National Academies Press: OpenBook

Guidance for Design Hydrology for Stream Restoration and Channel Stability (2017)

Chapter: Chapter 4 - User Guidance for the CSR Tool

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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
×
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
×
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
×
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
×
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
×
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
×
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
×
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
×
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
×
Page 39
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
×
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Suggested Citation:"Chapter 4 - User Guidance for the CSR Tool." National Academies of Sciences, Engineering, and Medicine. 2017. Guidance for Design Hydrology for Stream Restoration and Channel Stability. Washington, DC: The National Academies Press. doi: 10.17226/24879.
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28 C h a p t e r 4 This chapter provides step-by-step guidance for each tab in the CSR Tool workbook. Chapter 5 provides two examples of running the program (one sand-bed and one gravel-bed stream). For more detailed information on the hydrologic and hydraulic theory, and code methodology behind the tool, refer to the CSR Tool Reference Manual [Appendix D of the final report for NCHRP 24-40, down- loadable from the NCHRP Research Report 853 summary page on the TRB website (www.trb.org)]. The numbered steps in this chapter correlate to the numbers overlaid onto referenced screenshots of the CSR Tool tabs. Figure 4-1 shows a decision tree on selecting tabs to use and the order in which to use them to produce stable channel design solutions. The path in the decision table is determined by selec- tions on the “Startup” tab that refer to the type of river and hydrologic information. 4.1 Startup Tab This tab was created as a platform to set up a new project and define the project type to run the program. The following will give a step-by-step guide to setting up a new project to run the pro- gram. Figure 4-2 shows a screenshot of the “Startup” tab pointing out the areas on the sheet that are needed for each step in starting a new project. Step 1. Enter Project Info Summary (Optional) The first step is to enter the project information summary in the area provided (Figure 4-2). This is optional and solely for the user’s reference and will not be used to run the program. Step 2. Define Project Type The selections made in this step define variables in the program, equations, and inputs needed to perform the CSR analysis. The appropriate tabs required for the specified project type will be automatically unhidden in the workbook. This allows the user to easily follow the order as presented in Figure 4-3 to run the program and view the results. The variables selected will be displayed underneath the “Select” button for reference. Stream Type Press the “Select” button under “Stream Type” to define the stream type of interest for the project. The two choices are “Sand” or “Gravel/Cobble.” This distinction is used to constrain the type of sediment transport equations used in the analysis. Sand-bed streams commonly use User Guidance for the CSR Tool

User Guidance for the CSr tool 29 “total” load sediment transport equations, while gravel/cobble-bed streams use bedload sedi- ment transport relationships. There is no distinct threshold between these two channel types but rather a continuous spectrum and a mixture of many grain size groups (Montgomery and Buffington 1997). For user reference, Table 4-1 lists the delineation of all grain size groups. In general, the bed material of a sand-bed stream would primarily consist of sand (0.0625 to 2 mm) size particles in the distribution, and a gravel/cobble stream would primarily consist of gravel (2 to 64 mm) and/or cobble (64 to 256 mm) size particles. In other words, the stream would have a D50 within these ranges. More specifically, you can compare your stream’s sediment distribution to the sediment distributions used to derive the sediment transport equations that are available in the tool. These values are listed in the first row for each equation in Table 4-2. Comparing sediment distribution to Table 4-2 is the most accurate and appropriate way to ensure the integrity of the sediment transport equation output and the resulting design solutions. **Using the equations outside of the range used to develop them can produce unstable/erroneous solutions from the CSR Tool.** Startup Quick Reference Guide Hydrology Grain Size Distribution Supply Reach Design Reach Results Detailed Results Supply Reach Design Reach Results Detailed Results Hydrology FDC Grain Size Distribution Supply Reach Design Reach Results Detailed Results Supply Reach Design Reach Results Detailed Results Gravel Bed Sand Bed Sand Bed Gravel Bed Flow Record Pre-existing FDC Figure 4-1. Decision tree for the tab order and usage in the CSR Tool.

30 Guidelines for Design hydrology for Stream restoration and Channel Stability Transport Relationship Press the “Select” button under “Transport Relationship” to define the sediment transport equation that will be used to carry out the CSR analysis for the project (Figure 4-2). If “Sand” was selected for the stream type, then the Brownlie (1981) total load sediment trans- port equation will be automatically selected. This transport equation was developed to estimate the sediment transported in sand-bed channels. Refer to Table 4-2 for the boundaries Brownlie (1981) listed in his publication for developing this equation. This is the same equation that is 1 3 2 Figure 4-2. Screenshot of “Startup” tab with areas delineated for Steps 1 through 3. Figure 4-3. Decision tree for Step 2 (define project type) of the “Startup” tab.

User Guidance for the CSr tool 31 used for the Copeland method of stable channel design in the Hydrologic Engineering Center’s River Analysis System (HEC-RAS). If “Gravel/Cobble” was selected for the stream type, then there will be two choices under “Transport Relationship.” The Parker (1990) and Wilcock-Crowe (2003) sediment transport equations are bedload equations developed for gravel/cobble-bed streams. Refer to Table 4-2 to review the boundaries listed by the authors in developing these transport relationships. The Equation Variable Minimum Maximum Brownlie (1981) D50 [mm] 0.088 2.8 Unit discharge [m3/s/m] 0.012 40.0 Discharge [m3/s] 0.0032 22,000.0 Slope 0.000003 0.037 Hydraulic radius [m] 0.025 17.0 Temperature [°C] 0 63.0 Width/depth ratio ≥ 4.0 ≥ 4.0 Geometric standard deviation of particles sizes, σg ≤ 5.0 ≤ 5.0 Parker (1990) Gravel-sized particles [mm] 2.0 203.0 Sand-sized particles [mm] sand removed sand removed Sand in mixture [%] 3.3 (surface) 13 (subsurface) Wilcock-Crowe (2003) Gravel-sized particles [mm] 2.0 64.0 Sand-sized particles [mm] 0.5 2.0 Sand in mixture [%] 6.2 34.3 Depth [m] 0.09 0.12 Table 4-2. Boundaries of sediment transport equations used in tool. Bed Material Class Name Particle Diameter [mm] Boulder Very Large >2,048 Large >1,024 Medium >512 Small >256 Cobble Large >128 Small >64 Gravel Very Coarse >32 Coarse >16 Medium >8 Fine >4 Very Fine >2 Sand Very Coarse >1 Coarse >0.5 Medium >0.25 Fine >0.125 Very Fine >0.0625 Silt Coarse >0.031 Medium >0.016 Fine >0.008 Very Fine >0.004 Clay Coarse >0.002 Medium >0.001 Fine >0.0005 Very Fine >0.00024 Table 4-1. Grain size class delineations.

32 Guidelines for Design hydrology for Stream restoration and Channel Stability Parker (1990) equation is a well-respected bedload equation for streams that is recommended when the grain size distribution consists of primarily gravel/cobble particles and less than 3% to 5% sand. This equation will eliminate all sand (<2 mm) fractions in the distribution prior to calculating the bedload. The Wilcock-Crowe (2003) bedload equation is similar to the Parker (1990) equation, but it considers sand fractions in the calculations. This equation is recommended if there is a significant amount of sand (6% to 34%) in the mixture. This equation will take into account the effects on sediment transport of sand in the gravel/cobble mixture. Sand is known to greatly increase the transport of gravel/cobbles if present in the mixture (Wilcock et al. 2001). Hydrology Info Press the “Select” button under “Hydrology Info” to define the source type for the hydrology that will be used in the CSR analysis for the project (Figure 4-2). As stated in the CSR Tool Ref- erence Manual (Appendix D of the final report for NCHRP 24-40), the tool requires a sequence of flows over time for the channel reach of interest in order to perform a magnitude-frequency analysis and calculate the associated effectiveness or total sediment yield. The CSR Tool can derive this from a flow record or a pre-derived FDC. The hydrology information input for the upstream supply reach is assumed to be the same for the design reach downstream. The first selection, “Flow Record,” is for users who have a gaging station flow record represent- ing the flows of the supply and design reach. This is the recommended approach for the most accurate analysis, if the flow record is of significant length (more than 10 to 15 years) and repre- sentative of both the supply and design reach (Biedenharn et al. 2000). The CSR Tool is optimized to accept USGS gage data directly from the record in cubic feet per second (cfs). The program will automatically eliminate any “Ice” if present in the record. If “Flow Record” is selected, the “Hydrology” tab will appear when a new project is made. The second selection, “Pre-existing FDC,” is for users who have a pre-derived FDC to enter rather than a flow record. This feature was added to the program mainly to help with the great limitation of needing an extended flow record for the supply reach, which is often absent. There- fore, this feature should be used when a flow record of significant length is lacking or deemed unrepresentative of the flow regime. The program was optimized for the use of FDCs derived from SWAT-DEG in eRAMS. Further guidance on creating an FDC in ungaged basins can be found in Biedenharn et al. (2000). If “Pre-existing FDC” is selected, then the “Hydrology FDC” tab will appear when a new project is made. Preferred Units This selection is to choose the preferred units of the inputs and outputs of the program. Note: No matter which unit is selected, the grain size must be entered in millimeters and the flow record must be entered in cubic feet per second because these are the most common units for these variables. Step 3. Start New Project The last step on the “Startup” tab is to start a new project. With Steps 1 and 2 complete, press the “Start New Project” button as seen in Figure 4-2. Note: This will eliminate all previous results of the last project that was run. This will also unhide the tabs necessary to complete the analysis, based on the variables defined in Step 2, and highlight the required inputs on the associated cells of each tab.

User Guidance for the CSr tool 33 4.2 Quick Reference Guide Tab The “Quick Reference Guide” tab (Figure 4-4) can be viewed at any time to obtain a visual representation of the main concepts behind the CSR Tool analysis as presented in the CSR Tool Reference Manual (Appendix D of the final report for NCHRP 24-40). There are no required inputs on this tab. 4.3 Hydrology Tab This tab was created to take a flow record and sort it into a specified number of bins to be converted into a probability density function (PDF) of flows to be used in the CSR analysis. The following will give a step-by-step guide on running this tab. Figure 4-5 shows a screenshot of the “Hydrology” tab pointing out the areas on the sheet that are needed for each step. Step 1. Enter Flow Record Information/Tab Guidance Enter the flow record information summary in the area provided and/or press the “Tab Guid- ance” button to access a quick reference on how to run the tab (Figure 4-5). This is optional and solely for the user’s reference and will not be used to run the program. Figure 4-4. “Quick Reference Guide” tab of CSR Tool.

34 Guidelines for Design hydrology for Stream restoration and Channel Stability Step 2. Enter Flow Record This tab is designed to import flow records directly from the USGS database but is also capable of processing flow records from other sources. Select a gaging station for the supply reach of either mean daily flows or 15-minute flows. Long records of 15-minute data may be too large for spread- sheet analysis, although it may be favorable to use. Refer to Rosburg (2015) for further guidance on choosing 15-minute or daily flow data. Enter just the discharge in cubic feet per second from the flow record in Column B under “Enter Flow Record” as seen in Figure 4-5. Step 3. Sort Flow Record The program defaults to 25 arithmetic bins (recommended) to sort the flow record (Biedenharn et al. 2000). You can change this number in the “# of Bins” row. The program will decrease that number until no zero-frequency bins are present. In cases where there is still zero frequency at 10 bins, then the process starts again at 25 bins and combines the discharges above the zero- frequency bin into one. Press the “Sort Flow Record” button to bin the flows for the analysis. Column B will be sorted from lowest to highest flow and formatted. The required hydrology information will automatically be transferred to the “Supply Reach” and “Design Reach” tabs. (This flow record is assumed to be the same for the Supply and Design Reaches.) Review the summary of the sorting under “Sort Flow Record Summary” and the results per bin under “Hydrology.” 3 1 2 Figure 4-5. Screenshot of “Hydrology” tab with areas delineated for Steps 1 through 3.

User Guidance for the CSr tool 35 4.4 Hydrology FDC Tab This tab was created to take a pre-derived FDC and consolidate it into a specified number of bins to be converted into a PDF of flows to be used in the CSR analysis. The following steps guide you in running this tab. Figure 4-6 shows a screenshot of the “Hydrology FDC” tab pointing out the areas on the sheet that are needed for each step. Step 1. Enter FDC Information/Tab Guidance Enter the FDC information summary in the area provided and/or press the “Tab Guidance” button to access a quick reference on how to run the tab (Figure 4-6). This is optional and solely for the user’s reference and will not be used to run the program. Step 2. Enter Flow Duration Curve This tab is optimized to import FDCs generated by the SWAT-DEG Tool in eRAMS. Other sources of FDCs are compatible as well. Enter the FDC of exceedance probability in percent- age (%) versus discharge (cfs) under the corresponding labels in Columns B and C of the tab. This tab’s main purpose is to consolidate a detailed FDC to a condensed FDC of 25 to 50 bins to be used in the CSR analysis. The user can specify the number of bins to be consolidated to 1 2 3 Figure 4-6. Screenshot of “Hydrology FDC” tab with areas delineated for Steps 1 through 3.

36 Guidelines for Design hydrology for Stream restoration and Channel Stability in the “# of Bins” row. The program defaults to 25 bins (recommended) for the CSR analysis (Biedenharn et al. 2000). If the FDC entered is under 50 bins already, then the program simply uses all of the original values rather than sampling. Step 3. Consolidate FDC Press the “Consolidate FDC” button to logarithmically sample the original FDC to the speci- fied number of bins. The required hydrology information will automatically be transferred to the “Supply Reach” and “Design Reach” tabs. (This FDC is assumed to be the same for the supply and design reaches.) 4.5 Grain Size Distribution Tab This tab was created to sort grain size distributions of a gravel/cobble-bed stream type for the CSR analysis. The distributions are sorted to calculate the necessary statistical parameters to be used in the sediment transport calculations. Figure 4-7 shows a screenshot of the “Grain Size Dis- tribution” tab pointing out the areas on the sheet that are needed for each of the following steps. Step 1. Grain Size Sample Information/Tab Guidance You can enter a summary of the “Grain Size Sample Info” in the area provided and/or press the “Tab Guidance” button to access a quick reference on how to run the tab (Figure 4-7). This is optional and solely for the user’s reference and will not be used to run the program. 1 2 3 Figure 4-7. Screenshot of “Grain Size Distribution” tab with areas delineated for Steps 1 through 3.

User Guidance for the CSr tool 37 Step 2. Inputs for Grain Size In Column C of the tab, enter the percentage of bed material that is finer than the grain size class in Column B. If you selected the Parker (1990) transport equation, then no sand size classes (<2 mm) will be considered in the analysis. If you selected the Wilcock-Crowe (2003) transport equation, then all size classes will be considered and you can review the Sand Fraction (%) under “Distribution Summary.” The sediment transport equation development boundaries are sum- marized on the top right of the tab for reference. Step 3. Run Grain Size Press the “Run Grain Size” button to graph the distribution and calculate the distribution percentiles summarized under “Distribution Summary.” The necessary grain size informa- tion for the CSR analysis will automatically be transferred to the “Supply Reach” and “Design Reach” tabs. (This grain size distribution is assumed to be the same for the supply and design reaches.) 4.6 Supply Reach Tab The main purpose of the “Supply Reach” tab is to calculate the incoming sediment load pro- duced by the supply reach entering the design reach of interest for the CSR analysis. The follow- ing steps provide guidance on running this tab. Figure 4-8 shows a screenshot of the “Supply Reach” tab pointing out the areas on the sheet that are needed for each step. Step 1. Tab Guidance You can press the “Tab Guidance” button to access a quick reference on how to run the tab (Figure 4-8). This is optional, solely for the user’s reference, and will not be used to run the program. Step 2. Inputs for Supply Reach Main Channel Enter the main channel dimensions and characteristics of the supply reach in Cells C6 and C11. The bottom width, bank height (bankfull), and bank angle are dimensions of a simplified trapezoid that represents the actual supply reach cross-sectional geometry (see Figure 5-9 for a visual). The channel slope can be simplified as a bed slope with the steady, uniform flow assump- tion but can also be entered more accurately as a water surface slope or friction slope. Right and left banks (n) correspond to the Manning’s n roughness characteristics of each bank. For a sand-bed stream type, the roughness of the bed is calculated within the roughness predictors produced in Brownlie (1983), which accounts for sand-bed forms. For a gravel/cobble stream type, the roughness of the bed is calculated in conjunction with the bedload equations with the Limerinos (1970) equation. Grain Size If the channel type is sand bed, then D16, D50, and D84 are required inputs that you need to specify for the sediment calculations. If the channel type is gravel/cobble, then D16, D50, and D84 are auto- updated from the “Grain Size Distribution” tab. (For both channel types, these values are assumed to be the same for the design reach and automatically transferred to the “Design Reach” tab.)

38 Guidelines for Design hydrology for Stream restoration and Channel Stability Floodplain Enter the floodplain angle and roughness characteristics of the supply reach in Cells C17 and C18. This program models flows that break onto the floodplain as opposed to the Copeland method of HEC-RAS. The roughness and angle specified is assumed to be the same on both sides of the channel. Column I of the results will show if the flow was modeled as overbank (True) or not (False). Step 3. Run Supply Reach Press the “Run Supply Reach” button to run sediment transport calculations for the supply reach. The hydrology results will be auto-updated in Columns F and G. Review the hydraulic output for each bin discharge in Columns H and N and the sediment transport outputs in Col- umns O and Q. The “effectiveness,” or total sediment transported on average in a given year, for each bin discharge will be plotted in the bottom left, and a diagram of the supply reach channel geometry will be shown in the bottom right. The channel geometry diagram is on a generic scale, but all lengths and angles are proportional to each other. 1 3 2 Figure 4-8. Screenshot of “Supply Reach” tab with areas delineated for Steps 1 through 3.

User Guidance for the CSr tool 39 4.7 Design Reach Tab The main purpose of this tab is to define the desired design reach characteristics and set up the CSR analysis to produce stable channel design solutions. The following steps provide guid- ance on running this tab. Figure 4-9 shows a screenshot of the “Design Reach” tab pointing out the areas on the sheet that are needed for each step. Step 1. Tab Guidance You can press the “Tab Guidance” button to access a quick reference on how to run the tab (Figure 4-9). This is optional, solely for the user’s reference, and will not be used to run the program. Step 2. Inputs for Design Reach Main Channel Enter the main channel dimensions and characteristics of the design reach in Cells C6 and C9. The bank height is a bankfull depth that the program needs in order to know when the flow 2 1 3 Figure 4-9. Screenshot of “Design Reach” tab with areas delineated for Steps 1 through 3.

40 Guidelines for Design hydrology for Stream restoration and Channel Stability is overbank. This value can be iterated to find the right value for the design. The bank angle is for a simplified trapezoid that represents the cross-sectional geometry of the design reach (see Figure 5-9 for a visual). Right and left banks (n) correspond to the Manning’s n roughness characteristics of each bank, just like the supply reach. The bottom width and slope inputs are absent because these are the two variables that are varied by the program to find stable channel design solutions (CSR = 1). Grain Size The values for D16, D50, and D84 are auto-updated from previous tabs and assumed to be the same as the values for the supply reach. Floodplain Enter the floodplain angle and roughness characteristics of the design reach in Cells C15 and C16. The program will model overbank flows the same as the supply reach. The roughness and angle specified is assumed to be the same on both sides of the channel. Planform/Valley (Optional) Enter “Planform/Valley” characteristics to include them in the outputs. Entering a valley slope will allow the program to calculate the sinuosity, meander belt width, and channel braiding risk for each stable channel design solution. Setting a maximum belt width and buffer will tell the program to highlight the solutions in red that fall outside of these bounds. Review the “Plan- form Characteristics” subsection of the CSR Tool Reference Manual (Appendix D of the final report for NCHRP 24-40) for a detailed overview of these concepts and Figure 5-9 for a visual representation of the concepts. Program Constraints Enter the program width constraints. The minimum width is defaulted to 1 m or 3 ft to pro- duce the entire “family of solutions” even though it is an impractical solution. Set the maximum width (1.5 to 2 times the supply reach bottom width) to produce a full family of solutions. The program will loop this width range in conjunction with an automated range of slope guesses to find design channels with CSR = 1. Step 3. Run Design Reach Press the “Run CSR Tool” button to produce a family of stable channel width and slope com- binations (Figure 4-9) for the design reach that can pass the incoming sediment load from the supply reach with minimal aggradation or degradation (i.e., CSR = 1). Review the solutions on the “Results” tab and each width/slope combination details on the “Detailed Results” tab. There is a diagram showing the design reach channel dimensions on the “Results” tab. All angles and lengths are proportional except the bottom width is set at a generic length because this value varies for each solution. 4.8 Results Tab The “Results” tab will display the main results of the CSR Tool. This tab will have a plot of the “family of width and slope combinations” the program found that provide continuity of water and sediment (i.e., CSR = 1). These solutions will traditionally take a shape as seen in Figure 4-10. A shape similar to this should be expected for sand-bed channel types and, for gravel/cobble-bed channel types, less curl up at lower widths and a generally flatter curve should be expected.

User Guidance for the CSr tool 41 4.9 Detailed Results Tab The “Detailed Results” tab will display more specific results for each slope and width com- bination from the “Results” page. The far left of the tab displays the discharges per bin used in the analysis and the associated effectiveness for each from the supply reach. These results are displayed for reference to be compared to the bin-by-bin effectiveness of each slope and width solution for the design reach. Furthermore, a table of the sediment percentiles for each slope and width combination is displayed below each effectiveness table. For more information on sediment percentiles, refer to the CSR Tool Reference Manual (Appendix D of the final report for NCHRP 24-40). Figure 4-10. Family of width and slope combinations which provide continuity of water and sediment.

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TRB's National Cooperative Highway Research Program (NCHRP) Research Report 853: Guidance for Design Hydrology for Stream Restoration and Channel Stability provides written guidance and interactive tools to help hydraulic engineers assess the current conditions adjacent to a stream crossing and in the upstream watershed. Specifically, the guidance and tools provide support in assessing the current conditions adjacent to a stream crossing and in the upstream watershed to determine design effort, performing the appropriate hydrological and geomorphic analysis using a set of analytical and analog tools, and designing the channel through the stream crossing for stability and sediment balance.

In addition to the report, users can download the contractor’s final report; the spreadsheet-based Capacity Supply Ratio Stable Channel Design Tool (CSR Tool) for computing analytical channel designs that account for the full spectrum of sediment transporting events; an example of the CSR Tool being used on a sand bed stream (Big Raccoon); and an example of the CSR Tool being used on a gravel/cobble bed stream (Red River).

Disclaimer - This software is offered as is, without warranty or promise of support of any kind either expressed or implied. Under no circumstance will the National Academy of Sciences, Engineering, and Medicine or the Transportation Research Board (collectively "TRB") be liable for any loss or damage caused by the installation or operation of this product. TRB makes no representation or warranty of any kind, expressed or implied, in fact or in law, including without limitation, the warranty of merchantability or the warranty of fitness for a particular purpose, and shall not in any case be liable for any consequential or special damages.

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