Geomorphic Unit Tool
Embedded Files
Part 1 - Get Data, Unzip & Explore with RAVE
Part 1 - Get Data, Unzip & Explore with RAVE
For the first part of this assignment, I want you to do:
1.A Download the Provided Asotin Data (also scroll down to Assignment Dataset for more info) and see “Getting Data Downloaded and Organized Video”
Part 2 - Interpret It
Part 2 - Interpret It
1 North Fork Asotin Creek
Asotin Watershed is located in the southeastern corner of Washington near the Oregon and Idaho state lines. The Asotin Watershed is home to salmon and steelhead which are currently under the Endangered Species Act. In order to track the effectiveness of stream restoration they have done over eight years of topographic surveys under the Intensively Monitored Watershed Program (IMWs). In this project I looked at two sites located on the North Fork Asotin Creek.
2 North Fork Asotin F4
2.1: Qualitatively describe the in-channel geomorphology of this reach.
This is the downstream reach out of the two samples. Flow is going left to right and it's fairly straight. It's pretty shallow with the depth only going up to one meter. It's a relatively small reach compared to the drainage area and it's a single-threaded channel.
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?
My first thought was to pick 2011 and 2017 which are the first and last topographic survey data provided to us but you can miss a lot of information when you look at only the beginning and end. I decided to do 2012 and 2014 because I wanted to compare an intermediate time frame of 2 years which isn't too long but not too short. The in-stream channel valley units are basically the same but in 2012 there were larger out-of-channel units compared to 2014 which was much smaller.
Figure 1.1 - 2012 Tier 2 Unit Form
Figure 1.2 - 2014 Tier 2 Unit Form
2.3: What Tier 2 Forms are present in each year? Do they differ?
They both primarily have a mound, troughs, bowls, and bowl transitions so they don't differ a lot from the Unit Forms. In 2014 the walls and mounds extended outwards and became more prominent compared to 2012. The Unit Form in 2012 seems to be very mixed and intertwined but in 2014 it looked more linear and defined.
2.4: Do any of the Tier 2 Forms dominate the assemblage or is it fairly mixed? Is this true through time?
None of the Tier 2 Forms dominate the assemblages because it's fairly mixed. From 2012 to 2014 the channel became simpler and more streamlined. The channel also expanded a bit during those 2 years. The unit form shape also follows this trend which is not shown through a figure. In 2012 the primary form was planner followed by the same amount of convexity and concave. In 2014 the majority was planner form.
Figure 1.3 - Tier 2 Legend
Figure 1.4 - 2012 Tier 3 In-Channel GU
Figure 1.5 - 2014 Tier 3 In-Channel GU
Figure 1.6 - 2012 Zoom Tier 3 In-Channel GU
Figure 1.7 - Tier 3 In-Channel GU
2.5: What Tier 3 Geomorphic Units are present in each year?
Year 2012, represented by Figure 1.4 is a mix of glide-run, margin attached bars, rapids, and transitions. The in-channel GU Is more diverse this year compared to 2014. Year 2014, represented by Figure 1.5 majority is glide-run and a little bit of margin attached bar, tiny amounts of pools. It's pretty uniform with the glide-run from left to right in the middle with alternating margin attached bars on the sides with a small amount of scattered pool and pocket pools.
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?
Yes because it goes to a glide-run to a rapid to cascade and then a pool. You can also see the thalweg shifting to the left towards the margin attached bank leaving room for a pool to form. Pools are formed when there is a vertical force of water falling down creating more erosion which can be caused by the cascade.
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 general I think GUT does a good job of discriminating between units when channels are very distinct. In 2012 there were a lot of transition areas. In 2014 there are barely any transition areas because the features are more uniform. This could be a weakness because transition areas are really hard to categorize. I believe GUT works better with simple channels compared to very complex ones.
2.7: 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.
Figure 1.8 - Roughness Height Map & Legend
Figure 1.9 - Position Map & Legend
Figure 1.10 - Orientation Map & Legend
Figure 1.11- Slope Map & Legend
2012 Tier 3 Pool
2.7A : Pool
2.7 A1: GU Forcing: Geomorphic Unit, forced by the margin attached bars or planform from the glide-run to rapid
2.7 A2: GU Orientation: Diagonal
2.7 A3: GU Position: Mid-channel
2.7 A4: GU Low Flow WS Slope: Moderate
2.7 A5: GU Low Flow Relative Roughness: Moderate to High
2.7 A6: Tier 3 Name: Chute
2.7 A7: Which attributes key for discriminating?: This one kinda hard because nothing Identifies with a diagonal orientation but without that its a chute.
2.7 A8: Differences with GUT: Gut only has a couple of options for pools and this one is not very distinct but I would consider It as a chute.
Figure 1.12 - 2012 Tier 3 Pool
Figure 1.13 - 2012 Tier 3 Bar and Planner
2.7B : Bar (Marginal Attached Bar)
2.7 B1: GU Forcing: Platform
2.7 B2: GU Orientation: Longitudinal (Streamwise)
2.7 B3: GU Position: Margin attached (bank attached)
2.7 B4: GU Low Flow WS Slope: Moderate to steep
2.7 B5: GU Low Flow Relative Roughness: Moderate to High
2.7 B6: Tier 3 Name: Point bar
2.7 B7: Which attributes key for discriminating?: It has alternating and relative roughness and slope varies
2.7 B8: Differences with GUT: GUT doesn't have a a point bar unit.
2.7C : Planar
2.7 C1: GU Forcing: Not forced
2.7 C2: GU Orientation: Longitudinal (Streamwise)
2.7 C3: GU Position: Margin Detached
2.7 C4: GU Low Flow WS Slope: Moderate
2.7 C5: GU Low Flow Relative Roughness: Moderate to High
2.7 C6: Tier 3 Name: Rapid
2.7 C7: Which attributes key for discriminating? With the high roughness and moderate slope points to a rapid
2.7 C8: Differences with GUT: In GUT its labeled as glide-run and not separated but Its a rapid. GUT defines It as a margin detached but I would see It has mid-channel.
2.8: 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.
Figure 1.14 - 2012 Topographic Map (Hillshade and DEM)
2.8A - What is the tier 2 Form and the tier 3 shape of the unit you manually identified?
Looking at the top right of Figure 1.14 there is an area with low elevation connected to the bank. I would consider this a type of thalweg. For Tier 2 I would consider it a bowl and for Tier 3 it would be a bowl because its a specific area with greater depth them the rest of the reach.
2.8B - How do the boundaries of the unit you mapped compare with what GUT derived?
Just by looking at elevation model the area of the bowl ad pool seems a lot bigger then what GUT derived.
Figure 1.14 - 2012 Topographic Map (Hillshade and DEM)
2.8C - How does the type you identified compare with what GUT identified? Explain the discrepancies if they exist.
In general GUT also identified the area with a bowl and pool but it had a lot more transitional units in Tier 2 like bowl transition and trough along with a saddle unit where I classified it all as a bowl. Tier 3 followed my predictions pretty well with it just being a pool.
3 North Fork Asotin F6
3.1: Qualitatively describe the in-channel geomorphology of this reach.
Unlike the first one, this reach is not straight but meandering. It's mostly single channeled but there are some places that could be considered multi channeled.
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?
Like the first part I choose 2012 and 2014 because it's a 2-year change and I feel like it's not too short or too long it's intermediate. When you choose the first and last data to point you can miss a lot of information through variability. 2012 and 2014 are kind in the middle.
Figure 1.15 - 2012 Tier 2 Unit Form
Figure 1.16 2014 Tier 2 Unit Form
3.3: What Tier 2 Forms are present each year? Do they differ?
In both years all Tier 2 Forms: bowl, bowl transition, trough, plane, mound transition, saddle, mound, and wall are present throughout the whole reach.
3.4: Do any of the Tier 2 Forms dominate the assemblage or is it fairly mixed? Is this true through time?
In both year there is no Tier 2 Forms that is dominate. Its fairly mixed and this is the same both years. In 2014 there is a stronger presence of mounds coampred to 2012 but its hard to notice any other major changes.
Figure 1.17 - Tier 2 Unit Form Legend
Figure 1.18 - 2012 Tier 3
Figure 1.19 - 2014 Tier 3
Figure 1.20 - 2014 Tier 3 Lower Reach
Figure 1.21 - Tier 3 Legend
3.5: What Tier 3 Geomorphic Units are present each year?
I believe in both years all of the in-channel GU are present at least once. Glide-run is the most abundant followed by margin attached bar for both years. These reaches are more diverse than the first location we looked at.
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?
This is a an example of a riffle-pool sequence. The flow is going left to right and its a pool which turns into a glide-run to a rifle. Yes this is coherent but these types of processes happen during meandering and this stretch looks a bit straight.
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.
I believe GUT appears to be doing a good job at discriminating in-channel GU but I do seem more weaknesses in identifying units when reaches are more complicated. These reached dont have a ot of transitional areas like the last two though. Also most units have a harsh line separating the two units and in the real world that is very hard so I feel lke there should be more transition areas.
3.7: Identify in one of your surveys for this to 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.
Figure 1.21 - Slope Map & Legend
Figure 1.22 - Orientation Map & Legend
Figure 1.23 - Roughness Map & Legend
Figure 1.24 - Position Map & Legend
3.7A : Pool
3.7 A1: GU Forcing: Geomorphic unit
3.7 A2: GU Orientation: Longitudinal (Streamwise)
3.7 A3: GU Position: Mid-channel
3.7 A4: GU Low Flow WS Slope: Low to moderate
3.7 A5: GU Low Flow Relative Roughness: Low to High
3.7 A6: Tier 3 Name: Chute
3.7 A7: Which attributes key for discriminating?: When It comes to pools there are not many option for mid-channel positions and Its definitely not a secondary channel.
3.7 A8: Differences with GUT: GUT Identifies this feature as a pool but it correlates more with a Chute feature. For the GU forcing I believe Its GU and Chutes are usually planform.
Figure 1.25 - 2014 Tier 3 Pool
Figure 1.26 - 2014 Tier 3 Bar and Planar
3.7B : Bar
3.7 B1: GU Forcing: Flow Width and Platform
3.7 B2: GU Orientation: Longitudinal (streamwise)
3.7 B3: GU Position: Channel spanning and margin attached
3.7 B4: GU Low Flow WS Slope: Very steep on the North side and moderate on South side
3.7 B5: GU Low Flow Relative Roughness: High
3.7 B6: Tier 3 Name: Longitudinal Bar (Mid-channel bar)
3.7 B7: Which attributes key for discriminating?: Its has a very distinctive elongated streamwise orientation
3.7 B8: Differences with GUT: GUT and I both believe its a Longitudinal bar. In GUT there Is only two options for bars so Its very generalized.
3.7C : Planar
3.7 C1: GU Forcing: GU
3.7 C2: GU Orientation: Longitudinal (Streamwise)
3.7 C3: GU Position: Channel Spanning
3.7 C4: GU Low Flow WS Slope: Mostly low but a moderate as well
3.7 C5: GU Low Flow Relative Roughness: Moderate
3.7 C6: Tier 3 Name: Run
3.7 C7: Which attributes key for discriminating?: There Is only a couple of planer forms that has a shallow to moderate slope and moderate roughness.
3.7 C8: Differences with GUT: GUT classifies runs and glides together but they have there differences and It corresponds closely with a run.
3.8: 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.
Figure 1.27 - 2014 Topographic Map
3.8A - What is the tier 2 Form and the tier 3 shape of the unit you manually identified?
Tier 2 is a bowl in the top left corner and Tier 3 is a bank on the north (or top) side.
3.8B - How do the boundaries of the unit you mapped compare with what GUT derived?
When it comes to the edges they are a bit off because they stop half way to the banks. In some areas the different units are pretty close to the contour lines. The topographic Dem gives you a better idea of the shapes and elevation because GUT is on dimensional.
3.8C - How does the type you identified compare with what GUT identified? Explain the discrepancies if they exist.
I choose pretty distinct features and they correspond with the GUT identify. The bank Is a bit off when It comes to the full feature but It did a good job.
Figure 1.27 - 2014 Topographic Map
Main differences between F4 & F6
3. 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?
F4 was a more simpler site, It was fairly straight and it only had some geomorphic units and sometimes It only consisted on 3-4 geomorphic units. F6 was a lot more diverse and complex. I believe it had all the geomorphic units present In both years and It wasn't straight but It was a meandering reach.
3. 2 : What inferences can you make about geomorphic processes and behavior when contrasting GUT outputs between these two sites?
Straighter rivers usually don't have a lot of geomorphic diversity which means less habitat and processes that can happen In that reach. While meandering rivers have tons of diversity creating tons of habitat and different processes that can happen. This can mean it has a more complex flow regime compared to the straighter channel.
3.3 : If you only had one GUT output from each of these two sites (i.e. one snapshot) how representative would your inferences be about geomorphic processes? If you did not have the luxury of six or seven surveys, but just one, would your conclusions above be different?
It would not be very accurate because a lot can happen In a year. I decided a 2-year increment and I saw tons of change so only having one see you aren't able to see all the variability within the six to seven year surveys. Yes, my conclusion would be very different and depending on the year also bias.
Synthesis
4. 1 : How are the Tier 2 Forms from GUT different from what we discussed in the field?
There are a lot more variety and options then what was presented In the field. Its harder to see the cross sectional and longitudinally.
4. 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?
There a lot more Tier 3 that we discussed than whats In GUT and because of this units are generalized causing different outputs then when we use table 7 and 8 to Identify the feature.
4.3 : How would you apply to Tier 4? Do you have enough information here to do that?
I believe GUT has enough Information to accomplish tier 4. I did not explore the grain size sorting and vegetation association but there was a lot of information about those topics where you can come up with a decent analysis.
4.4 : Does exploring these GUT outputs give you more or less confidence in applying the fluvial taxonomy through manual mapping of topography versus identification in the field?
Yes, it gave me more confidence In applying fluvial taxonomy through GIS. The practice and working through each problems helped me familiarize myself with table 7 and 8. I don't know if I would be able to accurately identify features without the help of data of GIS. That data helped me a lot to identify what tier 3 In-channel geomorphic units. I don't have a lot of practice with real world examples.
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