U.S. Army Corps of Engineers, Omaha District In Association with Nebraska Silver Jackets PROJECT COMPLETION REPORT Regulated Flood Frequency Analysis for the North Platte River at North Platte, NE Contract W9128F-13-T-0011 Prepared by Riverside Technology, inc. October 14th, 2013 TABLE OF CONTENTS Table of Contents 1 Executive Summary ............................................................................................................ 1-1 2 Data Collection .................................................................................................................... 2-1 2.1 Climatology Data ........................................................................................................................ 2-1 2.2 Streamflow Data ........................................................................................................................ 2-1 2.3 Diversion Data ............................................................................................................................ 2-2 2.4 Reservoir Data ............................................................................................................................ 2-3 2.4.1 Time Series Data ................................................................................................................ 2-3 2.4.2 Operational Data ................................................................................................................ 2-4 2.5 Model Data ................................................................................................................................ 2-5 3 Unregulated Flow Frequency Computation..................................................................... 3-1 3.1 Basin Modeling ........................................................................................................................... 3-1 3.2 Flow Frequency Analysis ............................................................................................................ 3-1 3.2.1 Procedure ........................................................................................................................... 3-1 3.2.2 Results ................................................................................................................................ 3-4 4 Regulation modeling ........................................................................................................... 4-1 4.1 Seminoe Reservoir ..................................................................................................................... 4-1 4.1.1 Modeling Approach ............................................................................................................ 4-1 4.1.2 Modeling Results ................................................................................................................ 4-2 4.2 Pathfinder Reservoir .................................................................................................................. 4-3 4.2.1 Modeling Approach ............................................................................................................ 4-4 4.2.2 Modeling Results ................................................................................................................ 4-4 4.3 Alcova Reservoir ......................................................................................................................... 4-5 4.3.1 Modeling Approach ............................................................................................................ 4-5 4.3.2 Modeling Results ................................................................................................................ 4-5 4.4 Glendo and Guernsey Reservoirs ............................................................................................... 4-6 4.4.1 Modeling Approach ............................................................................................................ 4-7 4.4.2 Modeling Results ................................................................................................................ 4-8 4.5 Wheatland Reservoir ................................................................................................................. 4-9 4.5.1 Modeling Approach ............................................................................................................ 4-9 4.6 Grayrocks Reservoir ................................................................................................................. 4-10 4.6.1 Modeling Approach .......................................................................................................... 4-10 4.6.2 Modeling Results .............................................................................................................. 4-10 4.7 Lake McConaughy .................................................................................................................... 4-11 4.7.1 Modeling Approach .......................................................................................................... 4-12 4.7.2 Modeling Results .............................................................................................................. 4-13 5 Regulated flow frequency computations .......................................................................... 5-1 5.1 Procedure ................................................................................................................................... 5-1 5.2 Results ........................................................................................................................................ 5-1 6 Summary ............................................................................................................................. 6-1 7 References ............................................................................................................................ 7-1 Appendix A Associated File Descriptions ........................................................................... A-1 Appendix B HEC-SSP DSS Data Description .................................................................... B-1 Appendix C Unregulated Flow Frequency Plots ............................................................... C-1 Appendix D Reservoir Modeling Rules .............................................................................. D-1 i TABLE OF CONTENTS Appendix E Regulated Flow Frequency Plots ................................................................... E-1 Appendix F Tables of Annual Peaks ................................................................................... F-1 Table of Figures Figure 1-1. North Platte Watershed ........................................................................................................... 1-2 Figure 3-1. Instantaneous flow analysis results for North Platte .............................................................. 3-6 Figure 3-2. Volume-duration-frequency analysis results for North Platte. ............................................... 3-9 Figure 4-1. Simulation results for Seminoe Reservoir RES-J model ........................................................... 4-3 Figure 4-2. Simulation results for Pathfinder Reservoir RES-J model ........................................................ 4-4 Figure 4-3. Simulation results for Alcova Reservoir RES-J model .............................................................. 4-6 Figure 4-4. Simulation results for Glendo Reservoir RES-J model ............................................................. 4-8 Figure 4-5. Simulation results for Guernsey Reservoir RES-J model .......................................................... 4-9 Figure 4-6. Simulation results for Grayrocks Reservoir RES-J model ....................................................... 4-11 Figure 4-7. Lake McConaughy ResSim model display .............................................................................. 4-12 Figure 4-8. Simulation results for Lake McConaughy ResSim model ....................................................... 4-14 Figure 5-1. Regulated vs. unregulated peaks for North Platte .................................................................. 5-2 Figure 5-2. Regulated peaks at North Platte vs. probability ...................................................................... 5-3 Figure 5-3. Regulated flow vs. probability for North Platte, rank ordered ................................................ 5-4 Figure 5-4. Regulated flow frequency curves for all durations at North Platte ......................................... 5-5 Figure 5-5. Regulated flow frequency curves for instantaneous peaks at all locations ............................ 5-6 Figure C-1. Bulletin 17B plot for Mitchell ................................................................................................... C-1 Figure C-2. Bulletin 17B plot for Minatare ................................................................................................. C-2 Figure C-3. Bulletin 17B plot for Bridgeport .............................................................................................. C-3 Figure C-4. Bulletin 17B plot for Lisco ........................................................................................................ C-4 Figure C-5. Bulletin 17B plot for Lewellen ................................................................................................. C-5 Figure C-6. Bulletin 17B plot for Keystone ................................................................................................