Shoreline Erosion

[BadBass]

I had interesting thought the other day while out. I was fishing down out Scottsboro where I have fished all my life. The thing i noticed was the loss of shoreline at the entrance to Roseberry and the along the islands in the main river channel. Well okay if not protected soil shorelines will eventually erode away; however, something that i have noticed is that the rate of erosion has sped up of the last few years. The other thing i have noticed while fishing was the amount of sediments disturbed by the the large wakes created by OVER-SIZED boats. While I was fishing the several smaller boats (bass boats, cruisers, jet skis, etc...) passed by but the wake size and disturbance was minimal. But when 1 single over-sized boat came through throwing a very large wake (broke over the bow) large amounts of sediments were generated. The thing about the erosion at the entrance to roseberry is that is appears to coincede with the construction of the larger marina at the county park. Another look at my theory is Mud Creek entrance from the river. In the spring time, the creek gets lots of traffic; however, the shoreline is not eroding at near the rate of the area. Has anyone seen this effect at other places?

Okay, here comes the civil engineer in me. It would be nice if a governing agency would fund a study to develop damage factors of different style and size boats, similar to damage factors of developed for highway trucks. These factors could be used in determining rates of erosion, areas that require shoreline protection, or possibly applying appropriate tax rates to vessels in funding shoreline protection protects.
Yall guys tell me what you think, before approaching people with this concept?

 

[Guest]

IMO
1) Shoreline erosion can sharply be reduced by having buffers along the shoreline, but most landowners would rather cut down trees/mow their grass than have a strip of native trees and plants blocking their view.
2) Small boats can cause just as much erosion as large boats. The more important factor is how often the shoreline gets pounded by waves, not the size of the waves. Also lots of smaller wakes will eat out and undercut the bank leaving in danger of a collapse from dropping water (winter pool) or from a large wake.
3) The waterlevel changes from winter pool to summer pool and back to winter pool cause more erosion than all the wakes during the summer months.

 

[harbuck handyman]

I have definately noticed a significant size increase in the average pleasure boat ove the last few years. A lot of them are actually off-shore boats. Taxation for designated purposes tends to go into the general fund and is seldom used for the reason it was supposedly collected for and would be applied to all recreational boaters regardless of craft size.Commercial vessels would ,no doubt, be exempt. Therefore ,I don't believe increased user fees would help.Educating property owners about how and why to invest in shoreline stabilization might be a better route.

 

[SeqBass]

I agree with hardbuck. Educating the land owners along the shorelines would be a great help.

 

[BigFishGuide]

Believe it or not there use to be some islands on the upper side of Bennetts Lake at the green day beacon across from the rock quarry. They are all gone now due to erosion from barge traffic, pleasure boaters and bass boaters. All that's left is a shallow bar and a ton of stumps. Wish TVA had of rip raped them and saved them.

 

[SeqBass]

I believe it Berry. Wouldn't doubt the captain for a second....

 

[xroadsbasser]

Berry, your showing your age!!!!!!!!!!!!

 

[Guest]

BigFishGuide - 9/7/2007 12:45 PM]...Wish TVA had of rip raped them and saved them.

Rip-rap in some applications may excellerate erosion. The hard rocks forces the power of the wakes into the narrow areas between the rocks. The inbetween area, due to the concentrate flow, then has more erosion than pre-rip-rap area would have. Often the erosion is not noticed, because more rocks are dumped on top when the 1st batch of rocks start to slump.

I do not know the specific area you are talking about but this might be the case (or it could be someone didn't want to spend the money protecting the islands).

 

[Carl Guffey]

When rip-rap is applied or installed correctly, it works. A mat of flow-thru filtration fabric must be placed with one side or edge of material buried below winter pool and the opposite edge buried at/or above full pool. The best form of erosion control is native aquatic vegatation, bar none.

 

[BadBass]

Good thoughts. There are many, many factors in erosion along. Some of which yall have mentioned, but there's even more if your interested in a lecture of geotechics and surface water hydrology. Let me know if anyone is interested. Here's the thing on this there is really no data on the size and energy of the waves that some of these vessels creates. Equations and design variables exist for determining wave heights created by wind speed and propagation length. Yeap one thing about rip-rap is alot of time it is not designed property. Natural vegetation is always best. Taxation is never good. Think about how many times a dollar gets taxed.

 

[SpurHunter]

Lots of good thoughts on this post!

 

[rsimms]

xroadsbasser - 9/7/2007 1:44 PM

Berry, your showing your age!!!!!!!!!!!!

I'm a lot older than Berry. I remember those islands when they were much larger. The main Pryor Island (South end still exists), used to extend as a solid island nearly 1.5 miles to the North. It was a great "stake out" point for game wardens who wanted to watch what was going on.emoBigsmile It will be completely gone soon. And that is the exact island I was thinking of when I wrote about beavers increasing erosion problems in the story posted in another thread:
http://www.chattanoogafishingforum.com/forums/thread-view.asp?tid=12299&posts=18

The Bennett Lake and Mullens Cove Islands maintained their shorelines reasonably well until the late 1970's and early 1980's. That's when the beavers really came on strong and started digging dens every few yards in all those islands.

I miss the islands... they provided some great duck hunting opportunitites that are gone now. And I admit I have mixed feelings about whether rip rap would have been the answer. Obviously government wasn't going to spend that kind of money to protect natural resources. They'll usually only do that if high-dollar homes are at risk. Or "federally-protected archeological resources" in the case of Moccasin Bend.

However to keep from being a hypocrite ... I must maintain my strong belief that we should simply "let the river be a river."