Showing 34 results for Roc
S. A. A. Hashemi,
Volume 17, Issue 66 (2-2014)
Abstract
Check dams are considered as main measures for flood and sediment control in watersheds, and their uses have been rapidly increased from 1990 onward in Iran. This research is done in Darjazin watershed in north of semnan city. The check dams have been constructed from 15 years ago in two sub basins of the watershed for flood control in Mahdishar. More than 650 check dams were evaluated for effects on flood. The collected data in the field was fed to ArcGIS software. The effects of these structures on flood reduction were evaluated by HEC-GeoHMS extension and HEC-HMS model. Because of homogeneity of watershed management projects in the basin due to building more check-dams in different watercourses, any flood discharge is related to check dams. Evaluating the effects of check dams on flood by t-test showed significant differences between flood discharge before and after construction of check dams at 5 percent level. So, check dams have been able to reduce flood discharge by 16.7 percent on average.
A. Malekian, H. Alipour, M. Kheirkhah Zarkesh, S. Gharachelo,
Volume 18, Issue 69 (12-2014)
Abstract
Determine appropriate locations with accuracy and speed required is for Floodwater spreading very important. The main objective of this research, preparation, use and evaluation decision support systems is based on GIS and RS techniques to identify and prioritization appropriate areas Floodwater spreading in the study area. In this study area suitable for flood water spreading were selected based on major criteria four, sub criteria eight and index twentyfour. Finally five scenario will be provide and assessment (a scenario based on the relative values for the criteria four, and different scenarios four based on the obvious one of the main criteria). Comparison desirability average among the scenarios five indicate that it is Sub watershed (1) In the scenario third (infilteration preferred, water application preference and equality of all the main criteria) had a higher average desirability therefore between Sub watershed 2 in this scenario is preferred more than the other Sub. Of between the two sub watershed ivar region considering that the desirability average, sub watershed (1) and implemented of between scenarios, scenario (1) (infilteration major criteria preferred) were selected as first priority. Second priority for Floodwater spreading site selection is belong to sub watershed 2, and with scenario (1).
B. Khalili Moghadam, M. Afyuni, A. Jalalian, K. C. Abbaspour, A. A. Dehghani,
Volume 19, Issue 71 (6-2015)
Abstract
With the advent of advanced geographical informational systems (GIS) and remote sensing technologies in recent years, topographic (elevation, slope, and aspect) and vegetation attributes are routinely available from digital elevation models (DEMs) and normalized difference vegetation index (NDVI) at different spatial (watershed, regional) scales. This study explores the use of topographic and vegetation attributes in addition to soil attributes to develop pedotransfer functions (PTFs) for estimating soil saturated hydraulic conductivity in the rangeland of central Zagros. We investigated the use of artificial neural networks (ANNs) in estimating soil saturated hydraulic conductivity from measured particle size distribution, bulk density, topographic attributes, normalized difference vegetation index (NDVI), soil organic carbon (SOC), and CaCo3 in topsoil and subsoil horizon. Three neural networks structures were used and compared with conventional multiple linear regression analysis. The performances of the models were evaluated using spearman’s correlation coefficient (r) based on the observed and the estimated values and normalized mean square error (NMSE). Topographic and vegetation attributes were found to be the most sensitive variables to estimate soil saturated hydraulic conductivity in the rangeland of central Zagros. Improvements were achieved with neural network (r=0.87) models compared with the conventional multiple linear regression (MLR) model (r=0.69).
M. Sarmast, M. H. Farpoor, I. Esfandiarpoor Boroujeni,
Volume 19, Issue 73 (11-2015)
Abstract
Physical, chemical, and microscopic properties together with mineralogy are among useful techniques for dating and paleoclimatological interpretation and identification of varnishes. The present research was performed to evaluate the application of stone varnish in dating and landform development investigations in southern dry lands of Giroft area, Kerman Province. The mantled pediment was identified and divided into stable, unstable and moderately stable surfaces due to the type of geological sediments and stone varnish properties. Varnished stones were collected and their physico-chemical properties, petrography and scanning electron microscope characteristics, and clay mineralogy on geomorphic surfaces were studied. Silicon, Al, Fe, and Ca were the dominant elements found in stone varnishes of the area and varnish thickness varied from 100 to 600µm on different stones studied. The results of cation ratio (Ca + K)/Ti showed that the samples from stable surface were older than those on moderately stable and unstable surfaces. Clay coating and infilling were also observed on stones of stable surfaces. Chlorite, illite, palygorskite, smectite, kaolinite and sepiolite clay minerals were found in varnishes studied. Besides, scanning electron microscope images clearly showed layer morphology of rock varnish. The results of the research proved the potential of stone varnish application in relative dating investigations of different geomorphic surfaces in Giroft area.
M. Erfanian, H. Farajollahi, M. Souri, A. Shirzadi,
Volume 20, Issue 75 (5-2016)
Abstract
The aim of this study is to prepare the groundwater spring potential map using Weight of Evidence, logistic regression, and frequency ratio methods and comparing their efficiency in Chehlgazi watershed, province of Kurdistan. At first, 17 effective factors in springs occurrence including geology, distance to fault, fault density, elevation, relative permeability of lithological units, slope steepness, slope aspect, plan curvature, profile curvature, precipitation, distance to Stream, drainage Stream density, Sediment Transport Capacity Index (STCI), Stream Power Index, topographic wetness index (TWI) and land use/land cover (LU/LC) were selected. The validation processes of methods were conducted by relative performance characteristic curve (ROC). The area under an ROC curve (AUC) for the weight of evidence, logistic regression and frequency ratio was 85/8%, 79% and 89%, respectively. The results showed that all methods are suitable estimator for mapping the groundwater spring potential in the study area. But the frequency ratio method with the most amounts is the best method to produce and map the groundwater spring potential. Also, validation of the mappings based on the percentage of pilot springs, training springs and all springs showed that the logistic regression, WoE and frequency ratio, with 45, 56 and 45 percent of spring occurrence on the high potential classes respectively, had the highest validation.
A. R. Vaezi, H. Hasanzadeh,
Volume 20, Issue 75 (5-2016)
Abstract
Knowledge of variation in soil properties from each event to another is very important for the determination of critical periods during which soil is susceptible to erosion processes. This study was carried out to investigate soil loss in sequential rainfall events in Zanjan Province. Toward this, ten soil textures samples were taken and were transported to small plots (60 cm×80cm) with 20-cm depth) on a 8% slope land at three replications. The plots were exposed to ten simulated rainfalls with an intensity of 55 mm h-1 for 30-min and 5-day intervals. A total of 300 simulated rainfall trials were carried out at the plots. Results indicated that soil moisture, runoff production and soil loss were significantly affected by rainfall events (P< 0.001). Increasing soil moisture and consequently decreasing soil infiltration capacity were the most crucial element in increasing runoff production and soil loss in the sequential rainfall events, in a way that about 84% of soil loss variation in the rainfall events could be explained based on antecedent soil moisture. After the fifths rainfall event, no significant differences was found in soil infiltration capacity as well as runoff production because of soil moisture reaching to the water-holding capacity. Nevertheless, an increasing trend was observed in soil loss after fifth event which could associate with presence of more erodible soil particles on the surface and consequently increasing the concentration of surface flows.
A Fararooei, M. Noshadi, S. Amin Sichani,
Volume 22, Issue 1 (6-2018)
Abstract
PCBs are persistent organic pollutants which, due to high environmental hazards, must be traced, determined, and decomposed to reduce their risks. . To detect this material in the soil, the method of extraction and appropriate measuring conditions should be investigated. Two soil samples with two kg weight were selected with two different soil textures and the solutions of soil were made with the 1000 µg/ml aroclor 1254 mixture in a GC device. . Agilent GC-MS with stationary phase (CP 7477) was used to measure aroclor 1254. The analysis of variance and the test of the extraction mean of aroclor 1254 were compared in two soil textures. The results suggested that coarse texture soil (sandy loam) had a higher extract than the fine one (silty loam). The difference was statistically significant (P< 0.01). These findings suggested that the soil texture affected the extraction of aroclor from soil. In addition, four different levels of moisture (5%, 10%, 15% and 20%) produced in two soil textures and aroclor were measured. The highest level of extraction was obtained at 20% moisture, which was significantly higher than that in other levels (P< 0.01). The difference between the mean of extractions in the soil samples with 10% and 15% levels of moisture was non-significant (P> 0.05).
M. Zabardast, F. Daneshvar Vousoughi,
Volume 23, Issue 2 (9-2019)
Abstract
Seismic study of canyon sites has always been one of the important fields of seismic studies because of massive structures such as dams that are built in such sites. Jointed rock mass in rock canyon sites is one of the main site effects that can change the seismic waves. In this research, we studied the influence of this factor on the scattering of seismic waves. To fulfil this goal, we employed a coupled method combining the finite element method in the near field with boundary elements in the far field. To simulate the behaviour of jointed rock mass, we used the linear elastic model. Based on the results of the numerical analyses, jointed rock mass could have significant effects on the seismic waves in some special conditions. These conditions are the angle of incident wave, the thickness of layers and the material properties of the jointed rock mass. So it is necessary to consider this factor in the seismic structure design in the canyon sites.
F. Soroush, A. Seifi,
Volume 23, Issue 2 (9-2019)
Abstract
Evaluation of groundwater hydro chemical characteristics is necessary for planning and water resources management in terms of quality. In the present study, a self-organizing map (SOM) clustering technique was used to recognize the homogeneous clusters of hydro chemical parameters in water resources (including well, spring and qanat) of Kerman province; then, the quality classification of groundwater samples was investigated for drinking and irrigation uses by employing SOM clusters. Patterns of water quality parameters were visualized by SOM planes, and similar patterns were observed for those parameters that were correlated with each other, indicating a same source. Based on the SOM results, the 729-groundwater samples in the study area were grouped into 4 clusters, such that the clusters 1, 2, 3, and 4 contained 73%, 6.2%, 6.7%, and 14.1% of groundwater samples, respectively. The increase order of electrical conductivity parameter in the clusters was as 1, 4, 3 and 2. The results of water quality index based on the entropy weighting (EWQI) showed that all of the samples with excellent and good quality (36.3% of samples) for drinking belonged to the cluster 1. According to the Wilcox diagram, 435-groundwater samples (81.7%) in the cluster 1 had the permitted quality for irrigation activities, and the other 285-groundwater samples were placed in all four clusters, indicating the unsuitable quality for irrigation. The Piper diagram also revealed that the dominant hydro chemical faces of cluster 1 were Na-Cl, Mixed Ca-Mg-Cl and Ca-HCO3, whereas the clusters 2, 3, and 4 had the Na-Cl face. This study, therefore, shows that the SOM approach can be successfully used to classify and characterize the groundwater in terms of hydrochemistry and water quality for drinking and irrigation purposes on a provincial scale.
A. Foyouji Shahrezaei, M. A. Hajabbasi,
Volume 23, Issue 3 (12-2019)
Abstract
A well healthy environment can quietly affect the life quality and human community. In recent decades the need for and utilizing fossil had increased and thus the environmental pollutions including for soil has also increased. Petroleum contaminated soils are not suitable for agricultural, residential and social usage and cause economical, ecological and agricultural damage. To cope with this challenge, the use of additives such as carbon nanotubes has expanded to soil, but the use of these elements has raised concerns about their risk to biological processes and systems, such as effects on physiology and plant growth, and there have not been much studies on this issue. In order to investigate the interaction of soil petroleum pollution and carbon nanotubes on some plant characteristics such as wet mass, dry matter and plant length, seed and maize seedling were separately treated with 0, 10, 20 and 40 mg/l carbon nanotubes at the beginning. In pots containing soil with three levels of petroleum pollution, 2.43, 2.76 and 4.16% were cultivated with 3 replications. A completely randomized design was used in the form of factorial experiments. Wet mass, dry matter and length of shoot and root of plants were determined. The results showed that petroleum pollution had a negative effect on the growth characteristics. It was also observed that application of carbon nanotubes to maize (whether seed or seedling) depending on the concentration of these materials, could have different effects on plant growth parameters.
F. Sadeghdoust, N. Ghanavati, A. Nazarpour,
Volume 25, Issue 4 (3-2022)
Abstract
Street dust is mainly affected by the pollution of polycyclic aromatic hydrocarbons (PAHs). PAHs are a group of organic pollutants consisting of two or more benzene rings and are mainly produced during incomplete combustion. PAHs have attracted widespread attention due to their high carcinogenic and mutagenic properties in humans. Therefore, the purpose of this study was to investigate the sources and extent of the impact of these compounds on human health and the environment. To achieve this goal, 30 dust samples were collected from the sidewalks of the main streets of Dezful and the concentration of PAHs was determined by gas chromatography-mass spectrometry (GC-MS). The total concentration of PAHs in street dust of Dezful varied from 562.85 to 51447.10 μg / kg. The ratio of carcinogenic compounds to total PAHs was in the range between 0.73 to 0.91. Low molecular weight and high molecular weight PAHs accounted for 12% and 88% of total PAHs, respectively. The most important sources of PAHs in Dezful are the combustion of fossil fuels and petroleum products and emissions from vehicles and traffic. Moreover, incremental lifetime cancer risk (ILCR) in pathways ingestion in children was higher than in adults, but the ILCR in pathways dermal contact and inhalation in adults was higher than in children. The total cancer risk (CR) for children (5.77×10-3) was higher than adults (5.56×10-3), which shows the high potential for CR in the study area.
M. Mohammadi, B. Lorestani, Soheil Sobhan Ardakani, M. Cheraghi, M. Kiani Sadr,
Volume 25, Issue 4 (3-2022)
Abstract
Polychlorinated biphenyls (PCBs) can adversely affect human and environmental health according to long-term half-life and persistence in the environment. Therefore, this study was conducted to detect, identify, and health risk assessment of PCBs in surface soils collected from the vicinity of Arad-Kouh processing and disposal complex, Tehran, in 2020. A total of 30 surface soil samples was collected from 10 sampling sites near the Arad-kouh complex. After extraction of analytes, the gas chromatography/mass spectrometry (GC–MS) method was used to determine PCBs in soil samples. Based on the results, 15 congeners of PCBs were detected in the analyzed soil samples. Also, the minimum, maximum, and mean concentrations of total PCBs (µg/kg) were 269, 434, and 359, respectively. Moreover, the results of PCA and significant contribution values of low molecular weight homologs indicated that the presence of PCB compounds in the soil samples was connected with combustion processes in the soil. Besides, as among the detected PCBs, the TEF values only established for PCB105 showed that exposure to contaminated soil could be lead to a moderate level of carcinogenic risk through PCB105. Given that PCBs have adverse effects on the environment and human health, detecting, determining the concentration, source identification, and periodical monitoring of these compounds in different mediums to human health maintenance is strongly recommended.
M. Seifollahi, S. Abbasi, M.a. Lotfollahi-Yaghin, R. Daneshfaraz, F. Kalateh, M. Fahimi-Farzam,
Volume 26, Issue 2 (9-2022)
Abstract
Unpredictable settlement of earth dams has led researchers to develop new methods such as artificial neural networks, wavelet theory, fuzzy logic, and a combination of them. These methods do not require time-consuming analyses for estimation. In this research, the amount of settlement in rockfill dams with a central core has been estimated using artificial intelligence methods. The data of 35 rockfill dams with a central core were used to train and validate the models. The artificial neural network, wavelet transform model, and fuzzy-neural adaptive inference system are the proposed models which were used in the present study. According to the results, the best model for an artificial neural network had two hidden layers, the first layer of 18 neurons and the second layer of 7 neurons, with the Tansig-Tansig activation function, with a coefficient of determination R2=0.4969. The best model for the fuzzy-neural inference system had the ring function (Dsigmoid) as a membership function, with three membership functions and 142 repetitions with a coefficient of determination R2=0.2860. Also, combining wavelet-neural network conversion with the coif2 wavelet function due to the more adaptation this function has to the input variables, the better the performance, and this function, with a coefficient of determination R2=0.9447, had the highest accuracy compared to other models.
Sh. Shahmansouri, M.r. Mosaddeghi, H. Shariatmadari,
Volume 27, Issue 1 (5-2023)
Abstract
According to the rapid population growth, the challenging issue of production of economic and suitable food sources has led to greater attention to soilless culture greenhouse production systems. Components of growth media in horticulture are usually selected based on physical and chemical properties and their abilities in providing enough water and oxygen for roots. This study was conducted to investigate the feasibility of using some agricultural wastes (i.e., sawdust and wheat straw) and three rockwool types (i.e., raw, ground, ground, and sieved) as substitutes for commercial greenhouse growing media such as cocopeat and perlite. Several hydraulic, aeration, and chemical properties including easily available water (EAW), air after irrigation (AIR), water holding capacity (WHC), water buffering capacity (WBC), saturated water content (θs), bulk density (BD), total porosity (TP), water drop penetration time (WDPT), pH, and electrical conductivity (EC) were measured and scored in the growth media. Raw rockwool had larger particles compared to ground rockwool, which resulted in its faster water release. Processing of the rockwool decreased the saturated water content and saturated hydraulic conductivity due to the decrease in particle size. Four growth media were scored as very good and one was scored as good. The highest and lowest scores belonged to sawdust (34) and ground rockwool (30), respectively. The studied growth media with high TP, EAW, and WHC and low BD, EC, and WDPT can be used individually or combined with other commercial substrates for greenhouse growth media.
