Showing 35 results for Loss
A. Ahmadi, T. Honar,
Volume 18, Issue 70 (3-2015)
Abstract
One of the most important problems in the design of a stilling basin is determination of the exact location of the hydraulic jump or stabilization of the hydraulic jump. In the present study, the effects of different forms of end sills on hydraulic jump characteristics were studied. The experiments were carried out for three different forms of end sills, rectangular, square and stepped, with three heights in two distances and for Froude numbers in the range of 4.7-8.23. The results showed that the end sill with larger cross section (square and stepped) will have a greater effect on reducing sequent depths of hydraulic jump and increasing energy loss than narrow end sills. However, in this type of end sills, water fall and the risk of erosion at downstream is greater.
Engineer H. Talebikhiavi, Engineer M. Zabihi, Dr. R. Mostafazadeh,
Volume 21, Issue 2 (8-2017)
Abstract
Effective soil conservation requires a framework modelling that can evaluate erosion for different land-use scenarios. The USLE model was used to predict the reaction of appropriate land-cover/land-use scenarios in reducing sediment yield at the upland watershed of Yamchi Dam (474 km2), West Ardabil Province, Iran. Beside existing scenario, seven other land-use management scenarios were determined considering pattern of land-use through study area within a GIS-framework. Then, data inputs were prepared using terrain data, land-use map and direct observations. According to the model results, the generated erosion amount was 3.92 t/ha/yr for the current land-use (baseline scenario). For this purpose, conservation practices in dry farming slopes and implementing the scenario 5 (contour farming and remaining crop residuals) can reduce the sediment to 2.02 t/ha/yr. The lowest and highest decreases in sediment yield are projected to be through implementation of scenario 6 (irrigated farming protection with plant residuals) and 7 (biological soil conservation in dry and irrigated farming). The results indicated that, implementing scenario frameworks and evaluating appropriate land-use management scenarios can lead to the reduction of sediment entering the reservoir, and prioritizing soil conservations in the studied area.
A. R. Vaezi, Y. Mazloom Aliabadi,
Volume 22, Issue 1 (6-2018)
Abstract
Water loss and nutrients loss are one of the important signs of natural resource degradation in the catchments. The amount of loss of these resources is affected by several factors including the characteristics of rainfall. In this study, the data of stream discharge (Q), total dissolve solids (TDS), and total nutrient loss ratio (NR) along with rainfall characteristics were analyzed for the events from1988 to 2002 in the Tahamchai catchment, which is owned by a regional water company. Moreover, soil properties were determined by soil sampling from different points in the catchment surface. Based on the results, there was a significant correlation between Q of the river and rainfall height (r=0.24, p<0.05), while its correlations with the rainfall intensity and duration were not statistically significant. On the one hand, this result was due to the inverse relationship between rainfall intensity and rainfall duration; on the other hand, due to the temporal variations in vthe egetation cover in the area, it controlled Q in the intensive rainfalls. The highest Q was in spring (1.68 m3 sec-1) and March (2.58 m3 sec-1). In this period, rainfall height was high and the rainfalls interval was short. Moreover, vegetation cover was weak, so it could not control surface runoff and reduce Q in the catchment. TDS and NR also significantly varied during the months and their highest values were observed in December (282.55 mg l-1) and (61.77 mg l-1), respectively. Mg2+ had the highest amount of water loss in the catchment area. A negative correlation was found between Q and TDS (r=0.41, p<0.001) and NR (r=0.31, p<0.001). This study revealed that spring and autumn were the sensitive period for water loss and nutrient loss in the catchment, respectively. Therefore, promoting the vegetation cover in early spring and reducing improper agricultural practices (tillage and fertilization) could be substantial strategies contributing to conserving the catchment’s resources.
M. Raeisi Asadabadi, M. R. Nour, R. Fattahi,
Volume 22, Issue 2 (9-2018)
Abstract
In order to optimize the irrigation system performance, it is essential to get information about water balance components in the farm. So, the objective of this study was evaluating the performance of the WFD device in determining water penetrated fate in the soil at each irrigation occurrence as one of the important components in evaluating the irrigation water efficiency. By having the water amount infiltrated in the root zone and the deep percolation amount collected and determined by WFD device, contribution of surface losses related to every irrigation occurrence can be determined by the employing water balance equation. This research was carried out in the form of completely randomized design blocks in three replications and under the treatments of 60, 80, 100 and 120% of the irrigation requirement supply of a potato plant in the research farm of Shahr-e Kord University in 2014. To gather the growing season data, before the planting operation, various WFD devices were installed at different depths and locations along furrow. In addition to WFD data, input discharge (using counter), output discharge (measured by flume type 1) and values of soil moisture (theta-probe device) were collected during the harvesting season. The results showed that the mean Nash–Satcliffe coefficient of comparison between the values of calculated and measured surface losses corresponding to it, and also comparison of the values of the calculated and measured residual moisture before each irrigation occurrence were obtained to be 0.87 and 0.98, respectively. Quantity of this indicator in the two conducted comparisons represented the correct and exact performance of the WFD device in the farm operation evaluation. During the farm evaluation process under the experimental furrow, distribution uniformity averages in the experimental treatments were acquired to be 75.56, 83.78, 88.06, and 90.34%, respectively. Likewise, water amount average percolation of root zone (depth losses) in experimental treatments at each irrigation occurrence was measured to be 0.02, 0.07, 0.27 and 0.47m3 for each furrow.
A. Kavian , A. Alipour, K. Soleimani, L. Gholami,
Volume 23, Issue 1 (6-2019)
Abstract
Nowadays, acid rain serves as one of the most serious environmental problems has affected many regions in the world. This phenomenon is characterized by many environmental impacts, such as soil contamination and degradation. Acid rain immediately affects soil, causing soil particles to breakdown and be dispersed; this is the first step to initiate the soil erosion. Therefore, in this study, the effect of different pH levels of acid rain (at different levels) on the soil splash was investigated under laboratory conditions using a rain simulator and a cup splash. In the experiments, acid rains, with the pH values of 3.75, 4.25, 5.25 and normal rains at three intensities of 40, 60 and 80 mmh-1, were studied; finally, a number of 36 samples were taken for statistical analyses. SPSS 23 and EXCEL 2013 software and one way and two-way ANOVA were used for the statistical analysis at a confidence level of 95%. The results showed that at the intensities of 40 and 60 mmh-1, the splash rate was significantly different in all pH treatments, and the acid rain with pH of 3.75 showed the highest splash rate. However, no significant difference was found at the rain intensity of 80 mmh-1, despite the higher splash rate at the pH of 4.25 and 5.25 treatments. Also, the results of the comparison of the means showed that the soil splash rate was also increased with enhancing rain intensity. Finally, the two-way ANOVA test showed that the simultaneous interaction effects of the two factors of pH and rain intensity on soil splash was not significant.
S. Barkhordari, M. Hashemy Shahdany, A. Bagherzadeh Khalkhali,
Volume 23, Issue 3 (12-2019)
Abstract
Seepage losses and poor operational activities are the two main source of water losses throughout the agricultural water conveyance and distribution systems in irrigation districts. This study aims to investigate the performances of two strategies of “canal lining” and employing the “Canal Automation” in order to reduce the losses mentioned above. The investigation was carried out on a couple of main canal reaches of Moghan Irrigation Districts. Two numerical models were simulated by Seep/w software to compare the seepage rate between the canal with and without concrete lining. The results reveal that the ability of concrete lining to reduce seepage losses along the canal is about 10%. Performance assessment of the “Canal Automation” strategy to minimize operational losses within the main canal was carried out employing Model Predictive Control (MPC). The results of the latter strategy indicate that employing the MPC not only reduces the operational losses along the canal by 15% but also improves the operation of the main canal so that the minimum efficiency and adequacy performance indicator was obtained 100% and 83% respectively. Therefore; due to Executive considerations and financial constraints in the same cases, the potential of each of the two strategies can be considered to reduce the conveyance and distribution losses and ultimately choose the most suitable option.
T. Yousefi Babadi, M. Lotfalianand, H. Akbari,
Volume 23, Issue 4 (12-2019)
Abstract
Soil erosion and its consequences are important factors in forest road network management. Cutslopes are the most important source of making sediment among different parts of the forest roads structure. For this research, a new and bare road in district No. 2, series No. 5 of NekaChoob forest, was selected; then the study data was measured. The study design was a completely randomized design in 10 plots with the size of 2 m2 along 500 meters of road with the 8 natural rainfall events. The results of the Pearson correlation showed that among soil properties, the contents of the liquid limit at the 5% confidence level and the plastic limit at the 1% confidence level had positive correlations with runoff and soil loss. Also, organic matter at the 1% confidence level and the contents of the sand at the 5% confidence level had negative correlations with runoff and soil loss. With increasing the soil moisture and bulk density, runoff and soil loss were enhanced. The results of the multivariate model showed that soil loss could be estimated using the Plastic Limit and sand percentage variables with a the correlation coefficient of 0.948.
L. Piri Moghadam, A. Vaezi,
Volume 23, Issue 4 (12-2019)
Abstract
Sloping farmlands are the major sources of soil, water and nutrient losses in arid and semi-arid regions. Information about the impacts of different tillage practices on soil erosion, nutrient loss and crop nutrient uptake on the sloping farmland of semi- arid soil is, however, limited. This study was carried out to investigate the effects of tillage direction on soil, water, nitrogen and phosphorous losses and their uptake by plant in a rainfed wheat land. Field experiments were conducted in two tillage directions: downslope tillage and contour line tillage with four fertilization treatments: control, urea, triple superphosphate, and urea + triple superphosphate at the field plots with 1.75 m ´ 8 m in dimensions by using the randomized completely block design at three replications in Zanjan Township during 2014-2015. According to the results, Significant differences were found between the two tillage practices in soil loss (P < 0.001), water loss (P < 0.001), nitrogen loss soil loss (P < 0.001), and nitrogen uptake by wheat grain (P < 0.001), while phosphorous loss and its uptake did not show any statistically significant difference. Soil and water loss in the downslope tilled plots was 1.65 and 2.50 times higher than the contour line tillage, respectively. Nitrogen loss in the downslope tilled plots was 1.29 times more than that in the contour line tilled plots. Nitrogen loss in the plots was attributed to soil and water loss, so significant relationships were observed between nitrogen loss and soil loss (R2 = 0.59)
and water loss (R2 = 0.55). This study, therefore, revealed that the tillage direction is an important factor controlling runoff, soil loss, and nitrogen loss and its uptake by wheat in the rainfed lands of semi-arid regions. Application of the contour tillage is, therefore, the first step to conserve soil and water and to improve soil productivity in these regions.
A. R. Vaezi, Kh. Sahandi, N. Sadeghian,
Volume 24, Issue 2 (7-2020)
Abstract
In semi-arid regions, soils are weakly aggregated and subjected to water erosion processes especially rill and interrill erosion. There is no information on the rate of these water erosion types in semi-arid soils located in the hillslopes. Therefore, this study was conducted to determine the soils susceptibility to these erosion types in semi-arid region. A laboratory experiment was done in eight soil textures using in a 0.6 m × 1 m flume a simulated rainfall with 50 mm.h-1 in intensity for 60 min. Rill and interrill erosion rate was measured using soil loss amount per flume area and rainfall duration. Based on the results, both rill and interrill erosion rate were significantly varied among the soils textures (P<0.001). Silt loam was the most susceptible soil to rill erosion (0.22 g m-2 sec-1) and interrill erosion (0.15 g m-2 sec-1), whereas sand didn’t appear any soil loss by these water erosion types. The compression of soil loss resulted by rill and interrill erosion among the soil tectures showed that rill erosion rate for sandy clay loam, silt loam, loam and sandy loam was 3.2, 1.4, 1.1 and 2.8 times higher than interrill erosion rate, respectively. These differences were statistically significant. Silt content was the major factor controlling soil loss difference in these soils. This study revealed that the study semi-arid soils having higher silt content appears also higher rill erosion rate than interrill erosion rate.
A. Motamedi, M. Galoie,
Volume 25, Issue 2 (9-2021)
Abstract
The annual soil erosion in different regions of the world has been estimated using various empirical and numerical methods whose accuracy is very dependent on their utilized parameters. One of the most common methods in the evaluation of the mean annual soil erosion especially in sheet and furrow regions is the USLE method. In this relationship, almost all factors that normally affect the soil loss process such as land cover, slope, precipitation, soil type, and support practice parameter of soil have been employed but, in this research, it was shown that the accuracy of this method in mountainous areas covered by rock and snow is somewhat low. To do this, a part of the Tibet plateau in China, where observation soil loss data were available, was selected for investigation. To implement the numerical and analytical analysis, many maps including DEM, NDVI, orientation, soil type, mean monthly and annual precipitation for 30 years were collected. For increasing the accuracy of the model, the cover management parameter was extracted from high accuracy NDVI maps and all USLE parameters were calculated in ArcGIS. The final results were shown that the amount of annual soil loss which was estimated by the USLE method is more than the observed data which were collected by Chinese researchers. This is because the large areas of the study area are covered by lichen and snow where soil loss due to the erosion process is very low but these regions cannot be recognized from NDVI maps. Also, the analysis of the NDVI maps was shown that the relationships of Fu, Patil, and Sharma were not suitable for soil loss estimation in elevated mountainous areas. If the other relationships such as Lin, Zhu, and Durigon are used for the regions with a height of more than 5500 m, a new correction coefficient needs to be used for the C factor which was calculated as 0.2 for the study area.
M.m. Matinzadeh, J. Abedi Koupai, M. Shayannejad, A. Sadeghi-Lari , H. Nozari,
Volume 25, Issue 4 (12-2021)
Abstract
Using water and fertilizer management at the farm level can be increased water use efficiency and reduce the volume of drainage water, fertilizer losses, and other pollutants in farmland with deep underground drains such as Khuzestan agro-industrial Companies. In the present study, a comprehensive simulation model for the water cycle and the nitrogen dynamics modeling was used for water and fertilizer management modeling on farmland of sugarcane in Imam Agro-Industrial Company using a system dynamics approach. To reduce irrigation water consumption and nitrogen fertilizer losses, five different scenarios were considered including four scenarios of water management consist of 5, 10, 15, and 20 percent reduction in the amount of irrigation water (I1, I2, I3, and I4) compared to the current situation of irrigation in Imam agro-industrial Company (I0), and one scenario of integrated water and fertilizer management (20% reduction in the amount of irrigation water and urea fertilizer 210 Kg/ha, I4F). The results of modeling showed that the scenario of I4F caused to reduce 31, 70, 71, 70, and 85 percent of the cumulative volume of drainage water, cumulative nitrate and ammonium losses, total losses of cumulative nitrate, and ammonium by tile-drain and cumulative losses of denitrification process, respectively. Thus, the implementation of this scenario, not only saves water and fertilizer consumption but also reduces environmental pollution effectively. So the scenario of I4F (amount of irrigation water for six months 2656 mm and urea fertilizer 210 Kg/ha) is recommended for sugarcane in the Imam agro-industrial Company.
N. Pourabdollah, J. Abedi Koupai, M. Heidarpour, M. Akbari,
Volume 25, Issue 4 (12-2021)
Abstract
In this study accuracy of the ANFIS and ANFIS-PSO models to estimate hydraulic jump characteristics including sequence depth ratio, the jump length, the roller length ratio, and relative energy loss was evaluated in stilling basin versus laboratory results. The mentioned characteristics were measured in the stilling basin with a rectangular cross-section with four different adverse slopes, four diameters of bed roughness, four heights of positive step, three Froude numbers, and four discharges. The average statistical parameters of NRMSE, CRM, and R2 for estimating hydraulic jump characteristics with the ANFIS model were 0.059, -0.001, and 0.989, respectively. While, the mean values of these parameters for the ANFIS-PSO model were 0.185, 0.002, and 0.957, respectively. The results indicated that these models were capable of estimating hydraulic jump parameters with high accuracy. However, the ANFIS model was moderately more accurate than the ANFIS-PSO model to estimate the sequence depth ratio, the jump length, the roller length ratio, and relative energy loss.
A. Motamedi, J. Abedi-Koupai, A.r. Gohari,
Volume 26, Issue 2 (9-2022)
Abstract
Water scarcity and lack of soil fertility are two major problems in the agriculture sector. This study aimed to use Azolla anzali and Lemna minor as a cover for a free surface of the water since not only do they have the potential to reduce evaporation, but they can also produce green fertilizer. Therefore, a completely randomized design experiment with 4 treatments (Azolla anzali, Lemna minor, combination of Azolla anzali+ Lemna minor and control) was performed with three replications. The surface of the reservoirs was covered with the mentioned plants and the changes in water height were measured every other day and the amount of nutrients (nitrogen and phosphorus) of the plant tissue was measured three times at the beginning, middle, and end of the period. Eventually, water loss in tanks containing Lemna, Azolla, and Lemna+ Azolla, was 39, 33.2, and 28.7% less than the control tank. The highest amount of nutrients in plant tissue was observed in Lemna, Azolla+ Lemna, and Azolla treatments, respectively. Although the amount of nutrients in the combined treatment was not higher than that of Lemna more biomass was produced, which means it can provide more fertilizer. Finally, the combined treatment of the two plants is a more suitable option to be used.
A. Balvaieh, L. Gholami, F. Shokrian, A, Kavian,
Volume 26, Issue 4 (12-2022)
Abstract
Changes in nutrient concentrations of soil can specify optimal management of manure and prevent environmental and water resources pollution. The present study was conducted with the objective of changing macronutrients concentrations of Nitrogen, Phosphorus, and Potassium with amendments application of polyvinyl acetate, bean residual, and a combination of polyvinyl acetate + bean residual for time periods of one, two, and four months. The results showed that the application of soil amendments had various effects on changing Nitrogen, Phosphorus, and Potassium. The maximum amount of Nitrogen related to the treatment of bean residual at the time period of four months before simulation (with a rate of 44.62 percent) and minimum amount of nitrogen related to Polyvinyl acetate treatment at the time period of one month (with a rate of -1.92 percent). The minimum rate of Phosphorus was measured at the treatment of bean residual at the time period of one month before simulation (with a rate of 0.95 percent). The maximum amount of Potassium related to the treatment of Polyvinyl acetate at the time period of four months before simulation (with a rate of 189.35 percent) and the minimum amount of Potassium related to the combination of bean residual + Polyvinyl acetate at the time period of one month after simulation (with a rate of 40.66 percent). Therefore, the application of amendments has various effects on changing soil macronutrients at different time periods.
A.r. Vaezi, S. Rezaeipour, M. Babaakbari, F. Azarifam,
Volume 27, Issue 3 (12-2023)
Abstract
Improving soil physical properties and increasing water retention in the soil are management strategies in soil and water conservation and enhancing crop yield in rainfed lands. This study was conducted to investigate the role of tillage direction and wheat stubble mulch level in improving soil physical properties in rainfed land in Zanjan province. A field experiment was done at two tillage directions: up to the downslope and contour line, and five stubble mulch levels: zero, 25, 50, 75, and 100% of land cover equal to 6 tons per hectare. A total of 30 plots (2 m×5 m) were created. The results indicated that water infiltration and water content were considerably affected by tillage direction, whereas its effect on water holding capacity was not significant. This physical property of the soil was influenced by the inherent properties of the soil, including particle size distribution. The change of up to down tillage direction to the contour line increased soil infiltration to 11% and water content to 6%. The physical soil properties were wholly influenced by mulch consumption. Soil water content increased in mulch treatments along with water holding capacity and infiltration rate. The highest volumetric water content was at 100% mulch level (10.62%) which was 11% more than the control treatment. However, there was no significant difference between 100% and 75% mulch treatment. This revealed that the application of 75% stubble mulch in contouring tillage is a substantial strategy for improving soil physical properties and controlling water loss in rainfed lands of semi-arid regions.
Kimia Akhavan, M. Heidarpour, N. Pourabdollah,
Volume 28, Issue 3 (10-2024)
Abstract
One of the ways to improve the characteristics of the hydraulic jump in the stilling basin is to use natural and artificial roughness. Recently, due to the advantages of immersed plates compared to other non-continuous artificial roughness, such as the smaller number of these and the vanes' ability to design their geometry and arrangement, it has been approached more. In this article, the effect of submerged vanes with three contact angles of 45°, 75°, and 90° has been investigated on the improvement of the characteristics of a hydraulic jump and its effect on parameters such as the depth ratio, relative length, energy loss rate, and bed shear force coefficient has been evaluated. The results of this research showed that the average effect of submerged vanes on reducing the depth ratio, jump length, and roller length compared to the classical mode is 9.4%, 24.6%, and 28.4%, respectively and the average relative energy loss is 5.5% compared to the classical state and maximum relative energy loss at the angle of 90 degrees of submerged vanes is 6.5%. Considering these results and other conditions such as ease of construction and use, stabilization, and reduction of economic costs among the available choices of sunken vanes, the angle of incidence of 75° is a suitable option for the optimal design of the stilling basin.
A.r. Vaezi, F. Besharat, F. Azarifam,
Volume 28, Issue 4 (12-2024)
Abstract
The temporal distribution pattern of rainfall can play a role in the production of runoff and soil loss during rainfall. This study investigated four rainfall patterns: uniform, advanced, intermediate, and delayed rainfall under field conditions. The rainfall height in all rainfall patterns was 20 mm. In the uniform rainfall pattern, a constant rainfall intensity (40 mm h-1) was used and in the non-uniform rainfall patterns, a maximum rainfall intensity of 40 mm h-1 was applied for a 15-minute duration. The experiments were carried out in 60 cm × 80 cm plots on a hillslope with a slope gradient of 9% at three replications. Rainfall patterns were set up on the plots in five events with an interval of one week. The results showed a significant difference between rainfall patterns in runoff and soil loss (p<0.01). This difference was due to the destruction of surface soil structure and the reduction of water infiltration rate, especially during peak time of rainfall intensity (40 mm h-1). The highest runoff occurred in the delayed rainfall (3.43 mm) while, the highest soil loss (61.47 g m-2) was observed in the intermediate rainfall, which was associated with the peak intensity of rainfall at the end of the rainfall and its role in the destruction of the soil structure on the one hand, and the loss of infiltration rate on the other hand. Variation of runoff and soil loss from one event to another indicated that soil loss is in line with runoff production in uniform rainfall, while soil loss did not follow runoff in other rainfalls. Soil loss in these rainfalls was affected by both runoff production and availability of erodible soil particles. These results revealed the necessity of studying the rainfall intensity distribution pattern for accurate prediction of soil erosion and determining soil loss variation event by event in the semi-arid region.
M. Niroubakhsh, A.r. Masjedi, M. Heidarnejad, A. Bordbar,
Volume 28, Issue 4 (12-2024)
Abstract
The application of flip bucket and triangular launchers with different shapes has been given more attention due to safety and better energy consumption to protect the downstream bed of water structures, as well as economic benefits compared to other energy consumers. The objective of this research was to investigate the energy loss of the passing flow in the dentated flip bucket and dentated triangular sill spillways in laboratory and numerical conditions. Physical and numerical modeling was used in a rectangular flume with a length of 9 meters, a width of 0.5 meters, and a height of 0.5 meters, flip bucket, and triangular spillways with dentated with specific dimensions according to the USBR standard in different discharges intensities in laboratory and numerical conditions. The amount of energy loss in the dentated flip bucket spillway was 71.4% and the dentated triangular sill spillway was 74.8% in laboratory conditions, which showed that the dentated triangular sill spillway has a better performance in terms of energy loss than the flip bucket and triangular spillway. The results showed that the shape of the spillway geometry and the presence of the dentated at the end of the structure is an important and influential factor in the amount of energy loss of the currents passing through the dentated flip bucket and dentated triangular sill spillways, which causes more broken and compressed flow lines and, as a result, an increase in speed at the moment. The launch and finally the relative loss of energy is more downstream of the structure. After determining the better performance of the dentated triangular sill spillway in energy loss, the numerical simulation of the dentated triangular sill spillway was performed using the numerical calculation method in Flow-3D software. The results of the analyses indicated that the amount of energy loss in the dentated triangular sill spillway in the numerical calculations was 87.5%, which showed the alignment and correctness of the tests performed with the laboratory conditions.
R. Ghasemi Ghasemvand, M. Heidarnejad, A.r. Masjedi, A. Bordbar,
Volume 29, Issue 2 (7-2025)
Abstract
the impact of hydraulic loss on the performance of weirs should not be overlooked. In this study, a laboratory flume measuring 8 meters in length, 0.6 meters in width, and 0.6 meters in height was used to investigate the hydraulic loss of the weirs and their discharge coefficients. The weirs used in this research were of the labyrinth type, featuring both curved and linear designs. Dimensional analysis using the Buckingham method indicated that the discharge coefficient (Cd) relies on parameters such as the hydraulic head ratio (Ht/P), weir shape factor (Sf), hydraulic loss ratio (Hf/P), and Froude number (Fr). The results demonstrated that an increase in hydraulic head leads to a decrease in the discharge coefficient of the weirs. Furthermore, the intensity of flow blade interference over the weirs gradually increases the hydraulic loss with a rising hydraulic head. Hydraulic loss increases up to a certain level of hydraulic head before beginning to decline. Therefore, it can be stated that the hydraulic loss curve for weirs like ARCL exhibits a sinusoidal trend. At a hydraulic head ratio of 0.4, the ARCL weir experiences 227% more hydraulic loss compared to the APKW weir. At a hydraulic head ratio of 0.6, the RCL weir shows 200% more hydraulic loss than the PKW weir. The trend of hydraulic loss variation with increasing Froude numbers for ARCL and RCL weirs is also sinusoidal. The ARCL weir shows the highest hydraulic loss with increasing Froude number compared to the other weirs. All weirs modeled using FLOW-3D software showed values (Cd and Hf/P) that exceeded those from physical modeling, which is significant in terms of safety factors. Moreover, the error rate in numerical modeling varied based on different parameters and conditions, averaging between 10% and 30%. In some cases, labyrinth weirs exhibited higher error rates compared to piano key weirs.
Jahangir Abedi Koupai, Noshin Shafiee, Behrooz Mostafazadehfard, Mohammad Mehdi Matinzadeh,
Volume 30, Issue 2 (7-2026)
Abstract
One of the key factors in agricultural production is the availability of sufficient and usable nutrients for plant growth, and among these, nitrogen plays a particularly important role. The waste of nitrogen fertilizers due to the low efficiency of using fertilizers has caused environmental problems such as pollution of surface and groundwater by nitrate or ammonium. In this study, the influence of fertigation as a combination of urea, ammonium nitrate, natural zeolite of Semnan (CP), and modified zeolite by surfactant (SMZ) in the reduction of waste and manure fertilizer was evaluated. Two separate experiments with a completely randomized design with three replications were used for loam soil columns. Treatments consisted of four levels of zeolite application (0, 4, 8, and 16 g/Kg) and a fertilization level with a concentration of 60 mg per liter nitrate applied at three fertigations during six irrigations. In the first part of the study, the role of nitrogen fertilizers in fertigation as a combination of urea and ammonium nitrate (UAN) for ordinary soil was examined to reduce the concentration of nitrate and ammonium in the drainage water, and the results were compared with one of the fertigation applications. The results showed that the loss of fertilizer in the form of nitrate was reduced by 40 percent for the UAN treatment during the first period of fertigation. Since the results of the first part of the experiment showed that the concentration of ammonium nitrate does not reduce to the same level as drinking water, in the second part of the experiment, the soil amendments were used. The measured nitrate removal showed that the highest nitrate removal belonged to the soil mixed with 16 g/kg of modified zeolite in the surface layer of soil (SM16) treatment, and it was equivalent to 90 percent. The highest ammonium removal belonged to the soil mixed with 16 g/kg of natural zeolite in the surface layer of soil (CP16) treatment, and it was 85 percent. Therefore, the use of fertigation as a combination of nitrogen fertilizers with soil amendments for conditions where there is a potential for groundwater pollution by nitrate leaching is recommended.
