According to Ecosystem Marketplace, ecological restoration is a 25 billion dollar industry. Stream restoration in the United States alone makes up more than $1 billion of those $25 billion. Clearly, the U.S. believes that stream restoration is vital.
But why is stream restoration important? Stream restoration is important because it helps stop erosion as well as sedimentation in streams. This is paramount because sedimentation lowers the water quality of the stream and erosion leads to loss of land.
Increased sedimentation can often lead to a reduction in the size of a stream. Sedimentation can ruin recreational boating and fishing areas within the stream. An increase in erosion, on the other hand, can take land away from nearby residents and can threaten nearby bridges and roads.
Unhealthy streams can lead to the destruction of natural wildlife habitats. Fish and other aquatic animals flourish in good streams but can die rapidly when the stream’s natural equilibrium is damaged. The absence of wildlife often leads to further stream degradation, making future restoration efforts even more difficult.
How Are Streams Damaged in the First Place?
Before discussing how streams are restored, it is necessary to address how they can be damaged. Streams can be damaged in many ways, and by a wide range of external influences, including:
- Natural Disasters
Humans can damage streams directly or indirectly through urbanization, property development, and over-fertilization. Direct human intervention can occur when stream banks are covered in concrete or when culverts are created underneath bridges. These issues are easily seen by both professionals and non-professionals. Indirect human intervention is less apparent and is often overlooked.
For example, an area’s urbanization creates hardscapes that can lead to a dramatic increase in stormwater runoff. If stormwater runoff isn’t adequately managed it can quickly enter local streams. The dramatic increase of water into the stream causes it to flow faster and leads to flooding, which causes erosion and sedimentation.
Even over-fertilization can upset the natural balance of a stream. For instance, fertilizers can cause native vegetation to grow too fast in and around a stream. Massive unchecked plant growth can slow the stream down to a point where erosion is non-existent, and sedimentation is far too high. The stream then becomes unbalanced and the effects can be observed throughout the stream.
Local Animal Populations
Animals can also cause imbalances in a stream. Large numbers of grazing animals could reduce or even eliminate the native vegetation growing along a stream bed. Without natural plants for protection, the stream banks can quickly fall victim to erosion.
Unfortunately, animal-induced imbalances are also commonly caused by human activities. For instance, the deer population may be too high in an area because humans eliminate their natural predators. In other cases, farmers may have brought large numbers of grazing animals to an area.
Natural Disasters and Weather
Natural disasters such as landslides, earthquakes, and even wildfires can damage streams. For example, a landslide may force rocks and debris into part of a stream, slowing down the flow of water and increasing sedimentation in the process. On the other hand, a wildfire could destroy all the natural vegetation in an area, causing stream banks to fall victim to erosion.
Even the weather can greatly affect a stream. Heavy rainfall can flood streams while droughts can slow them down. High winds can damage stream banks, and fast-melting snow and ice can push water into a stream too quickly.
Fortunately, the consequences of these issues can be repaired, and many of them can be prevented. The key to achieving this is by using proper stream restoration techniques.
What Exactly is Stream Restoration?
Stream restoration is the act of restoring the balance of a stream so that the amount of erosion equals the amount of sedimentation into and out of each area of the stream. The restoration process can be done in many ways, and often makes use of several different techniques.
For example, repair steps for flood and hydraulic action must be taken in areas that have been damaged by flooding. Sediment control techniques also need to be applied to prevent soil, sand, and other materials from reaching the stream.
How is Stream Restoration Done
According to Oklahoma State University’s Biosystems and Agricultural Engineering Department, stream restoration consists of three parts. These parts include reshaping the channel and floodplain, building in-stream structures, and protecting the bank.
Some ways to accomplish these tasks are through:
- Slope changes
- Structural changes
- Vegetation management plans
- Hardscape removal
- Creation of floodplains
A stream’s slope can significantly impact its speed. Streams with steeper slopes run faster than ones without them. A natural and healthy stream rarely runs straight. Instead, it will meander, which means it wraps back and forth down the slope.
When a stream lacks meanders, it is susceptible to hydraulic action, otherwise known as erosion through mechanical force. One way to repair hydraulic action on such a stream is to change the way it runs by adding meanders. Meanders slow down the water, naturally reducing erosion.
In-stream structures like vanes can also reduce a stream’s slope. A vane is often created by placing a series of rocks in the stream to create a crossbeam that resembles a step in the stream. These vanes help create water flow disturbances that help slow it down. They are particularly useful during periods of high flows like massive rainstorms.
Structural changes are another way to repair a stream. A natural, healthy stream will have natural riffles and deep-water pools that slow water flow. To prevent erosion of vulnerable stream banks, it may also have rock formations or even fallen trees.
When these features are absent, water can flow through the stream quickly, causing damage to one or both sides of a bank. Areas within the stream can be dredged to create deep pools of water to help slow down flows, and natural structures can be added to further reduce the speed of the stream.
The first step to managing vegetation is to stop the cause of improper plant growth. For example, if runoff water transfers fertilizers into an area and increases vegetation to levels that are too high, steps must be taken to stop this. On the other hand, if grazing animals destroy all vegetation, it may be necessary to reduce or eliminate animal populations and re-plant.
Once the threat is removed, banks can be rebuilt, and natural watersheds can be created with native plant species. In some cases, animals and even insects could be introduced to keep the watershed healthy.
After planting the vegetation, the area must be monitored. Proper monitoring of the area will help to make any necessary changes as the vegetation begins to grow.
Hardscape Removal and Floodplain Creation
As we said earlier, hardscape can often be the cause of an unhealthy stream. Removing concrete banks is often a necessary part of stream restoration. Hardscape removal can serve several purposes designed to create a healthier stream.
First, removal will reduce the amount of water running off the concrete bank into the stream. Also, removing the barrier will enable the restoration company to rebuild natural watersheds and floodplains so water can flow in and out of the stream at a more natural pace.
Stream Beautification and Naturalization
Many of the steps involved in stream restoration will create a more natural and beautiful looking stream. However, companies can emphasize beautification and naturalization by making changes designed to enhance the appearance and usefulness of the stream.
In some cases, deep pools can be added to certain stream areas to reduce the stream’s slope and create habitats for natural fish species. Native flowers can be added to the watershed along the stream banks to protect the stream in a visually appealing way.
Stream restoration is an essential part of safeguarding our land, waterways, and wildlife. It can be used to prevent erosion and sedimentation, and even to create natural recreational areas. There are many ways to restore streams, and the current conditions of each stream will dictate which methods work best for the restoration plans.
Milestone Companies is proud to offer stream restoration services. Keeping our streams clean, healthy, and visually appealing is a top priority for our company. Check out our extensive list of civil construction services.