Little Salt Creek Watershed Master Plan
June 2009
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Cover and Table of Contents (443 M)
Executive Summary (615 K)
Section 1 – Introduction and Purpose (388 K)
- 1.1 Introduction
- 1.2 Goals and Objectives
- 1.2.1 Goals and Criteria
- 1.2.2 Watershed Inventory
- 1.2.3 Hydrology and Hydraulics
- 1.2.4 Water Quality
- 1.2.5 Geomorphic
- 1.2.6 Soil Assessment
- 1.2.7 Structures
- 1.2.8 Public Involvement & Facilitation
- 1.2.9 Capital Improvement Projects
- 1.2.10 Potential Guidelines/Ordinances
- 1.2.11 Technical Advisory Committee (TAC)
- 1.3 Public Participation Process
- 1.4 Technical Advisory Committee
Section 2 – Data Collection and Development (424 K)
Section 3 – Hydrologic Model Development (1.44 M)
Section 4 – Hydraulic Model Development (1.08 M)
Section 8 – Geomorphic Evaluation (899 K)
Section 10 – Implementation (42 K)
Appendices
- Appendix A - Digital Deliverables
- Appendix B - Public Participation Materials (Summary Documents, Attendance Lists, Minutes, Watershed News) (4.58 M)
- Appendix C - Hydrologic Model Input Data and Results (647 K)
- Appendix D - Hydraulic Model Input Data and Res (134 K)
- Appendix E - Aerial Photograph Interpretation (725 K)
- Appendix F - Hydraulic Structure Survey and Design Data (1.02 M)
- Appendix G - Geomorphic Data Summary By Reach (83 K)
- Appendix H - Soil Assessment Data (490 K)
- Appendix I - Watershed Inventory Data Table (16 K)
- Appendix J - Capital Improvement Project Prioritization Ranking Worksheets (163 K)
- Appendix K - Capital Improvement Project Cost Worksheets (75 K)
- Appendix L - Other Improvement Recommendations (580 K)
- Appendix M - Stream Profiles (5.46 M)
- Appendix N - Hydraulic Structure Performance Data (36 K)
- Appendix O - Water Quality and Bio-Assessment Reports (1.54 M)
- Appendix P - Groundwater Seep Survey Data (1.04 M)
Figures
- ES-1 Comprehensive Watershed Master Plan
- ES-2 Little Salt Creek Watershed Map
- ES-3 Little Salt Creek Floodplain Map Updates
- ES-4 Little Salt Creek Capital Improvement Project Location Map
- 1-1 Comprehensive Watershed Master Plan
- 1-2 Little Salt Creek Watershed Map
- 1-3 Project Organization Chart
- 1-4 Information stations at the public meetings
- 1-5 April 2008 Issue
- 1-6 Website information
- 2-1 North 1st Street Bridge
- 2-2 Concrete box culvert under Waverly Road
- 2-3 Little Salt Creek Hydraulic Structures Survey Map
- 2-4 Little Salt Creek Soil Boring Location Map
- 2-5 Little Salt Creek Dispersive Clays Location Map
- 2-6 Little Salt Creek Existing Project Locations Map
- 3-1 Little Salt Creek Watershed Map
- 3-2 Little Salt Creek Study Area Comparison
- 3-3 Little Salt Creek Subbasin Delineation Map
- 3-4 Little Salt Creek Existing Land Use
- 3-5 Little Salt Creek Hydrologic Soil Groups
- 3-6 Graphical Depiction of the Peak Flood Flow Frequency Analysis
- 3-7 Graphical Depiction of the Volume-Duration-Frequency Analysis
- 3-8 Little Salt Creek USGS Gauge Location
- 3-9 HEC-HMS calibration results compared versus the USGS gauge data
- 3-10 HEC-HMS calibration results (shifted) compared versus the USGS gauge data
- 3-11 Little Salt Creek HMS Results Locations Map
- 3-12 Little Salt Creek Future Land Use
- 4-1 Little Salt Creek Hydraulically Modeled Streams
- 4-2 thru 4-5 Little Salt Creek Split Flow Locations Map
- 4-6 thru 4-9 Little Salt Creek Multiple Structures Location Map
- 4-10 Comparison of HEC-RAS Model Output with the Rating Curve Provided by the USGS
- 5-1 thru 5-13 Little Salt Creek Floodplain Map Updates
- 6-1 Little Salt Creek Water Quality and Bio-Assessment Sampling Locations Map
- 6-2 Total Dissolved Solids Results
- 6-3 Total Suspended Solids Results
- 6-4 Rock Creek Road sample site facing upstream
- 6-5 Arbor sample site facing upstream
- 6-6 Weibull analysis of Little Salt Creek average daily flows at N 27th St and Arbor Rd
- 6-7 Little Salt Creek location of Flow Results
- 6-8 0.5" runoff event resultant hydrographs of existing and future conditions scenarios at Location 1
- 6-9 0.5" runoff event resultant hydrographs of existing and future conditions scenarios at Location 1(first 6 hours of runoff)
- 6-10 0.5" runoff event resultant hydrographs of existing and future conditions scenarios at Location 2
- 6-11 0.5" runoff event resultant hydrographs of existing and future conditions scenarios at Location 2 (first 6 hours of runoff)
- 6-12 0.5" runoff event resultant hydrographs of existing and future conditions scenarios at Location 3
- 6-13 0.5" runoff event resultant hydrographs of existing and future conditions scenarios at Location 4
- 6-14 0.5" runoff event resultant hydrographs of existing and future conditions scenarios at Location 5
- 6-15 0.5" runoff event resultant hydrographs of existing and future conditions scenarios at Location 6
- 7-1 Conservation culvert example
- 8-1 Lane's Stable Channel Balance
- 8-2 Dynamic equilibrium channel on the mainstem of Little Salt Creek
- 8-3 Incised V-shaped channel on Tributary 220
- 8-4 Deposition on Little Salt Creek Mainstem at W. Davey Road culvert
- 8-5 Channel Evolution Model (from Simon, 2001)
- 8-6 Meander Formation and Migration
- 8-7 Meander geometry
- 8-8 Little Salt Creek Hydraulic Gradient Map
- 8-9 Erodibility vs. 2-yr Hydraulic Gradient Graph
- 8-10 Stages of a river system (adapted from Rienick and Singh, 1980)
- 8-11 General channel profile of a watershed
- 8-12 Effect of dam resetting the stream formation sequence
- 8-13 Effect of stream crossings resetting the stream formation sequences
- 8-14 Hydrograph and Sedigraph
- 8-15 Little Salt Creek Observed Groundwater Seeps Map
- 8-16 Little Salt Creek Groundwater Seep Survey Locations
- 8-17 Little Salt Creek Existing Channel Process
- 9-1 Projected incision of Little Salt Creek between Raymond Rd and Bluff Rd
- 9-2 Little Salt Creek Capital Improvement Project Location Map
- 9-3 Rock Grade Control Structure Detail
- 9-4 Sheet Pile Grade Control Structure Detail
- 9-5 Stilling Basin Structure Detail
- 9-6 Waverly Road Bridge over Main Stem
- 9-7 Project 1 Proposed Improvements
- 9-8 North 14th Street Bridge over Main Stem
- 9-9 Project 2 Proposed Improvements
- 9-10 Mill Road Bridge over Main Stem
- 9-11 Project 3 Proposed Improvements
- 9-12 North 1st Street Bridge over Main Stem
- 9-13 Project 4 Proposed Improvements
- 9-14 W Raymond Road Bridge over Main Stem
- 9-15 Project 5 Proposed Improvements
- 9-16 NW 12th Street Bridge over Main Stem
- 9-17 Project 6 Proposed Improvements
- 9-18 W Branched Oak Road Bridge over Main Stem
- 9-19 Project 7 Proposed Improvements
- 9-20 North 19th Street Bridge over Main Stem
- 9-21 Project 8 Proposed Improvements
- 9-22 W Rock Creek Road Bridge over Main Stem
- 9-23 Project 9 Proposed Improvements
- 9-24 W Agnew Road Bridge over Main Stem
- 9-25 Project 10 Proposed Improvements
- 9-26 North 40th Street Culvert on Tributary 10
- 9-27 Project 11 Proposed Improvements
- 9-28 North 40th Street Culvert on Tributary 110
- 9-29 Project 12 Proposed Improvements
- 9-30 North 40th Street Culvert on Tributary 220
- 9-31 Project 13 Proposed Improvements
- 9-32 Waverly Road Culvert on Tributary 35
- 9-33 Project 14 Proposed Improvements
- 9-34 North 1st Street Culvert on Tributary 30
- 9-35 Project 15 Proposed Improvements
- 9-36 Oak Road Culvert on Tributary 45
- 9-37 Project 16 Proposed Improvements
- 9-38 W Davey Road Culvert on Tributary 1260
- 9-39 Project 17 Proposed Improvements
- 9-40 Davey Road Culvert on Tributary 260
- 9-41 Project 18 Proposed Improvements
- 9-42 Little Salt Creek Hydraulic Structures Survey Map
Tables
- ES.1 Capital Improvement Project Summary Results
- 2.1 Geomorphic Field Data Themes
- 3.1 Rainfall depths corresponding to each return period (note 500-yr depth is interpolated)
- 3.2 Lookup table used to define the curve number for each land use-soil group combination
- 3.3 Constant loss rates as defined by Skaggs and Khaleel (1982)
- 3.4 Results of the peak flood flow frequency analysis
- 3.5 Results of the volume-duration-frequency analysis
- 3.6 Comparison of peak flows resulting from modifications to each basin's initial loss parameter
- 3.7 Comparison of cumulative volumes resulting from modifications to each basin's initial loss parameter
- 3.8 HEC-HMS model results compared to the flood flow frequency analysis
- 3.9 HEC-HMS model results compared to the volume-duration-frequency analysis
- 3.10 HEC-HMS model resultant peak flows for the 2-, 5-, and 10-yr return periods
- 3.11 HEC-HMS model resultant peak flows for the 50-, 100-, and 500-yr return periods
- 3.12 HEC-HMS model resultant cumulative volumes for the 2-, 5-, and 10-yr return periods
- 3.13 HEC-HMS model resultant cumulative volumes for the 50-, 100-, and 500-yr return periods
- 3.14 Lookup table used to define the curve number for each land use-soil group combination
- 3.15 Breakdown of future land uses applied to agricultural lands within Tier 2
- 3.16 Calculated increases in imperviousness for the Tier 1 future land use scenario
- 3.17 Calculated increases in imperviousness for the Tier 2 future land use scenario
- 3.18 Guideline for modifying subbasin initial storage depth based on change in curve number
- 3.19 Look up table for the lag time multiplying factor due to changes in curve number (future CNs ranging from 62-80)
- 3.20 Look up table for the lag time multiplying factor due to changes in curve number (future CNs ranging from 81-98)
- 4.1 HEC-RAS Model Data Sets
- 4.2 Range of Manning's n-values utilized
- 4.3 Contraction and expansion coefficients utilized
- 4.4 Frequencies for coincidental occurrence based upon the ratio of watershed sizes
- 4.5 Assigned boundary condition stages for the Little Salt Creek
- 4.6 Locations and frequencies of the split flows
- 4.7 Locations and frequencies of multiple opening analysis
- 4.8 HEC-RAS model output at the gauge location
- 5.1 Little Salt Creek Confluence Level Pool Elevations (NAVD88)
- 6.1 Nebraska ICI Rating by Sample Site
- 6.2 Comparison of peak flows under existing and future conditions for the 0.5" runoff event
- 6.3 Comparison of total volumes under existing and future conditions for the 0.5" runoff event
- 6.4 Comparison of volumes within the first six hours of runoff under existing and future conditions for the 0.5" runoff event
- 8.1 Hydraulic Slope and Fluvial Geomorphic Process
- 9.1 Bridge and Culvert Topping
- 9.2 Capital Improvement Project Summary Results