Exploits watershed predictions

HydroATLAS data that can be used in gravel models to estimate gravel with the proper size for salmon spawning. Includes example predictions of gravel size. Click on a reach to see the data for each segment. Description of map contents and a link to download map shapefile are below map.

Description of map contents:

D50 Gravel size:

Gravel size is important to the Atlantic Salmon spawning; too fine or too coarse, and the salmon will either not spawn or have poor egg survival (Purchase 2018). We considered 16 - 64 mm to be the most suitable substrate size, and this is represented as green on th D50 map. However, salmon may spawn in substrate that isn’t ideal, represented by yellow on the map. Finally, unsuitable substrate is represented by orange.

D50 was predicted based on the following calculations (Wilkins & Snyder 2011)

D50 = 𝛕_b / (𝛒_s - 𝛒) * g * 𝛕^*

Parameters:
𝛕_b = 𝛒 * g * n^3/5 * [Q/W]^3/5 * S^7/10
𝛒 = density of water = 1000 kg/m³
g = acceleration by gravity = 9.80665 m/s²
n = channel roughness coefficient = n = 0.04 as estimate for gravel bed rivers from Barnes 1967
𝛒_s = sediment density = 2650 kg/m³
𝛕^* = Shields parameter = 0.04 to follow Wilkins & Snyder 2011

Variables to retreive from HydroSHEDs:
S = channel gradient, Calculated as the ratio between the elevation drop within the river reach (i.e. the difference between min. and max. elevation along the reach) and the length of the reach.
Q = Discharge (m³/s), Average long-term discharge estimate for river reach, in cubic meters per second.
W = channel width (m), Calculated as the surface river area of the river reach segment divided by length of the river reach segment.

CABD barriers and areas past:
Potential barriers to upstream salmon movement were sourced from the Canadian Aquatic Barriers Database. Barriers were filtered to remove those that are unlikely sufficient to impede movement: a fishway exists, barrier has been decommissioned/removed, barrier was a dam less than 5 m high, or barrier’s Used for Network Analysis field was false. Any stream segment upstream of a remaining barrier is considered potentially inaccessible. Many of these barriers may in fact be passable by salmon (e.g. passable rapid listed as waterfall) but we lack sufficient information to remove them from list. Therefore, each barrier must be assessed on an individual basis if being incorporated into management or research plans.

Data and citations:
Click here to download the Exploits HydroATLAS data shapefile

Barnes, H. 1967. Roughness Characteristics of Natural Channels. United States Geological Survey: Publications.
Canadian Wildlife Federation. (2024). Canadian Aquatic Barriers Database (CABD). Retrieved from https://aquaticbarriers.ca/
Linke, S., Lehner, B., Ouellet Dallaire, C., Ariwi, J., Grill, G., Anand, M., Beames, P., Burchard-Levine, V., Maxwell, S., Moidu, H., Tan, F., Thieme, M. (2019). Global hydro-environmental sub-basin and river reach characteristics at high spatial resolution. Scientific Data 6: 283. doi: https://doi.org/10.1038/s41597-019-0300-6
Lehner, B., Messager, M.L., Korver, M.C., Linke, S. (2022). Global hydro-environmental lake characteristics at high spatial resolution. Scientific Data 9: 351. doi: https://doi.org/10.1038/s41597-022-01425-z
Purchase, C. (2018). A systematic review on the effectiveness of salmonid spawning habitat improvements, and recommendations to potentially increase productivity of depressed Newfoundland Atlantic salmon (Salmo salar) populations.
Wilkins, and Snyder. 2011. Geomorphic comparison of two Atlantic coastal rivers: Toward an understanding of physical controls on Atlantic salmon habitat. River Research and Applications.