Volume Of Soil Loss Research Articles

A Simple Deposition Model for Debris Flow Simulation Considering the Erosion–Entrainment–Deposition Process

This study aimed to determine the depositional effect and improve the identification of debris flow risk zones. To accomplish this goal, we developed a two-dimensional debris flow model (Deb2D) based on a hyperbolic conservation form of the mass and the momentum balance equation with consideration of the erosion–entrainment effect as well as the depositional effect. In this model, we implemented a widely-used rheological equation—the Voellmy equation—and a quadtree adaptive grid-based shallow-water equation. This model was applied to two study sites to assess the depositional effect. The impact area, volume of soil loss, maximum velocity, inundated depth, and erosion depth resulting from the debris-flow modeling were compared with the field data. The simulation results with/without deposition were evaluated using the receiver operating characteristic method. The implementation results of the erosion–entrainment model with deposition showed superior accuracy when estimating the damage range and flow time.

Do roots bind soil? Comparing the physical and biological role of plant roots in fluvial streambank erosion: A mini-JET study

The roots of riparian vegetation can reduce fluvial streambank erosion by increasing soil resistance to erosion or by altering the applied hydrodynamic force of flowing water; however, the relative importance of these mechanisms is unknown. To assess the physical and biological effects of plant roots on streambank fluvial erosion, laboratory-scale testing was conducted using a mini Jet Erosion Testing (JET) device. Data analysis was conducted on three treatment groupings: (1) no roots (NR, n = 24); (2) synthetic roots (SR, n = 24); and (3) live roots (LR, switchgrass [Panicum virgatum], n = 12). Soil erosion was quantified by measuring the final volume of soil loss and calculating critical shear stress (τc) and the soil erodibility coefficient (kd). Potential explanatory soil and root properties, including percent water stable aggregates, root length density, and extracellular polymeric substances, were also measured. Kd was lower in rooted soil samples compared to NR when root length density was 2 cm cm−3 or higher, indicating that soil with densely packed fibers (either live and synthetic) have an impact on the applied hydrodynamic forces. However, τc was significantly higher in LR compared to both NR and SR, suggesting that only living roots provide additional soil protection by increasing soil resistance to fluvial erosion. The results of this study further emphasize that plant roots protect streambank soils from fluvial erosion through multiple mechanisms; nevertheless, further research is needed to determine which mechanism(s) plays a dominant role.

Developing a Methodological Framework for Estimating Temporary Drainage Capacity to Inform Land Requirements for a Highway Construction Project in Scotland

Silt pollution generated during major highway construction projects can prove detrimental to the water environment and the aquatic species that depend on it. Construction activities can leave many kilometers of exposed soil susceptible to erosion from surface water runoff, which can result in silt pollution and degradation of ecologically sensitive watercourses if appropriate mitigation is not in place. In Scotland, assurances need to be provided during scheme development to demonstrate that there is sufficient space to accommodate temporary drainage. In response, a methodological framework has been developed that can be applied before construction commences to estimate the required capacity of settlement ponds including runoff and soil loss volume estimation, which are estimated using the Rational Method and Revised Universal Soil Loss Equation (RUSLE). The application of the framework as a case-study has demonstrated the potential applicability of the approach and highlighted where further refinements can be made to increase the robustness for future applications by improving the accuracy of input parameters to address site-specific conditions. Furthermore, it demonstrates how adopting erosion control measures can reduce the land required to accommodate temporary settlement ponds.

Soil loss as a desertification risk indicator: mapping and simulation in the Salitre River Sub-Basin, Northeast Brazil

Discussions on desertification frequently highlight soil erosion as a striking feature of this phenomenon. In particular, the high spatial density of gullies represents a strong indication of the formation of desertification hotspots. In this study, through field activities and Monte Carlo simulations, we estimated the volume of soil loss by linear erosion on the slopes of the middle course of the Salitre river in the North of Bahia State. This estimative contributes to the recognition of a desertification process [...]

Experimental study of hydraulic characteristics on headcut erosion and erosional response in the tableland and gully regions of China

AbstractSevere long‐term gully headcut erosion, which further decreases the area of Yuan, is a serious yet poorly understood issue for local ecological environments and social development. Nevertheless, although the hydraulic characteristics of headcut erosion in the loess tableland and gully region of the Loess Plateau remain unclear, they constitute critical inputs in headcut erosion prediction models. The goal of this study is to evaluate the hydraulic properties of concentrated flow and the headcut erosion process and to identify the influence of flow energy consumption on headcut erosion in the loess tableland and gully region. A series of in situ simulated rainfall and runoff scouring experiments were carried out to achieve this goal under flow discharges of 100, 200, 300 and 400 L min−1 with a rainfall intensity of 0.8 mm min−1. The total sediment yield was 1660–3850 kg and increased linearly with increasing flow discharge. The contribution rate of soil loss volume at gully head increased with experiment time and was 2.7 times greater than at the upstream area. The concentrated flow was turbulent and supercritical during the erosion process. The headcut retreat distance, flow velocity, Reynolds number, shear stress, stream power, velocities at the brink and bottom, and flow energy consumption at 100–400 L min−1 were 5.5–25.5 cm, 0.63–1.48 m s−1, 1244–8593, 0.65–4.45 Pa, 0.61–4.22 W m−2, 0.78–2.47 m s−1, 5.23–5.88 m s−1, and 3.52–12.63 J s−1, respectively, all of which increased with increasing flow discharge. A positive power function was found between the sediment yield and flow energy consumption, which can be helpful in establishing soil erosion model based on erosion processes. These findings ultimately improve our understanding of headcut erosion in the tableland and gully regions of the Loess Plateau.

Relationship between Rainfall, Surface Runoff and Soil Loss on an Experimental Farm in the Middle Belt of Nigeria

Rainfall induced depletion of soil nutrients resulting from runoff and soil erosion are a main threat for agricultural lands, tending to reducing soil fertility, soil productivity and eventually leading to the un-sustainability of agricultural production systems. It is based on the problems associated with soil loss that the required mulch type, mulch cover and slope of the farming field need to be properly investigated and determined. This research therefore analyzed surface runoff and soil loss under different mulch treatment at a farm site in Benue State, in the middle-belt region of Nigeria. The main aim is to analyze the effect of varied mulching will have on runoff and soil loss volumes resulting from rainfall and examine the implication of the results on soil management practice in the region. Experimental plots of 20m long by 3m wide were carved out with an outlet down slope of 1.5m2 (20m×3m+1.5m2 = 61.5m2 ) were bordered with corrugated iron sheets and inserted with runoff and soil loss receptors. The experimental plots were treated with weighted organic materials (mulching, in tons) and planted with maize with plots of zero (0) tons as control (T1). The maize planted was spaced 25cm on row and 75cm on columns. The experimental plots were replicated and symbolized as (T1) = bare surface (0 tons A, B and C), (T2) = surface mulch +maize (4 tons A, B and C) and (T3)= surface mulch + maize (8 tons A, B and C). Rainfall data was collected over ten (10) rain events and runoff and soil loss measurements was analyzed with using correlation statistics, variability and regression. The results show that 96.14% runoff occurs on T1, 3.22% and 0.63% runs off on the T2 and T3 respectively with corresponding 193.7kg, 3.1kg and 0.5kg soil loss. The study finds out that mulching reduces simultaneously both runoff and soil loss in the region. The amount rainfall only has no significant effect on amount of runoff and volume of soil loss. The study revealed that, surface cover combined with simple cropping controls runoff and soil loss by 67% and 61% respectively. This will be useful to farmers in addition to the fact that mulching also has a collateral benefit of stimulating microbial activities and regulating soil moisture and temperature.

A comparative study of embankment breach parameters in different breach locations

In general, when an embankment breach occurs, the breach expands laterally due to erosion of both breach sides. However, when the breach occurs close to a solid wall, the erosion occurs primarily on one side. This paper presents a study on the comparative parameters of the breaches that occurred at the middle of the embankment width, and at the location adjacent to a solid wall. A physical model is constructed such that the breaches could be observed. The downstream slopes of the embankment model were set at 1:1, 1:1.5, and 1:2. Cohesive soil was used to construct the embankments with the bulk density distributions ranging from 1.4 to 1.7 g/cm3. The experiments were conducted by allowing water to flow over the embankment at different flow rates. The breach dimensions were measured and transformed into dimensionless breach parameters. These dimensionless breach parameters were analysed to ascertain their relation with relevant dimensionless flow parameters. The results reveal that for the same embankment slope and discharge rate, the breach parameters change depending on the location of the breach, except for the parameter of the soil loss volume. The distance between the breach location and the solid wall affects the values of the maximum breach width, the maximum breach depth, and the maximum scour depth. There is shown that breach depth and scour depth for breaches adjacent to the solid wall are deeper than those of the breaches occurring in the middle section of the embankment. In addition to these findings, the empirical relation among these dimensionless breach parameters obtained from other case studies are also discussed.

An experimental study on the effects of grass root density on gully headcut erosion in the gully region of China's Loess Plateau

AbstractVegetation plays an important role in gully headcut erosion in China's Loess Plateau, but little is known about the effects of root density on gully headcut erosion. This study attempted to investigate the effects of grass root density on gully headcut erosion and morphological development of the gully head using plots with different grass root densities (with bare land as the control). The experiment was performed on plots with different grass root densities, and the rainfall intensity and inflow discharge increased throughout the experiment. The results showed that headcut migration in bare land was mainly activated by upstream flow incision, headwall erosion, and plunge pool erosion, whereas headcut migration in grassland was driven by soil‐root matrix collapse at the headcut, headwall erosion, and plunge pool erosion. The soil loss rate (SLR), gully headcut retreat distance (GRD), gully area (GA), and upstream soil loss volume (SLVU) in grassland plots with different root densities were 45.64–68.45%, 66.97–85.38%, 69.26–78.18%, and 67.89–87.02% less than those in the bare land plots, respectively. However, as root density increased, the gully depth in the grassland plots increased from 19% to 59%, and the proportion of gully head soil loss volume (SLVGH) to the total soil loss volume increased from 63.37% to 88.37%. The SLR, GRD, GA, and SLVGH showed decreasing trends as the root density increased, as described by a Hill curve. Moreover, roots with diameters of 0–0.5 mm had greater effects on soil loss and morphological evolution than roots with larger diameters. Our results provide a reference for the reasonable selection of grass root density for controlling gully headcut erosion in China's Loess Plateau.

Impacts of headcut height on flow energy, sediment yield and surface landform during bank gully erosion processes in the Yuanmou Dry‐hot Valley region, southwest China

AbstractTo quantify the changes in flow energy, sediment yield and surface landform impacted by headcut height during bank gully erosion, five experimental platforms were constructed with different headcut heights ranging from 25 to 125 cm within an in situ active bank gully head. A series of scouring experiments were conducted under concentrated flow and the changes in flow energy, sediment yield and surface landform were observed. The results showed that great energy consumption occurred at gully head compared to the upstream area and gully bed. The flow energy consumption at gully heads and their contribution rates increased significantly with headcut height. Gully headcuts also contributed more sediment yield than the upstream area. The mean sediment concentrations at the outlet of plots were 2.3 to 7.3 times greater than those at the end of upstream area. Soil loss volume at gully heads and their contribution rates also increased with headcut height significantly. Furthermore, as headcut height increased, the retreat distance of gully heads increased, which was 1.7 to 8.9 times and 1.1 to 3.2 times greater than the incision depth of upstream area and gully beds. Positive correlations were found between energy consumption and soil loss, indicating that energy consumption could be used to estimate soil loss of headcut erosion. Headcut height had a significant impact on flow energy consumption, and thus influenced the changes in sediment yield and landform during the process of gully headcut erosion. Headcut height was one of the important factors for gully erosion control in this region. Further studies are needed to identify the role of headcut height under a wide condition. Copyright © 2018 John Wiley & Sons, Ltd.

Evaluation of brush wood with stone check dam on gully rehabilitation

Gullies are common features throughout the Ethiopian Highlands. Induced environmental degradation comprises not only the loss of soil volume and of arable lands, but also the triggering of landslides or off-site sedimentation problems. This experiment was initiated with the aim of evaluating the effect of brush (bamboo) wood with stone check dam on soil and water conservation (gully rehabilitation) at Benishangulgumuz region of Assosa zone (Assosa district of selga-19 for two consecutive research years (2013/14-2014/15) on farm land. The gully site was selected purposively based on the prevalence of gully erosion. Biophysical and socio -economic data were collected from the gully and participant farmers to evaluate the effectiveness of the measures. The potential of the check dam to conserve the soil was evaluated by using the pin installed in front the check dam to observe the change of gully depth, cross sectional area and soil loss data were collected. A total of 22 households were sampled to assess the perception, acceptance and adoption level of the farmers using simple random sampling technique. the result indicates that the gully depth and volume of soil loss, were reduced from 0.94m to 0.58m and volume of soil loss from 468 ton/ha/yr to 204 ton/ha/yr. The interviewed farmers response also indicated that, all (100%) of them were mentioned the presence and severity of soil erosion on their farm land and which is increasing from time to time in alarming rate and where all of the farmers mentioned loss of fertile top soil and in turn yield reduction as its integral effect. 95.5% of the farmers were confident enough to rehabilitate the gully using bamboo with stone check dam by supplementing with other biological measures and all (100%) of the farmers ratified the effectiveness of the measures to rehabilitate the gully and willing to implement on their farm land thereby to disseminate the technology to non- participant farmers.

Infiltration and Soil Loss Changes during the Growing Season under Ploughing and Conservation Tillage

Decreased water retention and increased runoff and soil loss are of special importance concerning soil degradation of hilly crop fields. In this study, plots under ploughing (conventional) tillage (PT) and conservation tillage (CT; 15 years) were compared. Rainfall simulation on 6 m2 plots was applied to determine infiltration and soil loss during the growing season. Results were compared with those measured from 1200 m2 plots exposed to natural rainfalls in 2016. Infiltration was always higher under CT than PT, whereas the highest infiltration was measured under the cover crop condition. Infiltration under seedbed and stubble resulted in uncertainties, which suggests that natural pore formation can be more effective at improving soil drainage potential than can temporary improvements created by soil tillage operations. Soil erodibility was higher under PT for each soil status; however, the seedbed condition triggered the highest values. For CT, soil loss volume was only a function of runoff volume at both scales. Contrarily, on PT plots, some extreme precipitation events triggered extremely high soil loss owing to linear erosion, which meant no direct connection existed between the scales. Improved soil conditions due to conservation practice are more important for decreasing soil loss than the better surface conditions.

Impacts of artisanal gold mining systems on soil and woody vegetation in the semi‐arid environment of northern Ethiopia

Gold mining is a tremendously important economic activity in rural districts of Ethiopia. We assessed the impacts of artisanal gold mining on soil and woody vegetation in northern Ethiopia. Estimation of soil loss, plant inventory, group discussions and transect studies were used to address the research questions. We employed t‐test to compare woody species and soil loss between mined and unmined sites. Moreover, we ran one‐way ANOVA to compare the average volume of soil loss among the mining sites. The study shows that gold mining removed colossal volumes of soil from the mining landscape with a significant difference among gold mining sites (P ≤ 0.05). Soil loss between the mined and unmined sites was also significant (P ≤ 0.05). Moreover, gold mining destroyed massive tracts of vegetation. Woody species encountered at plot level decreased from artisanal gold mined to unmined sites (P ≤ 0.05). Moreover, dead trees and exposed tree roots were higher in mined than the unmined areas (P ≤ 0.05). This discouraged regeneration and recruitment of woody vegetation. To conclude, gold mining system converted vegetated sites and farmlands into dysfunctional landscape. Therefore, we suggest that combined rehabilitation efforts are required to overcome the challenges of artisanal gold mining on sustainable land management in northern Ethiopia.

Effect of National-Scale Afforestation on Forest Water Supply and Soil Loss in South Korea, 1971–2010

Afforestation of forests in South Korea may provide an example of the benefit of afforestation on precipitation storage and erosion control. In this study, we presented the effects of afforestation on water supply and soil loss prevention. A spatio-temporal simulation of forest water yield and soil loss was performed from 1971–2010 using InVEST water yield and SWAT models. A forest stock change map was produced by combining land cover data and National Forest Inventory data. The forest water yield increased about twice with changes in forest stock and climate from 1971–2010 and showed a spatially homogeneous water supply capacity. In the same period, the soil loss decreased more than three times, and the volatility of soil loss, in the 2010s, was smaller than before. The analysis of the change in forest stock without considering climate change showed an increase of 43% in forest water yield and a decrease of 87% in soil loss. An increase in precipitation increased the water yield, but also increased the soil loss volume. A change in forest stock led to positive changes in both. This study presents functional positive effects of the afforestation program in South Korea that can be useful in various afforestation programs in other countries.

Effects of initial step height on the headcut erosion of bank gullies: a case study using a 3D photo-reconstruction method in the dry-hot valley region of southwest China

Headcut erosion has been recognized as one of the main processes involved in gully development in the dry-hot valley region of southwest China. To examine the effect of initial step height on headcut erosion processes, three headcuts were constructed ranging in height from 0.75 to 1.25 m on an active bank gully head, and a series of scouring experiments were conducted under a flow discharge of 120 L min−1. The morphological evolutions of the plunge pools and soil loss volume were estimated by three-dimensional photo-reconstruction methods (3D-PR). As the step height increased, the experimental results showed that: (1) the transformed potential energy and shear stress would increase by approximately 4.89 J s−1 and 26.4 Pa on average when the step height increased 0.25 m; (2) the mean depth and width of the plunge pool exhibited obvious growth, and the morphology of the cross-section developed from approximately V-shaped to U-shaped; and (3) soil loss volume increased logarithmically, with total soil loss volumes of 0.076, 0.105 and 0.116 m3, respectively. Although the significant effects of the initial step height on headcut erosion were verified, further quantitative studies are required to quantify the mechanism of headcut erosion, especially for plunge pool erosion.

Experimental and simplified model study of the development of ground settlement under hazards induced by loss of groundwater and sand

Most catastrophic failure in underground engineering is caused by soil and water loss. However, few studies have focused on the evolution of ground deformation during such a process. In this study, model tests were conducted to investigate the flow channel boundary (the interface between the flowing and stationary ground) and ground settlement profile during the flow process of sandy soil and water, and a simplified model was proposed based on the experiment results. The model was validated against measurements from laboratory model tests with fine and medium sand, and the tendency of the simplified model to predict the subsurface ground movement boundary was verified with case records of tunneling, which can also lead to similar soil loss. Finally, parameter analysis was performed according to the simplified model. The study showed that the flow channel boundary could be described by an ellipse for a planar problem (i.e., loosening ellipse). Furthermore, the flow channel boundary was related to the soil loss volume, buried depth of soil extraction location, and eccentricity of the loosening ellipse. The eccentricity of the loosening ellipse decreased with increasing average particle diameter. Peck’s curve could be used to describe the profile of the settlement trough when the mass loss ratio was not >20 %. The ground surface settlement profile changed to the shape of an “inverted triangle” with increased soil loss. The goodness of fit of Peck’s curve to subsurface settlement increased with depth before the deep ground flowed out from the opening. The effect of groundwater flow was considered in the model tests and simplified model to analyze the disaster mechanism, which can provide a reference for the further research.

Efficiency test of modeled empirical equations in predicting soil loss from ephemeral gully erosion around Mubi, Northeast Nigeria

A field study was carried out to assess soil loss from ephemeral gully (EG) erosion at 6 different locations (Digil, Vimtim, Muvur, Gella, Lamorde and Madanya) around the Mubi area between April, 2008 and October, 2009. Each location consisted of 3 watershed sites from where data was collected. EG shape, land use, and conservation practices were noted, while EG length, width, and depth were measured. Physico-chemical properties of the soils were studied in the field and laboratory. Soil loss was both measured and predicted using modeled empirical equations. Results showed that the soils are heterogeneous and lying on flat to hilly topographies with few grasses, shrubs and tree vegetations. The soils comprised of sand fractions that predominated the texture, with considerable silt and clay contents. The empirical soil loss was generally related with the measured soil loss and the predictions were widely reliable at all sites, regardless of season. The measured and empirical aggregate soil loss were more related in terms of volume of soil loss (VSL) (r2=0.93) and mass of soil loss (MSL) (r2=0.92), than area of soil loss (ASL) (r2=0.27). The empirical estimates of VSL and MSL were consistently higher at Muvur (less vegetation) and lower at Madanya and Gella (denser vegetations) in both years. The maximum efficiency (Mse) of the empirical equation in predicting ASL was between 1.41 (Digil) and 89.07 (Lamorde), while the Mse was higher at Madanya (2.56) and lowest at Vimtim (15.66) in terms of VSL prediction efficiencies. The Mse also ranged from 1.84 (Madanya) to 15.74 (Vimtim) in respect of MSL predictions. These results led to the recommendation that soil conservationists, farmers, private and/or government agencies should implement the empirical model in erosion studies around Mubi area.

A EVOLUÇÃO DAS FEIÇÕES EROSIVAS DA BACIA DO CÓRREGO ESPRAIADO, SÃO PEDRO (SP)

In the 1980s it was estimated the occurrence of 3,000 gullies erosion in the state of São Paulo, and around 80% of crops fields had erosion processes that exceeded the natural recuperation limit. An annual loss reaching about 200 million tons of soil. Thus, the goal of this paper was to identify and evaluate the evolution of erosive features in the córrego Espraiado basin in the municipality of São Pedro (SP) between the years 1962 and 2006. For that, the erosion features were mapped in these scenarios (1962 and 2006) using orthophotos and field trips were carried out to check all the features and to calculate the volume of soil loss. The results shows a 76% of decrease between 1962 and 2006. The highest soil loss was identified in 1962, 4.410.000 m3 , in other words, 300% higher than 2006 scenario (1.428.000 m3 ). On both scenarios, the erosion features were located in high and middle levels of the basin. Therefore, using more accurate orthophotos it was possible to identify important changes in the spatial distribution of erosion features and in the total volume in of soil loss.Key words: erosion features, São Pedro, GIS.

Using 3D photo-reconstruction methods to estimate gully headcut erosion

In this paper, for the first time, three-dimensional photo-reconstruction methods (3D-PR) based on Structure from Motion (SfM) and MultiView-Stereo (MVS) techniques are tested for estimating the volume of gully headcut retreat. The study was carried out using 5 small headcuts in SW Spain: two headcuts located along the channel and 3 lateral-bank headcuts. Firstly, the accuracy of the resulting models was tested using as benchmark a 3D model obtained by means of a Terrestrial Laser Scanner (TLS). Results of this analysis showed centimetre-level accuracies with average distances between the two point clouds for the five headcuts ranging from 0.009m to 0.025m. Then, using a Digital Elevation Model of Differences approach (DoDs) the volume of soil loss was estimated for every headcut. Total soil loss ranged from −0.246m3 (erosion) to 0.114m3 (deposition) for a wet period (289mm) of 54days in 2013. A different dynamic was observed for the main and lateral-bank headcuts, which showed erosion and deposition, respectively. Additionally, the use of historical photographs was explored with the aim of estimating long or medium-term erosion rates in gully heads. Results of this simulation pointed out to a clear decrease in the accuracy of the model when the photos are not acquired sequentially around the headcut. Finally, some methodological advices about the use of this 3D-PR procedure for monitoring small geomorphological features are presented.

Simulated headward erosion of bank gullies in the Dry-hot Valley Region of southwest China

Although the development and migration of gully headcuts can increase soil loss and accelerate landscape degradation considerably, little attention has been paid to the spatiotemporal variations of the morphological characteristics of bank gully heads in the Dry-hot Valley Region of southwest China. This study explored the in-situ variations in soil loss rates and morphological characteristics in active bank gully heads, testing the overland flow discharge with a range of 30 to 120Lmin−1. In response to this flow, actively migrating headcuts developed with retreat rates ranging from 2.6 to 7.9mmh−1. All experimental runs resulted in a gradual increase in soil loss volume, incision depth, and retreat distance over time due to set flow rates. For the gully beds and upstream areas of gully heads, the soil erosion rates were greatest at the beginning of each run and progressively decreased during the scouring test. Non-steady state soil erosion rates were observed in the headwall for the flow discharge levels examined for this study. This was due to an abrupt slope collapse after long-term scouring effects. As degradation progressed, similar trends emerged for temporal variations within the fractal dimensions of topographic surfaces, in both the gully heads and upstream areas. After the scouring was run for a period of 90min, asymptotic fractal dimensions of topographic surfaces were attained in the upstream areas and gully heads, suggesting that steady state morphological characteristics had been realised. It should be noted that headwall collapses are typically associated with a substantial increase in sediment yield where no other obvious change in morphological characteristics occurs in the headwall. Therefore, even though a significant difference in the soil erosion rates and fractal dimensions of topographic surface values could be found between the bank gully heads and upstream areas, the temporal variation in the morphological characteristics of bank gully heads was similar to those observed in upstream areas where ephemeral gullies developed.

Influencia de los factores topográficos en los procesos de piping, Murcia (España)

Usually, different mechanical, chemical or biological causes of piping development have been described, particularly those related to the hydraulic gradients and the presence of sodium into the soil. The main purpose of this paper is to analyze the topographic characteristicsof both the pipes and the agricultural plots where they appear, and to estimate the volume of sediment yield. Eight different zones, located in the Mula River basin, were studied. The slopes were terraced for cultivation and abandoned 30-40 years ago. 137 plots were selected for sampling, 71% of which showed piping processes. The results obtained show a concentration of pipes in certain areas. There is a high correlation between the volume of soil loss and the extent of piping; between the area affected by piping and the average length, depth and width of pipes; between the size of the plot and the degree of piping development; between the height of the terrace walls and the maximum depth of pipes; and, finally, between gradients and piping intensity. If topographic factors favour the presence of pipes, some plot levelling recommendations could be defined in order to minimize the risk of piping processes in the most susceptible areas.