Tate McAlpin

Efficient Implicit Finite-Element Hydrodynamic Model for Dam and Levee Breach

This technical paper presents the development and application of a pseudo-transient continuation (PTC)– inspired flow model for the simulation of dam and levee failure. The unstructured, implicit, Petrov-Galerkin finite-element model relies on computed residuals to automatically adjust the time-step size. The implicit time integration, together with the automatic time-step size selection through PTC, makes the model computationally efficient. The model is verified and applied to several analytic and real-world test cases that exercise model behavior and accuracy for several critical, transcritical, and subcritical flows. The result is an efficient and accurate prediction of both the speed and depth of shock waves as the dam-break flow passes over initially dry and wet land.

Hydrodynamics of Knik Arm: Modeling Study

An adaptive hydraulics (AdH) model was applied to lower Knik Arm near the Port of Anchorage, Alaska, to assess its ability to model a macrotidal system with complex hydrodynamics, including the formation and evolution of numerous gyres that are prominent at this site. Lower Knik Arm is an ideal system for this model evaluation because of the large tide range (approximately 10 m at Anchorage) and complex geometry of the system, which results in high velocities and the formation of numerous eddies throughout the study area. One eddy of primary importance is the one generated by Cairn Point, which occurs near the Port of Anchorage. Limitations of previous modeling studies and the availability of recent field data enabled this evaluation. The AdH results were compared with field data (water surface elevations, fluxes, and velocities) collected in August of 2002 and 2006, and favorable comparisons obtained for tidal amplification and eddy generation indicate that AdH reasonably reproduces the complex hydrodynamic conditions in lower Knik Arm. Simulations were also performed to investigate the importance of eddy viscosity specification, frictional specification, and bathymetry on the generation/evolution of eddies present in the system. Upon completion of the model validation, simulations were performed with modified Cairn Point configurations to investigate the impact to the eddy generated at the port. These results illustrate the variation in eddy generation through lengthening, lowering/reducing, or raising Cairn Point.

Removing Systemic Bias in Bed-Load Transport Measurements in Large Sand-Bed Rivers

AbstractBed-load sediment transport is important yet difficult to measure in large, sand-bed rivers. Prior work established in theory and validated in a flume study a method known as integrated section surface difference over time version 2 (ISSDOTv2), which computes bed-load transport using sequential three dimensional (3D) bathymetric profiles. The same work identified a source of systemic error leading to an underprediction of computed transport rates. This paper demonstrates how the systemic error can be removed from ISSDOTv2 calculations to produce a more accurate dune transport value. This is demonstrated by analytic and geometric examples, and with field data from the Missouri River at Kansas City. The results of these analyses indicate that field data do exhibit the systematic error and that it is possible to extrapolate a corrected dune bed-load transport rate from field data obtained at different measurement intervals. Additionally, error bounds on this corrected value can be set. Independent va...

Refinement Indicator for Dynamic-Mesh Adaption in Three-Dimensional Shallow-Water Equation Modeling

AbstractOne of the basic articles of discretization-based numerical modeling of three-dimensional shallow water equations is the spatial convergence of the mesh utilized. The process of creating a ...

Tidal Hydrodynamics in the Lower Columbia River Estuary through Depth Averaged Adaptive Hydraulics Modeling

The adaptive hydraulics (AdH) numerical code was applied to study tidal propagation in the Lower Columbia River (LCR) estuary. The results demonstrate the readiness of this AdH model towards the further study of hydrodynamics in the LCR. The AdH model accurately replicated behavior of the tide as it propagated upstream into the LCR system. Results show that the MSf tidal component and the M4 overtidal component are generated in the middle LCR and contain a substantial amount of tidal energy. An analysis was performed to determine the causes of MSf tide amplification, and it was found that approximately 80% of the amplification occurs due to nonlinear interaction between the M2 and the S2 tidal components.

Two-Dimensional Hydraulics and Sediment Transport Modeling of the Racetrack Reach of the Mississippi River, 1965–1969

This report documents the development, calibration, and validation of a numerical model for the Racetrack Reach of the Mississippi River between the Vicksburg, MS, Interstate-20 Bridge and approximately 12 miles downstream conducted for the U.S. Army Corps of Engineers, Mississippi Valley Division, Vicksburg, MS. The investigation was conducted via a combination of historical field data collection and numerical modeling of the hydraulics and sediment transport. The objectives were to model flow conditions and sediment transport from 1965 through 1969 and compare to historical surveys from 1965 and 1969 on the Mississippi River. A detailed Adaptive Hydraulics model was developed for this reach of the river. The model domain extends from 10 miles upstream of the Mississippi River Bridge in Vicksburg, MS, to 24 miles downstream of the bridge and adjacent portions of the Mississippi River and its floodplain. Unsteady flow simulations were evaluated for the time from 1965 through 1969. For this particular model application, the Wright-Parker suspended sediment entrainment function and the Meyer Peter Mueller with Wong Parker Correction bed-load entrainment function results best replicated the depositional/erosion patterns and magnitudes. The choice of hiding factor did not have a noticeable impact on the results. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. MRG&P Report No. 20 iii

Mississippi River : Natchez to Baton Rouge Hydraulic and Sediment Transport Model

This report documents the development, calibration, and validation of a hydraulic and sediment transport model of the Mississippi River between Natchez, MS, and Baton Rouge, LA, conducted for the U.S. Army Corps of Engineers, Mississippi Valley Division, Vicksburg, MS, using the Coastal and Hydraulics Laboratory-developed Adaptive Hydraulics numerical code. The numerical model adequately replicates the water levels observed in the field including a wide range of conditions from an extreme flood (Flood of 2011) to an extreme drought (2012). With the inclusion of the Old River Control Complex and Morganza Control Structure, this model is available to evaluate alternative operational procedures and associated relative water level impacts between these two structures for both normal and extreme flow conditions. This study further advanced the goal of the Mississippi River and Tributaries program in terms of developing numerical models to analyze the Lower Mississippi River in terms of shortand long-term impacts to the system. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. MRG&P Report No. 19 iii

Modeling Flap Gate Culverts in Adaptive Hydraulics (AdH)

PURPOSE: This Coastal and Hydraulics Engineering Technical Note (CHETN) describes the methodology and implementation of flap gate culverts in the 2-D Shallow Water (SW2D) version of Adaptive Hydraulics (AdH). See Figure 2 for an example of this type of structure. This technical note will outline how to calculate the culvert coefficient (K) for flap gate culverts for use in AdH and present a test case detailing the implementation of the structure into AdH input files. A synopsis of the test case results is also presented.

Bed-load and water surface measurements during the 2011 Mississippi River Flood at Vicksburg, Mississippi

The U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, Field Data Collection and Analysis Branch collected bathymetry data and water surface elevations during the 2011 Flood. According to the gage at Vicksburg, MS, the flood peaked at a stage of 57.1 and a flow of 2,310,000 cubic feet per second (cfs) on 17 May 2011, both the highest of record. The reported water surface data include a continuous water surface profile from river mile (RM) 597 to RM 362 and water surface measurements in the vicinity of the Yazoo Backwater levee and Vicksburg, MS. Bathymetry data were also collected and include five sets of surveys, compatible with the Integrated Section Surface Difference over Time Version 2 (ISSDOTv2) method of measuring bed-load transport. These five sets were surveyed at flow rates between 1.6 million and 2.3 million cfs. ISSDOTv2 was used to calculate bed-load transport for the five sets of data. These new bed-load data populate the Lower Mississippi River bed-load rating curve at higher flows and provide a higher level of confidence in the higher-flow portions of the curve. The resulting curve can be a powerful tool for inferring past bed-load transport and predicting future transport. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. MRG&P Report No. 18 iii

Formulation, implementation and testing of the Diffusive Wave (DW) module of Adaptive Hydraulics (AdH)

MOTIVATION AND BACKGROUND: Numerical simulation of inundation has been an integral part of flooding analysis since the advent of modern computing. These simulations have historically been performed using the Shallow Water Equations (SWE) in two dimensions (2D) due to the accuracy of results obtained. However, the solution of 2D-SWE can impose run-time constraints because of the computational intensity required (Prestininzi 2008); therefore, in general, 2D-SWE are of reduced use for problems where inundation results are required in a time-sensitive manner. In such instances, the computational efficiency and stability afforded by DW equations are of benefit.