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Showing 63 results for Erosion
Evaluation of Erosion Sensitivity of Lithological Units in Vaz Watershed, Mazandaran Province Using Fingerprinting
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.

Investigation of the Surface and Tunnel Runoff and Sediment Production in Saline-Sodic Soil under Different Slopes
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.

Assessment of Some of Wind Erosion Control Methods in Desert Areas (Case Study: Kashan Desert)
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.

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