Showing 72 results for Erosion
D. Khatibi Roudbarsara, A. Khaledi Darvishan, J. Alavi,
Volume 27, Issue 2 (9-2023)
Abstract
Soil erosion followed by sediment production is the most important phenomenon that causes soil and environment degradation in many areas and is increasing. Sediment fingerprinting is a method to identify sediment sources and determine the contribution of each source to sediment production. The present research was carried out to evaluate the relative erosion sensitivity of lithological units and to determine the contribution of each unit in bed sediment production using geochemical properties in the Vaz River located in Mazandaran province. The 33 soil samples were taken from the whole watershed and one sediment sample at the outlet of the watershed. Then, five tracers of B, Al, Sc, Mo, and Sn were selected as the optimal combination using three statistical tests range tests, Kruskal-Wallis, and discriminant function analysis. Finally, using optimal tracers and a combined multivariate model, the contribution of lithological units with very high (A), high (B), medium to high (C), and medium (D) sensitivity in bed sediment production were obtained using FingerPro statistical package and R software. The results showed that the contribution of lithological units with very high (A), high (B), medium to high (C), and medium (D) sensitivity in bed sediment production were 24.23, 50.77, 15.62, and 9.36%, respectively. Then, the specific contribution of each sensitivity class was also calculated to remove the effect of area on the results. The Qal lithological unit including the Quaternary sediments in the river bed and banks with very high sensitivity to erosion (A) and a specific contribution of 0.0807 % per hectare had the maximum contribution in bed sediment production in Vaz River.
S. Esmailian, M. Pajouhesh, N. Gharahi, Kh. Abdollahi,
Volume 27, Issue 3 (12-2023)
Abstract
Awareness of the number of changes in runoff and sediment on different slopes can be useful in modeling the production of runoff and sediment. Therefore, this study was conducted to investigate the production of surface and tunnel runoff and sediment in saline and sodic soils on different slopes. Saline-sodic soil was collected and transported to the laboratory. Laboratory experiments were performed on a soil bed in a rectangular flume at three different slopes (5%, 10%, and 15%) under simulated rain (30 mm/h) for one hour. An analysis of variance was used to investigate the effect of slope on runoff and sediment production, and the means were compared using Duncan's test at the five percent level using SPSS version 26 software. The results showed that there was a significant difference between the slopes of the runoff (P<0.001) and sediment (P<0.001). In the first minute of the experiments, due to the lack of moisture in the soil, the amount of runoff was low, but over time, the amount of runoff increased. It is because the pores are blocked by the dispersion of soil particles owing to the presence of sodium ions, which ultimately leads to a decrease in permeability. Similarly, in the last few minutes, outflow from the tunnel was observed, and this flow occurred only on slopes of 10% and 15%. The amount of sediment was also low in the first few minutes, which could be related to the low amount of runoff and the lack of sediment particle removal. Nonetheless, after the lapse of time, its amount increased, and the primary reasons were reduced permeability, increased runoff, and removal of fine particles from the soil surface.
M. Abtahi, M. Khosroshahi,
Volume 27, Issue 4 (12-2023)
Abstract
Biological operations to combat wind erosion must be carried out in the calm bed of dunes, which is often challenging due to high-velocity winds. Therefore, the necessary precondition for stopping the movement of sand is to create obstacles in the path of their movement, protecting newly planted vegetation from wind damage and ensuring stability during the initial years. In this project, various methods of preventing wind erosion, including creating a windbreak to reduce wind speed below the erosion threshold and sand spraying to increase the wind threshold, were evaluated in the dunes of Abuzidabad, Kashan, under severe wind erosion. The windbreaks used include mesh with a percentage of 50% porosity in a checkerboard with dimensions of 2.5 * 2.5 m, and cottonwood harvested from cotton fields in a grid of 5 * 5 meters. The height and distance of the windbreaks were calculated using the wind threshold speed and the maximum wind speed of the region. Sand spraying was tested on dunes and clay-salt panes with 50% and 30% density. To compare the rate of soil displacement in the above and control treatments, graded wooden indicators up to a height of one meter of sediment traps were used. In addition, the effect of net windbreak on the percentage of successful establishment of the Holoxylon sp. plant compared to the control was investigated. In this study, the cost of each method was calculated separately and compared with the cost of spraying oil mulch. The results showed that 50% sand spraying, in addition to having the best performance in stabilizing sands and preventing the formation of dust, as well as stability, also has a lower implementation cost than other methods. Therefore, the 50% sand spraying method is introduced as the best method to stabilize and prevent erosion at the lowest cost and also environmental compatibility.
S. Esmailian, M. Pajouhesh, N. Gharahi, Kh. Abdollahi, Gh. Shams,
Volume 28, Issue 2 (8-2024)
Abstract
Studying the process of soil erosion and evaluating its effective factors is one of the most important prerequisites for proper management of soil and water resources. This study was conducted to investigate the production of surface and pipe runoff and sediment using artificial rainfall on silt loam soil in the laboratory. So, the soil was collected from the study area and transported to the laboratory. Laboratory experiments were performed on a soil bed in a rectangular flume with three pipes, at slopes of 2%, 6%, 10%, 14%, and 18% under simulated rain (30 mm/h) for one hour. Related graphs were drawn in Excel to analyze the results, and Spearman's correlation test was used in SPSS software to check the correlation between runoff and sediment values in each slope. The results showed that with the increase in slope, the sum of surface and pipe runoff and sediment increased over time. For example, in a slope of 2%, the runoff and sediment in the initial moments of the experiment increased from 0 to 1.3 liters and 26.2 g m-2 at the end of the experiment. Also, the correlation coefficient between runoff and sediment in the slopes was 0.98, 0.62, 0.4, 0.93, and 0.15, respectively, which was significant in some, but in others, it was not significant because of soil loss.
A.r Vaezi, Kh. Sahandi, F. Haghshenas,
Volume 28, Issue 3 (10-2024)
Abstract
Water erosion can be affected by land use change and soil degradation by agricultural activities. This study was conducted to investigate the effects of land use change in poor pastures on soil physical degradation and water erosion in semi-arid regions. Experiments were performed in 42 soil samples taken from seven areas covering the two land uses: poor pasture and rainfed agriculture, which have different soil textures (clay loam, silty clay loam, sandy clay loam, silt loam, loam, sandy loam, and sandy loam). The physical characteristics of soils were measured in the samples of both types of land use and its changes were expressed as physical degradation of the soil. The soil's susceptibility to water erosion was measured under simulated rainfall with 50 mm h-1 intensity for 60 min. The results showed that the land use change in pastures leads to the physical deterioration of soils; so bulk density, porosity, macropore, field capacity, saturated point, aggregate size, and aggregate stability were degraded with a rate of 28, 22, 41, 11, 5, 62, and 63 percentages. The structural characteristics of soil (aggregate size and stability) had the highest physical deterioration due to the land use change in the pastures. The change in land use change greatly increased the sensitivity of soils to water erosion. A significant relationship was found between the susceptibility of water erosion and the soil's physical degradation. The soils with coarser and more stable aggregates have higher physical degradation by the land use change and in consequence show more susceptibility to water erosion.
S.m. Abtahi, M. Khosroshahi,
Volume 28, Issue 4 (12-2024)
Abstract
Today, wind erosion and dust are an environmental crisis, not just in desert areas but also in the entire country, and putting many costs. The combat against wind erosion in many desert areas by using oil mulches and the cultivation of compatible plants started in the 40s. However, the use of petroleum in addition to mulching the environmental problems, due to the high costs of purchase, displacement, and dispersion, is not economical. Therefore, the performance of non-oil and chemical mulch on dunes was investigated in Kashan. The research on fertilizer application of mulch under a completely randomized design includes: control (no mulch), a polymer mulch, potas, Fars, Paya, and Akrilik at 3 reps (3 sand hills) and the amount of erosion (with the help of the embedded indices in the hills), the survival of plants cultivated in the form of cuttings and seedlings, the percentage of humidity and temperature of each iteration were measured and variance analyses were performed. Field surveys and the results of the statistical analysis showed that the strength resistance of Fars, Paya, and Akrilik is almost the same. Observation of wood indices showed that Fars, Paya, and Akrilik mulches have almost the same strength in terms of wind resistance (almost no wind resistance). Fars mulch after 8 months of spraying showed small fractures due to the loss of flexibility. The study of soil temperature statistics showed that the treatments under mulch had no significant temperature difference compared to the control treatment. A comparison of soil moisture data indicated a high moisture percentage in the potash mulch treatment. The survival rate of cultivated plants was higher in Paya and Akrilik treatments. According to the results, Akrilik, Paya, and Fars mulch are recommended for sand fixation. One of the limitations of research in desert areas is the uncontrollability of environmental and human conditions. So, it is recommended to close the entire mulching area and use a mobile wind tunnel device at the project site to determine the wind slavery at different speeds.
A.r. Vaezi, F. Besharat, F. Azarifam,
Volume 28, Issue 4 (12-2024)
Abstract
The temporal distribution pattern of rainfall can play a role in the production of runoff and soil loss during rainfall. This study investigated four rainfall patterns: uniform, advanced, intermediate, and delayed rainfall under field conditions. The rainfall height in all rainfall patterns was 20 mm. In the uniform rainfall pattern, a constant rainfall intensity (40 mm h-1) was used and in the non-uniform rainfall patterns, a maximum rainfall intensity of 40 mm h-1 was applied for a 15-minute duration. The experiments were carried out in 60 cm × 80 cm plots on a hillslope with a slope gradient of 9% at three replications. Rainfall patterns were set up on the plots in five events with an interval of one week. The results showed a significant difference between rainfall patterns in runoff and soil loss (p<0.01). This difference was due to the destruction of surface soil structure and the reduction of water infiltration rate, especially during peak time of rainfall intensity (40 mm h-1). The highest runoff occurred in the delayed rainfall (3.43 mm) while, the highest soil loss (61.47 g m-2) was observed in the intermediate rainfall, which was associated with the peak intensity of rainfall at the end of the rainfall and its role in the destruction of the soil structure on the one hand, and the loss of infiltration rate on the other hand. Variation of runoff and soil loss from one event to another indicated that soil loss is in line with runoff production in uniform rainfall, while soil loss did not follow runoff in other rainfalls. Soil loss in these rainfalls was affected by both runoff production and availability of erodible soil particles. These results revealed the necessity of studying the rainfall intensity distribution pattern for accurate prediction of soil erosion and determining soil loss variation event by event in the semi-arid region.
J. Karimi Shiasi, F. Fotouhi Firoozabad, A. Fathzadeh, M. Hayatzadeh, M. Shirmardi,
Volume 29, Issue 1 (4-2025)
Abstract
One of the main factors contributing to water erosion is the inherent characteristic of soil erodibility. Erodibility depends on particle size distribution, organic matter, structure, and soil permeability. This research aimed to investigate changes in the soil erodibility factor across geomorphological facies. The soil erodibility index was estimated by sampling 58 points within the geomorphological facies of the Dorahan watershed, using the Wischmeyer and Smith method. In the laboratory, soil granularity distribution, organic matter, soil structure, the amount of gravel, lime, salinity, acidity, and sodium absorption ratio were measured. Results indicated that soil erodibility across the entire area ranges from 0.0148 to 0.0661 (t.hr/Mj.mm). The soil erodibility index (K) for the hro-p1 and hro-p2 facies is higher than for others and exhibits the widest range of variations compared to the other facies. The lowest range of changes within geomorphological facies is associated with the hrc facies. The erodibility index decreases from the east to the west of the basin due to the presence of exposed rock faces, which protect the soil as a cover layer.
S. Yousefi, S.n. Emami, M. Nekooeimehr, S. Mardanian,
Volume 29, Issue 2 (7-2025)
Abstract
In the present study, the Road Sediment Delivery Model (SEDMODL) and Geographic Information System (GIS) were utilized to estimate the average annual sedimentation caused by the forest road network in the oak forests in the west of Iran, Chaharmahal and Bakhtiari Provinces (Nazi forest road with a length of 5171 meters). Sedimentation from the study forest road network was estimated based on three basic factors in the model. Also, 30 erosion benchmarks were installed to measure the erosion and sedimentation rate at different distances from the road and in different parts of the study road and changes were measured during a year. The results showed that the average soil erosion at different distances from the Nazi road based on erosion benchmarks is 5.7 mm per year. In addition, the estimated erosion and sedimentation rate of the entire study road network based on the SEDMODL model is 2875 and 570 tons per year per kilometer, respectively. Model evaluation using erosion benchmarks showed that SEDMODL is a suitable model for estimating soil erosion on forest roads in the west of Iran (R2=0.78 and RMSE=0.73). It should be noted that statistical analysis of erosion hot-spot analysis showed that 39 percent of forest roads in Nazi showed very high erosion. Based on the results of the present study, it is suggested that conservative, protective, and road maintenance measures in areas with high erosion risk should be prioritized by decision-makers.
Iman Saleh, Seyed Masoud Soleimanpour, Majid Khazaei, Omid Rahmati, Samad Shadfar,
Volume 29, Issue 4 (12-2025)
Abstract
Soil loss and extensive degradation caused by gully erosion have always caused serious damage. Because direct field measurement and monitoring of gully erosion are costly and time-consuming, it is very difficult to determine the amount of soil loss caused by gully erosion. The present research was conducted to calculate the volume of soil loss due to gully erosion using machine learning models in the Abgendi watershed of Kohgiluyeh and Boyar Ahmad province based on field studies. Machine learning models include random forest, support vector machine, artificial neural network, and adaptive neural fuzzy inference system. The location of 68 gullies in the area was recorded. Hence, initially, digital layers of factors affecting the expansion of gullies, including topography, pedology, lithology, and hydrology, were prepared as independent variables to model soil loss caused by gullies. Then, representative gullies were selected in the studied watershed, and the volume of soil loss due to gully erosion was directly measured in the field as a dependent variable. The measured gullies were randomly divided into two training and validation groups. The results of the models were evaluated using root mean square error (RMSE) and R2, and the models were compared. According to the results, gully erosion in the Abgendi watershed of Kohgiluyeh and Boyar Ahmad province is increasing every year. Also, the amount of erosion and soil loss will increase when the amount of rainfall and the frequency of intense rainfall (≥5mm) are high. Among the machine learning models used in the present research, the random forest (RF) model was selected as the best model to predict soil loss generated by gully erosion.
Hamid Hosseinkhani, Elham Ghanbari Adivi, Rouhollah Fatahi Nafchi, Ali Raeisi,
Volume 29, Issue 4 (12-2025)
Abstract
Soil erosion and sediment transport are among the key challenges in the management of water and soil resources in Iran. In this study, the Modified PSIAC (MPSIAC) empirical model was applied to estimate sediment yield and evaluate the erosion status in the Plasjan watershed. The model is based on the assessment of nine influencing factors, including geological characteristics, soil properties, climatic conditions, runoff, land slope, vegetation cover, land use, surface erosion, and channel erosion. By assigning scores to each factor and integrating the spatial layers, the sediment yield intensity of each sub-watershed was quantified both qualitatively and quantitatively. The required base data were prepared and analyzed using the Geographic Information System (GIS). Subsequently, the final erosion index for each sub-watershed was calculated, and erosion hazard classes were determined according to the model’s standard tables. The total annual sediment production in the watershed was estimated at 803,301 tons, and the Sediment Delivery Ratio (SDR) was calculated as 14.48%, indicating considerable sediment deposition along the transport paths. The results showed that most sub-watersheds fall within the “moderate” erosion class, while insufficient vegetation cover, steep slopes, and land-use changes were identified as the main contributing factors to increased sediment yield. Based on these findings, identifying critical areas, implementing erosion control measures, and utilizing remote sensing and sediment monitoring technologies are strongly recommended. This study provides a scientific basis for improving watershed management and mitigating erosion-related risks in similar basins.
ُseyed Abolfazl Masoodian,
Volume 30, Issue 3 (10-2026)
Abstract
Rainfall erosivity is a key factor in soil erosion models. Although Iran’s climate is predominantly hot and dry, the occurrence of intense and heavy rainfall events, although infrequent, can cause significant damage to soil resources. In the Universal Soil Loss Equation, rainfall erosivity is calculated based on rainfall intensity. In this study, 45 years of hourly rainfall data from the ERA5 reanalysis dataset were used to estimate rainfall erosivity across Iran. The results revealed that the spatial distribution of rainfall events in Iran is highly heterogeneous. Central Iran, with fewer than 20 rainfall events per year, and the Caspian Sea coast, with nearly 450 events per year, represent two contrasting rainfall regimes. Both the Caspian coast and the Zagros highlands receive slightly less than 10 mm of rainfall per event, while the mean duration of rainfall events in these regions is approximately 10 hours. On the Caspian coast, moisture originating from the Caspian Sea, and over the Zagros Mountains, moisture originating from the Arabian Sea, contribute to the observed rainfall duration and amount per event. Rainfall event intensity in the western Zagros and along the entire southern coast of Iran is considerably higher than in other parts of the country. The transport of moisture from the Arabian Sea into Iran contributes to the high intensity of rainfall events in these regions. Rainfall erosivity is very low across most parts of Iran; however, the Zagros Mountains, the Caspian coast, and some mountainous areas exhibit relatively high levels of erosivity. The mean annual rainfall erosivity over Iran is approximately 80 MJ.mm.ha-1.h-1.y-1.
