wat is gully erosion?

Answer 1

A gully is a landform created by running water eroding sharply into soil, typically on a hillside. Gullies resemble large ditches or small valleys, but are metres to tens of metres in depth and width. When the gully formation is in process, the water flow rate can be substantial, which causes the significant deep cutting action into soil.

Gullying, or gully erosion, is the process by which gullies are formed. Hillsides are more prone to gullying when they are cleared of vegetation, through deforestation, over-grazing or other means. The eroded soil is easily carried by the flowing water after being dislodged from the ground, normally when rainfall falls during short, intense storms such as during thunderstorms. Gullies reduce the productivity of farmland where they incise into the land, and produce sediment that may clog downstream waterbodies. Because of this, much effort is invested into the study of gullies within the scope of geomorphology, in the prevention of gully erosion, and in restoration of gullied landscapes. The total soil loss from gully formation and subsequent downstream river sedimentation can be sizable.


The earliest usage of the term is from 1657. It originates from the French word goulet, a diminutive form of goule which means throat. It is possible that the term was derived from a type of knife at the time, a gully-knife, because hills that have gullies look as if they are cut open with a sharp knife.

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Answer 2

Gully erosion is caused when run-off concentrates
and flows at a velocity sufficient to detach and
transport soil particles. A waterfall may form, with
run-off picking up energy as it plunges over the gully
head. Splashback at the base of the gully head
erodes the subsoil and the gully eats its way up
the slope.
Gullies may develop in watercourses or other places
where run-off concentrates. In cultivation or
pastures, advanced rill erosion can develop into
gully erosion if no protective measures are taken.
Cattle pads can be a starting point for a small rill that
can develop into a large gully

Answer 3

Gully erosion is an advanced stage of rill erosion where surface channels have eroded to the point where they can not be removed by tillage operations. Gully erosion is responsible for removing vast amounts of soil, irreversibly destroying farmland, roads and bridges and reducing water quality by increasing the sediment load in streams. Gully initiation is thought to be a response to excessive water in the local environment caused by the removal of perennial vegetation.

A gully head forms as rill erosion deepens and widens creating a characteristic nick point or headwall. Most gullies extend up slope as a result of headwall migration. However, it is the collapse and slumping of the sidewalls which usually contributes the greatest proportion of soil loss.
Water running into the gully either scours the face or undercuts the head wall resulting in gully migration.
Widening of gully sides occurs by undercutting or slumping.
Gully head shape indicates if erosion is due to scouring (forward slope) or dispersion (undercut).
Believed to be a response to changed hydrological conditions

Answer 4

Gully erosion
Gully erosion is a highly visible form of soil erosion that affects soil productivity, restricts land use and can threaten roads, fences and buildings. Gullies are relatively steep-sided watercourses which experience ephemeral flows during heavy or extended rainfall.
Soil eroded from the gullied area can cause siltation of fencelines, waterways, road culverts, dams and reservoirs. Suspended sediments, which may have attached nutrients and pesticides, can adversely affect water quality. These fine, colloidal clay particles remain in suspension and may clog groundwater aquifers, pollute water courses and
affect aquatic life.Controlling gully erosion can be difficult and costly. It may be justified on better quality soils where there is
a reasonable chance of success or where a road or building is threatened by an advancing gully. However, controlling gullies over large areas of poor soils may be impracticable. For this reason prevention is far better than control.
How gullies develop Gully erosion is caused when run-off concentrates and flows at a velocity sufficient to detach and
transport soil particles. A waterfall may form, with run-off picking up energy as it plunges over the gully head. Splashback at the base of the gully head erodes the subsoil and the gully eats its way up the slope.
Gullies may develop in watercourses or other places where run-off concentrates. In cultivation or pastures, advanced rill erosion can develop into gully erosion if no protective measures are taken.Cattle pads can be a starting point for a small rill that can develop into a large gully.A watercourse is ordinarily in a state of balance where its size, shape and gradient are suitable for the flows it carries. If the balance is disturbed, for example by larger than normal flows, gully formation may begin. Gullies generally create far more
capacity than they need to accommodate the run-off
they are likely to carry. A four metre deep gully advancing into grazing land Widening of the gully sides may occur by slumping and mass movement especially on the outside curve of meanders. Scouring of the toe slope can lead to
mass failure of the side of the gully under gravity.This soil is then washed away by subsequent flows.Active gully sides are usually vertical but may adopt an oblique shape once they start to stabilise. This process may occur naturally but can be hastened by the adoption of various gully treatment measures.Run-off may enter a gully from the sides, causing
secondary gullies or branching resulting in a
'badlands' effect. The gully floor may be subject to further down-cutting as secondary gullies advance up the channel. Sediment deposition below gully heads results in a "steps and stairs" pattern.While peak flows from intense rainfall causes considerable gully erosion, the prolonged low flows
resulting from an extended wet period can also create problems. Constant trickle flows through a drainage line can saturate the soil in the trickle zone making it structurally weak and very susceptible to erosion. The constant wet conditions may also weaken the vegetation which then provides less
resistance to erosion.Gully depth is often limited by the depth to the underlying rock which means that gullies are normally less than 2 m deep. However on deep alluvial and colluvial soils gullies may reach depths of 10 to 15 m.

Answer 5

gully erosion is erosion caused by water