Showing 43 results for Tm
Sh. Mahmoudi, M. Naderi, J. Mohammadi,
Volume 17, Issue 63 (6-2013)
Abstract
This research was carried out to determine spatial distribution of heavy metals concentration in soil particle size classes using Landsat ETM+ reflectance in Southern Isfahan city in the vicinity of Bama mine. To fulfill this goal, 100 compound soil surface samples were collected randomly from the area. The samples were air dried and soil particle size classes 250-500, 125-250, 75-125, 50-75 and <50 μm were determined using appropriate sieves after dispersion of the bulk samples of soil using ultrasonic apparatus. Total Zn, Pb and Cd concentrations were measured using Atomic Absorption Spectrophotometer after wet digestion of samples in acid nitric. The results indicated significant negative correlation coefficients between heavy metals concentrations of soil particle size classes and soil spectral reflectance in the visible, near infrared and panchromatic bands of Landsat ETM+ satellite. Stepwise multiple regression models were used for estimating heavy metals concentration in soil particle classes through satellite data. Furthermore, spatial distributions of heavy metals were mapped using stepwise multiple regression equations. Results also showed heavy metals concentrations in all soil particle size classes were maximum close to the mines and decreased by increasing the distance from these sources.
S. Farahi, M. Hamidpour, H. Shirani, H. Dashti, M. Heshmati,
Volume 17, Issue 66 (2-2014)
Abstract
This research was conducted to study the effect of natural and polyacrylamide-modified montmorillonite on the sorption of Cd from aqueous solutions. The sorption of Cd on the sorbents was studied as a function of pH (Cd concentration: 10 mg L-1) in the range of 4-8.5, and as a function of metal concentration (Cd concentration in the range of 1-10 mgL-1) using a 24h batch equilibration. Experimental and modeling data from equilibrium investigations revealed that the Koble–Corrigan sorption model describes the interaction between Cd and the two sorbents better than the Freundlich and Langmuir models. The values of KF constant of Freundlich and KL constant of Langmuir models were higher for sorption of Cd onto the modified montmorillonite than for those of natural montmorillonite. Maximum sorption capacity calculated from the Langmuir model was 0.6 and 0.7 mg g-1 for natural and modified montmorillonite, respectively. These values are indications of high sorption affinity of Cd to montmorillonite in the presence of polyacrylamide. The amount of Cd sorbed by modified montmorillonite decreased by increasing solution pH while Cd sorption by natural montmorillonite increased by increasing the solution pH.
Z. Mahmoodi, H. Khademi ,
Volume 18, Issue 67 (6-2014)
Abstract
Atmospheric dust is an important source of heavy metals, particularly in urban environments. Heavy metals can easily attach to dust particles and be distributed in large areas. The objective of this study was to evaluate the status of major heavy metals in the atmospheric dust of Isfahan and adjacent cities. A total of 144 dust samples were taken during a period from August to December 2010 from Isfahan, Khomeynishahr, Falavarjan, Mobarake and Zarinshahr cities. Dust samples were extracted with HNO3 65% and the total concentration of metals including Pb, Zn, Cd, Cu, Ni, Co, Cr and Mn in the samples was measured by an atomic absorption spectrometer. The mean concentration of these metals was 223.5, 470.3, 3.5, 71.0, 82.0, 26.5, 24.4 and 426.3 mg kg-1, respectively. Results indicated that heavy metals concentration in any area was different depending on the source of pollution and it was much higher than the mean concentration of the corresponding heavy metal in soils. Besides, the highest deposition rate of all the heavy metals in this study was found in November-December period. This could be attributed to an increase in the use of heating systems and also to a temperature inversion event prevailed in the area. Atmospheric deposition seems to be an important pathway of heavy metals addition to soils. For example, it is responsible for 35-91% and 12-47% of Pb and Cd entering the soil in the area, respectively.
F. Jafari, H. Khademi,
Volume 18, Issue 70 (3-2015)
Abstract
Dust deposition occurs extensively in arid and semiarid regions of the world. Since dust particles are fine-sized, they have a high adsorption capacity and also high contamination potential. The objective of this study was to evaluate the temporal and spatial distribution of the rate of atmospheric dust deposition in different locations in Kerman urban area. Dust samples were collected monthly using glass traps installed on the roof of 35 one-story buildings in Kerman for 7 months from April 20 to Nov. 20, 2012 (a total of 245 samples). After each monthly sampling, traps were washed and dust samples transferred to the laboratory and weighed. The mean dust deposition rate of 7 months was mapped using the inverse distance weighting (IDW) approach. The wind rose of Kerman was drawn by WRPLOT 7.0.0. The results showed that the average rate of dust deposition decreased during the 7 months studied from 17.4 to 5 g/m2. month, which could be attributed to the decrease in wind velocity. The spatial distribution of the samples also showed that the dust deposition rate varied from 4.84 in the southern parts to 14.84 g/m2.month, mostly in the northern locations of the city. The wind rose based on the average wind speed of the 7 months of sampling indicated the prevailing wind blows from north, northeast and northwest and the dust spatial distribution well follows the wind direction. In general, the rate of dust deposition in Kerman city is high and therefore, the source of dust has to be well detected and proper management practices are necessary.
S. Norouzi, H. Khademi,
Volume 19, Issue 72 (8-2015)
Abstract
Spatial and temporal distribution of dust deposition rate (DDR) in Isfahan city and the influencing climatic parameters were studied. Dust samples were collected using glass trays placed on the roof of one-story buildings from 20 sites in Isfahan city for 12 months. Climatic data were obtained from Meteorological Organization and analyzed. The highest and the lowest amount of DDR in agreement with the direction of prevailing wind were observed for dry months with eastern and northeastern wind directions and wet periods with western and southwestern wind directions, respectively. This can indicate dust emission from the desert located in eastern part of Isfahan city. Statistically significant inverse correlation between DDR and precipitation and relative humidity, and significant and positive correlation of DDR with Min and Max temperatures in all the studied months and also with Max and average wind speed for dry sampling months may well justify the temporal distribution of DDR in the city. In dry months, finer particles from eastern desert can be transported a longer distance and deposited in the western part of the city, far from the source area. In wet seasons, however, soil aggregates become coarser as a result of particle adhesion. This, in turn, results in the deposition of dust near the source area as the transporting power of dust reduces.
A. Masjedi, M. Sobhani,
Volume 19, Issue 74 (1-2016)
Abstract
Riprap is used to control scouring around the bridge abutment. In order to study the stability of riprap around two bridge abutments with two different shapes, experiments were conducted in a laboratory flume made of Plexiglass in 180 degree bend. In this research, several experiments were done by placing the two bridge abutments made of Plexiglas in a series of riprap. Experiments included two different types of riprap with different densities, four different diameters and constant rate of discharge under pure water condition. In each experiment, flow depth was measured in terms of moving threshold, then stability was calculated by using the data obtained. The results showed that in the same conditions chamfered wing-wall is greater than vertical-wall. So, chamfered wing-wall is, on average, 9 percent more stable than the vertical wall.
Sh. Zand-Parsa, S. Parvizi, A. R. Sepaskhah, M. Mahbod,
Volume 20, Issue 77 (11-2016)
Abstract
In agricultural development many factors such as weather conditions, soil, fertilizer, irrigation timing and amount are involved that are necessary to be considered by the plant growth simulation models. Therefore, in this study, the values of soil water content at different depths of soil profile, dry matter production and grain yield of winter wheat were simulated using AquaCrop and WSM models. The irrigation treatments were rain-fed, 0/5, 0/8, 1 and 1/2 times of full irrigation conducted in Agricultral College of Shiraz University during 2009-2010 and 2010-2011. The models were calibrated using measured data in the first year of experiment and validated by the second year data. The accuracy of soil water simulation was used to refer to the accuracy of simulated evapotranspiration. The accuracy of soil water content at different layers of root depth in the validation period was good for the WSM model (Normalized Root Mean Squer Error, NRMSE= 0/14). But the AquaCrop model showed less accuracy for soil water content (NRMSE=0/26). However, the values of predicted and measured crop evapotranspiration were close together at full irrigation treatment, the accuracy of AquaCop predictions was decreased with inceasing water stress. WSM model has had a good estimation of the dry matter and grain yield simulation with NRMSE of 0/15 and 0/18, respectively. However, they were simulated with less accuracy in the AquaCrop model with NRMSE of 0/19 and 0/39.
M. Naserian, A. Masjedi,
Volume 21, Issue 4 (2-2018)
Abstract
River bend due to particular pattern, called 'Vortex Flow,' has greater erosion than straight path. Occurrence of scour around bridge abutment on curved paths is one of the main reasons for destruction of bridges. Riprap is one of the methods to control the scouring around the bridge abutment. The purpose of this study was to assess stability of the riprap around the bridge abutment at 180 degree river bend. In order to study stability of riprap around the bridge abutment, experiments were done in a laboratory flume made of Plexiglas under 180 degree bend, 2.8 m in central radius, 0.6 m in width and R/B=4.67. In this research, several experiments were done by placing a bridge abutment with vertical winged wall made of Plexiglas surrounded by a series of riprap. Experiments were done by three different types of riprap with different density 1.7, 2.1 and 2.42, four different diameters 4.76, 9.52, 12.7 and 19.1 mm and four rates of discharge under pure water condition. In each experiment, flow depth was measured in terms of moving threshold and failure threshold and then the formulas were calculated by using data obtained. The results showed that the relative diameter of riprap increased with increasing Froude number in terms of moving threshold and failure threshold. Finally, the suitable formula to estimate diameter of riprap around the bridge abutment at 180 degree bend were presented in terms of moving threshold and failure threshold.
O. Mohamadi, M. Heidarpour, S. Jamali,
Volume 23, Issue 3 (12-2019)
Abstract
Shortage of water resources and renewable per capita in last 30 years is put Iran on crisis threshold. Wastewater reuse is one of the battle solutions for water shortage and prevents wastewater depletion and environmental pollution. Thus, a pilot scale experiment was carried out to evaluate an integrated anaerobic/aerobic treatment for removal of BOD5 and COD, also to reduction of hydraulic retention time by considering optimum removal efficiency. The pilot was an anaerobic/aerobic bioreactor type under continuous-feeding regime based on a central composite design. The pilot was studied in different retention time and aeration was carried out between 5-15 hours. According to different retention times for COD removal efficiency, 24 hours was selected as optimum hydraulic retention time, that it is comparable to those obtained for 48 hours and over in plant roughly and could remove COD and BOD in acceptable ranges, results showed that average removal efficiency for BOD5 were 63.86 and 83.99 percent in aerobic and anaerobic phases, respectively. The average removal efficiency for COD was 76.5 and 74.35 percent for anaerobic and aerobic sections, respectively. The average removal efficiency for BOD5 and COD in this integrated aerobic-anaerobic pilot 95.24 and 94.8 percent, respectively.
A. Lotfi, M. Mamaghninejad,
Volume 23, Issue 4 (2-2020)
Abstract
Constructed wetland as a purification system plays an important role in water and wastewater treatment and so many research studies have been conducted to examine their efficiency for wastewater treatment. The aim of this study was to evaluate the efficiency of constructed wetland for Arak wastewater treatment plant. In this research, the efficiency of three horizontal subsurface constructed wetlands built with 3*12 meters in dimensions and 1 meter in depth was examined. In these constructed wetlands, two plants including Common reed (Phragmites australis) and Cattails (Typha latifolia) were planted and one unit was left unplanted. TSS, COD, BOD and TC parameters were measured in the 2 week samples and the results were analyzed by SPSS and Excel. The results showed that the type of vegetation had no significant influence on the organic matter removal in the subsurface constructed wetlands; however, the removal efficiencies in the planted constructed wetlands were more than those in the unplanted control one. The TSS, COD, BOD, FC and TC removal efficiency in the constructed wetlands changes was 79%, 60.7%, 45.6%, 86.1% and 90.1%, respectively, for Common reed wetland and 77%, 61.4%, 59.8%, 92.4% and 93.1%, respectively, for Cattails wetland; thee were 69%, 44.5%, 43%, 83.6% and 88.8% for the unplanted wetland, respectively. The results of this research also showed that the organic matter removal was dependent on the influent organics nature and biodegradability. The organic concentration in the wetland effluents met the Iranian regulation limits for different reuse applications, showing the constructed wetland could be a suitable technology for wastewater treatment in Iran.
R. Rakhshani, M. Farasati, A. Heshmatpour, M. Seyedian,
Volume 24, Issue 1 (5-2020)
Abstract
In this research, the impact of the Alagol wetland on the water treatment of Atrak River was studied. From June, 2016, to May, 2017, on the fifteenth day of the month, four samples of water were collected from the middle and the outlet of the wetland. Also, the wetland was fed only in the months of September, November and February. The parameters of acidity, electrical conductivity, phosphate, nitrate, dissolved oxygen, biochemical oxygen demand, chemical oxygen and ammonia were measured. The water pH at the entrance and exit was significantly different. EC was higher at the entrance, and its value was decreased in the middle and output. DO in the outlet of the wetland was higher than that in the middle and inlet, indicating the improved water quality and high dissolved oxygen in the wetland output. NO3, NH4, PO4, BOD and COD were higher at the entrance to the wetland; also, it was decreased in the outlet and middle, and the difference was significant. Further, according to the results of September, November and February, which were fed to the wetland, water quality in the middle and outlet of the wetland was improved toward the entrance of the wetland. According to the results, Alagol wetlands could reduce the phosphorus, ammonia, BOD, COD and DO, and their concentrations were lower than the limit. However, given that the salinity at the entrance of wetland was too high, its amount in the output was higher than the standard limit and the wetland could not significantly reduce salinity. The results of this study showed that that of water pollution in the inlet, except that the dissolved oxygen parameters and the temperature were high and decreased in the middle outlet. Due to the quality of the wetland outlet, Alagol wetland water could be used for fish farming centers.
E. Yarmohammadi, S. Shabanlou, A. Rajabi,
Volume 25, Issue 1 (5-2021)
Abstract
Optimization of artificial intelligence (AI) models is a significant issue because it enhances the performance and flexibility of the numerical models. In this study, scour depth around bridge abutments with different shapes was estimated by means of ANFIS and ANFIS-Genetic Algorithm. In other words, the membership functions of the ANFIS model were optimized using the genetic algorithm, finding that the performance of ANFIS model was increased. Firstly, effective input parameters on the scour depth around bridge abutments were defined. Then, by using the input parameters, eleven ANFIS and ANFIS-GA models were produced. Next, the superior ANFIS and ANFIS-GA models were introduced by analyzing the numerical results. For example, the correlation coefficient and scatter index for ANFIS model were calculated to be 0.979 and 0.070; for ANFIS-GA, these were 0.986 and 0.056, respectively. In addition, the average discrepancy ratio (DRave) for ANFIS and ANFIS-GA models was 0.984 and 0.988, respectively. Also, it was shown that the ANFIS-GA models had more accuracy, as compared to the ANFIS models. Moreover, a sensitivity analysis showed that Froude number (Fr) and ratio of flow depth to radius of scour hole (h/L) were the most influential input parameters for simulating the scour depth around bridge abutments.
Z. Kolivand, Sh. Ghazimoradi, F. Kilanehei, O. Naeini,
Volume 25, Issue 2 (9-2021)
Abstract
The reuse of treated wastewater in countries such as Iran that suffers from drought is considered an important challenge in water management programs. The application of modern wastewater treatment systems particularly attached growth systems, owing to the short time required for start-up, low land requirements, and the absence of problems associated with sludge handling may be a resolution. The objective of this study is to investigate the performance of the Moving Bed Biofilm Reactor (MBBR) in treating synthetic municipal wastewater and selecting an appropriate model. In this way, a bench-scale reactor possessing an effective volume of 15 liters, and synthetic wastewater with influent COD of 500 mg/l (similar to typical municipal wastewater) has been used and the experiments with media filling percentages of 30%, 50%, and 70% and hydraulic retention times (HRT) of 4, 8, and 12 hours have been carried out. The observed data show that the optimum bulk density and hydraulic retention time are 50% and 4 hours, respectively. Also, the kinetic study of reactor performance indicates that Grau second-order model has better conformation with Moving Bed Biofilm Reactor results. In addition, a regression model for predicting effluent COD based on the filling percentage and retention time is presented.
M. Abedinzadeh, A. Bakhshandeh, Mr B. Andarziyan, Mr S. Jafari, M Moradi Telavat,
Volume 25, Issue 3 (12-2021)
Abstract
Iran is located in the dry belt of the earth and is predicted to face water stress in the next half-century. Currently, the area of sugarcane cultivation in Khuzestan is over 85,000 hectares and due to the high water needs of sugarcane and drought conditions, optimization of water consumption and irrigation management is necessary to continue production. Therefore, in this study, the values of soil moisture, canopy cover, biomass yield in five treatments and irrigation levels (start of irrigation at 40%, 50%, 60%, 70%, and 80% soil moisture discharge) during 2 planting dates in the crop year 2015-2016 on sugarcane cultivar CP69-1062 in Amirkabir sugarcane cultivation and industry located in the south of Khuzestan was simulated by AquaCrop model. The measured data on the first culture date (D1) and the second culture date (D2) were used to calibrate and validate the model. The results of NRMSE statistics in canopy cover simulation in calibration and validation sets with values of 2.1 to 15.6% and 3.8 to 18.3%, respectively, and in biomass simulation with values of 6.2 to 15.2%, and 9.5 to 12.6%, respectively and coefficient of determination (R2), range 0.98 to 0.99 indicated that the high ability of the AquaCrop model in simulation canopy cover and biomass yield. whereas, the values of NRMSE of soil depth moisture in the calibration and validation sets ranged from 11.6 to 23.8, and 12.2 to 22.7, respectively, with a coefficient of determination (R2), 0.73 to 0.96 (calibration) 0.8 to 0.93 (validation) showed less accuracy of the model in the simulation. The best scenario is related to the third proposal that water consumption, water use efficiency, and yield are 1710 mm, 1.53, and 42.27 tons per hectare, respectively, which shows a reduction in water consumption of 360 mm.
F. Golabkesh, A. Nazarpour, N. Ghanavati, T. Babaeinejad,
Volume 26, Issue 2 (9-2022)
Abstract
The current study aims to find the best methods of using remote sensing and supervised classification algorithms in long-term salinity monitoring of salinity changes in the Atabieh area with an area of 5000 hectares in the west of Khuzestan province. The procedure is based on the separation of different levels of saline soils utilizing information obtained from Landsat 7 and 8 satellite images (2001 to 2015) along with salinity data taken from the study area, and salinity indices including SI1, SI2, SI3, NDSI, IPVI, and VSSI. The results show the expansion of the saline zone trend in the soils of the study area, among which, soils with EC of more than 16 dS m-1 (very saline) have the highest frequency. The area of saline soils has increased significantly over the past 15 years, with a saline land area increasing by more than 90%. The percentage of salinity class is low (S1). According to this study, the only significant index in soil salinity at a 95% confidence level is the SI3 index, which has been able to have a good estimate of the increasing changes in soils in the region. The results of the supervised classification showed that the support vector machine (with an overall accuracy of 95.78 and a kappa coefficient of 0.89) is more accurate. After the vector machine method, the methods of minimum distance, maximum likelihood, and distance of Mahalanobis have the highest accuracy, respectively. Based on salinity maps obtained in years in 2001, 2005, 2010, and 2015, it can be said that the salinity rate in the whole of the study area was progressing and at the same time the salinity area in the middle and high classes increased decreased and on the other hand, the salinity area in the high class in 2001 gradually increased and distributed in 2015 throughout the region.
J. Abedi Koupaei, M.m. Dorafshan, A.r. Gohari,
Volume 26, Issue 3 (12-2022)
Abstract
One of the most significant techniques for saline wastewater treatment is bioremediation. Halophytes are known as the plants that can tolerate the high concentration of salts, in such salinity common plants cannot be often able to survive. In this research, the feasibility of desalination by using halophyte (Chenopodium quinoa Willd.) was studied. Quinoa plants were grown in the hydroponic system in 12 containers including 9 containers with plants and 3 containers without plants as control. Fifteen plants were planted in each container and three salinity levels including 2, 8, and 14 ds/m for two different periods (15 and 30 days) were studied in a multi-factors completely randomized design. Three replications of each salinity level were conducted and the Electrical Conductivity (EC) parameters, including Calcium, Magnesium, Sodium, and Chloride ions were determined before and after treatment by Quinoa plants. The results showed that the Quinoa plants reduced 5.33%, 8.12%, and 9.35% of the EC at EC~2 dS/m (Marginal Water), EC~8 dS/m (Brackish Water), and EC~14 dS/m (Saline Water), respectively. Moreover, Calcium, Magnesium, Sodium, and Chloride ions decreased up to 10%, 7.62%, 5.60%, and 7.01%, respectively depending on the salinity levels. Therefore, the Quinoa plant has a relatively low potential in unconventional water treatment especially saline wastewater.
J. Abedi Koupai, A.r. Vahabi,
Volume 27, Issue 2 (9-2023)
Abstract
Awareness of water resources status is essential for the proper management of resources and planning for the future due to the occurrence of climate change in most parts of the world and its impact on different parts of the water cycle. Hence, many studies have been carried out in different regions to analyze the effects of climate change on the hydrological process in the coming periods. The present study examined the effects of climate change on surface runoff using the Atmosphere-Ocean General Circulation Model (AOGCM) in Khomeini Shahr City. The maximum and minimum temperatures and precipitation of the upcoming period (2020-2049) were simulated using a weighted average of three models for each of the minimum and maximum temperatures and precipitation parameters based on the scenario A2 and B1 (pessimistic and optimistic states, respectively) of the AOGCM-AR4 models. The LARS-WG model was also used to measure the downscaling. The HEC-HMS was used to predict runoff. The effects of climate change in the coming period (2020-2049) compared with the observation period (1971-2000), in the A2 scenario, the minimum and maximum temperatures would increase by 1.1 and 1.6 Degrees Celsius, respectively, and the precipitation would decrease 17.8 percent. In the B1 scenario, the minimum and maximum temperatures would increase by 1.1 and 1.4 degrees Celsius, respectively, and the precipitation would decrease by 13 percent. The results of runoff were different in the six scenarios in the way the most runoff reduction is related to the scenario of fixed land use and scenario A2 (22.2% reduction), and the most increase is related to the scenario of 45% urban growth and scenario B1 (5.8% increase). So, according to increase urban texture in the future and consequently enhance the volume of runoff, this volume of runoff can be used to feed groundwater, irrigate gardens, and green space in the city.
M. Sehat, A. Bordbar, A.r. Masjedi, M. Heidarnejad,
Volume 27, Issue 4 (12-2023)
Abstract
Today, abutments disrupt the normal flow of rivers and cause scouring and erosion of sedimentary materials around them, creating holes and resulting in much damage every year. Researchers have proposed various methods to reduce the power of water erosion. One of the essential methods in this regard is creating slots in abutments. Since the expansion of the scour hole endangers the stability of the bridge structure, this study examined the effect of slot dimensions in the support on the scour hole dimensions. The findings demonstrated that the presence of slots in abutments effectively reduces the dimensions of scour holes. With the slot, the volume of the scour hole can be reduced by up to 50%. Furthermore, as the relative speed of scouring increases by 75%, the depth of the scour hole also increased up to 140%. An increase in slot depth leads to a decrease in scour hole depth of up to 85%.
B. Akbari, H. Khademi,
Volume 27, Issue 4 (12-2023)
Abstract
Street dust enters the urban environments due to the resuspension of particles smaller than 100 micrometers. The magnetic properties of street dust and their relationship with the concentration of heavy metals have received less attention from researchers worldwide, and not much study has been performed on this issue in Iran. The objectives of this study were: (i) to investigate the spatial and seasonal changes in street dust, and (ii) to determine their relationships with the concentration of selected heavy metals in several cities in the Isfahan province. Sampling was carried out in the first half of the second month of each season including 20 samples from Isfahan city and 10 samples from Natanz, Shahreza, Falavarjan, Khomeinishahr, and Najafabad. The concentration of selected heavy metals was measured using an atomic absorption spectrometer. Also, the magnetic susceptibility values of the samples at low and high frequencies were determined and frequency-dependent magnetic susceptibility was calculated. The results showed that the presence of ferromagnesian minerals in the parent materials could be the reason for the high values of magnetic receptivity in Natanz City. However, the high level of this characteristic in the street dust of other cities could be due to human activities, especially in Isfahan city. Based on the results of principal component analysis, the high correlation of the first component with magnetic susceptibility and the concentration of zinc, copper, and chromium elements most likely indicates the absorption of these elements by particles close to superparamagnetic (SP). The high correlation of the second component with frequency-dependent magnetic susceptibility and concentration of nickel and cobalt is most likely related to the adsorption of magnetic elements and heavy metals into coarse polyhedral particles that remained on the street floor after the re-deposition of street dust particles. Also, the high correlations between magnetic parameters and the concentration of copper and zinc confirm their anthropogenic origin. On the other hand, low or negative correlations of Pb, Ni, Cr, and Co concentrations with magnetic susceptibility might confirm their natural or non-anthropogenic origin. The higher values of magnetic parameters of street dust in the spring season reflect the significant contribution of magnetic minerals in this season, compared to autumn and winter, and indicate the higher influence of human activities.
R. Sargholi, A. Bordbar, A. Asareh, M. Heidarnejad,
Volume 28, Issue 1 (5-2024)
Abstract
In the past, various methods have been proposed to control beach heel scouring. For shallow rivers (such as mountain rivers), various types of overflows are used. Therefore, the development of scour in cross-vane and w-weir structures for coastal protection was investigated in this study. The results showed that by installing a w-weir structure in a 90-degree position compared to a 30 and 60-degree position, a 37.9% and 19.7% reduction of scouring was observed, respectively. Also, by installing the cross vane structure in the 90-degree position compared to the 30 and 60-degree position, a 35.4% and 21.2% reduction of scouring was observed, respectively. With increasing width (L / B) (ratio of the width of structure to the width of flume), the w-weir structure decreased from 1.5 to 2, scour rate of 7.9%. Also, with increasing width (L / B) (ratio of the width of structure to the width of flume), the cross-vane structure has decreased from 1.3 to 1.7, and the scour rate has decreased by 4.7%. The w-weir structure had an average of 7.3% less scouring than the cross-vane structure.
