How to Control Erosion

Erosion happens when rain and wind wash and blow away the earth’s topsoil, making it impossible for trees and plants to grow, and leading to mudslides and clogged waterways. Erosion can turn once healthy, vibrant land into arid, lifeless terrain. Erosion is a common occurrence at construction sites and other areas where the land has been disturbed. The best way to control erosion is to restore the land to its natural state by planting groundcover and trees, which hold the soil together with their roots and prevent it from washing away. See Step 1 and beyond to learn how to assess your land and use the right control techniques to prevent it from eroding.

Understanding Your Land
Look for telltale signs of erosion. Erosion will look a little different depending on the natural features in your region, but there are a few fairly universal telltale signs. Look near areas where the land has been disturbed by construction or natural occurrences that might have washed away the soil. You’ll often find erosion near culverts, pipes that move water under a trail or road. [1]
Check for bald spots. Hillsides and slopes often have places where no trees or plants grow. You might see a buildup of soil below them.

Look for exposed roots. The soil might be washing or blowing off the top of roots that aren’t normally exposed to the elements.

Look for exposed rock that wasn’t there before. If you notice new boulders that seem to be getting bigger each year, the soil might be receding around them.

Look for channels and gullies. These are areas where water and wind have been able to cut through the soil, forming shallow channels or deeper gullies. This is a major sign of erosion that can lead to big problems if left unaddressed.

Go outside when it’s raining. A heavy rain will indicate where the water is forming channels and washing away the topsoil. You need this information in order to know how to best protect your land from further erosion. Here’s what to look for:
Watch where the water runs. On healthy land, the blow of each raindrop is absorbed by a plant before it hits the ground, where it is then quickly absorbed. In problem areas, where there’s no groundcover, it pounds the ground and breaks up the soil, then washes it away. Watch which direction it seems to be running and where it collects.

Look for standing puddles. Big, muddy puddles where the water isn’t being absorbed correctly could be a sign of erosion in that area.

Look at the color of the water in streams. In a healthy area, rainwater should be quickly absorbed into the ground and surrounding streams should run clear. In areas with erosion, you might see the streams get very muddy from soil runoff during a rainstorm.

Make a plan. The only real remedy for erosion is returning the soil to its natural state by making it hospitable to healthy vegetation growth again. The process by which you go about this task will be different depending on the state of your land and the location of the erosion.[2]
If you have light sheet erosion, which is erosion on a relatively flat area of land, you can plant vegetation right away. You’ll start with temporary groundcover to hold the soil together, then gradually move on to adding native plants that will restore the land to its naturally healthy state.

You may want to protect certain areas from further erosion by erecting barriers, such as rock piles.

If you have channels on your land, they’ll need to be broken up in order to prevent them from creating gullies.

If you have gullies, it will be necessary to use structures and digging techniques to support the soil before you can plant anything. If you try to plant seeds in a gully, they’ll just wash away in the rain.

Call the Soil Conservation Service to ask for advice. If you’re not sure how to proceed, the Soil Conservation Service is a really good resource. Call them and discuss your situation over the phone. You may also ask them to dispatch an expert to help you determine the best way forward.

Using Plants to Restore the Area
Plant emergency cover. You can do this right away on bare soil that is relatively flat and doesn’t have deep channels or gullies. Emergency cover plants are usually grasses or other groundcover plants that grow very quickly, putting down thick roots that will hold the soil together so it doesn’t wash away during the next rain. Check with your local nursery to figure out which fast-growing ground covers work well in your region. It’s best to plant a mix of plants, rather than just one, so that you have backups in case one type doesn’t take hold. Buy your seeds, then proceed as follows:
Use a hoe or garden rake to work compost or manure into the soil. You can also use a light fertilizer if you want. This will help nourish the seeds and give them the best chance of growing.

Broadcast the seeds a few days before rain is expected. Most grass seeds don’t need to be buried in the soil, so you should be able to simply broadcast them over the top.

Add a layer of mulch or brush mats. If you planted the seeds in an area on a slope, or in a place where you fear they might get washed or blown away, you can protect them by adding a light layer of mulch. Use brush or another light material that won’t stifle the seeds. For hillsides and places where you fear the mulch will wash away, lay a brush mat over the area to protect the seeds.[3] Here’s how to make one:
Lay out long pieces of brush in a vertical pattern.

Lay more brush pieces horizontally across the vertical pieces.

Attach them with small pieces of thin wire or twine.

Make the mat as small or large as necessary, then lay it over the ground.

Plant structural trees. Once the groundcover has grown up healthy and strong, strategically plant structural trees that will root even deeper in the soil to hold it together for a long period of time. Space them so that the entire area under threat will be served by the tree root system. You don’t want to choose trees that require digging a big hole and disturbing the soil, because it’s still too fragile for that. Rather, choose a type of tree that roots easily from a cutting and grows quickly.
Willow trees, black locust trees and elderberries are good selections for this purpose.

Growing a line of trees around a farm, if possible, can be a good idea for preventing most mechanical methods of erosion.

A lot of afforestation (also known as reforestation) activities are being managed on a global scale to preserve the soils.

A special modification of this is the riparian vegetation that is grown at the interface of any land and water line. The intention is to prevent the soils from migrating into the water line, or to prevent the water from seeping onto the land and carrying the soils away with it.

Plant permanent vegetation. After several seasons, when you’re confident the area is stable enough to house more permanent vegetation, it’s time to plant native species in the area. Talk with an expert at your local nursery or do online research to find out which plants and trees grow well in your region. It’s important to stick with native species, since they’ll have the best chance of surviving and preventing further erosion from occurring. The permanent vegetation should be a combination of the following: Trees




Other species native to your area

Erecting Barriers to Slow Runoff
Choose the appropriate kind of barrier. Erosion controls often involve the creation of a physical barrier, such as vegetation or rock, to absorb some of the energy of the wind or water that is causing the erosion. On construction sites they’re often implemented in conjunction with sediment controls such as sediment basins and silt fences.

Build retaining walls. These address both kinds of soil erosion control issues — both preventing it and fixing an existing problem.

Use rubble. In some places, the shorelines of rivers, streams, etc. are mechanically blocked by depositing some kind of rubble at the land-water interface. This becomes a mechanical blockage, preventing the water from eroding the soil on the land. This kind of a barrier is colloquially called rip rap.[4] Sometimes, wire baskets are specifically designed and erected at the land-water interfaces, and these are known as gaboon strips.

Employing Digging, Damming, and Grading Techniques
Consider digging contour trenches. This technique is useful if you’re worried that water runoff will wash the seeds and mulch away down a hillside. A contour trench is a shallow trench dug along the contour of a hillside so that it runs perpendicular to the flow of water. The purpose is to catch the water and give it time to sink into the soil before it runs off the hill. Dig a few short trenches around the side of the hill. Each one should be deep and apart.[5]
Groundcover can be planted below the trenches and this will protect them from being washed out.

Break up channels. A channel is a spot where running water cuts into the soil and forms a rut. It gets bigger with each rain, and can eventually form a gully, which is much harder to address. Stop a channel before it turns into a gully by using a hoe to break it up. Fill it in with compost or manure and rake the area so that it’s flat and smooth. This will prevent future rainstorms from cutting further into the soil in the area.
After breaking up a channel, replant it with groundcover, structural trees, and native vegetation according to the system outlined above.

Reduce the flow of water into gullies. Gullies are channels that have gotten out of control and have cut deep into the earth. Once enough topsoil and subsoil has been washed away, there’s nothing keeping heavy rains from washing out thousands of pounds of soil every season. When a gully cuts below the water table, it sucks away the water from the surrounding area, killing trees and vegetation on either side. Fixing gullies is a multi-step process that starts with reducing the water flow.
Reduce the amount of water pouring into gullies by addressing the situation at the top of the gully. There are probably bare spots and other signs of sheet erosion that you can work to fix by planting groundcover immediately. This will help the water absorb into the soil instead of flowing into the gully.

While some people recommend building diversion channels to make the water flow elsewhere, this usually just creates a new problem – namely, a new channel that could become a new gully. It’s better to work on fixing the gully once and for all.

Build a check dam to stabilize a gully bottom. In addition to controlling water, it’s important to stabilize the bottom of the gully and keep it from getting any deeper. To do that, you need to build a check dam, which is a small series of dams that slow the gush of water so that the gash in the ground begins to build back up.
Choose your dam material. You can use rocks, poles, planks, or another sturdy material. You can pack holes with straw or brush. Each dam will be about high.

Dig the first dam into the sides of the gully. Construct your dam by placing material across the gully so that it touches the bottom and digs into the walls on either side, so that the water can’t flow around it.

Make a notch in the middle. The middle of the dam should have a space where water can get through; otherwise it’ll just find a way around the dam.

Make a rock apron on the other side. The water needs a place to land on the other side so that its impact is reduced. Put a bed of rocks in front of the dam.

Erect more small dams to form a series. Depending on the size of the gully, put in several more dams. The system works most effectively if the dams are close together, so the water can’t pick up much speed in between them.

Grade the slopes on the sides of the gully. Once your check dam is in place, you need to start leveling out the gully. Use a shovel, a pick axe or another appropriate tool to begin knocking dirt from the sides of the gully into the bottom. The aim is to gradually level the gully by grading the sides so that the bottom fills in over time. It can take weeks or even months to finish the job, because each new rain is a bit of a setback.
Monitor the progress of your work each time it rains. If more dirt slides down the sides of the gully, keep working to level them to a gentler angle.

Make sure the check dams are working sufficiently. You might need to add more small dams, adjust the length of the sides, replace the aprons, and so on to ensure that water isn’t still cutting the gully deeper when it rains.

Plant the area. When your dam and leveling work has sufficiently slowed the gully’s growing cycle, you can plant it using the process above. Start with groundcover, use fast-growing trees to stabilize the area, and after a few seasons of healthy growth, plant native species that will return the land to its natural state.

Preventing Erosion
Minimize land disturbance. As much as possible, try not to disturb the soil in the area under concern. Removing trees and plants, driving heavy equipment over the area, clearing an area larger than you need, and many other practices used on construction sites can lead to erosion.[6] Don’t till. The predominant technique agriculturists use for erosion control is the no till method. This method, also known as conservation tillage, is farming practiced with a minimum amount of tilling. The tillage process, while enriching for the crop, also displaces the soil layers and makes it loose. Such a loose soil layer is more prone to erosion. Hence, agricultural practices that can produce a good crop without necessitating tilling are being put into use as a measure for erosion control.

Consider contour farming. Contour farming is very commonly practiced on sloping land areas. Here, planes of land are constructed by cutting off the land according to its contours. Small plane walls, called bunds, are erected along the contours of the land. Agriculture is practiced in the areas that these contours create. The effectiveness of this form of agriculture lies in the fact that the horizontally flat lands, together with the bunds, slow the runoff of rain water considerably.

Enrich the soil. Erosion control is not just about preventing the soil from getting washed or swept away. Methods to enrich whatever soil is present are also covered under erosion control practices.
One example is keeping the land fallow, like most Asian farmers do. Here, after three or four successive seasons of farming, the land is planted with a cover crop for one season. During this time, the soil can regenerate, gaining back some of the nutrients lost in the previous seasons.

Another method is to grow a single crop before the main cropping season in order to provide nutrients to the soil. Growing a leguminous crop can provide nitrogen to the soil because these crops can harbor the beneficial nitrogen-fixing Rhizome in their root nodules. Another example is Mucuna pruriens, a crop that adds phosphorus to the soil.

Use mulch and compost. Methods like adding mulch, fertilizers, etc., all contribute to increasing the productivity of the soil, and are also covered under erosion control.

Sources and Citations
Cite error: tags exist, but no tag was found



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s