Saving the Slope, and Consequently my Parents' Foundation

I am very new to all things permaculture and natural AG, working on a garden at our rental, but my first big project will be helping my parents keep their land on, well, their land.

They have a water-front property, right in front of a riverbend. They have some exposed patches of land that are obvious problems. The majority of their yard is covered in grass, including two intersecting slopes.

I have a plan to do a sort of semi-permanent terracing with natural materials until better soil can be built and soil health/fungal life can increase to help hold the slopes together.
By all means, comment away on these ideas, including any help with plant selection.

There are a couple of trees on the slope further away from the house, and I want to encourage them with some guilds or something, plant life that encourages soil and other plant health over time.

Then, there's the border of the property. They are losing what I consider a good amount of soil every year right off the edge of their lot. Beneath this tiny "cliff," are bare rocks, handy in this case for walking on when the water is low, but then jutting soil/grass/wild plant covered rocks above those. I imagine that it is only the mesh of roots that allows this clump of land to stay together. Still, There are many exposed roots, and I can see the sandy soil washing down with every light rain, or raised water line. It will cause dramatic change in just a few years, I think.  

My biggest challenges for planning are making the choices for products to invest in, including plants. I know I want more plants, with varying types and depths to the root systems, on the slopes closer to the house. We need to get something there before serious harm comes to the foundation of the home, but I am also wondering what can be done for the edge of the property near the water. When I look down over the edge of the lawn it is just a thicket of unknown plants.

Do I try to identify and save the best ones for erosion control? Do I keep whatever I can as nursery plants, and plant other plants that are stronger, and longer-lasting? (I don't think the soil can handle any digging of holes to plants adult plants, so I would be growing from seed or seedlings.) Should I also identify trees and plant new ones if there are (theoretically) better ones for this purpose? Do I aim to work with only native plants?

Their slopes seem very sandy, and even a few days after the rain has stopped, I can sink in a few inches walking down the slopes. Every time I step, there is obvious damage to the side of the slope and the grass planted there. The few small plants at the top, lining the path are starting to tilt to the side because their base is going out from under them. I believe there is a red clay right underneath much of the sandy top. Perhaps the quick filtration of the water through the sandy layer stops at this clay level...? They are in Texas, in zone 7b. The slopes could have ornamentals and, as long as they are attractive, edibles. These could be plants that require a little bit of year-to-year maintenance. The edge of the property would need to be pretty much hands-off for the rest of its life, excepting the planting of a few more plants here and there. It's dangerous to get to, and I can't expect my parents to do that work. It is also underwater from time to time throughout the year.

ANY thoughts, insights, advice, direction WELCOME!

Erosion you might do something about. Look around the "neighborhood" for ideas; others probably have a similar soil and plant environment. There are threads here about runoff  control and people may have some comments.

Pictures would help a lot to keep ideas on target.

But if you're losing land _because_ of a river, you have to get pretty serious if you want to keep it. If it's something that's ongoing right now and critical,  maybe best talk straight away with local "experts". Part of the "local" is because they can come and look close and personal and part is because they know what has been done in the area and what you can do legally and part is because they know _who_ might be available to do it. Maybe there is a river conservation group around,  maybe neighbors have had to deal with this, maybe you can find some engineers connected with the local highway department if there are lots of bridges and river crossing in your area. If you show up with a location (address, gps coords) and pictures and manage to keep it very informal and friendly, you might get a free consultation. Maybe. Find out where else this happens in your nearby area and what was done - and how/if it worked.

Investigating and asking locally is usually a good idea  for anything. Ask _everyone_, throw a wide net, get as many different opinions as possible.

But contesting land with big moving water is chancy. San Francisco throws a couple million$ a year at the beach 50 yards from their sewage plant, has been for about 10 years and THEY ARE LOSING a little each year. It's looking like they might have to rethink that facility in another 10 years; they already lost 50' of parking lot and a 4-lane road is now down to 3 lane. City of Pacifica just south of there is getting a little smaller each year despite dumping thousands of tons of big rock to protect the land.

If the river wants the land, you may be better deciding on a schedule and rear guard action rather than, at very great expense, trying to save what can't be saved. Again, what's happening locally?


Regards,
Rufus

Thank you so much for that. I have had it in my mind that anyone local or in any sort of authority would either not know how to do what we are wanting to do, or would be so skeptical and critical that they may try to stop us...I guess I am the skeptical one. I haven't even looked into who the experts are in the area. I will consider that.

I may be able to get decent pictures in a few weeks.

I was hoping to hear from someone with some insight or experience in building enough soil to make a difference, or maybe someone who can talk about experience with difference fungal inoculations and how some are more beneficial for holding the land together, or maybe about how one goes about choosing exactly which plants and how to place them.

There is a lot of information "out there," but I can get excited about a list of plants with supposedly amazing properties...and then draw a blank when I'm looking at the land and trying to draw up plans for it. I can't find a good resource for landscaping, the knitty-gritty details for planning a landscape, with all of these goals in mind, and from a permaculture perspective. Honestly, just a very informative and instructive book for landscaping from a permaculture standpoint whether on a slope or not would be great!

I've looked on other threads concerning slopes, but haven't seen these details being discussed. If I've missed some obvious resource, please point me to it!

I think building soil fast enough to fight erosion is...unlikely. Rock might help a lot, or a little...

More details about what you are facing might help generate more specific advice.

Without more details, I would probably be looking for perrenials with a mat-like growth pattern, and trees that might manage to sink deeper roots. Shallow rooted trees that get uprooted may worsen the problem.

Check to see if it is allowed to put in erosion controlling "sea wall" type construction, if so that will go far in preventing any more land loss.

Soil building is dependent upon organic matter being able to get into the soil, mulches do double duty since they not only buffer rain erosion but also leach organic materials down into the existing soil, enriching it and providing the foundation for the microbiome to flourish.

When planning guilds around preexisting trees, you have to first understand the needs of those trees (unless you aren't planning on keeping them), guilds do no good if they create stress on what is already there that you plan to keep in place.

Grass is one of natures best erosion proofing plants, it also sequesters mass amounts of carbon, provides homes for micro and macro organisms and adds organic matter as the hair roots sprout, die and decompose (this is a continual process with all plants, roots are born, live, die and decompose).

Redhawk

Switchgrass, a native, is one of the strongest plants to use to stop erosion.  It is nearly as strong as stone construction, plus has the other advantages Redhawk mentions. Personally I would plant a broad buffer zone of Switchgrass along the eroding area.  

The supplier I use:  https://www.seedsource.com/catalog/detail.asp?product_id=2005

Building upon other grass comments, you might take inspiration from beach preservation. In a lot of places, I’ve observed a very heavy rope like netting placed across front-line dunes. Beach grasses grow in the spaces. I’m guessing that these systems stabilize the sand while the deep-rooted grasses get established.

D

Hi Lanie,

If your parent's abode is in zone 7b Texas, then we are just due north of them by a few states (northern Minnesota).  We have almost exactly the same problem.....clay silty soils, house perched on the outside bend of a river, annual erosion eating away at the bank when running high, and trying to save what we have for the remaining years in this dwelling.  We are mixed about how much money and time we want to put into saving this house because the flood maps have been re-drawn following several years of above normal flooding.  The upshot being that our home is now considered to be placed in a "no build" zone.....so it would be pretty hard to sell when we need to vacate.

In the interim, I've been putting in some "supportive landscaping".....the pictures of which have been placed below.  Please note that I'm not an engineer nor have I consulted one in advance of these efforts.  The idea is simply to buy some time before the bank cuts too near to the house to do greater damage than it already has. (It is already evident that the weakening of the soil between the bank and the non-river-side of the house has caused sufficient pressure on the structure to induce a crack in the basement floor that parallels the run of the river.  If I roll a ball across the main-level floor from the river side of the house, it magically returns to me! :-) )  As for plants to aid in bank stabilization, we are just using what nature has provided (along with the rocks placed by the previous owners along the edge of the bank)....ash, box elder, elm, and some bank willows.  There is one hope in our favor here.....due to the flat, soft landscape, rivers here will cut bends until one day, and due to whatever natural force, the channel of the river cuts a new path.  Then the bend becomes an old oxbow, filling with water during flood season, but eventually silting in with time.  There are several of these channels already being tested by the river in the recent floods.

In the photos, you can see the proximity of the river to the house.  Clearly, this remains a work in progress.....  Good luck with the project.

Daniel Ackerman wrote: I’ve observed a very heavy rope like netting placed across front-line dunes.

Looks like that is available as "Jute Erosion Control Mesh" sort of a giant burlap.

Bamboo and willow rods, IMO, along with the mesh others mentioned.

Willow is probably a great idea, especially if you temporarily stabilize the slope through other means, like the rope. Bamboo can spread quickly, and their neighbors downstream might be a bit resentful. If they will grow in that climate, maybe consider grapefruit trees. When I was in Puerto Rico, we saw a lot of grapefruit trees planted along stream banks, and we were told that they were for erosion control. The side benefit was super tasty grapefruit. Other areas had bamboo, and it had grown by nightmarish proportions, choking out everything else.

Having had another look at the image posted, grapefruits and willows would be beautiful.

D

It sounds like you've got two problems.  The first is erosion from above—water flowing down the hillside and washing soil away.  You can do something about that.  The second is the river slowly eroding the bank from below.  Not too much you can do with that unless you're willing to spend some big bucks to engineer a solution using concrete or large stone erosion measures.

Regarding the first problem, I've had very good results with vetiver grass on a steep slope.  It puts down a thick and tangled root ball that sinks deep into the soil -- 5 feet or more.  I planted it on contour, with individual clumps of grass about a foot apart.  Over that first year as the grass grew and the clumps got much bigger, I was able to back-fill above it, creating a terrace.  In the following years, the grass continued to slowly spread outward, creating a thick "wall" of biomass along the slope, keeping mulch and soil from washing down the hillside.  Today, there is a thick wall of grass about 2 feet wide.  Every summer I hack it all back to about 18 inches or so, and drop all that mulch on the hillside below.  It's been a perfect solution for my situation.