Any thoughts on narrowleaf cottonwoods and cooling a river by planting tees over it?

Hi, sustainability student back again for some wisdom.
I have a Big Important Project analyzing how best to propagate trees along a river to shade and cool the water, with a focus on cottonwood trees.  I'm hoping to cover soil rehab with compost and cottonwood's plant and animal allies.  Covid-19 busted my plans of visiting relevant researchers and sites, so I have to restructure my project D:
The academic journals are a bit thin when it comes to this topic, so I wanted to know if anyone has any experience with planting trees along a river to lower the temps (or other reasons honestly), planting cottonwoods, soil rehabilitation, who gets along best with cottonwoods... tangentially related humorous anecdotes, I'll take anything at this point.
Thank you so much for reading.  I hope you're all staying safe and healthy.

The first thoughts that come to mind is the volume of water flow and the speed of water flow combined with the length and span of the planted area.  For example 200 feet of bank covered in trees with a high volume flow with a moderate speed is not likely to have any effect at all.  Whereas 20,000 feet of trees with a low volume of slower moving water may have quite an effect.  The distance between the trees would also make quite a difference as well, with 100 feet of open river water as opposed to complete canopy cover would make quite a difference in temperature as well.  

If the river is small and only 30 feet wide then you could cover most of it with canopy within about 30 years of Cottonwood growth, if the river is large and 100 feet wide then even a fully grown 50 year old tree isn't going to shade much water.  One would also have to consider the effects of more shade and cooler temps on plant life in the water as some plants do better in cooler temps and shade.  Doing such a thing might actually make it easier for certain unwanted plants to proliferate destroying habitat for other plants or animals in the ecosystem.  The shade could also potentially increase rates of mosquitoes or unwanted insect growth.

Is this about improving habitat for fish in a specific river?

The cooling of the river isn't what I'm analyzing, just the soil remediation, cottonwoods, and cottonwood sumbiotic relationship organisms.

Well.....
From a not really-permie pov.....
If your goal is to limit the chances of people cutting the trees for other purposes, than Cottonwood is ideal!
But if your intent has any kind of revolving usefulness beyond shade than its lousy.
Cottonwoods are an almost useless wood, close to impossible to split, have almost no BTU value, practically won't burn unless mixed with other woods. their seeding habits are great contributors to asthma (pollen load is horrific!), if whole logs are pressed into service they rot from the inside out, and they always rot. have almost no R value, if sawn makes a board that is prone to breakage, is heavy as hell, has no figure or attractive qualities, and finishes with any combination of polishes / stains / dies into something that is just plain ugly.

It may be noted that I am not really a fan of Cottonwood.

The only (anecdotal) value of Cottonwood that I've heard of is if you keep it moist it will last underground for a long time, I once saw a man request 3x10 planks for a septic top but never saw if it lived up to the hype.

I'd go for Black Locust (a nitrogen fixer), Willow, Alder (a smoking favorite), Maple (wonderful for any purpose, smokes well), or Birch (Cmon Birch Beer!).

Yes, the cottonwood is for shading purposes and habitat.  No lumbering involved.  They are chosen because they grow well next to a river.

Starlie Scarborough wrote:Yes, the cottonwood is for shading purposes and habitat.  No lumbering involved.  They are chosen because they grow well next to a river.

From what I can tell you are looking for information on the ecology and simbiotic relationships within a cottonwood forest in a river drainage region?

Cottonwoods do grow well beside water, as do it's close relatives the various poplars.

Another great tree capable of growing in and around water being the willows.  I have willows all around my ponds for shade.  At my last foster home we had cottonwoods around our 15 acre pond.

My brother in law rented some pasture for the last few years and it has a swampy drainage area and it is full of poplar and willow growing out of the standing water.  I thinned it all out for him a few years back and then milled it all into lumber.


The thing that grows the best in those environments around the trees are sedges and other water tolerant plants.  The sedges will be worldwide, but the type of water tolerant plants beyond that will change by climate and region.

As for non plant ecological footprint, there tend to be a lot of birds, amphibians, mosquitoes etc..  

These areas tend to have a very high organic content in the soil, the water movement tends to remove clays over time and silt in with organic materials.  This makes for a very organic rich soil that hold water well.

While I have been around environments like this all of my life, I have never really studied any of it, all I can give is some basics that I know for fact.  Honestly my attention was most always on not getting stuck and cutting trees...  Personally I love cottonwoods and have been trying to get some cottonwoods and poplars growing in the marshy area of my hay field by my ponds here on this farm.  My problem is that my goats tend to eat the bark on the trees faster than I can plant them.  I got rid of all of my goats two years ago though one escaped and stuck around and he is still eating all the trees that I plant here.  I planted another 20 poplars last fall and there is again no bark on them whatsoever.  I will be trying to shoot him again soon in defense of my trees and garden.

I don't doubt I can remember more with a bit of time, but that is about it at the moment, my thought patterns are not designed for this mode of thinking so I do not have most of what I have observed in memory when it comes to what you seem to be looking for.  Maybe something in here gives enough insight to get you headed in the right direction.  It is common out here on farms to have drainage and wet areas that are tough or impossible to farm and the government supports something called "riparian" zones in such regions of farms.  You may be able to find some information that is useful to you by studying "riparian" zones.