By Emily Folk of Conservation Folks
We dredge waterways for a range of reasons. Making them deeper and wider for the commercial shipping industry and preparing for projects such as the construction of bridges and piers are two major ones. In some situations, dredging can have environmental benefits such as removing pollutants from water. It can even play a role in preventing flooding and erosion.
Dredging, the process of removing sediment from the bottom of a body of water, can also have uses for sustainable farming operations.
Make Use of Existing Ponds
Ponds, lakes and other bodies of water can be valuable resources for farms. Over time, though, this water can become murky or polluted. This is especially true if erosion of pollutant runoff is occurring at high levels. If a body of water becomes too dirty, it is unusable.
Dredging a contaminated pond or lake can give it new life. By removing sediment, you also remove pollutants and excess dirt, resulting in clearer, cleaner water. You can then use the pond or lake to water livestock or crops. You could also raise fish or aquatic vegetation.
Be careful, though, when dredging your pond if it already contains plant or animal life. Some kinds of dredging can disturb the water ecosystem by destroying habitats, changing water flow or stirring up sediment.
Reuse Removed Sediment
Dredged sediment, whether it comes from a farm or somewhere else, can prove useful for farmers. After you remove the soil from the water and dry it, you can use it for growing crops. It's especially on farmlands where extensive erosion has occurred. Dredged sediment has various other uses as well, such as in land reclamation projects and as an aggregate in concrete.
Even polluted dredged sediment can be useful, even as soil for growing crops, if it is adequately decontaminated. Numerous methods exist for cleansing contaminated soil after dredging including:
- Separation techniques
- Chemical immobilization, which binds pollutants by adding other substances to the sediment
- Thermal immobilization, which uses heat to destroy contaminants
- Bioremediation techniques, including using microorganisms or plants to cleanse sediment and break down pollutants
Prevent Erosion and Flooding
In some scenarios, dredging can help to prevent or minimize erosion and flooding. Erosion is a serious problem for many farmers, as it causes loss of soil and soil nutrients from farmlands.
Worsening erosion can also cause increased flooding, which can further damage farms. When large volumes of soil erode into waterways, it tends to settle in lower flow areas and can raise the floor of the lakes, rivers or other bodies of water, which increases flooding risks. Dredging can return the floor to its former level. Although dredging is not a cure-all for flooding and isn’t the best course of action in every situation, when used strategically, it can help protect farmlands and other areas.
Dredged sediment itself has also been used to reduce erosion and flooding. Adding dredged soil is a common strategy for restoring habitats, especially depleted beaches.
Of course, sustainable land management and other responsible farming practices also help to reduce erosion and flooding. Research has found that decreasing agricultural runoff by 10 percent can reduce peak flooding by 50 percent.
Dredging can have numerous benefits for sustainable farming operations. Simpler dredging processes, such as the removal of sediment from small ponds, have rather straightforward benefits. Large-scale dredging projects, such as those that take place in lake, river or ocean waters, have more complex impacts.
It’s critical that we take the proper precautions and evaluate all of the potential effects of dredging projects, especially the environmental impacts, before beginning them. When used sustainably and strategically though, dredging can play an important role in sustainable farming practices.
Emily is a sustainability writer and avid gardener. You can read more of her work on her site, Conservation Folks, where she writes about helping tomorrow’s planet today.