Showing 33 results for salehi
J. Abedi Koupai, M. Salehi-Sirzar, S. S. Eslamian, J. Khajeali, Y. Hosseini,
Volume 18, Issue 68 (summer 2014)
Abstract
In order to investigate the effect of pest and water stresses on different growing stages of cowpea (Vigna sinensis) and pest occurrence, an experiment was conducted in Khazaneh Research station of Isfahan University of Technology. The experiment was carried out in a factorial complete randomized block design, in two different farms, with and without insecticide application. The treatments included severe water stress (50% water requirement), moderate water stress (75% water requirement) in four stages of cowpea growth, the first stage (from seed germination until flower in, second stage (from flowering until pod-filling), third stage (from pod-filling until harvesting) and the whole period of cowpea growth, in three replications. There was a control treatment in each farm with no stress in the whole period of cowpea growth, in three replications. The results showed that water stress had no significant effect on percentage of protein and mineral material. Result also showed that water stress had a significant effect (P≤ 0.01) on population of insects. Water stress significantly (P≤ 0.01) reduced the population of nymphs and adults of Empoasca decipiens Paoli and leaf minor damages, but water stress increased population of Thrips tabaci Lind. Considering the duration of first stage of growth (63 days), it is concluded that this stage had less sensitivity to water stress than the other stages. In regions, where farmers encounter water shortage for cowpea planting, the best performance can be obtained when moderate water stress (75% water requirement) is applied at the first stage of growth.
R. Karimi, M. Hassan Salehi, F. Raiesi,
Volume 18, Issue 69 (fall 2014)
Abstract
Improper use of rangelands may lead to their destruction. Therefore, the conversion of these degraded rangelands to agricultural lands and other land uses may improve their soil quality. The purpose of the present study was to evaluate the impact of cultivation in the degraded rangelands on some soil characteristics in Safashahr region of Fars province. Four land uses including the rangeland with sparse vegetation (degraded rangeland), the rangeland converted to agricultural land over 17 years, the agricultural land converted to apple orchard for 4 years and also to an apple orchard for 40 years were selected. Samples were randomly taken from each land use at two depths (0-20 and 20-50 cm) with five replications. The results revealed that land use change significantly increased organic matter and MWD in both soil depths. Bulk density and water dispersible clay increased in agricultural land and new orchard while a decrease was observed for old apple orchard. It is suggested the traditional farming to be replaced with new cultivation methods like minimum tillage and no tillage. Overgrazing of the rangelands must also be avoided.
M. Salehian Dastjerdi, A. Hemmat,
Volume 18, Issue 70 (winter 2015)
Abstract
Flood irrigation after planting induces wetting and drying cycles in arable soils. For this reason, the effect of this process on load-bearing capacity (pre-compaction stress pc) of a fine textured soil (silty clay) was studied. In this research, large air-dry disturbed soil specimens were prepared and some of them were exposed to five wetting and drying cycles. Next, the large soil specimens with/without wetting and drying cycles were compressed under three preloads (0, 100 or 200 kPa) and then the centre section of the preloaded soil specimen was firstly submitted to a plate sinkage test (PST). Then immediately one cylindrical sample was cored for confined compression test (CCT). The results showed that for reconstructed soil samples without wetting-drying cycles, the predicted pc using PST didn't significantly differ from the applied preload. Therefore, the PST can be used to determine the load-support capacity of the tilled soils. In PST, with an increase in soil water content from 0.9PL to 1.1PL, the amount of over-prediction in pc decreased. However, wetting-drying process significantly increased over-prediction in pc at the same water content. Hence, soil compressibility does not simply depend on the actual soil water content but also on the previous history of water content changes (i.e., wetting-drying cycles).
A. Hosseinpur, M.h. Salehi, F. Khaefi,
Volume 20, Issue 77 (Fall 2016)
Abstract
Potassium (K) fixation in soil is an important process which affects the availability of K to plants. There is limited information on K fixation capacity (PFC) of soils in Chahar Mahal & Bakhtiary province. This study was carried out with the aim of determining PFC and its relation with soil characteristics in 10 samples of surface soils in Chahar Mahal & Bakhtiary province. PFC was determined by adding six different levels of K by using KCl salt and measuring cation exchange capacity (CEC) in mineral, organic and clay fraction of soils. The results showed that the CEC in the mineral, organic and clay soils changes from 16.02-19.38, 1.71-3.27 to 29.3-39.8 cmol+/kg consequently. Potassium availability index (PAI) in the soils changes from 0.36 to 0.7 and Potassium fixation index (PFI) changes from 0.29 to 0.63. According to the results PFI and PAI showed significant correlation with whole and mineral fraction of the soil CEC, clay percent, pH and CaCO3 percent. The results of this study also showed that fixation of K fertilizer in the studied soils plays an important role in K dynamic of soil and K availability to plants.
S.a. Mohseni Movahed, M. Koochakzadeh, P. Salehimoghadam,
Volume 21, Issue 3 (Fall 2017)
Abstract
Basin irrigation is one of the conventional surface irrigation methods used to irrigate many crops all over the world. EDOBASIN, a new mathematical model for evaluation, design and optimal operation of basin irrigation has been introduced in this paper. In this model the linear combination of desired efficiencies are considered in an objective function, and based on decision variables that include discharge, length and width of basin and also restrictions of parameters, the optimal design is performed. This model is a simulation-optimization model in which the volume balance equations are used for hydrodynamic simulation and SA method are used for optimization steps. Optimization capabilities with various decision options and allowing weights to the indicators are good characteristics of this model. Comparison of advance time in this model with the well-known model SIRMOD for a real condition showed a good accuracy in the evaluation phase. In addition, the significant improvement of efficiencies after optimizing them simultaneously indicate that the model is an efficient tool for optimal design and use of this model for a data plot of an experimental field could enhance the efficiency of deep percolation ratio and application efficiency to 20% and keep constant the level of 100% for the efficiencies of water requirement and distribution uniformity.
H. Sarmadi, E. Salehi, L. Zebardast, M. Aghababaei,
Volume 22, Issue 2 (Summer 2018)
Abstract
Since the introduction of cities and urbanization, healthy water supplement and urban wastewater treatment have been considered as an important factor to evaluate progress in the urban areas. Tehran as a megacity is facing the lack of water. Tehran water supplement is far from its area; therefore, Tehran-Karaj plain has been considered in this study. So, Tehran water quantity index using the DPSIR model (Driving force, Pressure, Status, Impact and Response) in a period of 3 years (2008-2010) was considered in this paper. Driving forces included population, urbanization, green spaces, and industries. Pressures on urban water included water consumption, water losses, rainfall and evaporation. Then, Tehran water quantity status was investigated based on the existing water in dam reservoirs and groundwater resources. Their impacts on urban area were evaluated and finally, appropriate responses were presented. Some of the presented approaches included industries transmission, improvement of water consumption pattern, improvement of the water treatment plants status and unconventional water resources reuse, identification and rearrangement of subterranean, improvement of irrigation systems operation, and reduction of Tehran urban population.
S. Salehi, Sh. Esmael Zade, Gh. Panahi, K. Esmaili,
Volume 22, Issue 4 (Winter 2019)
Abstract
The effect of the uplift force in the hydraulics structures is against stability. So, determining and controlling this force can be very important. One of the ways to achieve this purpose is to decrease this force by using the hole drains; in this way, we can build perpendicular pipes with different diameters, leading to the durability of the structure. Therefore, an experimental model of concrete dam was constructed in the hydraulic laboratory. The dam's model was divided into five sections by using 4-hole drains with a thickness equal to the dam's foundation. By running experiments with the maximum water level at the upstream, dam hole drains were opened in their position. Hydraulic potential was estimated by using the Piezometer built in the flume body. Finally, by opening some hole drains, the uplift force was calculated from the equipotential lines. Therefore, the best case (which had the minimum force) was determined, which was a/L=0.4, to create the most proper hole drain in the dam foundation. (a: distance of drain to heel and L: length of the dam's foundation). To place the hole drain in this position, by applying the zero potential in this position, the up lift force was increased
S. Mirbagheri, M. Naderi, M. H. Salehi, J. Mohammadi,
Volume 23, Issue 3 (Fall 2019)
Abstract
Rivers are one of the most important source of water supply for drinking and farming purposes. Zard River is one of the surface water resources of Khuzestan province. The purpose of this study is to evaluate the quality of the river water and to observe the trend of changes in the water quality of this river in the Mashin station during the period of 1997-2015 by using the Man-Kendal, Spearman, variance analysis statistical methods and the least significant difference (LSD) and cluster analysis. LSD test shows SAR, Na, Cl, pH parameters up to 2010 (before Jare dam construction) were significant at 95% confidence level compared to 2015 (year of control). No changes were made after dam construction. According to Mann-Kendal non-parametric test, pH, Ca and SO4 have a significant upward trend to the 0.037, 0.393 and 0.376 respectively, the variables Cl, SAR, Na and temperature have a significant decreasing trend to the -0.387, -0.417, -0.386 and -0.1 respectively. Also Spearman test shows that the dam improved the quality of river water regarding to salinity. Variance analysis show that pH, SAR, Na, Cl, Ca and SO4 have significant difference. Cluster analysis classified the qualitative data before the construction of the dam in three clusters and after the construction of the dam were divided into two clusters where TDS variable was less distant than other variables. As a result, the quality of the irrigation water is changed downward and the TDS is more similar to the other variables compared.
D. Salehi, M. Goodarzi, H. Montaseri,
Volume 23, Issue 4 (Special Issue of Flood and Soil Erosion, Winter 2019)
Abstract
This research tried to provide a sustainable solution for the allocation of water resources of Zayandehrood basin in a way ensuring minimal conflicts and tension between the stakeholders in use of the water resources, four main decision makers of the basis, comprising Regional Water Company, conflicts among Agricultural Jahad Organization, and Department of Environment of Isfahan Province and Chaharmahal and Bakhtiari Province, were reviewed and 128 possible cased according to 7 scenarios were constructed and applied in the GMCR model. According to the GMCR approach, 6 balanced sustainable scenarios in different climatic periods of the basin were presented. Finally, the results were generalized for choosing the best mode in the form of a scenario within the WEAP model; also, the results obtained from these scenarios were presented using the criteria of system performance assessment. On the basis of the findings, Scenario II was developed, comprising the application of new simultaneous management of demand and supply, restrictions in drawing water from water tables, new prioritization in stakeholder allocation and new water portion plans in the basin as the best scenario with 81.4% sustainability index.
A. Vaezi, E. Zarrinabadi, Y. Salehi,
Volume 25, Issue 3 (Fall 2021)
Abstract
The effective use of rainwater is a key issue in agricultural development in arid and semi-arid regions. The tillage system as an important soil management measure can affect the rainwater retention, soil moisture content, and in consequence crop yield in rainfed lands. This study was conducted to evaluate the effects of slope gradient and tillage direction on rainwater use efficiency (RWUE) in rainfed lands in Zanjan Province. The field experiment was performed in five slope gradients (12.6, 15.3, 17, 19.4, and 22%) and two tillage directions (along slope and on contour tillage) at two replications. Mass soil water content was determined at 5-day intervals and runoff was measured after rainfalls. Wheat grain yield was determined for each plot and RWUE was computed using the proportion of wheat grain yield and precipitation. Base on the results, runoff, soil moisture, wheat grain yield, and RWUE were affected by tillage directions, so that runoff in contour line tillage decreased about 6.4 times compared to along slope tillage and in consequence increased soil moisture, wheat grain yield, and RWUE about 8.7, 24.8, and 24.8%, respectively. Increasing runoff production in contour line tillage at steeper slopes was associated with a lower capacity of cultivated furrows that strongly declined soil water retention and negatively affected wheat grain yield and RWUE in the lands. This study revealed that the efficiency of the contour tillage in water retention and RWUE decreases in steeper slopes in rainfed lands.
S. Salehi, A.r Esmaili, K. Esmaili,
Volume 25, Issue 4 (Winiter 2022)
Abstract
The objective of this study was to investigate how the earth dam is destroyed due to the effect of upstream and downstream slope of the body in overflow conditions. Therefore, eight models were provided that each model is constructed from the embankment dam with different upstream and downstream slopes (1:1, 2:1) and the soil properties (Sc) on breach formation. The time and method of dam break for flood discharges were investigated. The results showed that the upstream side slope of the embankment dam has less effect than the downstream side slope on the scour process resulting from the phenomenon and by increasing the downstream side slope of the embankment dam, the amount of erosion in the scour hole increases 28 %. Then, using nonlinear regression, relationships were presented to estimate the output flow rate and the location of the waterfall. A to the erosion and formation of the waterfall inside the body of sticky earth dams, two main outlines of the great waterfall and a series of waterfalls were presented. Finally, the formation of these waterfalls due to the effect of shear stress created during sediment erosion relative to the critical shear stress of the dam constituents was investigated and evaluated. Considering the limitations based on shear stress, the formation status of the type and the leaching pattern of the body of the cohesive earth dams during the overpass were estimated. Then, a general plan was presented to predict the behavior of the overflow stream in homogeneous and sticky soil.
S. Salehi, A. Mahmoodi Moghadam,
Volume 27, Issue 2 (Summer 2023)
Abstract
The present study investigated the related parameters to decrease the seepage through homogenous and heterogeneous earth dams by employing experimental models and solutions. Two heterogeneous earth dam models with vertical clay cores were considered to illustrate the effect of the electrokinetic application on the time failure factor. The seepage lines were measured along the longitudinal section from the heel to the toe using the observation wells by adjusting the electrodes of the electrokinetic application through the vertical clay core. The initial comparison expounds that adjusting the electrokinetic approach can decrease the level of the seepage line due to depleting water by considering horizontal drainage. Furthermore, the failure time was increased by 18 percent due to inputting the voltage in the clay content. The results indicated that the models with an electrokinetic approach were stabilized more than the ones. The hydrographs of the flow discharge were measured along the experimental tests to investigate the effect of electrokinetics with and without electrodes in 10 and 20 clay percent of the dam soil content. Results indicated that employing the electrokinetic application due to increasing clay content caused the effect of the electrokinetic was significantly increased and it caused the discharge flow reduced of 32 percent.
A.r. Hossienpur, M. Barati, M.h. Salehi,
Volume 27, Issue 4 (Winter 2023)
Abstract
The kinetics of potassium release may be affected by P When phosphorus (P) fertilizer is applied to soils. The objective of this study was to the effect of Ca(H2Po4)2 fertilizer on the kinetics of non-exchangeable potassium (NEK) release in 10 calcareous soils. The amount of 100 mg kg-1 of P as Ca(H2Po4)2 was added to the soils. Treated and untreated soils were incubated at 70% of field capacity and 25±1°C for 90 days. After that, the NEK release was studied by 0.01 M CaCl2 extractant in 2017 hours by successive extraction methods in the treated and untreated soils. The results showed the NEK released in treated soils less than in untreated soils. The mean cumulative NEK released after 2017 h in the treated and untreated soils was 260.6 and 303.3 mg kg-1, respectively. The release of NEK in all soils was fast in the initial stages and continued at a lower speed in the later stages until the end of the experiment. The kinetics of NEK release was evaluated using kinetic equations. Based on the highest coefficients of determination (R2) and the lowest standard error (SE), the kinetics of NEK release in treated and untreated soils were described by the power function equation. The results of this research could be helpful for the precise fertilizer recommendation for the study in calcareous soils.
