City of Lincoln
Watershed Stormwater Master Plans

Little Salt Creek

Little Salt Creek Watershed Master Plan

Table of Contents

Cover Page, Cover Letter and Signature Page (415 K)

Table of Contents (29 K)

Executive Summary (577 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

• 1.3.1 Open House Events
• 1.3.2 Citizen Advisory Committee
• 1.3.3 Website and Newsletter

1.4 Technical Advisory Committee

Section 2 – Data Collection and Development (423 K)

2.1 Watershed Inventory

2.2 Hydraulic Structure Field Survey

2.3 Base Mapping/Triangular Irregular Network

2.4 Geomorphic Investigation

• 2.4.1 Geomorphic Background Investigation
• 2.4.2 Geomorphic Field Investigation
• 2.4.3 Supplemental Geomorphic Aerial Photo Analysis

2.5 Soil Assessment

• 2.5.1 Methodology
• 2.5.2 Dispersive Soils
• 2.5.3 Saline Seeps
• 2.5.4 Summary and Recommendations

2.6 Existing Projects and Conservation Easements

Section 3 – Hydrologic Model Development (1.44 M)

3.1 Introduction

• 3.1.1 Basin Description

3.2 Methodology

• 3.2.1 Incorporation of Previous Little Salt Creek Model
• 3.2.2 Basin Delineation
• 3.2.3 Rainfall
• 3.2.4 Runoff Volume Calculation
• 3.2.5 Runoff Hydrographs (Lag Time)
• 3.2.6 Routing

3.3 Model Verification

• 3.3.1 Statistical Analysis of Stream Gage Data

3.4 Sensitivity Analysis

3.5 Model Calibration

• 3.5.1 Historical Storm Event Calibration

3.6 Modeling Results

3.7 Future Land Use

• 3.7.1 Calculation of Existing and Future Curve Numbers
• 3.7.2 Calculation of Changes to Initial Storage
• 3.7.3 Guidelines for Modifying the Hydrologic Model Initial Storage to Account for Future Land Use Changes
• 3.7.4 Modifying the Hydrologic Model Lag Time to Account for Future Land Use Changes

Section 4 – Hydraulic Model Development (1.08 M)

4.1 Introduction

4.2 HEC-RAS Model Development

• 4.2.1 Stream Network, Cross Sections, and Reach Lengths
• 4.2.2 Manning's n-Values
• 4.2.3 Roadway Crossings
• 4.2.4 Expansion and Contraction Coefficients
• 4.2.5 Ineffective Flow Areas
• 4.2.6 Boundary Conditions

4.3 Special Modeling Cases

• 4.3.1 Split Flow Locations
• 4.3.2 Multiple Structure Analysis
• 4.3.3 Roadway Skew Analysis

4.4 Model Calibration

4.5 Floodway Determination

Section 5 – Floodplain Management Tools (3.22 M)

5.1 Introduction

• 5.1.1 Floodplain Delineation Process
• 5.1.2 Study Floodplain and Floodway Maps

Section 6 – Water Quality and Bio-Assessment (615 K)

6.1 Water Quality

• 6.1.1 Water Quality Discussion

6.2 Stream Bio-Assessment

• 6.2.1 Stream Bio-Assessment Results

6.3 Water Quality • Bio-Assessment Summary

6.4 Water Quality Future Land Use Hydrology

• 6.4.1 Hydrology Modeling of Future Land Use
• 6.4.2 Low Flow Analysis

Section 7 – Drainage Criteria and Ordinance Review (92 K)

7.1 Introduction

7.2 Water Quality BMPs

• 7.2.1 Integrated Detention Facility
• 7.2.2 Alternative Site Design

7.3 Dispersive Soils

7.4 Conservation Culvert or Crossing

7.5 Adopt Revised Floodprone Area as Best Available Information

Section 8 – Geomorphic Evaluation (898 K)

8.1 Fundamentals of Fluvial Geomorphology

• 8.1.1 Major Models
• 8.1.2 Temporal and Spatial Implications
• 8.1.3 Sediment Transport

8.2 Little Salt Creek Evaluation

• 8.2.1 Channel Geometry
• 8.2.2 Boundary Material
• 8.2.3 Hydraulics
• 8.2.4 Sediment Transport Competency

8.3 Physical Stability of the Watershed

• 8.3.1 Existing Channel Process

8.4 Methods of Management

• 8.4.1 Watershed-Scale Stability
• 8.4.2 Local Stability
• 8.4.3 Conclusions

Section 9 – Capital Improvement Projects (1.71 M)

9.1 Introduction

9.2 Capital Improvement Projects

• 9.2.1 Problem Identification
• 9.2.2 Evaluation Approach
• 9.2.3 Stream Stability Projects

9.3 Other Improvement Recommendations

• 9.3.1 Problem Identification
• 9.3.2 Project Evaluation Approach

9.4 Prioritization

Section 10 – Implementation (42 K)

10.1 Introduction

10.2 Implementation of Capital Improvements

10.3 Policy and Ordinances

10.4 Education Program

10.5 Project Funding

10.6 Coordination Efforts

10.7 Additional Studies • Future Master Planning Scoping

• 10.7.1 Additional Studies Summary
• 10.7.2 Phase II Scoping

Section 11 – Glossary of Terms and References (54 K)

11.1 Glossary of Terms

11.2 References

Appendices

Appendix A - Digital Deliverables

Appendix B - Pubic Participation Materials (4.58 M)

Appendix C - Hydrologic Model Input Data and Results (647 K)

Appendix D - Hydraulic Model Input Data and Results (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)

Related Links

• Little Salt Creek Master Plan Study