Showing 14 results for chavoshi
S. Chavoshi, S.s. Eslamian,
Volume 3, Issue 3 (fall 1999)
Abstract
Designers of hydraulic structures are often faced with the problem of estimating flood frequencies at stream sites, where little or no flow information is available. A regional regression model is widely used which relates physical and climatological parameters to flow characteristics. In this study, a new method is used which is based on the station-year technique and combined records for several stream-flow gaging stations to make a single composite sample. This method, named ‘hybrid’, was proposed by Hjalmarson and Thomas (1992). It was applied to a group of records from 17 apparently homogeneous stream gaging stations to determine regional flood frequency equations. The study area consists of two adjacent basins, Gavkhoony and North Karoon in the central part of Iran. Using area and mean elevation of the catchments as the most important criteria in relation to peak discharge, the interactive process of the hybrid method was performed, resulting in two-parameter models of regional flood frequency. The performance of the hybrid method was evaluated by comparison with the regional relations determined from a multivariate regression. The comparison revealed that the accuracy of the hybrid method was significantly better than the regression method for low return periods.
S.s. Eslamian, V. Salimi, S. Chavoshi,
Volume 4, Issue 2 (summer 2000)
Abstract
Peak discharge is one of the basic parameters in the design of hydraulic structures. There are various methods for peak discharge determination. Regional flood frequency analysis is based on physical, climatological and hydrological characteristics of basins. The objective of this study is to examine different models for the estimation of quantiles for some catchments in western Iran (namely: Gharehsoo, Gamasiab, Kashkan, Seimareh, Sezar and Abshineh) for which only maximum daily mean discharge data exist. In this research, peak and maximum daily mean discharges for 11 stream gauging stations were collected for a 21-year period. The ratio of these two discharges (R) and mean and standard deviations of peak discharges and maximum daily mean discharges were computed. Catchment characteristics including catchment area, catchment perimeter, main channel length, mean elevation, mean slope equivalent rectangle length, circular ratio, Gravelius coefficient, drainage density, time of concentration, relief ratio and diameter of the circle having equal area with the catchment were computed. Linear regression analysis was performed between independent variables of the catchments and mean standard deviation of the parameter “R” to develop a relation. The results of this study can be applied to the estimation of extreme flow values for non-recording stream gauging stations (daily reading sites).
S. S. Eslamian, S. Chavoshi Boroojeni,
Volume 7, Issue 1 (spring 2003)
Abstract
Numerous methods are used in the investigation of floods in catchments such as regional flood frequency analysis. Regional flood frequency analysis relies on physical, climatic and ecological characteristics of catchments and applies statistical methods to study flow records. Hosking and Wallis developed Probability Weighted Moments and presented L-moments statistics as a new tool for flood frequency analysis. In this paper, the theory of L-moments was used to study the flood frequency of central catchments of Iran. A number of 27 sites each with more than 5 years of observed data were studied. In the first step, the diagram of L-kurtosis versus L-skewness was used and proper distributions for each site were applied. In order to eliminate the heterogeneous sites, homogeneous tests based on D, H1, H2 and H3 criteria were performed indicating that two sites appeared to be heterogenous. Next, using Goodness of Fit Test, the best regional distributions were determined which are GL, GEV, GN, PE3 and GPA, respectively. Finally, quantile estimates for distributions accepted at a 90% level were presented.
M. Khodagholi, Z. Eskandari, M. Saeidfar, S. Chavoshi,
Volume 12, Issue 44 (summer 2008)
Abstract
The effect of nitrogen and phosphorous fertilization on range species production was studied using factor combination method as factorial with 3 blocks and 12 treatments. Nitrogen in 4 levels of 0،25،50 and 75 kg N/ha and phosphorus in 3 rates of 0،30 and 60 kg N/ha were used. Results indicated no significant difference between nitrogen rates in different growth forms of grass, bush and Eurotia ceratoides. Nitrogen in 75 kg/ha rates caused an increase of 40 and 106% in grass and Eurotia production, respectively. The maximum rate of production was seen in N50 with 100 percent increase compared to N0. Moreover, no significant difference in phosphor rates of leguminous and grass was observed. P 60 kg caused 500 and 56 % increase in leguminous and grass production, respectively.
E. Chavoshi, M. Afyuni, M. A. Hajabbasi,
Volume 19, Issue 72 (summer 2015)
Abstract
Fluoride (F) is an essential element for humans and animals. The continuous ingestion of fluoride by humans and animals in excessive amounts has damaging effects. The objective of this study was to investigate the uptake of fluoride in spinach and alfalfa in an alkaline soil of Isfahan, Iran. Two plants were planted in lysimeters at Isfahan University of Technology research station site. The treatments consisted of two plants and three concentrations of F. Each treatment was performed in triplicate. All the plants were harvested after 125 days and the total plants' F concentrations were determined. The F concentration in both plants' roots were higher significantly (p<0.05) than the plants' shoots at both treatments. The F concentration in spinach root was 2.5 to 3 times greater than those values in alfalfa root. Totally, the RCFs and SCFs values of F were very low. This showed that these plants did not uptake much fluoride from the soil.
E. Chavoshi, M. Afyuni, M. A. Hajabbasi,
Volume 19, Issue 72 (summer 2015)
Abstract
Transport of fluoride and consumption of groundwater with excess fluoride concentrations poses a health threat to millions of people around the world. The objective of this study was to simulate transport of fluoride (F) using HYDRUS-1D model. The study was conducted in lysimeters at Lavark research station site in Isfahan. The treatments consisted of two concentrations of F (157 and 315 mg kg-1). The duration of the study was 125 days. Some of soil physical and chemical properties, soluble F and total F concentration were determined during the study. The results showed the transport of F in calcareous soil profiles. This may be due to the high pH and desorption of F ion as a result of repulsion by the more negatively charged soil surfaces. The highest concentration of total F and water soluble F were observed in the 10 cm surface soil layer. The concentration of F decreased with increased soil depth. The correlation coefficient was significant between the water soluble fluoride and the total fluoride (1% level). Also, the difference between the observed t- value and a critical value on the t distribution is statistically insignificant. It showed that the model simulated successfully water soluble F concentration in the soil profile.
E. Chavoshi, M. Afyuni , M. Ali. Hajabbasi,
Volume 19, Issue 73 (fall 2015)
Abstract
The sorption and desorption of fluoride by soil can play an important role in the transport of fluoride in soil. The study was conducted on the soil from Isfahan University of Technology research station site (two depths of 0-30 and 30- 60 cm). Fluoride sorption reactions were examined by equilibrating 0, 2.5, 5, 10, 25, 50 and 100 mg L-1 NaF solution with soils for 23 hr. The desorption experiments were performed using 0.03 mol L-1 NaCL solutions immediately following the completion of sorption experiments. The sorption isotherms of F were well described by the Langmuir and Freundlich models. The n values for Freundlich isotherm were 0.57 and 0.55 for two depths of the studied soil, respectively. The kF values for Freundlich isotherm were 0.026 and 0.025 mg (1-n) Ln g-1 for two depths, respectively. Maximum monolayer sorption capacities (q max) were obtained to be 0.4 and 0.35 mg g-1 for 1 and 2 layers of the studied soil, respectively. The desorption isotherms of F were well described by the Freundlich model. The fitted model parameters’ (kF and n) values for desorption branches were larger than these values for sorption branches. Also, the results showed a positive hysteresis (ndesrb sorb and kdesorb >Ksorb). It seems fluoride sorption to be reversible.
E. Chavoshi, M. Afyuni, M. A. Hajabbasi,
Volume 22, Issue 2 (Summer 2018)
Abstract
This study covers a large agricultural and industrial area of Isfahan province, including three types of land use, i.e., agricultural, uncultivated, industrial and urban types. A total of 275 samples from surface soil (0-20 cm) were collected and water soluble fluoride concentrations of them were measured. The spatial structure of water soluble fluoride in the soils was determined by omnidirectional variogram in the GS+ software. The spatial distribution of water soluble fluoride in the soil was mapped by employing the point kriging method in the SURFER software. The results showed that the mean of the water soluble fluoride concentration in Isfahan soils (0.85 mg L-1) was higher than the mean world soils (0.53 mg L-1). The water soluble fluoride showed moderate spatial dependence, indicating that the spatial variability of water soluble fluoride was mainly controlled by intrinsic and extrinsic factors. The mean water soluble fluoride concentration was significantly higher in agricultural and urban areas, as compared with the uncultivated land. This could be due to application of phosphate fertilizer in agricultural areas and the atmospheric fallout of fluoride from the industrial sources such as steel factories. According to the generated kriging map, the higher concentration of fluoride was mainly recorded around the Zayande Rood River and in the central and western parts of the study area.
E. Chavoshi, Sh. Arabi,
Volume 22, Issue 4 (Winter 2019)
Abstract
The objectives of this study were to estimate the concentration of lead (Pb) and cadmium (Cd) in agricultural products and the health risks of them on the human healths around the Irankooh Mine in Isfahan Province. The soil samples (0-20 cm of surface layer) and crop samples (rice and wheat) were collected using the composite and random sampling method. The total concentrations of Pb and Cd in soil were found to be 71.18 and 1.57 mg kg-1. The mean Pb concentrations in rice and wheat were 7.81 and 2.31 mg kg-1, respectively. These values for Cd were 0.15 and 0.124 mg kg-1, respectively. The mean daily intake of Pb through the consumption of cereals was more than the dietary reference intake (3.6 μg kg−1 day−1), but the daily intake of Cd was less than the dietary reference intake. The hazard index (HI) mean value for Pb and Cd for children and adults was 4.60 and 4.64, respectively. It showed that the consumption of the entire foodstuff could lead to potential health risks for consumers. There is also the cancer risk associated with exposure to lead.
K. Shirani, S. Chavoshi,
Volume 22, Issue 4 (Winter 2019)
Abstract
Catchment prioritization in terms of natural disaster intensity as well as prevention and control practices plays a main role in the natural resources and watershed management. In this study, a total of 24 sub-catchments in the Zohreh-Jarrahi basin were prioritized according to their morphometric parameters and using the mixed model of TOPSIS-Multivariate regression. A total of 12 morphometric parameters including constant component of channel maintenance, drainage density, ruggedness number, infiltration index, stream power index, stream frequency, slope, drainage texture rate, relief rate, form factor, bifurcation ratio and topography wetness index, in addition to rainfall, were studied and scored. Parameters were weighted by using multivariate regression and the spatial distribution of the observed flood events. TOPSIS model was used for the prioritization process. The results obtained from the weighting analysis showed that the ruggedness number, slope and rainfall had the highest effect on flooding in the study area with the score of 0.068, 0.024, and 0.016, respectively. According to the prioritization results, sub-catchments of Seidoon, Emamzadeh Jafar, and Takht Deraz, which had the minimum distance to the positive optimum (0.0028, 0.0029, and 0.0029, respectively) and the maximum distance to the negative optimum (0.0097, 0.0098 and 0.0095, respectively), showed the highest flooding intensity with the score of 0.7745, 0.7690 and 0.7625, respectively. In order to validate the results, prioritization results were compared to the observed flood events. Validation results also indicated the efficiency of the mixed model in delineation of catchments prone to flooding. Three sub-catchments of Seidoon, Emamzadeh Jafar and Takht Deraz were observed to have the highest number of observed flood events, thereby showing the high effectiveness of the model and also, the role of the morphometric parameters in flooding.
S. Chavoshi,
Volume 22, Issue 4 (Winter 2019)
Abstract
Regional flood frequency studies are initialized by the delineation of the homogeneous catchments. This study was based on "Region of Influence" concept, aiming to find the similar catchments in the south of Caspian Sea. The methodology utilized the Particle Swarm Optimization Algorithm, PSO, to optimize the fuzzy system over a dataset of catchment properties. The main catchment variables in relation to flood were determined by the principle component analysis method and employed as the inputs in the fuzzy system. Catchments grouping was performed over these fuzzy input variables by the iterative process. The optimum similar groups were obtained by PSO, and the heterogeneous L-moment index was used as the termination criterion for the optimization process. A total of 61 hydrometric stations located in the study area were selected and their relevant catchments' physical, climatic and hydrologic properties in relation to flood were studied. Principle Component Analysis by Variomax Rotation Factor over the catchments datasets tended to four out of 16 physical variables, including area, mean elevation, Gravelious Factor and Form Factor, as the main parameters in terms of homogeneity with 84 percent of accumulative variance. These variables, as well as mean annual rainfall, were used as the input data to define the fuzzy system. PSO algorithm was then employed to optimize the developed fuzzy system. The developed algorithm tended to yield the best result in the 9th iteration with 26 and 22 for the minimum average and the optimum values of cost function, respectively. The topology of the resulting algorithm included inertia weight, local and acceleration rates, the number of generations and population size, with the values of 0.7298, 1.4962, 1.4962, 10 and 5, respectively. This study tended to a total of 61 regions of influence, proportional to the relevant 61 sites. According to the geographical location of the catchments in the region, it could be concluded that the geographical proximity doesn't necessarily involve homogeneity. The obtained results indicated the efficient potential of PSO-FES in the delineation of the homogenous catchments in the study area.
S. Chavoshi Borujeni, K. Shirani,
Volume 24, Issue 3 (Fall 2020)
Abstract
Selection of the appropriate distribution function and estimation of its parameters are two fundamental steps in the accurate estimation of flood magnitude. This study relied on the concept of optimization by meta heuristic algorithms to improve the results obtained from the conventional methods of parameter estimation, such as maximum likelihood (ML), moments (MOM) and probability weighted moments (PWM) methods. More specifically, this study aimed to improve flood frequency analysis using the Artificial Bee Colony algorithm (ABC). The overall performance of this algorithm was compared to the conventional methods by employing goodness of fit statistics, correlation coefficient (CC), coefficient of efficiency (CE) and root mean square error (RMSE). The study area, Babolrood catchment located in southern bank of Caspian Sea, has been subjected to annual flooding events. A total of 6 hydrometry stations in the study area were delineated and their data were used in the analysis of 6 distribution functions of Normal, Gumbel, Gamma, Pearson Type 3, General Extreme Value and General Logistic. This analysis indicated that Gamma and Pearson Type 3 were the most appropriate distribution functions for flood appraisal in the study area, according to the ABC and conventional methods, respectively. Also, the results showed that ABC outperformed ML, MOM and PWM; so, Gamma could be recommended as the most reliable distribution function for flood frequency analysis in the study area.
N. Shahabinejad, M. Mahmoodabadi, A. Jalalian, E. Chavoshi,
Volume 24, Issue 3 (Fall 2020)
Abstract
Wind erosion is known as one of the most important land degradation aspects, particularly in arid and semi-arid regions. Soil properties, by affecting soil erodibility, can control the wind erosion rate. The aim of this study was to attribute the soil physical and chemical properties to the wind erosion rate for the purpose of determining the most important property. To this aim, wind erosion rates were measured in-situ at 60 points of Kerman province using a portable wind tunnel facility. The results indicated that wind erosion rates varied from 0.03 g m-2 min-1 to 3.41 g m-2 min-1. Threshold wind velocity decreased wind erosion rate following a power function (R2=0.81, P<0.001). Clay and silt particles, shear strength, mean weight diameter (MWD), surface gravel, dry stable aggregates (DSA<0.25mm), soil organic carbon (SOC), calcium carbonate equivalent (CCE) and the concentrations of the soluble Ca2+, K+ and Mg2+ were inversely proportional to the wind erosion rates following nonlinear functions. On the other hand, Wind erosion was significantly enhanced with increasing the sand fraction, soluble Na+, electrical conductivity (EC) and sodium adsorption ratio (SAR). According to the final results, among the studied soil properties, SAR and MWD were s the most effective properties controlling wind erosion in the soils of Kerman province. Therefore, it is recommended to consider suitable conservation practices in order to prevent the sodification and degradation of arid soils.
E. Javiz, A. Jalalian, M.r. Mosaddeghi, E. Chavoshi, N. Honarjoo,
Volume 26, Issue 4 (Winiter 2023)
Abstract
One of the most significant environmental crises in arid, semi-arid, sub-humid, and even humid regions is the destructive phenomenon of desertification and in the arid and semi-arid regions is wind erosion. These problems exist in large areas of Iran and it is necessary to use an environmentally friendly and economic method to solve this problem. In this study, calcium bentonite clay was used for the first time in Iran and perhaps in the worlds in the critical region of Sajzi, which covers an area of 65 hectares. Experiments were performed on the crusts after one year of mulching with bentonite clay. The results showed that wind erosion has a negative and significant correlation with the mean weight diameter and geometric weight diameter of aggregate, aggregates with diameters greater than 0.25 mm, shear strength, and penetration resistance. On the other hand, the results of the permeability test using double-ring and by three models (Kostiakov, Horton, and Philip) showed that the lowest mean square error (SSE) and the highest coefficient of determination (R2) belonged to the Kostiakov model in the mulch-applied and control samples. This result indicated the superiority of the Kostiakov model compared to Horton and Philip's models. Wind erosion intensity was also measured in situ using a portable wind tunnel at 20 points in the Sajzi region. The findings showed that mulch application has controlled more than 95% of soil erosion.
