Interpreting the GUT Tool

1. North Fork Asotin Creek Description

The two sites analyzed for this assignment were located in Southwest Washington and are both part of a tributary to the Snake River. The North Fork Asotin is identified by HUC 170601030201. The watershed is 113.97 square kilometers. The upper portion of the watershed is primarily closed tree canopy. The hillslopes of the middle and lower watershed area are primarily herbaceous shrub-steppe and grassland while areas of riparian vegetation can be described as mixed closed and open tree canopy. The two sites are located in the mid portions off the watershed, with NF-F4 located downstream from NF-F6.

2. North Fork Asotin F4

2.1 Qualitatively describe the in-channel geomorphology of this reach.

This reach is fairly straight being about 200 meters in length along the centerline with very little variation in geomorphology as you proceed longitudinally downstream. It is primarily composed of glides and runs with margin-attached bars and pools occurring frequently throughout this reach. It is a single thread channel with the width being fairly uniform as it is about 9 meters across the bank full width at the top and bottom of the reach.

2.2 Choose at least two survey years at this site to consider the temporal variability of morphology at this site. Which survey years are they and why did you choose them?

I selected 2011 and 2017 for the survey years I analyzed because this represents the maximum analysis time period for the data that was provided. This also means that even with no additional knowledge on hydrology and flow events within the analysis time period, the maximum change in geomorphic units can be seen as I analyzed the largest time frame available.

2.3 What Tier 2 Forms are present in each year? Do they differ?

In 2011, the dominant Tier 2 forms throughout the reach appear to be concavities: troughs, bowls, and bowl transitions. There is also a fair amount of planar features throughout this reach. The trough designation is nearly continually connected throughout the reach with one small exception of a small amount of the planar unit on the downstream end of the reach. The sides of the channel are characterized as mounds or mound transitions.

In 2017, the Tier 2 geomorphic units are more variable compared to 2011. The dominant form still appears to be trough, however, there are more breaks in the trough, allowing for an increased number of planar and even a few convex (saddle) units. The edges of the channel are characterized as narrow sections of mounds.

**Note: the 2011 image below is on top of a 2011 hillshade and the 2017 image below is on top of a 2017 hillshade of this reach.

2.4 Do any of the Tier 2 Forms dominate the assemblage or is it fairly mixed? Is this true through time?

In 2011, it appears that the concave units, troughs, bowls, and bowl transitions dominate in this reach and are connected throughout nearly the entirety of the reach. By 2017, geomorphic units in this reach are more mixed, breaking up the concave features to include convex features, such as saddles and mounds, and more planar features. It does appear, however, that troughs are still dominant in 2017.

2.5 What Tier 3 Geomorphic Units are present in each year?

In 2011, the dominant geomorphic unit appears to be the glide-run unit. This unit is nearly continuous throughout the reach. There are a few sections of this reach that contain rapids, chutes, and pools. The only other unit present in a significant extent is discontinuous margin attached bars along the channel edges.

In 2017, the dominant geomorphic unit is still glide-run and is nearly continuous throughout the reach. There is more variability in the other units present in 2017 compared to 2011. Now, there are a few riffle sections and mid-channel bars in addition to pools. The margin attached bars along the channel edges are still present.

2.6: Zoom in to 2 to 5 x bankfull width portion of the reach and look at the arrangement of geomorphic units. Is it coherent? Does it make sense based on what you have learned so far

I zoomed into the upper part of the reach for the 2017 dataset. The geomorphic units present make sense and are logical. It can be seen at the left most portion of this reach (flow goes from left to right) that the thalweg (the deepest part of the channel) comes out of a glide-run and around a mid-channel bar into a concave pool. Then the thalweg comes over a riffle saddle feature and transitions into another glide-run, then into a pool, and then back into another glide-run feature. The margin attached bars are all along the edges of the channel, which is consistent with the definition.

2.7: How well does GUT appear to be doing in each year at discriminating the in channel geomorphic units? Point out any weaknesses or concerns you might have.

In 2011, the thalweg aligns fairly close with the channel center line, indicating that a lot of the reach will contain uniform features. From looking at the 2011 DEM and contour lines of this reach, the contour lines are pointing upstream, indicating that this reach is dominated by troughs. The GUT output confirmed this by identifying nearly continuous troughs throughout the reach, which is depicted in Tier 2. However, when identifying the Tier 3 geomorphic units for this reach, the GUT output identified nearly continuous glide-run features, which are planar in shape. This is inconsistent. For planar features, the contour lines should cross the stream rather than point upstream.

In 2017, the thalweg is a little less aligned with the channel center line compared to that of 2011. This indicates that there will be less uniformity in the 2017 features. From looking at the 2017 DEM and contour lines of this reach, many of the lines are still pointing upstream, indicating trough shaped features. However, there are more highs and lows, indicating an increase in bowl or mound shapes. From just a visual inspection, it is hard to tell if these features are mid channel pools or bars. The GUT output confirmed that the areas where the contours point upstream are Tier 2 features of troughs and many of the channel contour circles are bowls. However, for Tier 3, the GUT output continued to identify a majority of the reach as glide-run, which is a planar feature for Tier 2. GUT is consistent with identifying pools for the Tier 2 bowl areas, and also identified two saddle features within this reach.

2.8 Identify in one of your surveys for this reach a distinctive pool, bar and planar feature. For all three identify all five attributes from the fluvial taxonomy (i.e., Table 6), then use those to identify the tier 3 name from Table 7 or 8 (this may differ than what GUT output is because it is not as resolved) and explain which attribute(s) were key for discriminating that unit from other units.

This analysis was done with the 2017 survey.

2.8A: Pool

2.8 A1: GU Forcing-- Unsure, but it could be forcing by planform (outside of the bend) or structural forcing from a boulder.

2.8 A2: GU Orientation-- Streamwise as it is oriented parallel to the flow.

2.8 A3: GU Position-- Mid-Channel

2.8 A4: GU Low Flow WS Slope-- Flat or Shallow (it is hard to tell which one)

2.8 A5: GU Low Flow Relative Roughness-- Low as the majority of the flow is not obstructed by substrate.

2.8 A6: Tier 3 Name-- A bar-forced or structurally-forced pool.

2.8 A7: What attributes key for discriminating?-- Orientation and position, without field photos or being present in the field, other attributes are hard to identify.

2.8 A8: Differences with GUT-- GUT just identified this as a pool.

2.8B: Bar

2.8 B1: GU Forcing-- Unsure, but could be planform or structural

2.8 B2: GU Orientation-- Streamwise

2.8 B3: GU Position-- Bank attached (although it would be more clear how bank attached this feature is by seeing it in the field)

2.8 B4: GU Low Flow WS Slope-- Possibly shallow, it is unclear.

2.8 B5: GU Low Flow Relative Roughness-- Low as the majority of the flow is not obstructed by substrate.

2.8 B6: Tier 3 Name-- Could be an eddy bar, reattachment bar, or lateral bar.

2.8 B7: What attributes key for discriminating?-- Orientation and position, without field photos or being present in the field, other attributes are challenging to identify.

2.8 B8: Differences with GUT-- GUT just identified this feature as a margin attached bar.

2.8C: Planar

2.8 C1: GU Forcing-- Not forced

2.8 C2: GU Orientation-- Streamwise

2.8 C3: GU Position-- Channel-spanning as some units are bank-attached on both side and span the entire low flow channel.

2.8 C4: GU Low Flow WS Slope-- Probably shallow, but it is unclear.

2.8 C5: GU Low Flow Relative Roughness-- Unsure, but probably low to moderate.

2.8 C6: Tier 3 Name-- Glide or Run

2.8 C7: What attributes key for discriminating?-- Low flow relative roughness and low flow slope

2.8 C8: Differences with GUT-- GUT identified this feature as a glide-run.

2.9: Turn off GUT and look just at the Topo DEM (e.g Detrended DEM and Contours) for one of the surveys. Manually map one geomorphic unit you think you can read in the topography.

This analysis was done with the 2017 survey.

2.9A: What is the tier 2 Form and the tier 3 shape of the unit you manually identified?

Tier 2 form is a convex saddle and Tier 3 feature is a riffle.

2.9B: How do the boundaries of the unit you mapped compare with what GUT derived?

GUT extended the riffle a bit further upstream that I did.

2.9C: How does the type you identified compare with what GUT identified? Explain the discrepancies if they exist.

Both GUT and I identified this unit as a riffle.

3. North Fork Asotin F6

3.1: Qualitatively describe the in-channel geomorphology of this reach.

This reach has a higher sinuosity compared to site NF-F4, although I still would not describe this reach as super sinuous. There is some variation in geomorphology as you proceed longitudinally downstream. Through time from 2011 to 2017, the geomorphology does change and become more complex and variable.

3.2: Choose at least two survey years at this site to consider the temporal variability of morphology at this site. Which survey years are they and why did you choose them?

I selected 2011 and 2017 for the survey years I analyzed because this represents the maximum analysis time period for the data that was provided. This also means that even with no additional knowledge on hydrology and flow events within the analysis time period, the maximum change in geomorphic units can be seen as I analyzed the largest time frame available.

3.3: What Tier 2 Forms are present in each year? Do they differ?

In 2011, this reach is dominated by troughs that are nearly continuously connected throughout the reach as well as mounds. There are also areas of discontinuous bowls and planar forms as well as areas of bowl transitions and mound transitions.

In 2017, there is more diversity in features present. There are sections of trough, mound, planar, saddles shape, and a few bowls throughout. There are also bowl transitions and mound transitions present.

**Note: the 2011 image below is on top of a 2011 hillshade and the 2017 image below is on top of a 2017 hillshade of this reach.

3.4: Do any of the Tier 2 Forms dominate the assemblage or is it fairly mixed? Is this true through time?

This reach is much more mixed and variable than site NF-F4 was. The trough shape is more dominant in the 2011 survey. I would also consider the trough shape to be more dominant in the 2017 survey as well, however, based on the visual inspection of both surveys, one could argue that there no single dominant form is present as there is a great amount of variability in forms.

3.5: What Tier 3 Geomorphic Units are present in each year?

In 2011, the dominant geomorphic unit identified is the glide-run that is nearly continuous through the entire reach. Margin attached bars and present along the channel edges. There are also a few pools present.

In 2017, the geomorphic units are much more mixed. There is still a large portion of glide-run, however, I would not consider this the dominant feature. There are also a number of pools, a riffle, a chute, and a number of margin attached bars and mid-channel bars.

3.6: Zoom in to 2 to 5 x bankfull width portion of the reach and look at the arrangement of geomorphic units. Is it coherent? Does it make sense based on what you have learned so far?

I zoomed into the more middle portion of the reach for the 2017 dataset. The geomorphic units present make sense and are logical. It was seem that at the left most portion of the reach (flow goes from left to right) that the thalweg (the deepest part of the channel) comes around a mid-channel bar, then into a pool and then goes over a riffle. This riffle splits the flow around a mid-channel bar, a chute is formed, and the flow comes back together followed by a margin attached bar and pool. This sequence matches to what seems to be reasonable.

3.7: How well does GUT appear to be doing in each year at discriminating the in channel geomorphic units? Point out any weaknesses or concerns you might have.

For both 2011 and 2017, I think GUT did a pretty good job differentiating units. However, the same concerns identified in the NF-F4 site regarding upward pointing contour lines on what was considered planar features in GUT continued. Another issue with GUT is that it simplified the identification of Tier 3 features (i.e., mid-channel bars, margin attached bars, pools, and glide-run) compared to the more specific classifications provided by Wheaton et al., 2015.

3.8: Identify in one of your surveys for this reach a distinctive pool, bar and planar feature. For all three identify all five attributes from the fluvial taxonomy (i.e. Table 6), then use those to identify the tier 3 name from Table 7 or 8 (this may differ than what GUT output is because it is not as resolved) and explain which attribute(s) were key for discriminating that unit from other units.

This analysis was done with the 2017 survey.

3.8A: Pool

3.8 A1: GU Forcing-- Planform (forcing could be induced by sinuosity) or Geomorphic Unit (forcing could be caused by another geomorphic unit)

3.8 A2: GU Orientation-- Streamwise

3.8 A3: GU Position-- Bank attached

3.8 A4: GU Low Flow WS Slope-- Flat or shallow

3.8 A5: GU Low Flow Relative Roughness-- Low

3.8 A6: Tier 3 Name-- Bar-forced pool (this pool was probably forced by the mid-channel bar upstream of it)

3.8 A7: What attributes key for discriminating?-- Position, forcing

3.8 A8: Differences with GUT-- GUT just identified this as a pool

3.8B: Bar

3.8 B1: GU Forcing-- Planform

3.8 B2: GU Orientation-- Streamwise

3.8 B3: GU Position-- Mid-channel

3.8 B4: GU Low Flow WS Slope-- Shallow to moderate

3.8 B5: GU Low Flow Relative Roughness-- Moderate to high but not sure

3.8 B6: Tier 3 Name-- Lateral bar, forced bar

3.8 B7: What attributes key for discriminating?-- Orientation, forcing

3.8 B8: Differences with GUT-- GUT just identified this as a mid-channel bar

3.8C: Planar

3.8 C1: GU Forcing-- Not forced

3.8 C2: GU Orientation-- Streamwise

3.8 C3: GU Position-- Mid-channel

3.8 C4: GU Low Flow WS Slope-- Shallow

3.8 C5: GU Low Flow Relative Roughness-- Low to moderate but not sure

3.8 C6: Tier 3 Name-- Glide or Run

3.8 C7: What attributes key for discriminating?-- Low flow relative roughness and low flow slope (although I am not completely sure about this)

3.8 C8: Differences with GUT-- GUT identified this as a glide-run

3.9: Turn off GUT and look just at the Topo DEM (e.g Detrended DEM and Contours) for one of the surveys. Manually map one geomorphic unit you think you can read in the topography.

This analysis was done for the 2017 survey.

3.9A: What is the tier 2 Form and the tier 3 shape of the unit you manually identified?

Tier 2 form is convex mound and Tier 3 unit is mid-channel bar.

3.9B: How do the boundaries of the unit you mapped compare with what GUT derived?

I extended the bar further downstream as when looking at the DEM and detrended DEM, this is where the bar appeared to end.

3.9C: How does the type you identified compare with what GUT identified? Explain the discrepancies if they exist.

I identified this unit as a mid-channel bar, the same as GUT did, because it appears to be in the middle of the channel. However, I decided to extend the mid-channel bar unit.

4. Differences between Site NF-F4 and Site NF-F6

4.1: What are the primary differences from exploring GUT between these two sites that you noticed between the in channel geomorphic units of these two sites?

Site NF-F4 was much more uniform and had more continuous glide-run units. Site NF-F6, however, started off with a more diversity of geomorphic units and with a higher sinuosity. Over time, the diversity of units increased at both study sites.

4.2: What inferences can you make about geomorphic processes and behavior when contrasting GUT outputs between these two sites?

From 2011 to 2017, both NF-F4 and NF-F6 became more complex with a higher diversity of geomorphic units. Without knowing about events that could have changed the geomorphology of this reach over time (floods, landslides, etc.), I can infer that over time, reaches will become more complex and diverse.

4.3: If you only had one GUT output from each of these two sites (i.e. one snap shot) how representative would be your inferences about geomorphic processes? If you did not have the luxury of six or seven surveys, but just one, would your conclusions above be different?

If I only had one GUT output from each of the two sites, I would not be able to compare how the two sites changed through time. Therefore, I would not be able to conclude that these reaches became more complex through time. With just having a single snapshot, I would only be able to conclude that at this single point in time, site NF-F6 is more complex than site NF-F4.

5. Synthesis

5.1: How are the Tier 2 Forms from GUT different than what we discussed in field?

The Tier 2 forms used in GUT and from what we discussed in the field are similar. We identified the wall, saddle, plane, trough, and bowl shapes. GUT, however, also identified areas of mound, mound transition, and bowl transition, which we did not identify in the field.

5.2: How are the Tier 3 GUs GUT exports different then the ones we discussed? Why do you think GUT does not output the same things?

The Tier 3 GUT outputs are more simplified from what we discussed in the field based on Wheaton et al., 2015. For example, GUT identified two types of bars: mid-channel bar and margin-attached bar, while Wheaton et al., 2015 identified 18 different bar types. GUT also just specifies one type of pool, where Wheaton et al., 2015 identified many more different types of pools.

GUT simplified the Tier 3 units because without the spatial analysis and field observations of all the key attributes, it is impossible to differentiate between some of the different types of units. For example, there is no data included in the GUT project that specifies the flow type, relative roughness type, or bed grain size. Without this information, it is significantly harder to identify a single unit type.

5.3: How would you apply Tier 4? Do you have enough information here to do that?

In order to apply Tier 4, you need vegetation and grain size information. Tier 4 names are simply Tier 3 names with one or more adjectives inserted in front of them. For example, a point bar could become a fine-grained point bar in a suspended load river or a gravel point bar in a gravel-bed river. While there is a vegetation layer in the GUT project, it is not at a fine enough scale to add accurate and useful information to a single geomorphic unit. Based on exploring the GUT Tool, there does not appear to be any information on grain sizes for any of the units included in the GUT project. Tier 4 characteristics would be best applied being in the field or using field-based photos.

5.4: Does exploring these GUT outputs give you more or less confidence in applying the fluvial taxonomy through manual mapping off of topography versus identification in the field?

GUT gave me more confidence in applying the fluvial taxonomy through manual mapping off of topography versus identification in the field because the boundaries of distinct units I could map in the field are using the contour lines and DEMs, which were very similar to what GUT identified. I also feel more comfortable identifying the Tier 2 unit form because my interpretation of the DEMs aligned with the GUT output. However, when identifying the Tier 3 units, I am feeling less confident with only using a DEM and contour lines. I think that being in the field would make it easier to identify Tier 3 units than having only the DEM and contour lines to go off of.