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Showing 68 results for Sediment
Variability of Sediment Components with Application of Vermicompost and Nano-manure and Various Moisture Levels
L. Gholami, A. Khaledi Darvisan, N. Karimi,
Volume 25, Issue 3 (12-2021)
Abstract
Soil loss can cause many intra-regional and extra-regional problems, on the other hand, the effect of soil moisture on processes of soil loss and sediment yield for the identification and simulation of soil hydrological response is necessary. Therefore, the application of soil conditioners is essential for soil and water conservation. The present study was conducted to investigate the effect of soil conditioners of vermicompost and nano-manure on variables of soil loss and sediment concentration at moistures of air-dried, 15 and 30%, and rainfall intensities of 50 and 90 mm h-1. The obtained results in addition to confirmation of the significant effect of each conservation treatment at the level of 99 percent on the intended components showed that the conservation treatment of vermicompost compared to nano-manure treatment had more effect on measured variables. Also, the conservation treatment of vermicompost could decrease the soil loss at soil moisture air-dried, 15, and 30 percent with rates of 72.15, 66.63, and 78.76 percent (50 mm h-1), respectively, and 45.01, 35.57, and 10.45 percent (of 90 mm h-1), respectively. The effect of conservation treatments, soil moistures, and rainfall intensity and the interaction effects of conservation treatments × rainfall intensity and rainfall intensity × soil moisture on changes of soil loss and sediment concentration were significant at the level of 99 percent. The application of vermicompost and nano-manure had acceptable results on studied parameters but the vermicompost effect was more than nano-manure. Therefore, due to the widespread use of different types of conditioners, nowadays, it is needed to move the application feasibility of conditioners such as vermicompost and nano-manure that these have not the adverse effects of environmental.

Effect of Angle, Height of Support and Pipe Line Diameter Size on Scour Hole
N. Alami, M. Saneie, H. Haji Kandi,
Volume 26, Issue 1 (5-2022)
Abstract
Scouring holes under the oil, gas, and water pipelines threaten their stability by bending and demolishing. This phenomenon can cause damage to the environment and the oil and gas industry. The present study investigated the effect of the pipe diameter, the height of support, and the angle of the pipeline with flow direction by applying the experimental aspects to the cohesive sediments. The experiments were carried out by considering three angles of deviation as zero,15, and 30 degree based on the flow direction. Three opening gaps were considered through the experiments based on the pipe height as 0, D/2, and D/4 from the sand bed. Furthermore, three pipe diameters were employed to investigate the effect of diameter size. The results indicated that by increasing the angle of deviation, the height of scour hole decreased significantly, however, the raising the opening gap between pipe and bed increased the sediment deposition and it causes the height of scour hole is decreased consequently which was constituted approximately 18 percent. Moreover, the pipe diameter affects the scour hole formation and its effect on a downward jet and horseshoe vortexes and the result indicate by increasing the piper diameter the scour hole is increased based on its effect on the flow configuration. Finally, based on the experimental data, an equation was estimated to predict the scour depth by employing the non-linear regression technique.

Investigation of Sedimentation of Small Catchments under Precipitation Pattern and Basin Characteristics in Arid and Semi-Arid Climate
P. Fattah, Kh. Hosseini, A.a. Hashemi,
Volume 26, Issue 3 (12-2022)
Abstract
Splash (raindrop) erosion plays an significant role in soil loss, especially in arid and semi-arid regions with poor vegetation. In this paper, by analyzing the pattern of rainfalls that occurred during 26 years in four basins located in Semnan County, their effect on the pattern of eroded sediments from the basin was investigated. Sedimentary layers from the sampling of retarding reservoir sediments in 2017 were related to the corresponding precipitations. Due to the occurrence of the highest amount of rainfall in each quarter of rainfall, rainfall hyetographs were divided into four categories. Cumulative precipitation curves with similar quartiles were drawn in one shape and compared with sediment curves and vice versa taking into account the physical characteristics of the basin. The results showed that the Aliabad basin (with less slope and more elongation) with an effective quarter of type 3 had the highest similarity in precipitation and sediment patterns. Also, the Western Soldereh basin (with the highest slope and the least elongation) with an effective quarter of type 2 had the least similarity in precipitation and sediment patterns. The results indicate the vital role of rainfall patterns on the resulting sediment patterns, which show up to 85% similarity.

Assessing Heavy Metals Pollution of the Mangrove Sediments along Tidal Flat of the Mehran River Delta, Persian Gulf
M. Pasandi, H.r. Pakzad, A.m. Halvaie Lengeh, M.r. Taherizadeh,
Volume 26, Issue 4 (3-2023)
Abstract
The relationship between the concentration of heavy metals and physicochemical factors was studied in the fine-grained sediments of the tidal section of the Mehran delta where mangrove trees have grown. Surface sediments of the tidal zone of the Mehran delta were sampled. The grain size distribution, calcium carbonate, organic matter contents, pH/Eh, and heavy metals concentration were determined in the mud fraction of the sediments. The presence of high calcium carbonate in sediments is an effective factor in the abundance of Mn, Cd, and Pb. Clay and organic matter as adsorptive have contributed to the high concentration of Zn, Cu, while Fe oxy-hydroxides have affected the concentration of Co, Cr, and Ni. According to the index of Enrichment Factor (EF), the average enrichment of the elements in the studied sediments from high to low order is Cr, Ni, Cd, Zn, Mn, Pb, Co, and Cu. According to the Pollution Load Index (PLI), none of the delta sediments including sediments from inside and outside of the mangrove forestare classified as polluted to the heavy metals. According to the Igeo Index, most samples, and only Cd, Cr, and Ni show slight pollution in some samples. Accordingly, there is no current threat of contamination of potentially toxic elements of natural and anthropogenic origins to the mangrove environment and Mehran delta.

Experimental Study of Bed Shear Stress in Straight Channels Covered with Dunes of Different Sizes
M. Badzanchin, M. Bahrami Yarahmadi, M. Shafai Bejestan,
Volume 27, Issue 1 (5-2023)
Abstract
The formation of bed form in alluvial rivers due to sediment transport has a significant effect on the hydraulic parameters of the flow such as bed shear stress. The formation of the bed form and its shape and geometry depends on the bed shear stress. Therefore, the relationship between bed form and flow parameters (such as bed shear stress) is complicated. In the present study; the effect of dune bed forms with different heights on bed shear stress has been investigated. Artificial dunes made by sand-cement mortar with a length of 25 cm and heights of 1, 2, 3, and 4 cm were used. In the tests of this research, flow discharge of 10, 15, 20, 25, and 30 l/s and bed slopes of 0, 0.0001, 0.0005, 0.001, and 0.0015 were used. The results showed that with increasing the relative submergence and Δ/λ, the bed shear stress increased in dune-covered beds. The formation of the dune bed form and the increase in its height leads to an increase in the bed shear stress. The bed shear stress in dunes with a height of 1, 2, 3, and 4 cm was, on average, 39, 80, 141, and 146% more than in plane beds, respectively. Moreover, form shear stress for dunes with a height of 1, 2, 3, and 4 cm was, on average, 27.37, 43, 57.11, and 58.74% of the total shear stress, respectively.

Investigating the Relationship between Suspended Sediment Concentration and Watershed Characteristic of the Kan River in Tehran Using Principal Component Regression
S. Jalali, K. Nosrati, Z. Fathi,
Volume 27, Issue 2 (9-2023)
Abstract
The geomorphic characteristics of the watersheds are interrelated and the temporal and spatial scale in the form of season and sub-basins affect the concentration of suspended sediment. One of the objectives of this study was to investigate the relationship between suspended sediment concentration and watershed characteristics of Kan River using principal components regression and to recognize the effect of seasons and sub-basins on sediment concentration. The concentration of suspended sediment during four rainfall-runoff events in three seasons and in sub-basins was measured and calculated. The sixteen physiographic and land use characteristics were determined in the sub-basins and the main factors were identified and the scores of each factor for each feature were calculated using principal component analysis (PCA). The results of variance analysis showed that the concentration of suspended sediment was significant in terms of time scale and spring had the highest rate of sedimentation. Redundancy analysis and canonical analysis on the properties that participate in the first factor (PC1) showed the characteristics of the percentage of erodible formation, relatively erodible formation, and percentage of free construction activity, respectively. Road (slope leveling) and stream length are the most essential attributes of sub-basins in the production and concentration of suspended sediment in the study area.

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.

Numerical Modeling of the Flow Separation Zone over Dunes under the Impact of Sediment Injection
M. R. Taghizadeh, A. Motamedi, M. Galoie, F. Kilanehei,
Volume 27, Issue 4 (12-2023)
Abstract
Understanding flow behavior over bedforms is one of the most complex topics in sedimentary engineering. Despite numerous studies that have been conducted on river beds, the understanding of the interaction between flow and bed in turbid and clear waters is still impoverished. The present study mainly focused on simulating clear and turbid flows using SSIIM software. This study modeled the flow through a 12-meter channel with nine consecutive dunes of 1-meter length and 4 cm height. Nine simulations were performed to investigate the effects of flow velocity and flow separation zone in clear and turbid water. Finally, the results were compared with the experimental results of previous researchers using the PIV. The modeling results showed that the length of the flow separation zone increases with increasing velocity, and the highest probability of flow separation occurs at the highest velocity. In turbid flow, flow separation is less than the same flow condition in clear flow, and as fluid density increases, the length of the flow separation zone decreases. This study demonstrates the acceptable functionality of the SSIIM software and its accuracy in estimating flow behavior with and without sediment.

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