Gullies are typically caused by increased rates and intensity of surface runoff. Unchecked rill erosion may evolve into this more substantial form, which can result from poor land-use management and is exacerbated by natural processes. Clay soils are generally less resilient than sand- and loam-based ones, and because clay minerals bind to water molecules, their loss can reduce the moisture-holding capacity of the soil and perpetuate the erosive cycle. Does this Spark an idea?
Instructions
1. Prevent gullies before they arise. This is much easier than attempting to control them once they've formed, when climatic, geological and fluvial processes sometimes collude in perfect conditions for their enlargement. For example, where gullies start in areas of fragile clay subsoil atop decomposed granite, great U-shaped channels over a hundred feet deep may eventually develop. Such mammoth scours can be subject to landslides, especially in the face of storms and weather-related phenomena. Proper land use---maintaining stabilizing vegetation, rotating crops and addressing the effects of disturbances like overgrazing, mining, logging, fires and road construction---can go a long way to preventing the financial and ecological havoc that gullies wreak.
2. Rotate crops, maintain cover vegetation and riparian buffers, recycle organic matter back into the soil and, in general, practice ecologically sensible land management to prevent or control gully erosion on agricultural land. The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFR) notes that strip and contour planting may reduce erosion by 50 percent or more, for example.
3. Fully inspect any existing gullies. OMAFR recommends measuring the amount of water runoff entering the gully---which reflects various aspects of the local basin, from size to soil type---and the dimensions of the channel, including its slope. Determine the source and orientation of surface runoff in the area.
4. Manage runoff. This is essential to remedying gully development or avoiding the features in the first place. Where slope is relatively gentle---under 25 percent---broad, shallow skeins of stable vegetation called waterways can dissipate flow energy and reduce erosion, and may be combined with chute spillways and grade control structures which, through riprap and other materials, help break up the gradient. Drop pipes and subsurface tile systems may be implemented to transfer water down sharper slopes.
5. Monitor erosion control systems regularly. Especially where vegetation has been planted in waterways, riparian buffer zones or the like, stay vigilant to ensure its establishment.
Tags: reduce erosion, surface runoff