Form Of Gullies Research Articles

Gully Erosion Zoning in the Middle Volga Region

The article presents a new scheme of zoning of modern gully erosion in a large region of the Russian Federation. Automated landscape zoning by means of artificial neural networks was carried out in order to determine the natural and anthropogenic conditions for the development of the gully network. Erosion zoning was implemented on the basis of large-scale geoinformation mapping of gullies by the method of visual interpretation of high- and ultra-high-resolution satellite images for 2017–2021. The basins of small rivers (1314 in total) with an average area of 91 km2 are taken as operational-territorial units. 22688 gullies (including their holes) were identified in the study area, the average length of which is 65 m, and the total length of the gully network is about 1500 km. The density of the gully network averages 12 m/km2, reaching a maximum of 301 m/km2. The density of gully dissection is used as an indicator for the zoning of gully erosion, this indicator indirectly reflects the intensity of gully formation in geo-space. The dominant (84% of basins) are areas either with no gully dissection or having weak or very weak gully erosion. The main reasons for the widespread damping of gully erosion are related to changes in land use and in the climate system, as well as an evolutionary factor – the transition of many gully forms to the balka stage of development.

What type of gully is that? The need for a classification of gullies

AbstractDespite over a century of investigations into gullies and gully erosion, the characterization and categorization of gullies and the varied definitions, nomenclatures and terminology used has caused some confusion in understanding and communicating the relationships of gully forms and processes around the world. We firstly review the gully literature and highlight how a lack of consistency in gully definition and characterization prevents unifying theory from being developed within this important field of research, since it is often unclear whether different landscape features being discussed are comparable. We propose that conventionally employed qualitative planform and cross‐sectional characteristics of gullies alone are inadequate to define gully types, yet both these features remain central to most modern gully descriptions. We discuss the need to revise and augment these basic characteristics with clearly defined morphogenetic attributes such as landscape context, soil material characteristics, erosion processes, hydrological integrity, modes of development, and head/side‐wall morphology for an effective, practicable, generic gully classification scheme. Central to a gully classification scheme is the need for a clear definition of what a gully is – and is not – for which geomorphological criteria are proposed to differentiate a ‘gully’ from other ‘incisional land surface forms’. This gully definition hinges largely on the identification of a retreating head scarp and the internal erosion by mass‐movement and other sidewall slope erosion processes, coupled with the transport of the soil materials from the gully void. By defining a gully and synthesizing descriptions of gully ‘types’ from the literature and our own experience, we propose key morphogenetic attributes of gullies necessary to form a framework for a systematic gully classification scheme. An initial, eclectic classification framework is presented as both a summation and a synthesis of the literature review, and as a progenitor to a dynamic generic classification scheme that is proposed in a follow‐up article.

Spatio-Temporal Assessment of Gully Erosion in the Zone of Intensive Agriculture in the European Part of Russia

Using the method of mapping by high resolution satellite imagery mapping, a study was made of the key areas which are located in the southern part of the forest, forest-steppe and steppe zones of Tatarstan and of Orenburg, Saratov and Voronezh oblasts. Two key indicators were determined: the gully length density and gully head density within the basins; results of the investigation were used in compiling respective maps in vector format. It is established that the density of the gully length in the basins varies over the range from 0 to 0.5 km/km2 (from the absence of gullies to strong gully erosion), and the density of gully heads from 0 to 3 units/km2. The slope type of gullies is dominant in all basins (about 80%), while the coastal and bottom types have approximately the same proportion (14 and 10%, respectively). Using methods of mathematical statistics we determined a high directly proportional dependence of the indicators of the contemporary gully network on the level of ploughness of the basins and the mean annual precipitation amount, and an indirectly proportional dependence on the level of sodding. An abrupt reduction in gullying indicators was determined. It was found that among the chief reasons behind an abrupt reduction in the gullies to date is a decrease of the rate of agricultural development, with an additional factor, namely, a dramatic decrease in surface runoff down the arable slopes during spring snowmelt caused by climate warming. It is concluded that that a significant part of the gully forms in the study area is currently inactive and massively passes into the balka stage.

Anthropogenic factors influencing the development of gullies on the Idah-Ankpa Plateau of north central Nigeria

The Idah-Ankpa Plateau (IAP) of north central Nigeria is beset by land degradation in the form of gullies. The proliferation of gullies on this plateau landscape has been spectacular and aggravated since the end of the Nigerian Civil War in 1970 (ECAN 1982). On the IAP, gullies scarify urban and agricultural lands and silt up streams and reservoirs, thus damaging the productive and aesthetic qualities of the environment. Tackling the gully erosion problem requires adequate information on the causative factors of this environmental phenomenon. Oparaku et al. (2015) carried out a study of the land degradation problems of the IAP and reported that many urban drainage structures, high-value buildings, roadside drains, and culverts have been lost to gully erosion at Ankpa, Dekina, Ayangba, Ofu, and Ogwulawo.

Non-symmetrical levee breaching processes in a channel bend due to overtopping

A series of experiments were done to reveal the overtopping breaching process of non-cohesive and cohesive levees in a U-bend flume. The flood hydrograph and breaching geometry were measured and analyzed in detail. The results show that the levee breaching processes can be briefly divided into four stages: slope erosion, longitudinal headward gully-cutting, lateral erosion, and relative stabilization. For non-cohesive levees, non-symmetrical lateral development of the breach occurs throughout the four stages, and the final non-symmetrical coefficient is approximately 2.2–2.6. Larger flow discharge or higher water level can accelerate the breaching process, while coarser sands tend to accelerate the process initially but depress the process at the end. The fluvial erosion rate of a non-cohesive breach shows a power-function relation with the excess wall shear stress. For cohesive levees, a plateau forms in the breach partially blocking the flow in the first two stages. The breach flow is approximately perpendicular to the levee body, and, thus, the erosion rates of the two breach sides are almost the same. Non-symmetrical lateral development mainly occurs in the third stage when the deep gully forms. The final non-symmetrical coefficient is approximately 2.7–3.3. It is expected that these findings can provide a valuable experimental dataset and a theoretical basis for breach closure and flood alleviation.

Improving watershed management practices in humid regions

AbstractIn many parts of the world, watershed management practices have been extremely effective. However, implementation of soil and water conservation technologies in the humid African highlands, while beneficial in the short term, were remarkably unsuccessful in the long term. Insights from community knowledge perspectives have revealed that alternative methods are needed. Although conservation practices are designed to conserve water in semi‐arid areas, safely draining excess water is needed in humid areas. The objective of this paper is to review current watershed management approaches used in humid regions as exemplified by those used in Ethiopian highlands and then based on these findings propose more effective practices. Although current government sponsored practices primarily protect the hillsides, direct run‐off is generated from areas that become saturated on valley bottoms near rivers and on specific parts of the hillsides with degraded soils (or with highly permeable surface soils) and with perched water tables on slowly permeable horizons at shallow depths. In these areas, direct run‐off is increasing with deforestation and the soil degradation, demanding additional drainage ways that evolve in the form of gullies. Therefore, watershed management interventions for erosion control should prioritize revegetation of degraded areas, increasing sustainable infiltration, and rehabilitating gullies situated at saturated bottomlands.

The influence of slope morphology on gullies: Terrestrial gullies in Lake George as analogues for Mars

Terrestrial gullies provide a useful benchmark to compare martian gully forms against. We compare pole and equator facing gullies in an unnamed crater located in the martian southern mid-latitudes with gullies located on the Lake George escarpment south of Gearys Gap, New South Wales, Australia. Our investigations showed gully morphology at both sites is greatly influenced by thickness of readily erodable regolith, local slope and the presence or absence of bedrock exposures in the gullies. We found that the martian pole-facing gullies are the most similar to those of Lake George and both systems are therefore likely to have been eroded by liquid water. Although the martian gullies possessed much greater volumes of eroded sediment, they had not eroded to underlying bedrock. This contrasts with the smaller Lake George gully channels where numerous bedrock exposures, observed during our survey, affected their slope and overall morphology. Similarly, although dominated by dry processes, multiple bedrock exposures are present within the equator facing martian gullies affecting their cross sectional area and hence sediment transport. The studied sites all showed significant influence from initial slope angles, indicating that interpretation of gully forms such as slopes below the angle of repose, curved profiles and sinuosity must be placed in context of local environments. This analysis can be applied to other regions of Mars and Earth and provide a greater understanding of how geomorphologic processes operate on both worlds.

About to Lose all the Soil in Zaka’s Ward 5, Zimbabwe: Rewards of Unsustainable Land Use

Soil erosion which manifests itself in the form of gullies, rills and sheet wash is animmensely complicated process involving the interaction of many biological, social,economic, environmental and political factors. It varies in its occurrence bothspatially and temporally. The ultimate result of soil erosion is that it reduces cropyields and ruins agriculture, though the exact extent of soil erosion and landdegradation is not known.The study was carried out in Masvingo Province, ZakaDistrict, Ward 5 with 4502 households using the questionnaire survey, interviewand field observations as research methods. The study established that populationpressure ( people and livestock), as evidenced by, cultivation of steep slopes,stream bank cultivation, deforestation and overstocking are major problems .Fromthe results, it emerged that people continue to compound the problem by settlingand extending farmlands on steep slopes, stream banks, grazing land and dambos/veils. Therefore, there is need to educate people on conservation, proper tillage,proper or correct stocking rates, develop a proper land tenure system and avoidingland degradation. There are patches of abandoned land on account of failure tosupport crops or grazing. This means that there is need for soil conservationmeasures to be instituted so as to save the soil from further deterioration. This isnot to say nothing has been done before, rather it is the enormity of the problemthat dictates that form and decisive action needs be taken sooner rather than latter.Measures which have been implemented are fragmented and seem to have metwith very limited, if at all any, success so there might be need to revisit both theapproach ,methods, techniques and strategies which have been tried hitherto witha view to blend them with the yet untried and untested methods.

About to Lose all the Soil in Zaka’s Ward 5, Zimbabwe: Rewards of Unsustainable Land Use

Soil erosion which manifests itself in the form of gullies, rills and sheet wash is animmensely complicated process involving the interaction of many biological, social,economic, environmental and political factors. It varies in its occurrence bothspatially and temporally. The ultimate result of soil erosion is that it reduces cropyields and ruins agriculture, though the exact extent of soil erosion and landdegradation is not known.The study was carried out in Masvingo Province, ZakaDistrict, Ward 5 with 4502 households using the questionnaire survey, interviewand field observations as research methods. The study established that populationpressure ( people and livestock), as evidenced by, cultivation of steep slopes,stream bank cultivation, deforestation and overstocking are major problems .Fromthe results, it emerged that people continue to compound the problem by settlingand extending farmlands on steep slopes, stream banks, grazing land and dambos/veils. Therefore, there is need to educate people on conservation, proper tillage,proper or correct stocking rates, develop a proper land tenure system and avoidingland degradation. There are patches of abandoned land on account of failure tosupport crops or grazing. This means that there is need for soil conservationmeasures to be instituted so as to save the soil from further deterioration. This isnot to say nothing has been done before, rather it is the enormity of the problemthat dictates that form and decisive action needs be taken sooner rather than latter.Measures which have been implemented are fragmented and seem to have metwith very limited, if at all any, success so there might be need to revisit both theapproach ,methods, techniques and strategies which have been tried hitherto witha view to blend them with the yet untried and untested methods.

Detection of gullies in roughly textured terrain using airborne laser scanning data

Airborne laser scanning data contain information about surface features, some of which are of subtle form. These features are usually embedded within the terrain, and rarely form distinct shape-transition to their surroundings. While some efforts have been made in extracting linear elements from laser scanning data, attention was mostly turned to dominant elements that are very clear and distinct. We present in this paper a detection model for gullies of various dimensions using airborne laser scanning data. Gullies are regarded as one of the main landform-reshaping agents, having a pejorative effect on the environment and on regional development. They are commonly observed along receding lakes as a common response to water-level drop. The paper demonstrates how a multi-scale approach enables the extraction of various gully forms, from well developed to subtle. It then proposes an optimization driven model for handling fragmentation in the detection. Results show that using the proposed model, gully networks can be reconstructed and ∼30 cm deep features can be identified and separated from their surroundings using moderate point density data.

Sowing the Seeds of Soil Conservation

In their Perspective (“Monitoring earth's critical zone,” 20 November 2009, p. [1067][1]), D. deB. Richter Jr. and M. L. Mobley argue for the importance of monitoring Earth's belowground critical zone for sustaining life and humanity. Their message echoes a similar call from a different era. “The Nation that destroys its soil destroys itself.” These words of President Franklin Delano Roosevelt in his 1937 letter to all state governors referred to the Soil Conservation Act of 1935, which recognized the need to sustain soil resources. The Standard Soil Conservation District law was subsequently adopted by all 50 states, plus Puerto Rico and the Virgin Islands. Historical aerial photos across the country from 1947 to 2004 ([ 1 ][2]) provide evidence that the law has been effective in protecting many farmlands and show that visible erosion in the form of gullies is now almost nonexistent in comparison with the erosion that occurred in the 1930s. In the decades since the Natural Resources Conservation Service started the National Resources Inventory in 1982, soil erosion on U.S. croplands has decreased 43% ([ 2 ][3]). ![Figure][4] Fighting erosion. Contour stripcropping is one method used to protect soils. CREDIT: RON NICHOLS/USDA-NRCS Laws like the one President Roosevelt championed in the 1930s are more important today than ever. Urban sprawl, land degradation, environmental pollution, and anthropogenically accelerated erosion (to name just a few) are detrimental to sustainable food production and quality water supply for the growing world population. Modern soil vulnerability to global change and anthropogenic threats (beyond just croplands) is unprecedented. This issue was not addressed in the 1930s law but could have devastating effects. Monitoring and protecting the belowground critical zone is a crucial step to ensure that we do not lose ground for sustainability. 1. [↵][5] 1. L. E. Mathews , Aerial Photography Field Office Historical Imagery Holdings for the United States Department of Agriculture (2005); [www.apfo.usda.gov/Internet/FSA\_File/vault\_holdings2.pdf][6]. 2. [↵][7] Natural Resources Conservation Service, National Resources Inventory 2003 Annual NRI: Soil Erosion (2007); [www.nrcs.usda.gov/technical/NRI/2003/SoilErosion-mrb.pdf][8]. [1]: /lookup/doi/10.1126/science.1179117 [2]: #ref-1 [3]: #ref-2 [4]: pending:yes [5]: #xref-ref-1-1 View reference 1 in text [6]: http://www.apfo.usda.gov/Internet/FSA_File/vault_holdings2.pdf [7]: #xref-ref-2-1 View reference 2 in text [8]: http://www.nrcs.usda.gov/technical/NRI/2003/SoilErosion-mrb.pdf

Alluvial gully erosion: an example from the Mitchell fluvial megafan, Queensland, Australia

AbstractConsiderable attention has been focused on the role of gullies as a contributor to contemporary sediment loads of rivers in Australia. In southern Australia rapid acceleration of hillslope gully erosion has been widely documented in the post‐European period (∼ last 200 years). In the northern Australian tropics, however, gully erosion processes operating along alluvial plains have not been well documented and can differ substantially from those gullies eroding into colluvium on hillslopes. Aerial reconnaissance surveys in 2004 along 13 500 km of the main stem rivers that drain into the Gulf of Carpentaria (GoC), identified extensive areas of alluvial lands that have been impacted by a pervasive form of gully erosion. More detailed remote sensing based mapping within the 31 000 km2 Mitchell River fluvial megafan has identified that active gullying into alluvium occupies ∼ 0·4% (129 km2) of the lower Mitchell catchment. These alluvial gullies are concentrated along main drainage channels and their scarp heights are highly correlated to the local relief between the floodplain and river thalweg. While river incision into the megafan since the Pleistocene has developed the relief potential for erosion, other factors such as floodplain hydrology, soil dispersibility, and vegetation also influence the distribution of gullies. In this paper we present a conceptual model of alluvial gullies, and contend that they represent a distinct end member in the continuum of gully forms that have been described in the geomorphic literature. An understanding of the processes driving this form of alluvial gullying can only be gained when they are differentiated from widely described colluvial hillslope gully models and theories. We present evidence of type examples of alluvial gullying in the Mitchell, and through analysis of their distribution and morphology at different scales, highlight some of the key mechanisms that are potentially initiating these features and driving their expansion. Copyright © 2009 John Wiley & Sons, Ltd.

Experimental simulation of martian gully forms

Gullies are widespread on slopes on the surface of Mars and have been investigated by numerous authors, yet their formation processes remain elusive. In an attempt to understand the possibility of a water-based origin for these forms, we undertook a series of flume experiments at Earth surface temperatures and pressures. Our objectives were to produce forms that resemble those most commonly observed on Mars, documenting their morphometric characteristics and identifying any statistically significant relationships between form and controlling factors of slope and flow rate. Experiments were conducted in a 1×1.5 m 2 flume filled with medium grain size sand. The experiments were run over a slope angle range of 10–30°, corresponding to the range for gullies on Mars. Water from a constant-head tank fed through 5 mm silicone hose to a rotameter and then released just below the surface at the top of the slope. Gullies were produced at slope angle values of 10°, 20°, and 30° and flow rate values of 445, 705, 965, and 1260 mL min −1 at each angle. Eighteen parameters were identified and subsequently measured on each gully produced in the flume. Gully forms were successfully reproduced and displayed development of the fundamental morphological components observed on Mars: alcove, channel, and apron. Slope–gully form relationships for each component revealed the following results: higher slope angles formed shorter gullies with thicker apron deposits. Moreover, longer gullies were seen at higher flow rates. We concluded that forms visually similar to those observed on Mars can be created by water in the laboratory flume under terrestrial conditions. Morphometric parameters can be measured and permit identification of controlling factors. Experimental simulation of gullies appears possible with proper scaling of experimental parameters. Although not directly scalable to Mars, flume gully parameters may be used to develop numerical models in the future.

Soil erosion on a sub-tropical coastal dune complex, Transkei, Southern Africa

A fossil dune complex on the east coast of southern Africa is presently undergoing extensive accelerated erosion, with concomitant dune reactivation and degradation, unconfined erosion (sheetwash and wind deflation) and extensive development of V-shaped, ravine-type gully forms on hillslopes composed of thick sequences of Quaternary (Berea Formation?) dune sands. The sands comprise a thick, reddened, ferralitic sand carapace overlying white, poorly cemented quartzitic sands. Soil erosion has resulted from degradation of the red dune sand cover. Despite the cohesionless nature of the host materials, gully forms developed on dune sands are typologically similar to those developed in regolith or soft bedrock. This demonstrates that gully forms are influenced by the degree of homogeneity, rather than the absolute strength, of the host material subject to erosion. Factors which have contributed to erosion are discussed.