WSP02347

• File Number: 8102
• Description: Arkansas River Basin Basic Hydrology
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 5/7/1999
• Author: Inter-Fluve Inc
• Title: Fluvial Geomorphic Assessment of Upper Arkansas River - Final Report
• Water Supply Pro - Doc Type: Report/Study

May 7, 1999

Fluvial Geomorphological Assessment
Upper Arkansas River

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Table of Contents (continued)

6.3,3. Channel Migration Rates and Cutoffs.......,.,..............................................." 41
6.4. Effective Discharge and Morphologic Change..................................................... 41
6.5. Geomorphic Evolution.... ............. ................ ""'''''''''''''''''''''' ....... ............,.. '"'''''' 43

7. Hydraulics and Sediment Transport.......,...................................................................47

7.1. Site Selection ........................................................................................................ 47
7.2. Hydrologic Influence on Sediment Transport...................................................... 48

7.2.1. Event Discharges .......................................................................................... 48
7.2.2. In-Channel Discharges.... .... .....,.......,..... "'"'' ....... ............ ......... .......... "'''''''' 53

7.3, Hydraulic Analysis.......... ................ ........... .......... ......... ... ...... ..... ............ .............. 54
7.3 .1. Methods.......................................................................".....................,.......... 54
7.3.2. Model Construction and Calibration.............................................,............... 55
7.3.3, Hydraulic Modeling Results......................................................................... 57
7.4. Incipient Motion Analysis............................................................,........................65
7.4.1. Determination of the Dimensionless Shield's Parameter ............................. 66
7.4,2. Reach Average Incipient Motion Results and Analysis ............................... 67

7.5. Conclusions,... ..........,..... .... ",,"'''''''''''''''''''''''' ........ ..............,.... ......... ......... ........ 74

8. Channel Stability and Potential for Erosion or Exposure of Mine Waste .................75
8.1. Floodplain/Terrace Configurations.......................................................................75
8.2. Subreach 1: Upstream of California Gulch (RM 10.9-12) ................................... 76
8.3. Subreach 2: California Gulch to Lake Fork (RM 9.2-10.9)................................, 76
8.4. Subreach 3: Lake Fork to Railroad Bridge (RM 7.0-9.2)..................................... 79
8.5. Subreach 4: Railroad Bridge to Hwy 24 Bridge (RM 5.5-7.0)............................ 81
8.6. Subreach 5: Hwy 24 Bridge to Big Union Creek (RM 3.3-5.5).......................... 82
8,7. Subreach 6: Big Union Creek to Hwy 55 Bridge (RM 2.1-3.3).......................... 86
8.8. Subreach 7: Hwy 55 Bridge to bedrock constriction (RM 0-2.1)........................ 89

9. Process-Based Treatment Alternatives ......................................................................91
9.1. Tailings Entrainment Processes ............................................................................ 91
9.2, Alternatives Development ...,................................................................................ 91

9.2.1. Bank Protection............................................................................,................ 92
9.2,2, Migration Corridor.. ..... ........... ..... ........ ....... ......... '"'''''''''' .............. ..... ......... 92
9.2.3, Alternative 3: Compound Channel............................................................... 95
9.2.4. Relocation of Perched Channel Threads....................................................... 99
9.2.5. Channel Relocation ........ ....,.. ........ .......... ..... ......... .............. ""'" ................... 99
9.2.6. Modification of Floodplain Topography.................................................... 100
9,2.7, Modification of Augmentation Patterns.......,.............................................. 100
9.2.8. Floodplain Bankline Vegetation Enhancement .......................................... 100
9,2,9. Grazing System Modifications ...................................................................100
9.3. Subreach-based conceptual treatments ...............................................................103

9.3.1. Subreach 1 ................................................................................................... 103
9.3 ,2. Sub reach 2............. ... "'''''''''''''''' ..... ................... ""'"'' ....... ..... ........ ............ 103
9.3.3. Subreach 3.. .....,.,.. "'"'''''''' .......... ............... ......... ............ ............................ 103
9.3.4, Subreach 4............. .... ........ ................... ...,. ..... """'" ......... .... ...... ................. 103
9.3.5. Subreach 5 ................................................................................................... 104
9.3 .6. Sub reach 6............... .......... ...... ....... ........ ............. .......... ...... ....... ........... ...... 104

9.3.7. Subreach 7 ................................................................................................... 104