-bends and decrease flow velocity along the outer bank of such channels. Since the early 2000s, Colorado State University's Hydraulics Lab has assisted the U.S. Bureau of Reclamation (USBR) in refining design guidelines for bendway weirs, rock vanes, and other in-stream rock structures. This effort has entailed optimizing the layout of configurations of bendway weirs and rock vanes. The present study, however, focuses on the failure modes of bendway weirs and rock vanes, and led to the development of refinements to the design recommendations for individual bendway weirs and rock vanes so that such structures can perform as intended, even though the structures have encountered scour. Live-bed conditions were selected for the experiments, as such conditions involve active bed-sediment transport and, thereby, pose more severe conditions than do clear-water conditions in which little bed-sediment transport occurs. To investigate live-bed failure modes at bendway weirs and rock vanes, two flumes were used: a straight flume and a curved flume. The experiments used different parameters suggested in technical literature as documents as affecting bendway-weir and rock-vane performance (e.g., structure geometry, spacing, flow condition, and angle relative to a channel's outer bank). The straight flume was chosen for its capacity to create the constrained flow conditions needed to illuminate the failure modes, which then were verified using the curved flume, which was wider and subject to the effects of flow curvature. Each experiment involved a series of three bendway weirs or rock vanes. Preliminary experiments indicated that three structures were needed, because of observed differences in the failure modes at the three structures in a series. Experimental results revealed that failure modes of bendway weirs and rock vanes were primarily driven by rock dislodgement due to contraction scour at the tip of such structures, and by dune-trough presence at the upstream face (the first rock structure) and flow impingement (against the second rock structure). Also, flow swept some rock from the crest of bendway weirs and rock vanes. The observed failure modes in the straight flume were confirmed by the experiments using the curved flume, though the curved flume's curvature of flow and greater width partially obscured the failure modes. The failure modes led to refinements regarding the design recommendations for the structure of bendway weirs and rock vanes. The recommendations essentially specify the widening and lengthening of the crest of bendway weirs and rock vanes, so that these rock structures may experience controlled failure to accommodate scour but preserve their main dimensions.Item Open Access Live-bed failure modes of bendway weirs and rock vanes in alluvial channels(Colorado State University. Libraries, 2022) Wittmershaus, Alex, author; Ettema, Robert, advisor; Thornton, Christopher, advisor; Kampf, Stephanie, committee memberBendway weirs and rock vanes are instream rock structures primarily used for managing the alignment of a channel's thalweg. Built from rock, bendway weirs and rock vanes are intended to function by directing flow away from a channel's outer bank and thereby reducing flow velocity along the outer bank. The present study investigated how bendway weirs and rock vanes placed in curved, alluvial channels subject to live-bed flow conditions (active bed-sediment transport) may fail. Further, the experiments then sought to recommend design dimensions so that bendway weirs and rock vanes accommodate failure (and loss of rock), thereby enabling them to continue performing as intended. A curved flume was constructed in Colorado State University's Hydraulics Laboratory to conduct experiments that illuminated the failure modes and to confirm (or modify) preliminary design recommendations obtained from experiments using a straight flume fitted with three bendway weirs or rock vanes. The curved flume experiments involved a series of six bendway weirs or rock vanes and used a hydrograph procedure to simulate the rising limb of a hydrograph of flow along a medium sized river like the Middle Rio Grande; the proportions of the flume were like selected bends in that river. Six bendway weirs or rock vanes were needed to direct flow around the curved flume, as opposed to the need for three bendway weirs or rock vanes in the experiments in the straight flume. Two sizes of non-uniform bed sediment also were used (a medium sand and very coarse sand) for the experiments. The two sands were used to see if bed sediment size affected the failure modes. The experimental results showed that bendway weirs and rock vanes experienced rock dislodgement primarily via contraction scour, which undermines the end, or tip, of these instream structures. Destabilized rock then tumbles into the scour zone along the channel's shifted thalweg, armoring the bed. This observation was observed for both the beds comprised of medium sand and very coarse sand. As flow depth increased above the mean elevation of the bendway weirs or rock vanes, contraction of flow reduced as more flow passed over the structures. The flow field at each bendway weir or rock vane changed. The hydrograph procedure yielded similar changes in bed bathymetry for beds of medium sand and very coarse sand over the rising limb of the hydrograph. When (Δy+H)/H = 0.75, a deep scour hole formed in between the first two structures in the configuration within about 15 minutes. Then, when (Δy+H)/H = 1.25, the scour hole was partially filled with sediment and extended downstream largely along the series of bendway weirs or rock vanes. Further, when (Δy+H)/H = 2.0, the scour hole was again partially filled with sediment, but scour extended along the entire configuration of bendway weirs or rock vanes, thereby delineating a defined thalweg. As the flow depth increased, the maximum scour depth along the thalweg decreased for the experiments. The bendway weirs and rock vanes experienced structural deformation due to rock dislodgement primarily from contraction scour. Less rock dislodgement occurred for these instream structures placed on the medium sand than when on the very coarse sand. Also, the rock vanes experienced less rock dislodgement than did the bendway weirs in general. This finding is attributed to upwards slope of the crest of rock vanes; the sloped crest directed more flow around each rock vane and over the already armored bed. The results from using the hydrograph procedure in a curved flume confirmed the preliminary design recommendations from the straight flume. The design recommendations required that bendway weirs or rock vanes be lengthened by 2d100 and their crests be widened by d100; here d100 is the diameter of the largest rock used to build bendway weirs or rock vanes. This lengthening and widening accounts for the shortening and narrowing of bendway weirs or rock vanes subject to scour. A prior study recommended the size of rock chosen in design to form bendway weirs or rock vanes.Item Open Access The effects of bend radius on flow around a configuration of bendway weirs: insight from a numerical model(Colorado State University. Libraries, 2019) Hogan, Taylor, author; Thornton, Christopher, advisor; Ettema, Robert, advisor; Williams, John, committee memberBendway weirs have been used and refined for decades by hydraulic engineers to control thalweg location within alluvial rivers and to decrease flow velocity along the outer bank of channel bends. Although these structures have been used in a variety of applications, there are still a wide range of acceptable design parameters that vary in accordance with the specific design methodology being used. Since the early 2000s, Colorado State University's Hydraulics Lab has assisted The U.S Bureau of Reclamation (USBR) in refining the design of bendway weirs and similar in-stream rock structures. During this period of time, Colorado State University and The USBR have utilized hydraulic and numerical models to develop systematic design guidelines for bendway weirs and other in-stream rock structures. Hydraulic modeling has also provided a large database of velocity and water surface measurements that have been used to calibrate and validate subsequent numerical models. The partnership between Colorado State University and the USBR has led to design recommendations and equations in which the effect of many variables and their sensitivity in overall bendway weir design has been identified. This study investigates the parameter radius of curvature over channel top width, Rc/Tw, and its effect on the flow field around bendway weirs, as its significance in bendway weir design is not well known. To investigate the effects of Rc/Tw on the bendway weir flow field, the 2D numerical model SRH-2D was used in conjunction with AutoCAD Civil3D software. The SRH-2D model was created using the bathymetry of the hydraulic model and then also calibrated and validated using data collected in the hydraulic model. AutoCAD Civil3D was used to create four different bend radii while holding Tw constant, representing Rc/Tw values between 3.0 and 8.0 which are typical of the Middle Rio Grande that the hydraulic model represented. Two additional trapezoidal channel models were also created to isolate the possible effects from specific channel geometry on the bendway weir flow field comparisons. 2D numerical modeling results revealed that the bend radius of curvature had negligible effect on the bendway weir flow field. Velocity patterns in the trapezoidal and native bathymetry channels changed negligibly in location and magnitude across varying bend radii. Cross-sectional velocity distributions were also evaluated and showed that the inner and middle third lateral sections of the channel showed the same (within fractions of a percent) velocity increase after the installation of bendway weirs. The outer fifth of the channel resulted in 6% velocity decrease only varying approximately 0.1% between bend radii. Overall numerical modeling results showed that the bendway weir flow field was negligibly affected by the bend radius of curvature, Rc.