Gully erosion, the most impressive and striking erosion type, has been recognized as one of the major global environmental problems. Soil erosion generally is a function of slope attributes. Except for recently cleared areas, much of the susceptible land has already been conspicuously affected by erosion, and this is the most reliable indicator of the susceptibility of similar land. We combine these to assess the hazard of gully erosion following forest clearing, expressed in terms of the probability of daily rainfall that is capable of initiating. Gully erosion, caused by a thinning of the vegetation cover, is typified by the nineteenth century epicycle of valley trenching or arroyo cutting in the alluvial valleys in the southwestern united states. The aim of this study is therefore to determine and analysis the factors responsible for gully development and with preferring solutions. Gully erosion definition of gully erosion by merriamwebster.
Gully erosion control natural resources conservation service. Gully erosion susceptibility mapping using artificial intelligence and. May 05, 2015 the devastating gully erosion in auchi, edo state, nigeria. The spatial distribution of gully erosion shows three main zones in the studied area. The first is that present control measures are not entirely satisfactory in particular, a more detailed understanding of the mechanisms of different kinds of gullies is needed so that treatments can be designed to suit.
Future work in greece should combine the current, large scale. A study of early gully control structures in the colorado front range by burchard h. Gully erosion a gully is a landform created by running water, eroding sharply into soil, typically on a hillside. Gully erosion is best characterised as a bed instability that subsequently causes in bank instabilities. According to the concept most generalized, in sheet erosion, thin layers of material are uniformly removed from the soil surface due to the action of an. Gully erosion may be a significant source of sediment to the stream. A study of early gullycontrol structures in the colorado. Many states in nigeria are currently under the threats of this phenomenal process, southeastern part of the country being the most affected.
Controls on gully formation following forest clearing in a. Largescale land management to prevent and reduce alluvial. Ofomata indicated that gully erosion types are the most visible forms of erosion in nigeria mainly because of the remarkable impression they leave on the surface of the earth. Gis based soil erosion estimation using epm method. Gully erosion is a key process of land degradation and desertification posing a. Gully erosion gc4pvpq was created by fredd000 on 10720. The first is that present control measures are not entirely satisfactory in particular, a more detailed understanding of the mechanisms of different kinds of gullies is. Results from the interpretation of spot 51999 and quick birds 2009 imageries and field measurements showed that gully variables length, depth and widths have significantly increased in the last 10 years. Gully erosion is an advance stage of rill erosion as rill erosion is the advanced stage of sheet erosion.
Hudson observed that in simplest terms steep land is more vulnerable to water erosion than flat land for reasons that erosive forces, splash, scour and transport, all have greater effect on steep slopes. Repair work done in the early stages of newly formed gullies is easier and more economical than letting the. Asfpm arid regions committee introduction riverine erosion is a significant, but unstudied, flood risk for many nfip communities. Gully erosion occurs in channels with u or vshaped cross sections located in. The natural factors that influence erosion in ankpa and its environs include. Alluvial gully erosion in australias tropical rivers. Gully control designed to fix valley bottoms at a certain base level stabilizes the valley floor through sediment accumulation in the gully channel. The soil conservation society of america defines a gully as a channel or miniature valley cut by concentrated runoff.
It can be classified as subhumid tropical environment with an average annual rainfall of. Dec 23, 2014 this study examines the causes and consequences of gully erosion, as perceived by the local people of dangara area, nigeria. Normal or geologic erosion is the wearing away of the land under natural environmental conditions. Land degradation due to soil erosion, particularly gully erosion by. Under natural conditions gullying is an important process of landscape evolution. Gully erosion is the process by which gullies are formed.
A determination of the beginning date is critical use aerial photos, producer knowledge, etc. Any concentration of surface runoff is a potential source of gully erosion. In 1999, fema reported that approximately onethird of the nations streams experience. Its a other size geocache, with difficulty of 2, terrain of 2. Data were derived from field measurements, satellite imageries, and laboratory analysis. Gully erosion may cause considerable soil losses and produce large. Ephemeral and classic gully erosionworksheet forms of erosion by water include sheet and rill, ephemeral gully, classic gully and stream bank. Mapped areas of concentrated alluvial gully erosion and soils with high erosion risk i. Gully erosion department for environment and water. For ephemeral gully dimensions width, depth or length that exceed the increments shown in these tables, combine the erosion rates from two or.
Evaluation of recent advanced soft computing techniques for. Plate 17 should be targeted for largescale land management changes and localised intensive rehabilitation actions to cumulatively reduce sediment yields to downstream rivers, wetlands, estuaries, coasts, and offshore reefs. This study examines the causes and consequences of gully erosion, as perceived by the local people of dangara area, nigeria. The incidence of gully erosion in obolloetiti in udenu local government area of enugu state has assumed alarming proportions thereby gaining local government recongnition as an ecological disaster. To model the gesm, 12 affecting factors on gully erosion were identified. Each set is merged together with an equal number of random locations expressing the absence of the gulling process over space camilo et al. The rills or small channels often only 30cm deep are caused when water running across the surface of the ground gathers in a natural depression in the soil, and erosion. The guardian nigeria newspaper brings you the latest headlines, opinions, political news, business reports and international news. Gully erosion is the removal of soil along drainage lines by surface water runoff.
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. Heede, research forester introduction the control of gullies is an important step in watershed rehabilitation. It is a subcatchment of alemaya lake with an approximate area of 9 km 2. Gully erosion article about gully erosion by the free. Gisbased machine learning technique is used for gully erosion susceptibility. It can also incorporate and combine different data types because it does not assume anything about the distributions of the data. Gully erosion the guardian nigeria news nigeria and. Several discontinuous gullies developing on a hillside can merge and. Deposition occurs where the agents of erosion lay down sediment. Protecting the soil from runoff stops potential land degradation and assists with water quality protection. Grass hedges for gully erosion control introduction grass hedges are narrow strips feet wide of stiff, erect, densely growing grasses planted across the slope perpendicular to the dominant slope.
Comparison of machine learning models for gully erosion. Sheet, rill and gully erosion is the unwanted removal of soil from the land surface or through incised channels by the action of rainfall and runoff. Prepare a new technical guidance document for erosion and sediment control esc for land disturbing activities in the auckland region. It can also incorporate and combine different data types because it does not assume. Gully erosion definition is soil erosion produced by running water. The devastating gully erosion in auchi, edo state, nigeria. Check whether the erosion is active gully erosion can look dramatic, but if the gully has stabilised it may be better to leave it alone. It happens when water from rainfall does not soak into the soil, but runs across it instead. On agricultural land, gully development is known to be caused mainly by hydraulic erosion due to concentrated overland flow poesen et al. The warke watershed a project paper presented to the faculty of graduate school of cornell university in partial fulfillment of the requirement for the degree master of professional studies mps by birara chekol tarekegn january 2012. Geotechnical assessment of gully erosion at ankpa area, north. Some of the most known soil erosion models are usle universal soil loss equation, 1965, epic erosionproductivity impact calculator, 1984, eurosem european soil erosion model, 1993, rusle revised universal soil loss equation, 1997, rill grow a model for rill initiation and development, 1998, semmed soil erosion model for mediterranean regions, 1999, egem ephemeral gully erosion.
Gc4pvpq gully erosion earthcache in northern territory. Erosion is defined as the withering away of the surface of land by either rain or irrigation water, wind or ice. Procedures to adopt when modelling soil erosion 365 table 1 9. A study of early gullycontrol structures in the colorado front range by burchard h. Gully erosionsusceptibility mapping gesm is one basic method 3 to understand the mechanisms behind gully erosion. Pdf the contribution of gully erosion to total sediment production. However, humaninduced gullying is a serious form of land degradation reducing soil fertility. Pdf determining the contribution of gully erosion to the total. These hedges function to slow water runoff, trap sediment and prevent gully development dabney et al. The warke watershed a project paper presented to the faculty of graduate school of cornell university in partial fulfillment of the requirement for the degree master of professional. Prevention is better than cure 2012 2 on the other hand, in a lot of places poorly managed footpaths and cattle trafficking lines have been transformed to sever gully areas. Affordable and search from millions of royalty free images, photos and vectors. I hope we can do something about this and help the people in the community. Gully erosion a gully is a landform created by running water, eroding sharply into soil, typically on.
Chapter gully erosion and its control chapter gully erosion and its control gullying occurs in many parts of queensland. Disturbing dispersive soils may reactivate the gully and cause more erosion. These hedges function to slow water runoff, trap sediment and prevent gully development dabney et. Geotechnical assessment of gully erosion at ankpa area. Assessment of gully erosion in eastern ethiopia using. Rill erosion is a type of erosion that results in small, yet well defined streams. Pdf gullies are an important part of the soil erosion process and. Towards an assessment of the ephemeral gully erosion. Evaluation of recent advanced soft computing techniques.
To check whether the erosion is active, look at the gully head, walls and floor. Objectives provide a userfriendly guidance document, which provides practical methodologies and technologies, suitable for the current market and ideally proven to. Further information can be found in assessing agricultural land maschmedt 2002. The slope length and the amount of soil erosion have always been proportional to the steepness of the slope. Accelerated erosion, as used here, is a term applied to that erosion brought about by man or by climatic. Land degradation due to soil erosion, particularly gully erosion by water, is the main threat in the amhara region. Each set is merged together with an equal number of random. Photo 1 urban gully erosion migrating along a constructed stormwater drain qld photo 2 rural gully erosion migrating through pastoral land sa. Alluvial gully erosion, tropical rivers, northern australia, basal sapping introduction gully erosion has been identified as a dominant sediment source in many regions within australia and internationally gobin et al.
Erosion control treatment selection guide usda forest service. Once started, gullies will continue to move by headward erosion or by slumping of the side walls unless steps are taken to stabilise the disturbance. When portions of a classic gully are actively eroding. Gully erosion is possibly the most destructive and certainly the most spectacular form of the latter. In pakistan, 75% of the country is affected by water and wind erosion and gully erosion affects 36% of the agricultural area of the country according to g. Erosion caused by concentrated flow begins where overland flow converges to channelized flow conditions. Each type is associated with the progressive concentration of runoff water as it moves downstream. The motive of this study is to combine the rbf method with ica and compare. Gully erosion, however, can also occur within a watercourse, typically within the upper reaches, and typically resulting from an active headcut migrating rapidly up the valley. The number of years the gully has been actively eroding is important in gauging the severity of the total erosion.
Gully erosion erosion soil and water farm management. Sheet erosion occurs when a very thin layer of surface dirt or soil is removed from a large area. The study area, damota subcatchment, is located at about 3 km east of alemaya university campus and was selected as a typical hararghe highland catchment severely affected by soil erosion in general and gully erosion in particular. If untreated, the ephemeral gully may develop into a classic. Hillsides are more prone to gully erosion when they are cleared of vegetation, through deforestation, overgrazing or other means. The following state costshare practices are designed to address this concern. Four categories of land were delineated on the basis of gully length km per unit area km 2. By clicking agree and continuing to use this site you agree to our use of cookies. An ephemeral gully typically erodes to the tilled depth. The new tp90 erosion and sediment control guideline. Enormous amounts of time and money are used by international, national, state, and local agencies attempting to arrest the growth of gullies and thus prevent the destruction of. Distribution of gully erosion in victoria vro agriculture. Gully erosion is often caused by the hydraulics of saturation overland flow.
The four types of erosion are sheet erosion, rill erosion, gully erosion and splash erosion. Mass movement any one of several processes that move sediment downhill. Through water erosion, approximately 400 thousand gully erosion formations were formed, covering over 500 thousand hectares according to g. Gully erosion the guardian nigeria news nigeria and world. The distribution of gully erosion in victoria was derived from the unpublished research of lindsay milton in the 1970s and reassessed by sargeant in the 1980s. Estimating soil loss from gully erosion ephemeral or classic definitions ephemeral gully a shallow channel cut by concentrated runoff where soil loosened by mechanical operations is removed, generally between tillage operations.