A gully is a landform created by running water, mass movement, or commonly a combination of both eroding sharply into soil or other relatively erodible material, typically on a hillside or in river floodplains or terraces.
23-623: A couloir ( French: [ku.lwaʁ] , "passage" or "corridor") is a narrow gully with a steep gradient in a mountainous terrain. A couloir may be a seam, scar, or fissure, or vertical crevasse in an otherwise solid mountain mass. Though often hemmed in by sheer cliff walls, couloirs may also be less well-defined, and often simply a line of broken talus or scree ascending the mountainside and bordered by trees or other natural features. Couloirs are especially significant in winter months when they may be filled in with snow or ice, and become much more noticeable than in warmer months when most of
46-401: A study examined the geoenvironmental causes driving gully erosion. It focuses on catchment management for gully erosion and geotechnical analysis. Through fieldwork, data was gathered utilizing GIS and GPS methods. According to the study, gully erosion occurs throughout, with Nanka/Oko having the highest concentration. The gully characteristic map shows variations in length and depth, emphasizing
69-631: A variety and combination of processes. The erosion processes include incision and bank erosion by water flow, mass movement of saturated or unsaturated bank or wall material, groundwater seepage - sapping the overlying material, collapse of soil pipes or tunnels in dispersive soils, or a combination of these to a greater or lesser degree. Hillsides are more prone to gully erosion when they are cleared of vegetation cover through deforestation , over-grazing , or other means. Gullies in rangelands can be initiated by concentrated water flow down tracks worn by livestock or vehicle tracks. The flowing water easily carries
92-451: A way that exposes the subsoil to running water. When observed in situ, dispersive soil textures may feel 'soapy', and in many cases the physical structure of subsoil layers will be prismatic or columnar. A simplified version of the Emerson soil dispersion test can be completed in the field on a 20-minute to two-hour timescale. Laboratory tests used to diagnose a soil as dispersive focus on
115-1029: Is a severe environmental problem that lowers crop quality and may cause famine and food shortages. It also causes the soil to lose organic content, which has an impact on plant viability. As items washed from fields end up in rivers, streams, or vacant land, erosion also contaminates the ecosystem. Because of increased population expansion and increasing land demand, erosion also threatens the natural ecosystem, encroaching on natural forests. Important assets including homes, power poles, and water pipelines may also be destroyed. Effective land management techniques can prevent gullies. These techniques include keeping vegetation along drainage lines, using more water, classifying drainage lines as distinct land classes, stabilizing erosion, preventing vermin, distributing runoff evenly, keeping soil organic matter levels high, and avoiding over-cultivation. These tactics guarantee uniform rates of penetration and robust plant coverage. One serious environmental problem endangering sustainable development
138-463: Is also required. Possible sources can include weathering from soil parent materials or wind-blown salt deposition. Sodium ions are highly mobile in the soil solution and so they accumulate in the lower parts of the landscape. The dispersive portion of a soil profile is generally confined to the subsoil , where soil-forming processes concentrate clay minerals and sodium. This means that dispersive soils may not be identified until they are disturbed in
161-553: Is gully erosion. Gullying prevention and control methods are dispersed and lacking, and they have low success and efficacy rates. This review attempts to make a valuable contribution to effective gully prevention and management techniques by combining information from previous research. It is possible to stop the creation of gullies by changing how land is used, conserving water and soil, or implementing specific actions in areas with concentrated flow. Plant leftovers and other vegetation barriers can prevent erosion, although their usefulness
184-596: Is limited. The biophysical environment, terrain, climate, and geomorphology are examples of external elements that affect gully prevention and control. Stabilizing gullies entails altering water flow to lessen scouring, sediment buildup, and revegetation. Water can be securely moved from the natural level to the gully floor using a variety of structures, including drop structures, pipe structures, grass chutes, and rock chutes. Structural modifications can be required along steep gully floors. Vegetation can reestablish itself thanks to sediments deposited over flatter gradients. Until
207-548: Is localized in the Coastal Plain Sands, Nanka Sands, and Nsukka Sandstone of the Anambra-Imo basin region. The most affected deposits are unconsolidated or poorly consolidated and have short dispersion times. Public education is essential for a sustainable termination strategy, and collaboration between the government, donors, the private sector, and rural people is crucial. Gullies are widespread at mid-to high latitudes on
230-452: The cation exchange capacity of a soil sample and its cation breakdown. Soil cations are dominated by Ca , Mg , K , and Na , as well as H in acidic soils. The exchangeable sodium percentage ( "ESP", (sodium / (total cations)) * 100 ) is a key indicator derived from these measurements. Where ESP exceeds 5%, dispersive behaviour becomes possible, and is highly likely where ESP exceeds 15%. The best management approach to these soils
253-591: The deeper subsurface is also a possible explanation for the formation of some Martian gullies. Dispersion (soil) Dispersion is a process that occurs in soils that are particularly vulnerable to erosion by water. In soil layers where clays are saturated with sodium ions (" sodic soils "), soil can break down very easily into fine particles and wash away. This can lead to a variety of soil and water quality problems, including: Dispersive soils are more common in older landscapes where leaching and illuviation processes have had more time to work. A source of sodium
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#1733085572849276-443: The eroded soil after being dislodged from the ground, typically when rainfall falls during short, intense storms such as thunderstorms . A gully may grow in length through headward (i.e., upstream) erosion at a knick point . This erosion can result from interflow and soil piping ( internal erosion ) as well as surface runoff . Gully erosion may also advance laterally through similar methods, including mass movement, acting on
299-432: The gully walls (banks), and the development of 'branches' (a type of tributary ). Gullies reduce the productivity of farmlands where they incise into the land and produce sediment that may choke downstream waterbodies and reduce water quality within the drainage system and lake or coastal system. Because of this, much effort is invested into the study of gullies within the scope of geomorphology and soil science , in
322-413: The least important issue. This implies a notable variation in the average evaluations across impacted individuals, underscoring the necessity for long-term repair approaches. Reducing soil loss, raising public knowledge of environmental issues, passing environmental legislation, and giving residents funds to strengthen their coping mechanisms are all advised by the study. In Agulu-Nanka, Southeast Nigeria,
345-558: The necessity of considering gully vulnerability and giving erosion hazards immediate attention. Gullies can be formed or enlarged by several human activities. Artificial gullies are formed during hydraulic mining when jets or streams of water are projected onto soft alluvial deposits to extract gold or tin ore . The remains of such mining methods are very visible landform features in old goldfields such as in California and northern Spain. The badlands at Las Medulas , for example,
368-543: The prevention of gully erosion, and the in remediation and rehabilitation of gullied landscapes. The total soil loss from gully formation and subsequent downstream river sedimentation can be substantial, especially from unstable soil materials prone to dispersion . When water is directed over exposed ground, gully erosion removes soil near drainage lines. This may result in divided properties, loss of arable land, diminished amenities, and decreased property values. Additionally, it can lead to sedimentation, discoloration of
391-650: The rainier months. Gullies develop when a rill is neglected for an extended time, thickening and expanding as soil erosion persists. The factors influencing gully erosion were investigated in Zaria, Kaduna state, Nigeria, utilizing SRTM data, soil samples, rainfall data, and satellite imagery. The findings indicated that the factors that had the biggest effects on gully erosion were slope (56%) and rainfall (26%), land cover (12%), and soil (6%). The investigation concluded that each particular component significantly influenced soil loss. The loss of fertile farmland due to gully erosion
414-408: The restoration is finished, damaged areas should be walled off. Eastern Nigeria's people and ecology are seriously threatened by gully erosion. A research project focused on 370 families and nine risk regions evaluated the region's gully erosion issues. The greatest perceived problem, according to the results, was biodiversity loss. In contrast, damage to properties, roads, and walkways was ranked as
437-816: The snow and ice may recede. These physical features make the use of couloirs popular for both mountaineering and extreme skiing . Gully Gullies resemble large ditches or small valleys , but are metres to tens of metres in depth and width, are characterized by a distinct 'headscarp' or ' headwall ' and progress by headward (i.e., upstream) erosion . Gullies are commonly related to intermittent or ephemeral water flow, usually associated with localised intense or protracted rainfall events or snowmelt. Gullies can be formed and accelerated by cultivation practices on hillslopes (often gentle gradients) in farmland , and they can develop rapidly in rangelands from existing natural erosion forms subject to vegetative cover removal and livestock activity. The earliest known usage of
460-519: The surface of Mars and are some of the youngest features observed on that planet, probably forming within the last few 100,000 years. There, they are one of the best lines of evidence for the presence of liquid water on Mars in the recent geological past, probably resulting from the slight melting of snowpacks on the surface or ice in the shallow subsurface on the warmest days of the Martian year. Flow as springs from deeper seated liquid water aquifers in
483-833: The term is from 1657. It originates from the French word goulet , a diminutive form of goule which means throat . The term may be connected to the name of a type of knife used at the time, a gully-knife. Water erosion is more likely to occur on steep terrain because of erosive pressures, splashes, scour, and transport. Slope characteristics, such as slope length and amounts proportionate to slope length, affect soil erosion. Relief and soil erosion are positively correlated in southeast Nigeria. There are three types of topography: mountains, cuesta landscapes, and plains and lowlands. While highlands with stable lithology avoid gullying yet allow for vigorous runoff, uplands with friable sandstones are more prone to erosion. Gully erosion can progress through
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#1733085572849506-410: The water supply, and creating a haven for rodents. Water rushing over exposed, naked soil creates gullies and ridges that erode rock and soil. When water rushes across exposed terrain, it erodes or pushes dirt away, creating rills. Gravity causes rift erosion on a downward slope, with steeper slopes generating greater water flow. Sandier terrains are more commonly affected by rills most prevalent during
529-787: Was created during the Roman period by hushing or hydraulic mining of the gold-rich alluvium with water supplied by numerous aqueducts tapping nearby rivers. Each aqueduct produced large gullies below by erosion of the soft deposits. The effluvium was carefully washed with smaller streams of water to extract the nuggets and gold dust. Gully initiation results from localized erosion by surface runoff, often focusing on areas where forest cover has been removed for agricultural purposes, uneven compaction of surface soils by foot and wheeled traffic, and poorly designed road culverts and gutters. Termination of gully processes requires water-resource management, soil conservation, and community migration. Gully erosion
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