10  Level-2 Bankfull Analysis

🟡 Intermediate

The purpose of this SOP is to demonstrate the workflow of fluvial geomorphology (fluvgeo) rapid watershed assessment in ArcGIS Pro. This approach uses a suite of planning analysis tools to rapidly assess and identify sediment sources, pathways, and sinks for watershed analysis. Level 2 Estimate Bankfull is to estimate the REMed bankfull elevation for the base year for each reach. This is accomplished by identifying and mapping riffle cross sections and roughly estimate an initial bankfull elevation for the base year for each reach. The data from level 1 will be needed to start this estimate bankfull process.

Application and Data Setup

🔧 Practical

Level-1 Data

1. Sites must have had a Level-1 analysis run. That data is essential to completing Level_2 analysis.
2. Level-1 software application and tools will be needed for Level-2 analysis.

Data access in ArcGIS Pro

1. 🧰 Fluvgeo toolbox requires the use of a mapped drive for accessing the data in ArcGIS Pro. UNC connection will create errors with some of the Fluvgeo tools.
2. Create a mapped drive and use that connection in ArcCatalog.

Analysis Workflow

🔧 Practical

Create Riffle Cross Section Layers– for Channel

1. Copy the 🗺️ XS line feature class in the most recent database and rename one 🗺️ XS_Layout_riffles_ch feature class (Ex. xs_300_150_riffels_ch).

Select the XS_section that represent best represent rock riffle areas in the reach.

1. Select between 3 and 6 riffle location based on the length and characteristics of the reach.
2. Riffle Identifying Characteristics:
   1. A straight reach between two meander bends, areas in the cross-overs between river bends
   2. Clear indicators of the active floodplain or bankfull discharge
   3. Presence of one or more terraces
   4. Channel section and form typical of the stream
   5. A reasonably clear view of of geomorphic features
   6. Areas of high water surface slope (in the case of high gradient streams)
   7. Areas of minimum depth and width
   8. Channel width parallel and consistent
   9. Avoid tributary influences
   10. Cross sections should be drawn wide enough to capture the top of bank
3. Points in the LAS dataset can assist in locating riffles if the stream. Use symbolized LAS point layer to identify dense clusters ground points in the reach.
4. Imagery can also be used to identify potential riffle areas in the reach.
5. Once XS_section have been identified delete all other XS sections that are not determined to be riffles.

XS Resequence the riffle XS_sections

1. In the catalog pane, go to the 🧰 FluvialGeomorph toolbox. Expand tools and select 🛠️ XS Resequence.
2. Feature_dataset for the most recent year.
3. Xs_fc for the 🗺️ XS_Layout_riffles_ch feature class.

Resize the XS_Layout_riffles_ch

1. The riffle cross sections need to snapped perpendicular to the channel polygon at the current riffle location.
2. Save Edits

Create Floodplain riffle layer

1. Copy the 🗺️ XS_Layout_riffles_ch line feature class to the current year feature dataset and rename it 🗺️ XS_Layout_riffles_fp.
2. Edit the 🗺️ XS_Layout_riffles_fp line feature class to the full width of the floodplain polygon. The 🗺️ XS_Layout_riffles_fp line feature class must line up with the 🗺️ XS_Layout_riffles_ch line feature class.
3. Save edits.

Calculate Cross Section Watershed Area – for the channel and floodplain riffles

1. In the fluvialgeomorph folder, expand layers and add 🗺️ NHDPlusFac_National.tif raster.
2. Right click the layer, go to data, then export raster
3. Add the output to the event folder.
4. Clipping geometry is displaying current extent. Make sure you are zoomed out to the whole county, so each site is located within extent.
   1. Optional: Create a clip for each project site of the 🗺️ NHDPlusFac_National.tif raster with the extent zoomed out 1:50000 centered on the site.
5. Go to FluvialGeomorph toolbox open 🛠️ XS Water Area tool.
6. 📊 Snap distance is 🧮 100.
7. Start with the more recent data first.
8. Hit Run.
   1. If it doesn’t work zoom into the mile radius of site and clip FAC. Having a smaller clip will also reduce the tool runtime.
   2. The result is a new attribute field in the 🗺️ XS line feature class that has a calculated watershed area for each regularly spaced cross section.
9. Once it is done running, open attribute table and see if anything in the 📊 watershedareaSqMile is off.
   1. Some of the cross sections 📊 Watershed_Area_SqMile may not follow the trend. If this is the case, manually enter in the values to fill in the gaps. If most of the cross sections are missing these or display incorrect values, rerun 🛠️ Watershed Area Tool and increase the 📊 snap distance.
   2. Check for other streams and bodies of water feeding into the stream that would validate the abrupt changes in the watershed area.

Import riffle cross sections into GDB feature dataset.

1. Import the finished 🗺️ XS_Layout_riffles_ch and 🗺️ XS_Layout_riffles_fp feature classes to the earlier year feature dataset.

XS River Position

1. In the FluvialGeomorph toolbox, select 🛠️ XS River Position.
2. Enter feature dataset for more recent geodatabase.
3. Input 🗺️ Riffle_XS line feature class.
4. Input 🗺️ Flowlinepoints feature class.
5. Hit Run. Complete for both the 🗺️ channel_XS and 🗺️floodplain_XS feature classes.
6. The result adds new fields in the attribute table of the 🗺️ XS line feature class.
7. Two temporary charts will populate the Contents tab under the 🗺️ XS line feature class (XS 📊 Seq by 📊 km_to_mouth, 📊 XS Seq by Watershed Area sq mile). If the charts are removed from the contents pane, you will need to run the 🛠️ XS River Position Tool to view them again.
   1. Open both Charts and inspect for any issues in the data.
   2. Note: This step provides charts which help see if there are gaps in the data.
8. Repeat 🛠️ XS River Position Tool for the older gdb.

XS Points

1. In the FluvialGeomorph toolbox, select 🛠️ XS Points.
2. Enter feature dataset for more recent geodatabase.
3. Input 🗺️ XS line feature class.
4. Input 🗺️ dem_hydro raster.
5. Change 📊 dem_units to 🧮 ft.
6. Input 🗺️ REM raster for the 📊 REM_dem.
7. 📊 Station Distance is 🧮 1.
8. Hit Run. Complete for both the 🗺️ channel_XS and 🗺️ floodplain_XS feature classes.
9. Points have been created every foot along the Cross Section with an Elevation. This will provide a visual elevation profile for each cross section.
10. Repeat these steps for the older gdb.

XS Point Classify

1. In the FluvialGeomorph toolbox, select 🛠️ XS Point Classify.
2. Enter feature dataset for the most recent year.
3. Input 🗺️ XSpoints feature class.
4. Input 🗺️ channel polygon feature class.
5. Input 🗺️ floodplain polygon feature class.
6. Leave 📊 buffer distance as 🧮 default.
7. Repeat for earlier event 🗺️ XSpoints feature class.

Run Report

🔧 Practical

XS Dimensions Level 1

1. In the FluvialGeomorph toolbox, open 🛠️ XS Dimensions, Level 1.
2. 🗺️ XS line feature class for the newest event are added into 📊 xs_line fc.
3. Enter 🧮 4 for the 📊 lead_n.
   1. This sets the moving window to average 4 XS’s above and below the XS being calculated.
4. Leave the 📊 use_smoothing box 🧮 unchecked and 📊 loess_span as 🧮 0.1.
5. Check that the vert_units are in ft.
6. After the tool completes, refresh the folder the gdb is in and you should find a .csv file in there.

Join from CSV (Data Management toolbox)

1. In the FluvialGeomorph toolbox, open 🛠️ Join From CSV located in the 🧰 Data Management toolset.
2. 🗺️ features point feature class will be the feature dataset of the most recent gdb.
3. Fc will be the 🗺️ XS line feature class.
4. Choose 🧮 Seq in the dropdown for the 📊 fc_field.
5. The csv_file will be the .csv file created from the 🛠️ XS Dimensions Level 1 Tool.
6. 📊 Csv_field will match the 📊 fc_field so it should also be 🧮 Seq.
7. Hit Run.
8. A new line feature class ending with dims_L1 will be added to the feature dataset.

Go to the USGS StreamStats website to get the 50-percent AEP flood value for the stream reach .

*Note - Other sources can be used to get the watershed discharge. 
Check with hydrologist requesting the analysis for additional sources.*

Step 3. i

1. Select the state of the reach on the left of the stream.
2. Zoom into the location for the stream reach until the stream layer shows.
3. Click the delineate button.
   1. On the map select the base of the stream reach. The watershed calculation will start. When it is complete a delineation of the reach will show.
   2. Click Continue.
   3. Select all 4 options under Regression Based Scenarios.
   4. Below expand Basin Characteristics and Select All Basin Characteristics.
   5. Click Continue. The calculations for the report will run.
   6. Once the calculations are completed scroll to the bottom of the left panel, check all the boxes and click Open Report.
   7. Add the site name to the report title. a. Ex. Site193 JODAVIESS County SWCD Stream Stats Report.
   8. Add any comments need to the comment section.
   9. Scroll to the bottom and print the report to PDF. Save to the site folder.

Open the PDF Stream Stats Report from the site folder.

1. Locate the 50-percent AEP flood value under the Peak-Flow Statistics Flow Report section around page 8 of the report. This value will be used in the Level 2 report.

L2 XS Dimensions

1. In the FluvialGeomorph toolbox, open 🛠️ XS Dimensions, Level 2.
2. 🗺️ XS dimension level 1 for the riffles into the 📊 xs_line fc. Ex. xs_300_150_riffels_ch_103_5_dims_L1
3. 🗺️ XS_points_channel_riffles are added to the 📊 XS_point_fc. Ex. xs_300_150_riffels_ch_103_5.
4. 📊 Bankfull_elevation is from the 📊 channel depth of the 🗺️ bank_rawchannel feature class. Ex. 103.5
5. Enter 🧮 4 for the 📊 lead_n.
   1. This sets the moving window to average 4 XS’s above and below the XS being calculated.
6. Leave the 📊 use_smoothing box 🧮 unchecked and 📊 loess_span as 🧮 0.1. Can be adjusted up to 1.
7. Check that the 📊 vert_units are in 🧮 ft.
8. 📊 Discharge method is 🧮 model_measure.
9. 📊 Discharge_value is the 🧮 50-percent AEP flood value from the watershed discharge report.
10. After the tool completes, refresh the folder the gdb is in and you should find a .csv file in there.

Join from CSV

1. In the FluvialGeomorph toolbox, open 🛠️ Join From CSV located in the 🧰 Data Management toolset.
2. 🗺️ Features dataset will be the feature dataset of the most recent gdb.
3. Fc will be the 🗺️ XSchannelriffles _dims_L1 line feature class.
4. Choose 🧮 Seq in the dropdown for the 📊 fc_field.
5. The csv_file will be the 🗺️ .csv file created from the ``XS Dimensions Level 2 Tool.
6. 📊 Csv_field will match the 📊 fc_field so it should also be 🧮 Seq.
7. Hit Run.
8. A new line feature class ending with 🗺️ *dims_L2 will be added to the feature dataset.

Generate Level L2 Estimate Bankfull Report

1. In the FluvialGeomorph toolbox, open the 🛠️ Report – L2 Estimate Bankfull located in the 🧰 Reports toolset.
2. 📊 Stream will be the🧮 ReachName which was created when making the flowline. Copy and paste the 🧮 ReachName from 🗺️ XS feature class attribute table.
3. 📊 Flowline_fc will be the 🗺️ flowline feature class from the recent survey event.
4. 📊 Xs_dimensions_fc will be the 🗺️ XS line feature class created during the 🛠️ Join From CSV tool.
5. 📊 Xs_point_ch_1 will be the 🗺️ flowlinepoints feature class from the most recent survey event.
   1. 📊 Xs_point_ch_2 will be the 🗺️ flowlinepoints feature class from the older survey event.
6. 📊 Xs_points_fp_1 will be the 🗺️ XSpoints feature class created from the 🛠️ XS Points tool. Use the data from the most recent survey event.
   1. 📊 Xs_points_fp_2 will be the 🗺️ XSpoints feature class for the older survey event.
7. 📊 Survey_name_1 will be the 🗺️ survey event feature class of the most recent data (ex: 2022).
   1. 📊 Survey_name_2 will be the 🗺️ survey event feature class of the older data (ex: 2012).
8. 📊 Features_fc will need the 🗺️ features point feature class that was created to indicate roadways, site improvements, or other bodies of water.
   1. 📊 Channel_fc will be the lower number 🗺️ bank_raw layer feature class that represents the channel.
9. 📊 Floodplain_fc will be the higher number 🗺️ bank_raw layer feature class that represents the floodplain,
10. 📊 Dem will need the 🗺️ dem_hydro.
11. Regions will be selected based on needs for the site. They calculate an estimate of specific hydraulic dimension for a given drainage area. One to four curves can be selected for a report. Ex. IL sites normally use Southern Driftless, Lower Southern Driftless, and Eastern United States.
12. 📊 From_elevation is the 🧮 low end number from a range built around the 📊 channel bf_estimate number.
    1. Ex if your bankfull estimate for the reach is 104 the range could be 100-106. Making 100 the from_elevation and 106 the to_elevation. The range should be roughly 2-5 numbers below and above the bankfull estimate.
13. 📊 To_elevation is the 🧮 high end number from a range built around the 📊 channel bf_estimate number.
14. 📊 By_elevation must be a number divisible by the 📊 bf_estimate. It normally ranges from 0.1-2.
15. 📊 Bf_estimate will be the 🧮 50-percent AEP flood from Stream Stats or other source.
16. 📊 Check the box for: 🧮 show_xs_map.
17. Change 📊 profile_units to 🧮 feet.
18. 📊 Check boxes for 🧮 aerial and 🧮 elevation.
19. 📊 Xs_label_freq and 📊 exaggeration should already be set to 🧮 10 and 📊 extent_factor is 🧮 1.2.
20. 📊 Output_dir is where the 📑 report will be stored. Each project has a 📁 Reports folder.
21. 📊 Output_format is 🧮 word_document.
22. Hit Run.
23. Review 📑 Report for errors and anomalies in the data.

Next Steps

☑️ Evaluate

Review the report.

1. Go to chapter Level 2 Bankfull Report under Report Reviews.
2. Refer to the FG Technical Manual as need for more detailed information.
3. Revise and/or rerun as needed.