Progress in gully erosion research: IV International Symposium on Gully Erosion
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Publication Open Access Soil erosion on the bottom of hollows in steppe zone of Ukraine(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Zubov, A. R.; Zubova, L. G.Soil erosion, undoubtedly, is one of the main ecological and agricultural problems in the world. Quantity of eroded lands in Ukraine achieves 10.5 millions ha. Annual losses of soil constitutes about 600 millions tons in the country. Gully erosion and other kinds of soil degradation are very extended in east party of Ukraine. Often forming of gullies begin in the links of primary hydro-graphical network, i.e. on the bottom of the hollows. In the countries of the former USSR the application of so-called “measures of constant action” (the soil-protection ground hydrotechnical constructions, runoff-regulating forest shelterbelts and other linear boundaries) are the most recognized way of the soil protection. The aims of this are: 1) to define quantitative indicators of soil loss due to water erosion; 2) to study the soil protection role of MCA on the slopes with hollows.Publication Open Access The role of preferential flow through soil-pipes in ephemeral gully erosion(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Wilson, G.V.The objective of this study was to quantify the hydrologic conditions under which discontinuous soil-pipes reestablish ephemeral gullies and continuous soil-pipes initiate ephemeral gullies.Publication Open Access Historical gully erosion with loess areas of SE Poland – Natural conditions and human impact(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Zglobicki, W.; Baran-Zglobicka, B.; Gawrysiak, L.Gullies constitute one of the most characteristic elements of loess relief in SE Poland. Particularly dense net of permanent gullies – in some places more than 10 km?km-2 – appears in areas of specific conditions of abiotic environment which favour gully erosion. However, it is generally believed that these conditions were not a natural landscape (Bork 1989, Schmitt et al. 2006, Vanwalleghem et al. 2003). Only after the devastation of the natural plant cover of mixed and deciduous forests, resulting from agricultural expansion, the erosion began to develop dynamically. The purpose of this article was to determine the influence of natural factors and human activity on the processes of gully erosion (density of permanent gullies). The existing gully systems were examined and the achieved results give an idea about the processes taking place in the past.Publication Open Access Influence of soil structure, pore-water pressure, and tailwater height on headcut migration in upland concentrated flows(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Wells, R.; Alonso, C.V.; Bennett, S.J.The primary objective of this study was to determine the impact of soil texture, soil pore-water pressure, and tailwater height on scour hole dimensions, migration rate and sediment yield in headcuts migrating under steady surface runoff conditions.Publication Open Access A general sediment transport model for linear incisions(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Vanwalleghem, T.; Giráldez Cervera, Juan Vicente; Jiménez Hornero, F.J.; Laguna, A.Previous research has shown that the functional relationship between sediment transport and shear stress, discharge and slope is non-linear. The different datasets that support this hypothesis are however all derived from flume experiments or river channels. No calibration was done at the field scale. Recenltly, Istanbulluoghi et al. (2003) successfully calibrated the sediment transport function with field data from eroding gullies in the Idaho Batholith. However, the field data presented covered only a relatively limited range of condition. In this study, more field data is presented that supports the field-scale calibration over a wider array of shear stress conditions in the lower range.Publication Open Access Seepage erosion impacts on edge-of-field gully erosion(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Wilson, G.V.; Fox, G.A.; Chu-Agor, M.L.Concentrated flow is generally considered the controlling mechanism for gully erosion whereas subsurface flow is often overlooked. The two mechanisms of subsurface flow attributed to gully erosion are seepage flow and preferential flow through soil-pipes. Seepage erosion typically occurs in duplex soils in which a perched water table develops above a water-restricting horizon. The effect of seepage is usually considered to be limited to the production of surface runoff and the impact of increasing soil water pressures on reducing soil shear strength. However, recent studies by Wilson et al. (2007), Fox et al (2006, 2007), and Chu-Agar et al. (2007) have demonstrated that seepage erosion can be the controlling process of streambank failure and by analogy may be a significant contributor to gully erosion. Seepage erosion is used to describe the process of sediment transport out of the gully face by liquefaction of soil particles entrained in the seepage. The undercutting of the gully face by seepage erosion results in bank failure which may be a contributing factor to headcut migration and gully widening. This paper will review this recent work on seepage erosion.Publication Open Access Gully erosion risk zoning: proposal of a methodology and case study(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Viero, A.C.; Castro, N.M.R.; Risso, A.; Goldenfun, J.A.Gullying is the most advanced, complex stage of erosion processes, with more local destructive power than other types of erosion (São Paulo, 1990). In this paper, we propose a method to generate gully erosion risk zoning in the far south plateau of Brazil, based on geological characteristics, soils and geomorphology.Publication Open Access Some examples of ephemeral gully erosion in an Atlantic area of NW Spain(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Valcárcel, M.; Paz, A.; Vidal, E.This study aimed to describe types of ephemeral gullies and to determine their origin, evolution and importance as sediment sources in Galicia (Northwest Spain). Concentrated erosion was surveyed on medium textured soils, developed over basic schist of the Ordenes Complex series (Corunna province, Spain) from 1997 to 2006. The studied region has a humid Atlantic climate with a mean annual rainfall of about 1000-1500 mm. Precipitation distribution is uneven, with a maximum between October and March and a minimum in the summer. The geological materials of the study area consist of basic metamorphic rocks and granite. Gullies formed within the field where runoff starts, gullies collecting the runoff from an upstream area and discontinuity gullies due to abrupt slope changes were identified (Valcárcel, M. et al., 2003). Ephemeral gullies formed by incision along linear elements generally showed large sections in zones with high slope, so that a gradual decrease from the maximun crosssection, both toward the head and downstream, occurred. This variation from head-cut to outlet of the gully may be attributed to the small flow rates at the upstream and saturation of the transport capacity downslope, where sedimentation initiates (Casalí et al, 1999).Publication Open Access Comparison of historical evolution of gully networks on both Slovak and Moravian forelands of the white Carpathians(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Stankoviansky, M.; Létal, A.; Damankosová, Z.The main objective of the contribution is to present the preliminary results of comparison of historical evolution of gully networks in both Slovak and Moravian forelands of the White Carpathians. This geomorphic unit represents the flysch mountain range situated in the boundary zone of Slovakia and the Czech Republic, reaching the elevation 970 m. The Slovak foreland of the White Carpathians, i.e. the Myjava Hill Land, belongs among those areas in Slovakia that were the most affected by disastrous gullying in the past. This fact was one of the main reasons to choose precisely this area for detailed investigation of historical gullies, lasting at the moment approximately one decade. The study of the Moravian foreland of the White Carpathians, i.e. Hluk Hill Land, started in 2006. Its first goal was to find out if the density of gully network on the Moravian side is comparable with that at the Slovak side. Beside the density of gully networks also the age of gullies and causes of their formation on both sides of the frontier were subjects of this comparison. Comparison of gullies on both forelands of the White Carpathians is introduced in the context of the review of the research dealing with the historical evolution of gullies in Slovakia and Czech Republic.Publication Open Access Causes of gully erosion in arid ecosystem: case study southern part of I.R. Iran(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Soufi, M.This research demonstrated that the I.R. region is prone to gully erosion. The study area had limited gully erosion four decades ago. With accelerating urban development during the past, two to three decades, areas of gully erosion increased. Comparison of gully advancement showed that the area of gully erosion increased 4 times in four decades before. Gullies are located around urban areas with more deteriorated cropland and roads. Statistical analysis revealed that area of gully erosion could be attributed to the area of bareland and road length. The overall the impact of bareland area is more significant than road length in study watersheds, although their contribution in individual site is completely different.Publication Open Access Effectiveness of palm and bamboo geotextiles in reducing concentrated flow erosion(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Smets, T.; Langhans, C.; Poesen, J.; Knapen, A.Rills and gullies, caused by concentrated flow erosion, represent an important sediment source in many environments (Poesen et al., 2003). Studies indicate that vegetation can be very effective in controlling gully development. However, the establishment of a vegetation cover can be delayed or obstructed by the development of rills and gullies due to concentrated flow erosion. Before the vegetation has reached a critical cover and root density to significantly reduce concentrated flow erosion, a period of high erosion risk occurs. Hann and Morgan (2006) indicate that applying geotextiles on the soil surface is the most efficient method to control erosion until a critical vegetation cover has been established. Preliminary investigations suggest palm-mat geotextiles could be an effective and cheap soil conservation method, with enormous global potential. However, very little is known about the effectiveness of (palm) geotextiles in reducing concentrated flow erosion. Almost no data are available on the impacts of palm geotextiles on the hydraulic, hydrologic and erosion characteristics of concentrated flow for a range of environmental conditions. Therefore, the objectives of this study are (i) to assess the effectiveness of two palm-mat and one bamboo geotextile in increasing the hydraulic roughness of the soil surface under concentrated overland flow and in reducing soil erosion rates by concentrated flow on an erodible soil type and for a range of flow shear stresses; and (ii) to investigate which is the most appropriate hydraulic variable (e.g. shear stress, unit length shear force or stream power) to predict the net soil detachment by concentrated flow.Publication Open Access Discharge and gully erosion in a small rangeland catchment(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Schnabel, Susanne; Gómez Gutiérrez, Á.; Sanjosé Blasco, J.J.Valley bottom gullies are a common feature in rangelands. Although these gullies are found in the bottom of drainage lines, information about the relationship between discharge and gullying is scarce (Crouch, 1990; Thomas et al., 2004). This may in part be due to the large temporal variation of this phenomenon making necessary monitoring of runoff and erosion for a large number of years. Since 1990 research is carried out on the development of valley bottom gullies in small wooded rangeland catchments in southwest Spain. Erosion varies strongly along the gully section with high losses related to headcut retreat (Schnabel et al., 1999). The importance of extreme events producing exceptional sediment losses has also been demonstrated (Schnabel, 1997). In the year 2000 investigation started in the Parapuños experimental basin. The present paper aims at understanding the relationship between gully erosion and catchment hydrology.Publication Open Access Morphology and controlling factors of landslide cirque gullies: a case study from the Sprogu gravas nature monument (SE Latvia)(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Soms, J.Human-induced changes of landscape and the vegetation cover have been recognized in the majority of studies focusing on gully formation as one of the most important factors triggering the development of gullies throughout the world. However, detailed studies of singular erosion landforms in south-eastern Latvia, particularly those that are located on steep slopes of river banks modified by mass movement processes and presently found under forest, indicate that these gullies are not a geomorphic features resulting entirely from human agricultural activities. Such short, bottleneck-shaped gullies (Crosta, di Prisco, 1998), described in Latvia as landslide cirque or spring cirque gullies (Venska, 1982), can be found in deep river valleys and subglacial tunnel valleys in Latvia, but few studies have reported on their morphological characteristics and their origin. This study investigates these landslide cirque gullies initiated via mass movement processes in the local case-study area of the river Daugava Valley in south-eastern Latvia. The objectives are (1) to determine the spatial distribution of these gullies, (2) to measure their morphological and topographical characteristics and (3) to interpret the factors that led to their development.Publication Open Access Estimating sediment yield from gully erosion using easily measurable morphometric characteristics in Darehshahr region, south of I.R. Iran(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Sadeghi, S.H.R.; Noormohammadi, F.; Soufi, M.A case study was conducted in a part of Ilam Province, I.R. Iran, to establish a reliable model for estimating sediment yield from gully erosion. The attempt was satisfactory and led to an applicable model whose input could be obtained through a simple field measurement or applying remote sensing. The finalized factors can be found out through interpreting high resolution aerial photos or images and with the help of necessary soft wares or techniques. Although the model was statistically sound especially for the study area but the more numbers of gullies in different types distributed in miscellaneous climates and land uses may help to draw final conclusions.Publication Open Access Waterfall erosion as a main factor in ephemeral gully initiation in a part of Northeastern Iran(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Sadeghi, S.H.R.; Rangavar, A.S.; Bashari, M.; Abbasi, A.A.The present study assesses the factors controlling gully formation in a study area located in northeastern Iran. Gully erosion in northeastern Iran is very high because of the high rate of human encroachment and the resulting impacts on soil erosion.Publication Open Access Seepage flow in aquifers with open and closed boundaries(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Römkens, M.J.M.; Prasad, S.N.At previous gully erosion conferences, the effect of surface seal development on gully formation and growth was analyzed (Prasad and Römkens, 2003) and the effect of hydrological conditions on gully growth was discussed (Römkens and Prasad, 2005). In the latter study, it was suggested that seepage forces, i.e., exit gradients, may appreciable affect gully growth and that solutions of Laplace’s equations for a quasi-steady state flow field might be helpful in assessing the effect of seepage on gully growth. In this presentation, seepage flow is discussed, based on selected studies that used conformal mapping procedures. These studies may be helpful in making assessments of the impact of seepage on gully erosion.Publication Open Access The importance of the presence of gullies in the production of sediments in semiarid areas (Murcia, south-east of Spain)(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Romero Díaz, A.; Martínez Lloris, M.; Alonso Sarría, F.; Belmonte Serrato, F.The study has shown how the existence of gullies remarkably increases the rates of erosion and, therefore, the volume of sediments that arrives at the dikes of hydrological correction. A consequence of this is the need to carry out works of this type in basins with reservoirs to avoid its filling, in spite of the little life utility of the constructed dikes.Publication Open Access Surfaces of gullies generated by piping process in abandoned fields (south-east of Spain)(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Romero Díaz, A.; Marín Sanleandro, P.; Sánchez Soriano, A.The piping process have an important development in old agricultural terraced fields. The abandonment of these fields, together with the lithologies, hydraulic and climatic characteristics favour the quick development of pipes. Its subsequent evolution is the development of a landscape with gullies, with a deteriorated and non-recoverable space for agricultural use, in addition to constituting an important sediment source with elevated rates of erosion.Publication Open Access Gully erosion in semi-arid landscapes - monitoring of processes and development(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Ries, J. B.; Marzolff, I.; Seeger, M.The research project MoGul (Large-scale Monitoring of Gully Erosion in Semi-Arid Landscapes) at Trier and Frankfurt University investigates the various types, development and dependencies of gullies as well as geomorphological processes involved in gullying. The investigations are carried out at different sites following a transect from the semi-arid Ebro Basin in Northeast Spain, via the sub-humid Baza and Guadalentín Basins in Southeast Spain and the arid Drâa Valley in South Morocco to the semi-arid Oudalan in Sahelian Burkina Faso. Investigations on short-term gully change are mostly realised using field methods for quantification of linear headcut retreat rates. The lack of image resolutions corresponding to the magnitude and dynamics of gully erosion usually prevents the use of remote sensing data, which in contrast to field measurements allow for the rapid and spatially continuous coverage of a site (Marzolff, 1999; Ries and Marzolff, 2003). The objective of this paper is to present an overview of the first results of the MoGul project on gully monitoring which employs large-scale aerial photography taken from remote-controlled platforms (hot air blimp and kites).Publication Open Access Influence of snowmelt and heavy rainfalls on water and sediment yield from loess gully catchment (Lublin upland – Poland)(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2007) Rodzik, J.; Furtak, T.; Zglobicki, W.The surface discharge from the gully catchments of the Lublin Upland (Poland) usually is not very high and amounts to about 15 mm·yr-1. It is mainly an episodic discharge of snow/rainfall regime. Surface runoff and rill erosion are caused by rains of the total >10 mm and intensity >1 mm·min.-1, the main factor of gully erosion is however snowmelt runoff. Most of the material set in motion at that time remains at the bottom of the gully, and can be carried away during heavy rainfalls.