JOURNAL OF WATER AND SOIL RESOURCES CONSERVATION
Year:2022 | Volume:11 | Issue:3|Papers Count:9

Background and Aim: In this study, a new overflow with a v-shaped structure was used as a barrier in the culvert. The main purpose of the present study was to investigate its performance on changes in flow resistance properties such as the square root of the Modi friction coefficient and the Manning roughness coefficient. Method: The present study experiments were performed on the physical model available in the hydraulic laboratory of the Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz. This physical model includes a laboratory flume 10 meters long, 0. 25 meters wide, and 0. 5 meters high. At the beginning of each experiment, the structures were glued to the flume bed at specified relative distances. After 24 hours of gluing the systems, the flume's flow rate and slope were adjusted. The desired flow rate was adjusted using a triangular overflow with an angle of 53 degrees located downstream of the flume and the slope through the jack. A point gauge with an accuracy of 0. 1 mm was used to remove the water surface profile. Results: By increasing the dimensionless flow in a relative distance between structures and a certain slope, the manning roughness coefficient of the structure decreases. So that at a slope of 10%, the relative distance between the structures was 1. 3, the value of the Manning roughness coefficient of the system from dimensionless flow decreased from 0. 20 to 0. 43 by 30%. By increasing the relative distance between structures at a certain flow rate, the manning roughness coefficient of the structure decreases, which is similar to the effect of the relative distance between structures on the square root of the friction drop coefficient of the structure. Conclusion: In examining the impact trend of the V-fish structure, it was found that dimensionless flow has an inverse effect on the flow friction coefficient and the manning roughness coefficient of the structure. On the other hand, the inverse relationship between landing number and flow friction coefficient, and manning coefficient of the structure was determined. It was found that the relative distance between the structures also has an inverse effect on the flow friction coefficient and the manning coefficient of the structure. The inverse effect of the Reynolds number on current resistance parameters was also extracted. The best condition of the fish road structure with v-shaped overflow occurs in the relative distance between the 1. 3 and 10% slope structures.

Background and Aim: Local scouring has been identified as one of the important factors that cause the structure of bridges, breakwaters, and piers to rupture. The complexity of the scouring mechanism has made this one of the most important fields of civil engineering studies. In recent years, many studies have been performed on local scouring around bridge piers. Due to the great importance of predicting and estimating the scour pattern in the vicinity of bridge piers, many studies have been done on this type of structure. Method: In this study, for the first time, using a new extreme learning machine (ELM) method, the scour depth near the foundations of the twin bridges was simulated. First, effective parameters were identified and four ELM models were developed. Then, numerical results were validated using Monte Carlo simulation and the cross-validation method. Then the sin activation function was determined as the best activation function. In addition, ELM results were compared with artificial neural network (ANN) models that ELM models estimated scour values more accurately. Uncertainty analysis was performed for the superior ELM and ANN models and a relationship was proposed for the superior model. Partial derivative sensitivity analysis (PDSA) was also performed for all input parameters. Results: Among the existing activation functions, the sin function had the optimal performance compared to other activation functions. According to the analysis of modeling results, ELM 1 model was introduced as the superior model. This model was a function of all input parameters. Also, by removing the landing number, the accuracy of the numerical model was significantly reduced, so the mentioned parameter was identified as the most effective parameter in scouring modeling around the bases of the twin bridges by the model of Strength training machine. Conclusion: By analyzing the modeling results the superior ELM model was introduced. The results of ELM models were also compared with ANN models, which showed that ELM models simulate scour values more accurately. For the superior ELM model, a relation was proposed to calculate the scour hole depth, and further uncertainty analysis showed that this model had a higher performance than the actual value. In addition, the relative derivative sensitivity analysis for the input parameters showed that with increasing the landing number, the value of the objective function (scour depth) increases.

Background and Aim: Evaluating the response of rivers to natural changes and man-made manipulations are of great importance in managing river water quality. The main purpose of this study is to evaluate the negative effects of quantitative management without qualitative management of river flow. In this regard, by simulating water quality in river exploitation scenarios based on environmental policies, including minimum flow allocation, reduction of flow quality from aquaculture standards, taking into account the quality factors and pollution caused by the development of marginal urban communities, will be discussed. Method: The present study, which should be omitted was conducted on the Azadrud River in the Sarvabad region of Kurdistan Province. In this regard, by measuring quantitative and qualitative parameters in two monthly periods, the QUAL2KW quality model was calibrated and validated. In the first part of the study, the quality of the river along 22 km was simulated by changing the flow rate based on flow allocation scenarios in the Tenant method, and in the second part, the values of qualitative parameters in different flow management scenarios were compared with the accepted standard values for aquaculture (fish). Results: Based on the results, while the minimum environmental discharge according to the Tenant method for the studied river is 1. 1 m3/sec, the critical quality discharge for March and April were estimated at 7. 7 and 10 m3/sec, respectively. The study showed that the poor tenant scenario is not suitable for allocating the minimum environmental flow to meet the quality requirements of the river at all. Conclusion: The results showed that the conventional flow allocation method, i. e., without considering the quality conditions of the river, is not suitable and can cause serious damage to the environmental conditions of the river. This study showed that ignoring the quality conditions at the time of flow allocation causes the ecological health of the stream to be lost and the river to not meet the required standard for aquaculture.

Background and Aim: River behavior is affected by two categories of natural, and human factors. Natural factors such as floods, soil erosion, mass movement and human factors such as facility construction, land-use change, and sand removal from the bed, play a key role in the behavior and intensification of river changes. The serious and irreparable dangers that may be posed by river movements and changes indicate the need to study its morphology in the study phase before any action is taken. The network of streams continuously changes its location based on time, environmental factors and human interventions. It is very important to study the stream changes to provide the should be omitted management solutions for the should be omitted soil conservation. One of the new methods in this regard is to use the should be omitted fractal geometry. The purpose of this study was to calculate the fractal dimensions of the stream and to investigate its relationship with the morphometric characteristics of the basin Method: To do this, a should be added topographic map of the should be added basin in Firouzkouh, Tehran province was prepared. The map of the streams was prepared and the morphometric characteristics of the basin were determined by using the ARC GIS 10. 3 software. Then, three fractal dimensions of the should be added drainage network (stream branch), drainage density, and basin area were calculated. Finally, the morphometric characteristics of the basin associated with the fractal dimensions were investigated by entering the data obtained from the calculations in the SPSS 18 and Curve Expert software Results: The results showed that the minimum and maximum fractal dimensions of the bifurcation ratio were 0. 25 and 2. 99, of should be omitted the drainage density was 0. 19 and 2. 34, and of should be omitted the area was 0. 76 and 2. 60. The fractal dimension of the should be added, the should be added dimension of drainage density, and the should be added fractal dimension of the should be added total area of the basin were 1. 84, 0. 71, and 1. 46, respectively. The fractal dimension of the should be added ratio and the sub-basin area were inversely related with the determination coefficient of 0. 90, and the fractal dimension of drainage density and the area and the fractal dimension of an should be added area with the sub-basin area was directly related with the determination coefficients of 0. 88, and 0. 87, respectively. The more elongated the basin and the lower the form, roundness, and elongation factors, the smaller the bifurcation dimension. the fractal dimension of the area is directly related to the compactness factor, elongation factor, form factor, bifurcation ratio, equivalent rectangle width, and equivalent rectangular length, and is inversely related to other variables. Based on the results, the more elongated the basin and the smaller the form, and elongation factors, the lower the area dimension. The fractal dimension of drainage density is directly associated with the circularity factor, compactness factor, elongation factor, form factor, area ratio, bifurcation ratio, equivalent rectangle width and equivalent rectangular length, and is inversely associated with other variables. Therefore, as the basin becomes more circular, the fractal dimension of the drainage density is increased. Therefore, the fractal dimension of drainage density is increased then as the basin becomes more rounded Conclusion: According to the coefficient of explanation of the obtained models for the relationship between fractal dimensions, and morphometric properties, the studied fractal dimensions can be easily calculated and analyzed using morphometric properties. Due to the importance of stream characteristics in the management of watersheds in terms of flood, erosion, and soil conservation, the fractal models can be used to make quick and accurate decisions for the should be omitted management. Finally, considering that the use of fractal geometry is a new method in studying the characteristics of waterway networks, it is suggested that basins be analyzed fractally in different regions with different morphometric conditions.

Background and Aim: This study aims to analyze the frequency of bivariate precipitation characteristics using Copula functions. for this purpose, daily rainfall data of Aloni station located in Khanmirza plain during the statistical period of 1986-2012 were used. After evaluating the rainfall events recorded at Aloni station in the study period (763 events), rainfall duration, rainfall depth, and then rainfall intensity of the events were calculated. Studies show that in the study area, usually rainfall events with an intensity of 5 mm/hr and more lead to floods, so in this study, the events that led to floods were selected to continue the calculations. Then, the common distributions in hydrology were fitted to each of the rainfall characteristics (duration, intensity, depth of rainfall) and the distributions that had the best fit to each of the rainfall characteristics were selected. Then, ten Copula functions were used to create a multivariate distribution of rainfall characteristics. Method: In this study, at first rainfall characteristics such as intensity, duration and depth were extracted for rainfall data leading to floods. Then the common margin distribution functions in hydrology were fitted to the characteristics. Then, after selecting the best margin distribution to create the cumulative distribution function (CDF) to create the multivariate distribution of rainfall characteristics, fitting the Copula functions of Clyton, Ali-Mikhaiel-Haq, Farli-Gumble-Morgan Stern, Frank, Galambos, Gamble-Hauggard, Placket, Filip-Gumble, Joe, and Gumble-Barnett on the mentioned variables were studied in pairs and for each pair of precipitation characteristics, the best Copula function was determined by comparing with the corresponding values of the empirical Copula. Then, using good criteria, the fit of the best Copula function for rainfall characteristics was determined. Since the condition for using Copula functions is the existence of a correlation between the studied features, so using Spearman, Pearson, and Kendall correlation coefficients, the correlation between the features was investigated also the cases of joint and conditional return periods, both probability and conditional and Kendall return period, which is basic concepts for analysis based on Copula functions, were evaluated. Results: The results of the analysis showed that the general extreme value distribution function (GEV) on rainfall characteristics (intensity, duration, depth) was known as the best distribution function and the results of the goodness of fit test showed that the Joe Copula function as The superior Copula function is based on the characteristics (intensity and duration) and (intensity and depth) and the Farli Gumble Morgan Stern Copula function was known as the superior Copula function on the depth and duration characteristics of rainfall. The results of both probability and conditional probability showed that when the flooding rainfall is 8 hours, the probability level will be 45 mm for the probability level of 0. 2 and the probability of precipitation for the same level for the duration of is not necessary. It can be omitted15 hours. It will be 51 mm. The results of the Joint return period for “, and”,state showed that for the depth of rainfall of 60 mm and the intensity of rainfall of 60 mm/hr., the return period in the "and" state is less than 20 years. Based on the "or" mode for the same amount of intensity and depth of rainfall, the return period is less than 10 years (about 6 years). For a 25-year return period, provided the duration of the rainfall is 12. 5 hours or more, the rainfall depth will be 75 mm. Conclusion: Based on the results of comparing the values of theoretical Copulas with the corresponding values of empirical probability, the Joe Copula function was recognized as the superior Copula function to create a bivariate distribution of rainfall intensity and depth characteristics, as well as a pair of rainfall intensity and duration characteristics. Farli-Gumble-Morgan Stern Copula had a better fit for rainfall duration and depth data. Then, using superior fitted Copula functions, useful information such as probabilistic and conditional probability as well as joint and conditional return periods were extracted. The maximum rainfall depth recorded at Aloni station was 114. 7 mm and its duration was 14. 40 hours. The seasonal "or" is 60 years old. The results of the joint and conditional return periods in this study have been widely used in hydrological and water resources studies, including flood risk analysis, drought, watershed management, and rangeland management.

Background and Aim: to better management of solute transport in porous media, it is essential to recognize their transport behavior using appropriate models. In this research, convection-dispersion equation (CDE) and mobile-immobile model (MIM), as physical equilibrium and non-equilibrium models, respectively, were used to simulate the bromide transport through saturated and unsaturated forest soil, with clay loam texture, and rangeland soil, with sandy loam texture, columns (diameter of 6 and height of 10 cm). Method: to obtain the BTCs, the PVC soil columns with a height of 10 and a diameter of 6 cm were prepared. The breakthrough experiment was carried out in near saturation and saturated condition under a water head of-1 and 3 cm, respectively. The soil columns were saturated from the bottom with a Ca(NO3)2 solution of 0. 01 molar as the background solution. At near saturation, the CaBr2 solution with a concentration of 0. 01 M equal to a pore volume was injected into the saturated columns of the background solution through the infiltration disk. A Mariotte bottle was used to establish a constant water head. After CaBr2 injection started, the effluents with a volume of 0. 1 pore volume were collected at different times, and their bromide concentrations were determined using a pH-meter equipped with a bromide selector electrode. After the complete injection of CaBr2, the steady-state saturated flow of the background solution was re-established. The experiment continued until the bromide concentration in the effluent were almost zero. The measured concentrations, by dividing by the initial concentration, were converted to relative concentrations (C/Co). Then the BTCs was plotted as C/Co versus time or the number of pore volumes. Results: The values of mass transfer coefficient (ω, <100) and mobile water fraction (β, <1) as an indicator for determining the equilibrium and non-equilibrium indicated that bromide transport behavior within these columns was anomalous or non-Fickian transport. Hence, the non-equilibrium or the mobile-immobile model (MIM) is suitable and more efficient than the Fickian-based CDE model. The fitted breakthrough curves (BTCs) and the higher determination coefficient (R2) and the lower root mean square error (RMSE) values of the MIM model compared to those of the CDE confirmed the effectiveness of the MIM model in simulating bromide transport in the forest and rangeland soil columns. Conclusion: Better fit of measured and estimated breakthrough curves of bromide with non-equilibrium model compared to CDE equilibrium model, especially in the tail of breakthrough curves indicates more accuracy and the should be added efficiency of the non-equilibrium model. Given that the samples were replaced in the columns as disturbed, it can be said that heterogeneity conditions were established in the columns experiments. According to Huang et al. (2005) and Berkowitz et al. (2008), heterogeneity could be one of the reasons to justify the better performance of non-equilibrium models in the present study. The high efficiency of the non-equilibrium model compared to the equilibrium model in this controlled laboratory research cannot be a reliable judgment in evaluating these models. Accurate judgment will depend on conducting research and experiments in real and field conditions, taking into account more effective parameters.

Background and Aim: Watershed management projects are designed and implemented to protect primary resources (i. e., water, soil, and vegetation) and sustain production by maintaining soil fertility and agricultural sustainability, so understanding the problems of the watershed is an undeniable necessity for future planning and implementation of natural resources management. Effective management of the country's natural resources and control of their degradation based on explanation and adoption of a coherent structure and framework to properly identify watershed problems and determine the appropriate strategy to determine the implementation of measures as an emerging approach to watershed management is essential. Therefore, in the present study, a model approach of combining pressure-state-response and strategic planning approaches in comprehensive management and problem-oriented watershed management was used. Method: In this study, the PSR conceptual model was used to identify the problem of the Mikhsaz watershed. Appropriate criteria for identifying problems were evaluated in four categories of climatic factors: hydrology, human and. In this regard, the indicators and criteria affecting the river basin were summarized after examining the autocorrelation and alignment between the criteria. Due to the different sources of information, all data were standardized for criteria with positive and negative effects on the health of the region, respectively. The main problems in different parts of the watershed were identified based on the value of each of the factors affecting the class. Qualitative and quantitative strategic analysis has also been used to determine the optimal strategy. In the next stage, the analysis of internal and external factors, after identifying strengths, weaknesses, opportunities and threats, internal and external tables were created and analyzed. Finally, Quantitative Strategic Planning (QSPM) analysis was prepared. Finally, strategies for managing the Makhsaz watershed were presented. Results: The results showed that the main problem of the Mikhsaz watershed is related to the limitation of soil depth, which is exacerbated by changes land-use and increased specific erosion and, increases flood damage. Therefore, with should be omitted the intervention of human factors, especially land-use change has led to problems. Among the considered criteria, soil depth, land use changes, and special erosion, respectively, had the worst situation with scores of 0. 40, 0. 51, and 0. 53, respectively, which caused disturbances in the performance of the watershed. Focusing on the main and determining problems is of special importance. ST is also a good strategy. Achieving maximum utilization of internal strengths and advantages to deal with and minimize external threats and damage. Also, the result of quantitative strategic planning analysis showed that the should be added first should be omitted priority is given to the strategy of reducing resource degradation and then strategies to reduce temporary and permanent migration, increase household income and strengthen soil and water conservation programs with attractiveness scores of 1. 58 and 52. 5, respectively. 1, 1. 51, and 1. 50 are the next priorities. Therefore, with the existing opportunities and strengths, the weaknesses and threats in the study watershed can be overcome. Conclusion: The present study was conducted to identify the problems of the should be added watershed in western Mazandaran using the conceptual model of pressure-state-response (PSR) and determine the optimal strategy for problem management using SWOT analysis. The results showed that the main problems of the Mikhsaz watershed include limited soil depth, land-use changes, and special erosion. Also, the result of quantitative strategic planning analysis showed that first first should be omitted priority is given to the strategy of reducing resource degradation. The results of the study indicate the need for executive measures commensurate with the type and importance of each of the factors affecting the study indicators in the river basin. Therefore, the strategy of using the potential advantages of environmental opportunities should be used to compensate for the weaknesses in the watershed.

Background and Aim: Climate change led to increasing the severity of stress, and today’, s life of all plants is challenged by rapid environmental changes. Water is an important component in all physiological processes of the should be added, accounting for 80 to 95% of the plant’, s biomass. Except in high humidity environments, plants are likely to be exposed to water deficit stress throughout their life cycle. water deficit stress decreases the quantity and quality of the plant product and in addition reduces the water use efficiency as well as reduced the absorption of nutrients. to reduce the effects of water deficit stress on plants, various methods are used, including mineral nutrition with trace elements such as zinc. Method: to investigate the effects of foliar application of zinc on the morph physiological and biochemical traits of safflower cultivars under drought stress, an experiment was conducted as a should be added split-plot based on of should be deleted randomized complete blocks design with three replicates during 2019-2020. Experimental factors include drought stress as the primary factor, and safflower cultivars and zinc foliar application as secondary factors. The plant’, s canopy temperature was determined using an infrared thermometer. Seed oil was extracted from the mature seeds of safflower cultivars by the should be added apparatus using hexane solvent. Results: Water deficit stress was applied in two levels (regular irrigation (control) and irrigation cut-off when the grain filling stage begins),safflower cultivars in this experiment were Isfahan, Linas, Padideh, Parnian, and Goldasht,foliar application of zinc was in three levels (0, 0. 5 and 1 kg. ha-1 Zn). Results showed that water deficit stress decreased stem diameter, head diameter, number of classes per plant, number of seeds per plant, seed yield, biological yield, oil yield, relative leaf water content. Whereas, water deficit stress increased the should be added of the should be added environment. Foliar application of 1 kg. ha-1 Zn improved seed yield, biological yield, oil yield, relative leaf water content. Conclusion: The results of this study showed that the water deficit stress significantly decreased the growth rate and consequently biological yield, oil yield, and relative water content (RWC) of safflower plants and on the other hand, the application of zinc under optimal irrigation (control) and water deficit stress improved the mentioned traits. Based on the obtained results, it can be stated that the application of zinc can be one of the appropriate solutions to mitigate the effects of water shortage in the grain filling stage of the studied cultivars of safflower.

Background and Aim: Pivot weirs are one of the most important structures to control and regulate the water level. Three-Pivot elevator weirs can be installed as one or more gates in a row in the waterways. Each of them has an independent hoist system to change the weir angle relative to the bed. The hydraulic conditions of this type of weirs (especially in multi-gates and different angles) are not studied. Therefore, the hydraulic conditions of these weirs were investigated. Method: In this study, flow modeling was performed to analyze the weir discharge coefficient and select the appropriate turbulence model using Ansys CFX software. The model was evaluated using Wahlin and Replogle experimental data for for different angles and discharges. Also, RNG K-, , K-, , standard k-,and SST turbulent model were compared. By determining the turbulence model, the optimal shape of the crest was studied in 3 types: Sharp, circular (upstream and downstream of crest edge in round shape) and semicircular (upstream of crest edge in a round shape). Results: Comparison of the model output results for different turbulence models showed that the standard k-,turbulence model is generally more consistent with laboratory readings so that for low angles the relative error calculated was between 1. 4 to 3. 1% less than the other models. Relative error between was calculated to be less than 4. 4%, which showed a very good agreement between the model output and laboratory results. Conclusion: The results of calculating the discharge coefficient in elevator weirs showed that the discharge coefficient for weirs with an angle of 70 degrees and the semicircular crest are 0. 7 to 7. 9 percent higher than the weirs with circular and sharp-crested weirs, respectively. Similarly, the increase of discharge coefficient for weirs with an angle of 27. 8 degrees was obtained between 0. 4 to 3. 2 percent. Therefore, weirs with semicircular crest edges have the highest discharge coefficient.