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Examples of permaculture solutions to river flood control?  RSS feed

 
Posts: 4
Location: Rocky Ripple, IN
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Aloha Permies! So grateful to have found this amazing community of people working with and for the earth! And for the wellspring of knowledge and experience y'all are sharing!

I live in a flood plain and currently, my town and city government are trying to get us flood protection. While my neighbors and I do want that safety for our community, we believe that the way they are going about it would be disastrous environmentally, socially and financially. At present, we have an earthen levee which has prevented flooding for about 75 years (WPA era). They want to put in a flood wall, driving sheet piling down 30-40 feet to the bedrock and adding concrete walls on top. They would also strip all the trees and vegetation along the river and cover the bank in rip rap. They propose to bring equipment in via the river, which is hard enough to navigate with a canoe in many places, as it can be quite shallow and rocky. This seem like it would be extremely harmful, if it's even possible. Currently, our stretch of river (about a mile) is a beautiful, rich riparian corridor. This would be devastating to wildlife and would destroy the river we love, along with all its valuable ecosystem services. Due to the nature of the proposed funding mechanism, it would also usher in gentrification and force many residents out of their homes, due to greatly increased property taxes. There is a whole host of other problems with their proposed wall, which I can elaborate on if needed. However, I would like to focus on solutions. Clearly, my neighbors and I do not find the proposed solution to be an acceptable one on many fronts. We have been communicating this to our representatives without much luck. The city is currently working on initiatives to be more sustainable and environmentally responsible and we are hoping that if we can offer better ideas on how they might approach flood protection and watershed management, perhaps we can avoid this wasteful, destructive wall and preserve our river. It's also worth noting their proposed plan costs 65 million which the city doesn't really seem to have.

What I am hoping y'all can help me with is finding solid examples of more sustainable solutions to flood control. I have found many amazing examples of water harvesting earthworks and plantings being used to mitigate stormwater. For example, Village Homes in Davis, California and the work of Brad Lancaster and community in Tucson, Arizona. However, these are very different climates than here in central Indiana and are being used for a different application. Our annual rainfall approaches 40 inches here and the ground is often frozen in winter. These things make me wonder if water harvesting earthworks would be feasible as part of a solution. I know I have read that in many places, they simply give the river more room to spread out. Some places, they have routed the water somewhere less harmful during flood events. For example, a quarry or farm field and then compensated the owners for any loss. I'm wondering if there's some way to combine that strategy with water harvesting earthworks to get us flood protection without destroying the river and the town as it is. Ideally of course, everyone along the river would work together to ensure they aren't contributing to runoff which is causing these problems, but I know that would take a lot of work to make reality.

I know this is an extremely complex and ambitious thing to try to approach, but my heart cannot bear the idea of what they wish to do and I have to try something. There must be some way for people to live in harmony and balance with the river and I want to find it. So please, bring on examples and any thoughts you may have to help. The Wapahani river, myself and my community would be most grateful. Thank you!
 
pollinator
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Management of flooding really needs to be done on a regional basis.  It's very difficult to do it on a small neighborhood or individual home basis, however, properties which have focused on water management can sometimes get through these events with minimal damage.  Here's Geoff Lawton's farm in flood:  


He used to have a video of a 2 acre homestead in Minnesota next to a flooding river, which had structures to pacify the water and protect the homestead as the water rose, but it doesn't seem to be on the internet anymore.  The promo video is all that remains:  


Peter Andrews has done extensive work revitalizing and managing eroding and flooding waterways.   [youtube]https://www.youtube.com/results?search_query=peter+andrews+natural+sequence+farming[/youtube]

Brad Lancaster, whom you mention, has a tremendous amount of information about water management in his book Rainwater Harvesting for Drylands and Beyond, Volume 2

Your city's plan is insane, in my opinion, and if at all possible you need to get a water management expert such as Brad to come to your city and dissuade the powers that be from pursuing this idiotic idea.
 
Posts: 50
Location: East tn
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Sepp holzer has some interesting content on this topic.

His general take is that low lamds belong to floodplains and that roads and buildings dont belong down there.

Not sure the level of building that is exposed, but 65 million would buy a fair bit of land and move a fair bit of houses.

Alternatively, for 20k each(ish) you could raisehouses onto stilts allowing occasional floods to flow through.

Probably not what you were hoping to hear, but given climate extremes, the bold move may be the best move.
 
Heather Olivia
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Location: Rocky Ripple, IN
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Thank you both for the replies!

Tyler, I totally agree that a regional approach would be the way to go. Asking my city and those around it to completely rethink how they manage their watersheds is not something I know how to even begin doing. But I will be looking into it, once the immediate danger of this poorly thought out plan is past. The video of Geoff Lawton's farm in flood is pretty incredible. I haven't heard of Peter Andrews, but will have to check it out. Thanks! I have Brad's first book, need to order the second.
Hearing someone else express that it seems insane is more helpful than you might realize. I was actually contemplating contacting Brad Lancaster or someone similar, so I will be doing that soon.

J Davis, I agree that rivers need room and for humans to develop flood plains isn't a wise move. Of course, then I also moved to one...but I accept the risk and we are making efforts to make our home at least more resilient if it does flood. There are about 300 homes in the town. Elevating them seems like a great idea, which we have repeatedly suggested, but for some reason hasn't been seriously considered. Probably because the company they "consulted" with on this is one that would stand to profit from building a flood wall.. I appreciate your honesty. I think it's important to be realistic.

I should clarify, while I am looking for long term solutions to address this issue within my community, right now my main goal is to find evidence to convince my city government that this is a bad plan so they put the brakes on it. My neighbors and I are attending the first of three public hearings on it tomorrow. With any luck, the board of public works will be reasonable when presented with what we already know about how ridiculous this situation is and the wall will be out of the picture. Once I know the river is safe, then I want to focus on how the town can work to protect residents and homes in a sustainable way. So I'm open to hearing all thoughts, but would most appreciate those that might help stop the insanity at the moment.
 
Posts: 16
Location: Ontario - zone 5b
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My background isn't hydrology and I can't provide engineering advice, but I do deal with hydrlogists/hydrotechnical engineers on occasion, but I'll try to provide some perspective on why I think they are doing this, as I can see why you are concerned.... I am afraid I'm going to agree mostly with your engineers though. If you make it to the bottom of this long post, I have some links that might help you.

First - the community probably shouldn't have been been allowed to have been built there. It's quite obvious from the satellite imagery that it's in a flood plain area (which is why you have your berm). Rivers flood on an annual basis, but also have bigger floods occasionally - there is the 20 yr flood, the 100 yr flood, the 300 yr flood, the 1000 yr flood, etc. These are reflections of the statistical likelihood of a flood on any given year reaching a certain height. These numbers and heights change as more information comes out and as the climate changes, and they collect more data (how do you predict a 100 year flood with <100 years of data points? or the 1000 year flood with 200 years of data?). The US actually does a fairly good job of doing this compared to Canada.  

Unfortunately, exacerbating the problem with these changing data points for weather (as you rightly point out) is the build up of cities, which causes water to drain more quickly into the watershed, exacerbating flooding. Can we fix that? We can help (permeable pavements, including catchment ponds in neighbourhoods, keeping wildlands, underground water catchment... etc), but it would take a big code change, and many years to retrofit (should we, is not a question asked here, but... I have some strong opinions ont that one too). So... not a short term solution to your problem, which is that on any given year you have a 1/100 chance of having your house wiped away in a flood. Also, river systems are very complex and operate as a system - meaning if something changes upstream (for example, someone else put in a flood wall), then there are downsteam effects (because there is a new flood wall upstream, the river can't flood in that area, so there's more water downstream to flood things and the flood elevation rises). Flood modelling is complicated, and I am glad I don't do it :)

How I think they thought this through:

So - best solution for the river's health perspective and engineering headache perspective - take away/remove everything in the flood plain - including your houses. This will create a rich riparian environment, and the river will meander and change it's course and never flood anyone (probably most likely, if we figure out the flood plain correctly). Which, unsurprisingly, isn't usually a popular option.

Next solution - raising the river banks - is what someone did to build your berm. OK, good solution, if you build it high enough. Unfortunately, soil doesn't stack vertically. So they would have to expand the width of the berm as well as the height. It's a bad idea to encroach on the existing river (which would narrow it and increase velocity). So they'd have to widen it back towards the houses. Which would probably mean they'd have to tear down all the houses on the river bank. Not a great solution.

OK, so assuming you want to keep all the houses, you have to build vertically, and access from the river. That probably means some sort of a flood wall. The engineers will have done some calculations and determined that the velocity of the water is high enough that there is a risk that water velocity will be fast enough that the river banks will wash away (hence the riprap).

Some other ideas:

As for your other idea - The idea of catching water to divert the flood is an interesting one, and can be really effective. it's been done large scale elsewhere. Google the red River Flood Way which protects Winnipeg. I think there's another one planned for Calgary. The issue with these solutions is, unfortunately, you still have to put the water somewhere and you usually end up flooding someone else's home/farm etc, and those people are usually not pleased about sacrificing their property to save yours. So yes, a potentially good solution if you have somewhere uninhabited to store/route the water, but also potentially a really expensive one in a built up urban and suburban area.

I think you are also concerned about maintaining the aquatic environment and still being able to use the river recreationally... I really don't know the particulars of the project (more than a quick google), but would be curious if there could be a compromise/hybrid solution - for example, installing a wall but then restoring the river bank and shoreline and stabilizing them using tree trunks and vegetation. Usually there's a limit to the water velocity for which this is feasible, but if it's in the overlap zone between riprap working/vegetation working, you might be able to sway them in that direction. I don't know the US laws for environmental protection, but it's really hard to get permitting to disturb a river in Canada, and usually they really like you to put it back the way you found it or better. I really hope you get a chance to have a productive talk with the engineers and have someone explain the alternatives they have considered, and you get to ask questions about why and how.

A few links that might be interesting for your discussions:

https://www.fema.gov/pdf/about/regions/regionx/Engineering_With_Nature_Web.pdf <- explanations on why riprap is bad, and plants are good, and some design information.

https://www.thespec.com/news-story/9100831-dead-christmas-trees-find-new-purpose-in-hamilton-harbour-wetlands/ <- a small scale project near me

http://www.dfo-mpo.gc.ca/Library/277708.pdf <- a Canadian guide for more natural stabilization.

Good luck! I really respect your determination to look deeper into this and try to find alternatives.
 
Catie George
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Oh! And I'd suggest using the terms "water quality"(check if the water intake for your city is downstream?) "fish spawning grounds" "soft engineered solution" "recreational value" "city aesthetics" and discussing maintenance costs.  If riprap is being used due to water speed, you may find some information regarding using boulder baffles, log jams, gravel bars, etc to slow water and prevent scour. It's easier to engineer riprap or concrete wall than a functioning more natural system, but on a natural river I think it's probably worth the time to do it right.
 
Mother Tree
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Sepp Holzer designed a water retention landscape to rehydrate the landscape and prevent flooding in Tamera in Portugal.

There's a longish thread about it here - Tamera and their water retension landscape

 
Posts: 2079
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I didn't see this touched on above, but one of the major problems with a plan as proposed is that it will move the water downstream more rapidly, and increase the intensity of flood events downstream from you. This is why planners should be looking at whole watersheds, not simply play whack-a-mole with wherever the most intense problem is.

Here in the UK there are projects looking at whole watersheds that are both incredibly cost effective and environmentally friendly. For example, reforesting upland areas drastically reduces peak water flows during rain events. Frequently this is farmland that is, at best, marginal.

What Nature Does For Britain is an excellent book that looks at this, with other things. It is written from a UK perspective, but many of the lessons are universally applicable.
 
pollinator
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This may sound a bit off the wall, but the city where I live had major flooding problems and came up with a solution in the mid 90s that so far is working pretty well. The areas where the floods tended to be the worst and most devastating were along a river that was basically a dirty creek. The surrounding areas were de-occupied (purchased by the city, residents directed to new public housing) and set aside as park areas, all featuring large "linear ponds", which basically become rivers during floods. Water is routed into these ponds from around the city. Large trees were planted along these areas to soak up more volumes of water and have less runoff.
They apparently did not deepen the river channel, but rather looked at wider areas along the riverbanks accommodate major volumes of water a few times a year (within the parks, it doesn't bother anybody or cause major damage). The ponds never dry out, when it gets really low it's down to the small creek volume again, but the trees around help maintain it green and the parks are an asset to the city.
This is an almost absurdly simplistic summary of the situation, but it's been pretty widely publicized (even though it is not perfect by any means, there are still always flood issues, but mostly in other areas that were not yet populated when this plan was put into place.). you can read more about it here. http://i2ud.org/2013/08/flood-management-in-curitiba-metoropolitan-area-brazil/
 
Tyler Ludens
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Michael Cox wrote:I didn't see this touched on above, but one of the major problems with a plan as proposed is that it will move the water downstream more rapidly, and increase the intensity of flood events downstream from you. This is why planners should be looking at whole watersheds, not simply play whack-a-mole with wherever the most intense problem is



This is a very important point.  The "traditional" city approach to rivers is to channelize them (remove vegetation and line with concrete or riprap) which not only destroys the ecosystem but make flooding much worse for everyone downstream.

Many communities with channelized rivers are now trying to remove the concrete and bring native vegetation back.

Here are some articles:

https://www.americanrivers.org/conservation-resource/daylighting-streams-breathing-life-urban-streams-communities/

https://www.theguardian.com/cities/2017/aug/29/river-runs-global-movement-daylight-urban-rivers

https://e360.yale.edu/features/restoring_the_los_angeles_river

http://www.ecrr.org/RiverRestoration/UrbanRiverRestoration/tabid/3177/Default.aspx
 
Heather Olivia
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Thank you all for your perspective, examples and information! This stuff is amazing and I was able to use lots of it to back up what I wanted to communicate to the Board of Public Works. The real life examples are especially inspiring and encouraging to see. I apologize I haven't been keeping up with this thread better. Since I last posted, the Board of Public Works had their hearing and voted. Several of the board members heard and shared our serious concerns and questions. Two of five voted no, so there is a continuance! There will be another vote Wednesday. Apparently, this is an almost unheard of occurrence for something to not just sail through. So we've been researching, strategizing, writing a press release and emailing the board and others basically non-stop. Plus we're currently remodeling our house and trying to prep the garden for spring. So my brain is pretty much melted.

I didn't see this touched on above, but one of the major problems with a plan as proposed is that it will move the water downstream more rapidly, and increase the intensity of flood events downstream from you. This is why planners should be looking at whole watersheds, not simply play whack-a-mole with wherever the most intense problem is.

Here in the UK there are projects looking at whole watersheds that are both incredibly cost effective and environmentally friendly. For example, reforesting upland areas drastically reduces peak water flows during rain events. Frequently this is farmland that is, at best, marginal.

What Nature Does For Britain is an excellent book that looks at this, with other things. It is written from a UK perspective, but many of the lessons are universally applicable.


I wholeheartedly agree and have been repeating this point. There are multiple places down and upstream of us where there are flooding issues and this seems completely irresponsible to exacerbate them. I made the suggestion that a whole watershed approach was needed to truly address these problems at the last hearing. The engineer who's running this dismissed me, saying that was impossible except in very small, rural situations. I don't believe him. I also highly question whether the approach they are suggesting here (clear cut, sheet piling to bedrock and riprap on banks) would lead to landslides which could dam the river or at least, temporarily increase flood risk here by destabilizing the berm. The banks of the berm are very steep in places and currently well secured by trees. This seems like yet another serious problem set aside to "deal with later".
Book ordered! Looking forward to reading it.

Unfortunately, exacerbating the problem with these changing data points for weather (as you rightly point out) is the build up of cities, which causes water to drain more quickly into the watershed, exacerbating flooding. Can we fix that? We can help (permeable pavements, including catchment ponds in neighbourhoods, keeping wildlands, underground water catchment... etc), but it would take a big code change, and many years to retrofit (should we, is not a question asked here, but... I have some strong opinions on that one too).



I would be very interested to hear your thoughts on the question of "should we".

A few links that might be interesting for your discussions:

https://www.fema.gov/pdf/about/regions/regionx/Engineering_With_Nature_Web.pdf <- explanations on why riprap is bad, and plants are good, and some design information.

https://www.thespec.com/news-story/9100831-dead-christmas-trees-find-new-purpose-in-hamilton-harbour-wetlands/ <- a small scale project near me

http://www.dfo-mpo.gc.ca/Library/277708.pdf <- a Canadian guide for more natural stabilization.

Good luck! I really respect your determination to look deeper into this and try to find alternatives.  



Thank you! These are gold! I especially like the last one. So many cool techniques!

Thank you again to all! Hopefully I shall have good news on Wednesday and our community can get to work on finding a sustainable solution instead of fighting this crazy plan! Prayers for the water welcome and appreciated!



 
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