Gully erosion is the severe stage of soil erosion caused by surface water runoff along drainage lines, resulting in deep channels. This phenomenon is often triggered by a “nick point,” such as a rabbit burrow, root hole, stock/vehicle track, or bare soil, where fast-flowing runoff scours away the soil and undermines vegetation. Once the vegetation and topsoil are removed, gullies spread rapidly, causing significant soil loss and environmental degradation.
Key Facts
- Maintain vegetation along drainage lines and eliminate grazing from these areas.
- Plant deep-rooted perennial grasses and trees to increase water usage and maintain healthy vegetation.
- Identify drainage lines as a separate land class that needs to be protected.
- Stabilize sheet or rill erosion immediately.
- Maintain high levels of organic matter in the soil.
- Avoid excessive cultivation and manage the land according to its capability.
Control Measures for Gully Erosion:
- Catchment works: Reduce and divert the flow of water into stable drainage lines.
- Increase infiltration rates and water uptake by plants.
- Divert and store water.
- Subdivide the catchment into appropriate land classes and apply suitable grazing and cropping practices.
- Cooperatively tackle the problem by forming a landcare group.
- Use diversion banks, contour cultivation, and maintain farm tracks and culverts.
- Utilize trees and deep-rooted perennial pastures to reduce runoff.
- Stabilizing gullies: Divert and modify the flow of water to reduce scouring and allow revegetation.
- Use grass chutes, pipe structures, rock chutes, and drop structures to safely redirect water.
- Install structures along gully floors to prevent soil and vegetation loss.
- Construct dams to slow the flow of water into the gully head.
- Fence off damaged areas from stock until restoration is complete.
- Avoid filling gullies with solid objects, as it can lead to further erosion.
Causes of Gully Erosion
Gully erosion occurs due to various factors, including:
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Excessive Clearing and Inappropriate Land Use
Clearing vegetation for agriculture, urbanization, or other development activities can expose the soil to erosive forces. Inappropriate land use practices, such as overgrazing, can also contribute to gully erosion.
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Compaction
Soil compaction caused by heavy machinery or grazing can reduce infiltration and increase runoff, exacerbating gully erosion.
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Lack of Groundcover
Bare soil, devoid of vegetation, is highly susceptible to erosion.
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High-Intensity Rainfall
Intense rainfall events can generate excessive runoff, leading to gully erosion, especially in areas with poor soil structure or steep slopes.
Prevention of Gully Erosion
Preventing gully erosion is crucial for maintaining soil health and productivity. Several measures can be taken to prevent gully erosion, including:
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Maintaining Vegetation
Preserving natural vegetation along drainage lines and eliminating grazing in these areas helps stabilize the soil and reduce runoff.
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Planting Deep-Rooted Vegetation
Planting deep-rooted perennial grasses and trees increases water usage and maintains healthy vegetation, which helps prevent soil erosion.
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Identifying Drainage Lines
Recognizing drainage lines as separate land classes allows for targeted management and protection.
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Immediate Stabilization
Promptly stabilizing sheet or rill erosion can prevent the development of gullies.
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Maintaining Organic Matter
High levels of organic matter in the soil improve soil structure and water infiltration, reducing erosion.
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Avoiding Excessive Cultivation
Minimizing cultivation and managing land according to its capability helps prevent soil disturbance and erosion.
Control Measures for Gully Erosion
When gully erosion occurs, specific control measures are necessary to mitigate further damage and restore the affected area. These measures include:
Catchment Works
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Reducing and Diverting Water Flow
Catchment works aim to reduce and divert the flow of water into stable drainage lines.
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Increasing Infiltration and Water Uptake
Implementing practices that enhance infiltration and water uptake by plants helps reduce runoff and erosion.
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Subdivision of Catchment
Dividing the catchment into appropriate land classes allows for targeted grazing and cropping practices.
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Cooperative Efforts
Forming landcare groups enables cooperative efforts to address gully erosion issues across multiple properties.
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Diversion Banks and Contour Cultivation
Utilizing diversion banks and contour cultivation techniques helps disperse erosive water flow and reduce its impact.
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Trees and Perennial Pastures
Planting trees and deep-rooted perennial pastures aids in reducing runoff and utilizing excess water.
Stabilizing Gullies
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Diverting and Modifying Water Flow
Stabilizing gullies involves diverting and modifying the flow of water to reduce scouring and facilitate revegetation.
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Structures for Water Redirection
Employing structures like grass chutes, pipe structures, rock chutes, and drop structures safely redirects water away from erosive areas.
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Structures along Gully Floors
Installing structures along gully floors helps prevent soil and vegetation loss due to excessive water flow.
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Dams for Water Flow Control
Constructing dams can slow down the flow of water into the gully head, reducing erosion.
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Fencing and Restoration
Fencing off damaged areas from stock allows for revegetation and restoration efforts to proceed undisturbed.
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Avoiding Solid Objects
Filling gullies with solid objects like old drums or concrete is counterproductive, as it can lead to further erosion.
Conclusion
Gully erosion is a severe form of soil erosion that can have detrimental effects on soil health, productivity, and the environment. Preventing gully erosion is essential through measures such as maintaining vegetation, planting deep-rooted plants, identifying drainage lines, stabilizing erosion, and managing land appropriately. When gully erosion occurs, control measures like catchment works and gully stabilization techniques are necessary to mitigate further damage and restore the affected area. By implementing these strategies, we can protect our soil resources and ensure sustainable land management practices.
References
- https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0008/255158/fact-sheet-5-gully-erosion.pdf
- https://agriculture.vic.gov.au/farm-management/soil/erosion/gully-erosion
- http://erosioncontrol.okstate.edu/gully-erosion
FAQs
What causes gully erosion?
- Gully erosion is caused by excessive runoff, often due to factors like deforestation, poor land management practices, overgrazing, and intense rainfall events.
How can I prevent gully erosion?
- Prevent gully erosion by maintaining vegetation, planting deep-rooted plants, identifying and protecting drainage lines, stabilizing erosion, and managing land according to its capability.
What are some control measures for gully erosion?
- Control gully erosion through catchment works (reducing and diverting water flow, increasing infiltration), and gully stabilization techniques (diverting water flow, installing structures, constructing dams, fencing off affected areas).
How do I stabilize the gully head?
- Stabilize the gully head by using structures like grass chutes, pipe structures, rock chutes, and drop structures to safely redirect water away from erosive areas.
What is the role of vegetation in gully erosion control?
- Vegetation helps prevent gully erosion by slowing down runoff, increasing infiltration, and holding the soil together with its roots.
How can I manage land to prevent gully erosion?
- Manage land to prevent gully erosion by avoiding excessive cultivation, minimizing compaction, and implementing contour farming and terracing techniques.
What are some common mistakes to avoid when fixing gully erosion?
- Avoid filling gullies with solid objects like old drums or concrete, as this can lead to further erosion. Additionally, do not attempt to stabilize gullies without proper assessment and planning, as this can worsen the situation.
When should I seek professional help for gully erosion control?
- Seek professional help when gully erosion is severe, when it is actively progressing, or when you lack the expertise or resources to implement effective control measures on your own.