Technical Report No. SRH-2010-22 SRH Model Applications and Progress Report on Bank Erosion and Turbidity Current Models Conducted under Appendix No. 8 to the Agreement between American Institute in Taiwan (AIT) and Taipei Economic and Cultural Representative Office (TECRO) for Technical Assistance and Cooperation for Water Resources U.S. Department of the Interior Bureau of Reclamation Technical Service Center Denver, Colorado February 2011 Mission Statements The mission of the Department of the Interior is to protect and provide access to our Nation’s natural and cultural heritage and honor our trust responsibilities to Indian Tribes and our commitments to island communities. The mission of the Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public. Cover Figure: Looking upstream at the Chi-Chi Weir (photo taken in November, 2009) SRH Model Applications and Progress Report on Bank Erosion and Turbidity Current Models Conducted under Appendix No. 8 to the Agreement between American Institute in Taiwan (AIT) and Taipei Economic and Cultural Representative Office (TECRO) for Technical Assistance and Cooperation for Water Resources Report Prepared by: Yong G. Lai, Ph.D., Hydraulic Engineer Sedimentation and River Hydraulics Group, Technical Service Center Blair P. Greimann, P.E., Ph.D., Hydraulic Engineer Sedimentation and River Hydraulics Group, Technical Service Center U.S. Department of the Interior Bureau of Reclamation Technical Service Center Denver, Colorado Peer Review Certification: This document has been peer reviewed per guidelines established by the Technical Service Center and is believed to be in accordance with the service agreement and standards of the profession. Questions concerning this report should be addressed to Timothy Randle, Group Manager of the Sedimentation and River Hydraulics Group (86-68240) at 303-445-2557. PREPARED BY: _____________________________________ DATE:________________ Yong Lai, Ph.D. Hydraulic Engineer Sedimentation and River Hydraulics Group (86-68240) _____________________________________ DATE:________________ Blair Greimann, Ph.D., P.E. Hydraulic Engineer Sedimentation and River Hydraulics Group (86-68240) PEER REVIEWED BY: _____________________________________ DATE:________________ Jennifer Bountry, M.S., P.E. Hydraulic Engineer Sedimentation and River Hydraulics Group (86-68240) Table of Contents Page Executive Summary .............................................................................................. 1 1 Introduction ............................................................................................... 6 2 SRH-1D Modeling Study of Tachia River .............................................. 8 2.1 Background ........................................................................................... 8 2.2 Modeling Overview .............................................................................. 8 2.3 Input data .............................................................................................. 9 2.3.1 Model Parameters .......................................................................... 9 2.3.2 Upstream Boundary Conditions .................................................. 10 2.3.3 Downstream Boundary Conditions ............................................. 13 2.3.4 Internal Boundary Conditions ..................................................... 13 2.3.5 Lateral Inflows ............................................................................ 14 2.3.6 Channel Geometry and Flow Characteristics .............................. 15 2.3.7 Sediment Model Parameters ........................................................ 18 2.3.8 Upstream Sediment Boundary Conditions .................................. 18 2.3.9 Lateral Sediment Discharge ........................................................ 18 2.3.10 Sediment Bed Material ............................................................ 18 2.3.11 Water Temperature .................................................................. 20 2.3.12 Erosion and Deposition Limits ................................................ 20 2.3.13 Sediment Transport Parameters ............................................... 23 2.3.14 Cohesive Sediment Transport Parameters ............................... 24 2.3.15 Bedrock Geometry and Parameters ......................................... 24 2.4 2000 to 2005 Simulation Results ........................................................ 30 2.5 Sensitivity Study ................................................................................. 46 2.5.1 Reference Shear Stress ................................................................ 46 2.5.2 Active Layer Thickness ............................................................... 47 2.5.3 Transport Formula ....................................................................... 47 2.5.4 Manning Roughness Coefficient ................................................. 48 2.5.5 Minimization ............................................................................... 49 2.5.6 Bed Sub-layer Transfer ............................................................... 50 2.5.7 Hiding/Exposure Coefficient ....................................................... 51 2.6 2005 to 2008 Results ........................................................................... 53 2.7 Future Predictions ............................................................................... 55 2.8 Modeling Summary ............................................................................ 55 3 SRH-2D Application to Chosui River ................................................... 57 3.1 Description of the Engineering Scheme Simulated ............................ 57 3.2 Numerical Model Details .................................................................... 59 3.2.1 Solution Domain and Mesh Generation ...................................... 60 3.2.2 Bathymetric and Topographic Data ............................................ 61 3.2.3 Representation of Flow Roughness and Bed Gradation.............. 64 3.2.4 Boundary Conditions................................................................... 67 3.2.5 Other Model Parameters .............................................................. 69 3.3 Model Results ..................................................................................... 70 3.4 Summary ............................................................................................. 75 i 4 Bank Erosion Modeling – A Progress Report ...................................... 77 4.1 Introduction ......................................................................................... 77 4.2 Bank Erosion Processes ...................................................................... 77 4.2.1 Hydraulic Fluvial Processes ........................................................ 78 4.2.2 Mass Failure Processes ................................................................ 79 4.3 Important Factors Associated with Bank Erosion .............................. 83 4.4 Bank Erosion Model Review .............................................................. 86 4.4.1 Empirical Models ........................................................................ 86 4.4.2 Process-based Models ................................................................. 88 4.4.3 Summary ..................................................................................... 91 4.5 Proposed Bank Erosion Models .......................................................... 91 4.5.1 A General Discussion of Basal Erosion ...................................... 92 4.5.2 Non-Cohesive Bank Model ......................................................... 93 4.5.3 Cohesive Bank Model ................................................................. 96 4.5.4 BSTEM Technical Description ................................................... 96 4.6 Progress of Non-Cohesive Model Development .............................. 111 4.7 Progress of Cohesive Model Development ....................................... 117 5 Turbidity Current Modeling – A Progress Report ............................ 118 5.1 Background ....................................................................................... 118 5.2 Plunge Point Determination .............................................................. 118 5.3 Governing Equations ........................................................................ 122 5.4 Numerical Methods ........................................................................... 125 5.5 Preliminary Case Study Results ........................................................ 130 5.5.1 Unsteady Modeling with SRH-2D ............................................ 130 5.5.2 A Numerical Issue Associated with the Turbidity Current Numerical Method .................................................................................. 137 5.5.3 Simulation of Turbidity Currents in the Laboratory Setting ..... 139 5.6 Potential Model Limitations ............................................................. 147 6 References .............................................................................................. 148 ii Index of Figures Page Figure 1. Flows used in simulations from January 2000 to October 2005. .......... 11 Figure 2. Simulated flows for the period November 2005 to October 2008. ....... 11 Figure 3. Peak flows at given years near Shih-Gang Dam (Water Resources Agency,