Showing 130 results for Char
K. Ghaderi, B. Motamedvaziri, M. Vafakhah, A.a. Dehghani,
Volume 25, Issue 4 (12-2021)
Abstract
Proper flood discharge forecasting is significant for the design of hydraulic structures, reducing the risk of failure, and minimizing downstream environmental damage. The objective of this study was to investigate the application of machine learning methods in Regional Flood Frequency Analysis (RFFA). To achieve this goal, 18 physiographic, climatic, lithological, and land use parameters were considered for the upstream basins of the hydrometric stations located in Karkheh and Karun watersheds (46 stations with a statistical length of 21 years). The best Probability Distribution Function (pdf) was then determined using the Kolmogorov-Smirnov test at each station to estimate the flood discharge with a return period of 50-year using maximum likelihood methods and L-moments. Finally, RFFA was performed using a decision tree, Bayesian network, and artificial neural network. The results showed that the log Pearson type 3 distribution in the maximum likelihood method and the generalized normal distribution in the L moment method are the best possible regional pdfs. Based on the gamma test, the parameters of the perimeter, basin length, shape factor, and mainstream length were selected as the best input structure. The results of regional flood frequency analysis showed that the Bayesian model with the L moment method (R2 = 0.7) has the best estimate compared to other methods. Decision tree and artificial neural network were in the following ranks.
A. Kasra, A. Khosrojerdi, H. Babazadeh,
Volume 26, Issue 1 (5-2022)
Abstract
N. Azadi, F. Raiesi,
Volume 26, Issue 1 (5-2022)
Abstract
Biochar as an efficient strategy for the improvement of soil properties and organic waste management may reduce the potential effects of abiotic stresses and increase soil fertility. However, the effects of this organic amendment on soil microbial indicators under combined salinity and pollution have not been studied yet. Therefore, the objective of this study was to evaluate the influence of sugarcane bagasse biochar on some soil bioindicators in a Cd-polluted soil under saline and non-saline conditions. A factorial experiment was carried out with two factors, including NaCl salinity (control, 20 and 40 mM NaCl) and sugarcane bagasse biochar (soils unamended with biochar, amended with uncharred bagasse, 400 oC biochar, and 600 oC) at 1% (w/w) using a completely randomized design. Results showed that salinity increased the mobility of Cd (12-17%), and subsequently augmented its toxicity to soil microorganisms as indicated by significant decreases in the abundance and activities of the soil microbial community. Conversely, sugarcane bagasse biochar application reduced the concentration of soil available Cd (14-18%), increased the contents of soil organic carbon (89-127%), and dissolved organic carbon (4-70%), and consequently alleviated the effect of both abiotic stresses on soil microbial community and enzyme activity. In conclusion, this experiment demonstrated that the application of sugarcane bagasse biochar could reduce the salinity-induced increases in available Cd and mitigate the interaction between salinity and Cd pollution on the measured soil bioindicators.
F. Khafi, A.r. Hossienpour, H. Motaghian,
Volume 26, Issue 2 (9-2022)
Abstract
One of the significant factors affecting biochar properties is the pyrolysis temperature. This study aimed to investigate the effect of pyrolysis temperature on the properties and fractionation of Zn and Pb in biochars produced by sewage sludge. Biochars were prepared at temperatures of 300 to 700 °C and the physicochemical properties, availability, and fractionation of Zn and Pb were investigated. The results showed that pH, pHzpc, percentage of calcium carbonate, cation exchange capacity, specific surface area, and porosity in biochars were higher than in the feedstock. By increasing biochar production temperature, the mentioned properties increased. FT-IR revealed that the OH functional group is present in free form, either in the structure of C-OH and -COOH and aliphatic-CH2 groups in the sewage sludge. By converting sewage sludge to biochar, the intensity of these peaks decreased. In contrast, peaks representing complex aromatic structures appeared. The availability of Zn and Pb in biochar was reduced as compared to sewage sludge. The results of fractionation indicated that sewage sludge has bio-availability and toxicity of Pb and Zn. the amount of oxide and residual fractions of these two metals increased by converting sewage sludge to biochar at different temperatures. Therefore, it seems that biochar production from sewage sludge reduces the toxicity and bio-availability of Zn and Pb. Also, by incrementing the temperature of production, the bio-availability potential (bonding with organic matter), and non-toxicity (residual) of these metals increased.
M. Sabouri, A.r. Emadi, R. Fazloula,
Volume 26, Issue 2 (9-2022)
Abstract
A compound sharp-crested weir is often used to measure a wide range of flows with appropriate accuracy in open channels. In this study, experiments were performed to investigate the hydraulic flow through a compound weir of circular-rectangular with changes in hydraulic and geometric parameters in free and submerged flow conditions. The characteristics of the weirs include rectangular spans width of 39 cm, a circular radius of 5, 7.5, and 12.5 cm, and heights of 10 and 15 cm. The results showed that by increasing the radius and height of the Weir, upstream water depth increases around 28.4%. At a constant h/p, the discharge coefficient increases with the increasing radius of the circular arc. Also, in the submerged conditions, the discharge coefficient is less (around 40%) than in the free flow condition, which is due to the resistance of the depth of the created stream against the passage of the flow.
I. Hasanpour, M. Shirvani, M.a. Hajabbasi, M.m. Majidi,
Volume 26, Issue 2 (9-2022)
Abstract
Low organic matter content and alkaline pH of calcareous soils in arid and semi-arid regions are the main reasons for the low nutrient availabilities for plants in these soils. One way to improve the chemical properties and fertility of calcareous soils is the application of organic substances such as biochar produced from pyrolysis of organic wastes. However, biochars have an almost predominant alkaline pH, which exacerbates plant nutrient deficiencies in calcareous soils when used for a long time. Pyrolysis of some organic wastes under controlled temperature conditions can lead to the production of acidic biochar. The effect of acidic biochars on several chemical properties of two calcareous soils in Isfahan province was investigated in the present study. Treatments included two types of biochar (pine cone and rice husk), three levels of biochar addition (one, three, and six percent), two types of soil (a sandy loam (Tiran) and a clay loam (Lavark)), and two incubation periods (one and six months). The results showed that applying biochar could slightly decrease soil pH but raised soil electrical conductivity. In addition, the amount of organic carbon, total nitrogen, and available concentration of manganese in all treatments and the concentrations of available phosphorus, potassium, iron, zinc, and copper in the most of treatments showed a significant increase compared to the control. Amending soil with biochar at a 6% rate caused the most significant changes in the measured parameters in both soil types. In general, the results of this study indicated that acidic biochar produced from pine cones and rice husk can be used as a suitable conditioner to improve the chemical properties and fertility of calcareous soils.
T. Mohammadi, V. Sheikh, A. Zare,
Volume 26, Issue 4 (12-2022)
Abstract
Trend analysis of stream flow provides practical information for better management of water resources on the eve of climate change. Therefore, the present study investigated river flow variations during three decades as well as projections of future discharge in the Gorganrood watershed. The Man-Kendall method has been used to detect the trend and methods of Pettitt, SNHT, and Buishand to identify points of a sudden change in discharge time series in 8 stations of Aq Qala, Galikesh, Gonbad, Haji Ghoshan, Nodeh, Ramyan, Sadgorgan, and Tamar. The Mann-Kendall trend test showed the existence of a significant negative trend (flow reduction) on a daily and annual scale in all stations. Monthly, the strongest negative trend in Aq Qala, Galikesh, Gonbad, Haji Ghoshan, and Ramyan stations was related to July, but in Nodeh and Tamar stations, it was related to August and February, respectively. A decreasing trend was observed in all stations on a seasonal scale, but this trend was not significant in some seasons. The results of the analysis of change points in discharge showed that the change points in the data used in this study are more of a decreasing and in some cases incremental type and some stations, no change points have been identified at all. Therefore, the number of decreasing changes in the studied hydrometric stations is significantly higher than the incremental changes and is more visible from 1993 to 1997 and 2005-2007 in three and four stations, respectively. Also, the most incremental changes among the stations are related to the Aq Qala station in 2017 with a flow rate of 234 cubic meters per second. Investigation of the flow of the basin in the past decades showed significant monotonic and abrupt changes which are mostly toward decreasing the basin’s discharge. The downward trend in discharge values at different time scales for all hydrometric stations of the Gorganrood watershed, which will be more severe in the future due to global climate change, and increasing the region's water needs for various future use due to population growth and the expansion of industries can also be considered as a serious warning for policymakers, planners, and local managers to prevent a possible water crisis in the region in the future with proper planning.
R. Mousavai, M. Rasouli Sadaghiani, E. Sepehr, M. Barin,
Volume 27, Issue 1 (5-2023)
Abstract
can provide useful information about P adsorption and the factors affecting it. A batch experiment was performed with phosphorus concentrations (0 to 35 mg/L) in two soils with different electrical conductivity (EC) (2 and 15 dSm-1) by a variety of biochar treatments including simple apple-grape biochar (BC), rock phosphate- biochar (BC-RP), enriched-biochar (BC-H3PO4-RP), enriched-biochar (BC-HCl-RP), triple superphosphate (TSP), and control (Cont). The results indicated that phosphorus sorption capacity varied between the soils. Biochar treatments were effective in reducing the phosphorus adsorption of both soils. Due to BC-H3PO4-RP and BC-HCl-RP treatments, the maximum phosphorus adsorption of soils decreased in S1 soil by 14 and 23 % and in S2 soil by 26 and 19%, respectively. Also, the use of these treatments decreased the parameters of Langmuir absorption intensity (KL) of S1 soil to 0.085 and 0.066, respectively and S2 soil to 0.11 and 0.15, L/mg respectively, and Freundlich absorption capacity (KF) of S1 soil decreased to 19.2 and 22.5 and S2 soil to 28.2 and 28.1 L/kg, respectively. Enriched biochars significantly reduced the buffering indices of both soils indicating phosphorus adsorption decreased and increased the availability of phosphorus for the plant. The standard phosphorus requirement of S2 soil was lower than S1 soil by both equations. Therefore, enriched biochar can be an effective strategy to increase phosphorus availability and reduce the use of chemical fertilizers in saline and non-saline conditions; however, more field studies are needed for a clear understanding of the potential of P-enriched biochar as a fertilizer alternative.
S. Salehi, A. Mahmoodi Moghadam,
Volume 27, Issue 2 (9-2023)
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.
E. Mirzakhani, H.r. Motaghian, A.r. Hosseinpur,
Volume 27, Issue 3 (12-2023)
Abstract
In addition to the distribution of elements in the soil solid phase, element species in the solution are also very important due to their importance of providing elements for root uptake. For a deeper study of the chemical cycle of elements in saline soils treated with biochar, the study of speciation is very useful and provides a method to reduce or transform the toxicity caused by toxic elements in saline soils. Therefore, to investigate the effect of biochar on Cd speciation in two saline calcareous soils, 15 mg kg-1 Cd as cadmium chloride was added to the soil sample (200 g), and the soils were incubated for three weeks at 25±2 °C at 80% field capacity. After the incubation period, salinity levels of 20 and 40 mmol kg-1 as sodium chloride (equal to 3.65 and 7.30 dS m-1) were added to the soils. Then, the 1% (w/w) of the sugarcane bagasse and biochars produced at 400 and 600 °C were added to the soils, and then incubated for three months at 25±2 °C at 80% field capacity. At the end of the incubation period, for the speciation of Cd in the soil solution (in a 1 to 2 ratio), the concentration of dissolved cations and anions in the soil samples was measured. The results showed that the interaction between salinity, biochar, and soil on Cd2+, CdCl+, CdCl20, and Cd(SO4)22- was significant. The application of biochar in sandy soil reduced (p <0.05) the concentration of CdCl+, CdCl20, CdSO40, and CdOH+ species compared to the control soil, while it did not affect clay soil. Also, salinity caused by sodium chloride in sandy soil increased the concentration of CdCl+ and CdCl20 species and decreased CdSO40 and CdOH+ species compared to the control soil (p <0.05). The results showed that biochar in saline sandy soil was more effective than clay soil in reducing Cd toxicity.
M. Majedi Asl, T. Omidpour Alavian, M. Kouhdaragh, V. Shamsi,
Volume 27, Issue 3 (12-2023)
Abstract
Non-linear weirs meanwhile economic advantages, have more passing flow capacity than linear weirs. These weirs have higher discharge efficiency with less free height upstream compared to linear weirs by increasing the length of the crown at a certain width. Intelligent algorithms have found a valuable place among researchers due to their great ability to discover complex and hidden relationships between effective independent parameters and dependent parameters, as well as saving money and time. In this research, the performance of support vector machine (SVM) and gene expression programming algorithm (GEP) in predicting the discharge coefficient of arched non-linear weirs was investigated using 243 laboratory data series for the first scenario and 247 laboratory data series for the second scenario. The geometric and hydraulic parameters were used in this research including the water load (HT), weir height (P), total water load ratio (HT/p), arc cycle angle (Ɵ), cycle wall angle (α), and discharge coefficient (Cd). The results of artificial intelligence showed that the combination of parameters (Cd, H_T/p, α, Ɵ) respectively in GEP and SVM algorithms in the training phase related to the first scenario (Labyrinth weir with cycle wall angle 6 degrees) were respectively equal to (R2=0.9811), (RMSE=0.02120), (DC=0.9807), and (R2=0.9896), (RMSE=0.0189), (DC=0.9871) in the second scenario (Labyrinth weir with a cycle wall angle of 12 degrees) it was equal to (R2=0.9770), (RMSE=0.0193), (RMSE=0.9768), and (R2 = 0.9908), (RMSE = 0.0128), (DC = 0.9905), which compared to other combinations has led to the most optimal output that shows the very favorable accuracy of both algorithms in predicting the coefficient the Weir discharge is arched non-linear. The results of the sensitivity analysis indicated that the effective parameter in determining the discharge coefficient of the arched non-linear Weir in GEP and in SVM is the total water load ratio parameter (HT/p). Comparing the results of this research with other researchers revealed that the evaluation indices for GEP and SVM algorithms of this research had better estimates than other researchers.
H.r. Owliaie, E. Adhami, M. Najafi Ghiri,
Volume 27, Issue 3 (12-2023)
Abstract
Soil resources are important components of the ecosystem, and therefore, their quality should be considered. One of the important factors affecting the quality of soils is land use change. The present study was conducted to investigate the effects of land use change and deforestation on some soil fertility and biological characteristics in the forest area of the Yasouj region. In this area, four land uses of dense forest, sparse forest, deforested (degraded) lands, and rainfed agriculture were randomly sampled from two slope classes. In each land use 10 soil surface samples were taken. Fifteen soil fertility and biological characteristics were measured using routine methods. The results showed that dense forest and deforested (degraded) lands had the best and worst conditions, respectively, in terms of the measured parameters. Among the measured characteristics, the values of alkaline phosphate, exhaled respiration, nitrogen, basal respiration, acid phosphatase, manganese, and zinc showed the greatest decrease respectively, and the values of phosphorus and potassium exhibited the least decrease, as a result of land use change from dense forest to degraded lands. The findings showed that the conversion of ecosystems such as forests to agricultural lands or deforestation has led to a severe decrease in the fertility and biological indicators of soil quality. Therefore, the protection programs of these areas should be more considered.
R. Hosseinpour, H.r. Asgari, H. Nikanhad Qermakher, E. Malekzadeh, M.k. Kianian,
Volume 27, Issue 4 (12-2023)
Abstract
The soils of desert areas are mostly low in organic matter and may fluctuate greatly in terms of acidity. Biochars are one of the materials used to improve and modify some soil characteristics. This compound is very resistant to decomposition and remains in the soil for a longer period, reducing agricultural waste and turning it into a soil conditioner. This leads to keeping carbon in the soil, increasing food security, increasing biodiversity, and reducing deforestation. In this research, an attempt was made to investigate the biochar of fodder beet plant waste produced at different pyrolysis temperatures and its physical and chemical characteristics. For this purpose, fodder beet wastes were collected from settlements around Birjand and after being crushed and air-dried, they were pyrolyzed in an electric furnace under limited oxygen conditions at a temperature range of 300-700 degrees Celsius. Then, the characteristics of the produced biochars were performed with 3 repetitions of measurements and statistical analyses with SPSS software. The results of this research showed that the characteristics of biochars changed significantly with temperature change. The highest yield percentage (59%), organic carbon (56.33%), total nitrogen (0.53%), water retention (0.84g/g) at 300 and 400 degrees Celsius, and the highest amount of ash (% 76), acidity (8.21) and electrical conductivity (0.1ds/cm) was obtained at a temperature of 700 degrees Celsius. The percentage of carbon and the efficiency of biochar produced at temperatures of 300 and 400 degrees Celsius were higher than other biochar produced at other temperatures. Biochar produced at 300°C has better characteristics in terms of carbon percentage and acidity efficiency compared to biochar produced at 400°C. Although these differences were not statistically significant, due to biochar production being more economical in terms of energy consumption, it is recommended to produce biochar at a temperature of 300 degrees Celsius.
S. Barani, M. Zeinivand, M. Ghomeshi,
Volume 27, Issue 4 (12-2023)
Abstract
In this study the effect of orifice number and dimensions in combined structure sharp crested rectangular weir with multiple square orifice was investigated. For this propose, some experiments in different flow rate, different orifice number and dimensions were done. The results showed that by different orifice numbers and dimensions, flow discharge increased at the same upstream flow head. This increasing trend was observed in all numbers and dimensions of the investigated experiments. The analysis of the quantitative results showed that by increasing the number of orifices, the discharge rate through the combined structure of weir-orifice was increased on average 2.06 liters per second and by increasing each centimeter of orifice dimensions, the discharge was increased by 2.82 liters per second. Also by calculating the percentage of flow rate increase, it was observed that by adding the orifice number, it increases by 18.7% and by increasing the size of the orifice by one centimeter, the flow rate increases by 28.1%.
A. Barikloo, S. Rezapour, P. Alamdari, R. Taghizadeh Mehrjardi,
Volume 27, Issue 4 (12-2023)
Abstract
Soil quality is one of the most crucial factors determining crop productivity and production stability. The soil's physical, chemical, biological, and ecological characteristics affect its quality. Numerous researchers have concentrated the evaluation on a small number of soil quality indicators because measuring all soil quality indicators would be time-consuming and expensive. This study looked at the spatial autocorrelation of soil quality in the southwest areas of the Urmia Plain to establish the minimal data set for quantitative assessment. To accomplish this, 120 composite soil samples were collected from a depth of 0 to 60 cm, and the soil quality index was then calculated using the IQI method in 4 modes: Total-Linear (IQIwL-TDS), Total-Nonlinear (IQIwNL-TDS), Minimum-Linear (IQIwL-MDS), and Minimum nonlinearity (IQIwNL-MDS). 22 physical and chemical characteristics were used to choose the data set. The characteristics of sand percentage, sodium absorption ratio, cation exchange capacity, Available phosphorus, active calcium carbonate, and nickel concentration were chosen as the minimum data set (MDS) using the decomposition method into principal components. The linear IQIMDS mode produced the greatest soil quality index result, whereas the non-linear IQIMDS mode produced the lowest. The non-linear mode of the IQI index has a greater correlation coefficient (R2=0.85) than the linear mode of the IQI index (R2=0.73), according to an analysis of the linear and non-linear correlation coefficient between the soil quality index with the total category and minimum data. The findings of computing the global Moran's index for study sets of IQI soil quality index data revealed that the soil quality data are not independent of each other and are spatially autocorrelated, distributed in clusters, and have spatial autocorrelation. Getis-ord GI statistics indicated that the eastern and southeastern parts of the research region comprise clusters with poor soil quality, salt marshes produced by Lake Urmia's drying up, and surrounding arid plains.
M. Baki, J. Abedi Koupai,
Volume 28, Issue 1 (5-2024)
Abstract
The improvement of water consumption efficiency is very significant, especially in arid and semi-arid regions. In this research, the effects of three hydrogel rates (0, 10, and 50 Mg ha-1) and three irrigation regimes (50%, 70%, and 100% of water requirement) on growth, yield, and oil production of Thymus daenensis were studied in a lysimetric experiment. The process of hydrogel synthesis was performed with sodium alginate as the main bone of the polymer and acrylic acid and acrylamide as monomers with the rapeseed meal biochar was made at 300 ºC. The results showed that the essential oil content produced by the plant was impressed by the hydrogel application. The essential oil content increased with an increase in water deficit, but the essential oil yield decreased in the lysimeters with water deficit compared to the ones without water stress. Besides, the application of 50 Mg ha-1 hydrogel caused a 17% increase in the dry matter and a 12% increase in the plant's height. According to the results of this experiment, the application of hydrogel caused the improvement in most characteristics of the Thymus daenensis in water stress conditions.
E. Karamian, M. Navabian, M.h. Biglouei, M. Rabiei,
Volume 28, Issue 1 (5-2024)
Abstract
Cultivation of rapeseed as the second crop requires drainage systems in most of the paddy fields of the Guilan province. Mole drainage, as a low-cost and shallow drainage method that is suitable for rice cultivation conditions and easier to implement than pipe drainage, can be a solution in the development of second-crop cultivation. The present study was conducted to evaluate the drainage of mole drainage and nitrogen fertilizer management on the quantity and quality of drainage at Guilan University. In this regard, an experiment was conducted under two treatments including drainage and nitrogen fertilizer (i.e. traditional mole drainage and sand-filled mole drainage), and 180 and 240 kg of nitrogen fertilizer per hectare in three replications. After each rainfall during the plant growth period, water samples were taken from the drains, and parameters of electrical conductivity, pH, total suspended solids, total phosphorus, turbidity, concentrations of ammonium, chloride, nitrite, nitrate, and phosphate were measured. Also, the outflow from the drains and the water table level were measured by piezometers during the rain and after that. The results of the mean comparison of pH and total suspended solids showed that most of them were obtained with 7.49 and 281.25 mg/liter, respectively, in the mole drain filled with sand and the traditional mole drainage and 180 fertilizer treatment. The highest mean of electrical conductivity and turbidity was observed as 651 micro mohs/cm in the traditional mole drainage and 240 fertilizer treatment and with 67.76 NTU in the traditional mole drainage and 180 fertilizer treatment. The statistical analysis showed that the effect of drainage treatment on the amounts of ammonium, nitrite, nitrate, phosphate, and total phosphorus was not significant. The outflow from the traditional mole drainage was 49% lower than the sand-filled mole drainage. The traditional and sand-filled mole drains were able to drain excess water with average reaction coefficients of 0.8 and 0.83 per day during the growth period, respectively. Considering the speed of water discharge, drain discharge, and the main non-significance of qualitative parameters among drainage treatments, mole drainage filled with sand is recommended for the development of rapeseed cultivation in paddy fields.
M. Neisi, M. Sajadi, M. Shafai Bejestan, J. Ahadiyan,
Volume 28, Issue 3 (10-2024)
Abstract
Side weirs are hydraulic structures employed in irrigation and drainage channels as diversion devices or head regulators. The increasing efficiency of the structure of side weirs for constant head has been one of the concerns of researchers in the last decade. The use of different forms of sharp crest, labyrinth, piano key, and increasing the length of the overflow by changing the geometry of the crest have been investigated. In this research, a new type of triangular-shaped side weir has been studied in the laboratory under different hydraulic conditions in sub-critical flow conditions. The results demonstrated that by inclining the crests of the triangular side weir, the amount of vortex created at the entrance of the opening was reduced. So the discharge coefficient and the flow volume over the side weir showed an increase of up to 27% and 48%, respectively, compared to the normal triangular and rectangular side weirs. Also, after analyzing the data, a non-linear equation was presented to estimate the discharge coefficient with the dimensionless parameters of the ratio of the upstream depth to the weir height (y1/p) and the upstream Froud number (Fr1) with an accuracy of ±15% and NRMSE=0.134.
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.
M. Shayannejad, E. Fazel Najafabadi, F. Hatamian Jazi,
Volume 29, Issue 3 (10-2025)
Abstract
Regarding the increasing need for water resources and the decline of surface water resources, awareness of these resources is a crucial need in planning, developing, and protecting them. This research was conducted to model the water quality index (the most widely used feature of determining water quality) using machine learning models (Random Forest and Support Vector Machine) in the Zayandehrood River. Regarding the large number of water quality indices, the NSFWQI index was used in this study. First, this index was calculated, and then, input data, including water quality characteristics of 8 stations over 31 years, and the river water quality index were used. In this research, 80% of the data was used in the training stage, and the remaining 20% was used in the evaluation stage. The optimal model was selected based on the evaluation criteria, including R2, CRM, and NRMSE. The results showed that the Support Vector Machine algorithm (0.931 < R² < 0.982, 1.321
