Catchment Scale Controls on River Geomorphology
Embedded Files
1- Map of the Logan River Watershed
10 Digit HUC: 1601020303
Left: Location of the Logan River Watershed in the state of Utah.
Right: Up-close of the Logan River Watershed with the mainstem of the Logan River highlighted in blue.
Maps created using Arc GIS Pro.
2- Longitudinal Profile
1- Longitudinal Profile (created using Google Earth Pro).
2- What is the base-level control of the Logan River today (the feature and its elevation)?
The confluence of the Logan River with the Little Bear River at 1344 meters as reflected in the longitudinal profile.
3- What was the base-level control of the Logan River about 18,000 years ago (feature and elevation)?
Lake Bonneville, this is reflected by the remnants of the lake and features such as the Bonneville Shoreline, which is generally in the elevation range of 1520-1620 meters.
4- What is the mainstem length of the Logan River in kilometers?
82 km (50 miles)
5- What is the concavity (show calculation)?
Concavity = 2A/H
Equation for calculating concavity where A is the height difference between the middle point of the longitudinal profile and a line spanning from the end points of the profile, and H is the total fall of the profile.
A value of 0.6 indicates a concave upward profile which reflects a relatively standard river profile that is being controlled by its base level.
6- Label any knickpoints (if present) and pose a working hypothesis about the controls?
The two most prevalent knickpoints that can be seen in the longitudinal profile of the Logan River are: The East Cache Fault (1430 m) and a lithology change (2273 m).
Smaller knickpoints within this profile could likely be attributed to features such as First and Second dam where water is slowing down and backing up creating knickpoints.
3- Catchment Morphometrics
1- What is the catchment length in meters?
The catchment length is roughly 49,075 meters as measured in Google Earth Pro.
2- What is its catchment area in square meters and in square kilometers?
646.56 square kilometers
646,562,000 square meters
3- What is the the catchment perimeter length in meters and kilometers?
172.404 km
172,404 meters
4- Calculate the circularity ratio.
Circularity Ratio = 0.27. This means the catchment is relatively elongate and is primarily controlled by geologic structure.
5- Calculate the elongation ratio.
Elongation Ratio= 0.15. The further the value of the elongation ratio from 1.0, the more elongate the catchment is, and therefore the slower the runoff from the basin is.
6- Calculate the form factor of the Logan River Watershed.
Form Factor = 0.02. This is further confirms the highly elongate features of the Logan River Watershed.
7- What is the catchment relief of the Logan River Watershed?
H = 1,125 m as determined through the Longitudinal profile.
8- What is the relief ratio of the Logan River Watershed?
Relief Ratio = 6.52. Relief ratio measures the relative steepness of the river. 6.52 is a high relief ratio, indicating the the watershed is steep and features a large drop in elevation over the course of its path.
9- What is the drainage density of the Logan River perennial drainage network?
Drainage Density = 0.33. A low drainage density value like this can mean large spacing between streams and possibly low connectivity between stream networks. This could likely be due to the mountainous terrain of the Logan River Watershed as well as the large size of the watershed.
10- What is the drainage pattern of the Logan River drainage network?
The Logan River has a dendritic drainage pattern.
4- Stream Order
For the perennial drainage network of the Logan River:
Stream orders are based on the Strahler Stream order method.
1- What is the stream order of the Logan River at its mouth?
The Logan River is a 4th order stream at its mouth.
2- What is the stream order of Temple Fork at its mouth?
Temple fork is a 3rd order stream at its mouth.
2- What is the stream order of Temple Fork at its mouth?
Temple Fork is a 1st order stream at its mouth.
4- Does the Logan River appear to obey the Hortonian laws of stream network composition?
1- Number of streams of a given order decreases
Yes, the Logan River decreases in first, second and third order streams as stream order increases.
2- Mean stream length
The Logan River appears to uphold the principle that as stream order increases, the mean stream length increases as well.
3- Catchment area increases
True. This applies to the Logan River because although it is elongate, as stream order increases the overall catchment area draining to the river is increasing.
Methods:
Both Arc GIS Pro and Google Earth Pro were used for all mapping and calculations for this assignment as well as referencing the provided project_bounds.geojson file to ensure that values were at least in the appropriate range. Equations were taken from Geomorphic Analysis of River Systems by Kirstie A. Fryirs and Gary J. Brierley.
Shapefiles and KMZ files were downloaded from the Riverscapes Consortium Context for HUC 1601020303 for WATS 5150.
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