مجله محیط زیست و مهندسی آب
سال هفتم شماره 3 (پاییز 1400)

An increase in the hydraulic capacity of flow conveyance over a weir per a given stage of a stream upstream of the weir is feasible by extending the effective length of the crest of the weir per unit width of flow section. In this work, in order to study the hydraulics of the flow and compare the values of the passing discharge, a 3-D simulation of the flow field on arced labyrinth weirs (single-cycle and double-cycle) was carried out in Flow3D software at the hydraulic loading rate of 0.05 to 0.74 by statistical analysis and the comparison of results obtained from numerical modeling of experimental data. Weirs utilized in this study were three single-cycle weirs (10, 12, and 15 cm in height) and three double-cycle weirs (5, 6, and 7.5 cm in height) examined in a rectangular flume having 8.4, 0.3, and 0.45 m length, width, and height, respectively. The results showed that the data of the numerical model were well conformed to the data of the experimental model. According to the results, a 50% increase in the weir's height will raise the discharge coefficient by 25.5%. Furthermore, the discharge coefficient in a single-cycle arced labyrinth weir at hydraulic loading rates less than 0.4 was higher than the discharge coefficient in a double-cycle arced labyrinth weir. Moreover, the corresponding values were nearly equal at higher hydraulic loading rates.

Cyclodextrin (CDs)/polyether black amide (PEBA) polymeric nanostructures are of particular practical importance due to their nature including porosity, biocompatibility and biodegradability as new polymeric nanocomposites. The aim of this research work was to optimize the odour and taste causing algae in drinking water using PEBA/CDs nanoadsorbents. The design of experiments and the effect of experimental parameters on the rate of algae removal was done systematically by Fractional Factorial method. RSM optimization method was used to achieve the highest algae removal performance. FTIR spectroscopy, SEM images, BET technique and mapping analysis were used to characterize these nanostructures. These analyzes showed that the nanoadsorbents synthesized had ideal properties such as homogeneous morphology and fiber size distribution in the nanometer range. In addition, according to data obtained from BET technique, the surface area of the sample was about 840 m2/g. The results of studies on Navicula algae showed that PEBA/CDs polymeric nanoadsorbents can affect the quality of drinking water by reducing the number of algae colonies to 5 colonies. The results of analysis of variance showed that the parameters of dose of polymeric nanoadsorbents, water volume and contact time (Pvalue = 0.000) affect the rate of algal removal. The results showed a reduction in the number of algae colonies by 3 colonies. The use of novel nanostructures as well as the systematic studies used in this study can be used as a new strategy to improve the quality of drinking water.

Nickel is highly toxic and directly associate with health risk such as damage to kidney, liver and central nervous system. This study evaluated the potential of a chicken feather for the removal of nickel from aqueous solutions. Freundlich, Langmuir and Temkin isotherm models were used to characterize the bio sorption of the mentioned metal onto the chicken feather. In the batch system, parameters of pH (4-8), adsorbent dosage (0.01- 0.06 g/l), contact time (15-120 min), nickel initial concentration (5-200 mg/l), and temperature (15-40 °C) were studied. Studies have shown that the maximum Nickel uptake efficiency occurred at pH = 6, concentration of 50 mg / g, contact time of 60 minutes, ambient temperature of 25 ° C and adsorbent mass of 0.03 g. The thermodynamic parameters such as Gibb's Free Energy (ΔG), Enthalpy (ΔH) and Entropy (ΔS) indicated that the adsorption of nickel ion were spontaneous and endothermic at 288–313 °K. Comparing the determination coefficients between measured data and obtained value from pseudo- second-order model (R2 = 0.95) and pseudo- first-order model (R2 = 0.65) showed that the pseudo- second-order model describes experimental data better. Also, comparing the Langmuir, Freundlich and Temkin isotherm for nickel adsorption by chicken feather nanoparticles showed that Freundlich isotherm (R2 = 0.87) was more proper than Langmuir isotherm (R2 = 0.82) and Temkin isotherm (R2 = 0.67) in describing adsorption process. According to the results of this study, chicken feather nanoparticles adsorbent with a high efficiency of 96.8% can be used to remove Nickel from aqueous solutions.

In recent years, various methods have been used to remove heavy metals from aquatic environments; one of which is the adsorption process. Graphene oxide nanoparticles have received much attention due to their high adsorption capacity and high surface area. In this study, melamine-modified nanographene oxide adsorbent was used to remove Pb from aqueous solution. Experiments were performed at pH (3-8), temperature (15-50 °C), Pb concentration (5-200) mg/l, adsorbent (0.01-0.06 g), and contact time (15-150 min). Results showed that the maximum Pb adsorption efficiency by modified nanographene oxide occurred at pH = 6, concentration of 20 mg/l, contact time of 60 min, ambient temperature of 22 °C and adsorbent dosage of 0.01 g. In the study of metal equilibrium isotherms, the Freundlich model was more consistent with the experimental data. Given that the Freundlich model is used to describe heterogeneous adsorbent surfaces, it can be concluded that lead adsorption by graphene oxide nanoparticles has been done in several layers. Modified nanographene oxide with its large surface area, hydrophobicity, high negative charge density, ease of fabrication and high adsorption could be used as an effective adsorbent for metal removal. According to the results of this study, a melamine-modified nanographene oxide adsorbent with a high efficiency of 98.8% can be used to remove lead from aqueous solutions.

Flow duration curve (FDC) is one of the most appropriate criteria for recognizing the hydrological response of catchments. Understanding the interaction of drought phenomenon along with FDC indices is a suitable tool for optimal water resources management of catchment. The aim of this study was to investigate the temporal relationship between drought and FDC indices in the Kaka-Reza, karstic catchment. In this study, the common period (1982-2017) was considered for the corresponding hydrometric and rain gauge stations. The standardized precipitation index (SPI) and standardized discharge index (SDI) were then calculated at time scales of 3, 6, 9, and 12 months. Precipitation duration curve (PDC) and FDC were plotted and curve indices were calculated and standardized. The relationships between drought index and FDC indices were investigated and analyzed. The results showed the general trend of changes in SPI and SDI in the respective time scales follow each other. However, the most consistent trends are related to the time step of three months. The rate of relative changes in the section of low flow indices (Q90/Q50) were very small and around 0.6% and in the high flow (Q25/Q50) was around 4.41%. The correlation between FDC and PDC showed coefficient of determination of 0.904. The rate of slope change was from 0.5 to 5% and trend of its changes was a slight upward slope during the research period. The small amount changes of FDC indices and slope of FDC showed the role of karst phenomenon in determining the shape of FDC as well as controlling flow fluctuations and providing stable flow during the drought period.

Polycyclic aromatic hydrocarbons (PAHs) are among the important organic pollutants in the aquatic ecosystems generally generated by natural and human processes. The purpose of this study was to determine the concentration and distribution of PAHs and the origin of these compounds in the surface sediments of the Protected Chalous River in Mazandaran Province. Sampling of surface sediments of the riverbed was performed at four stations located along the river (Darkala, first ring bridge, Chalous fountain bridge and estuary). The extraction and analysis of PAHs was performed using standard Soxhlet method in two stages: column chromatography and gas chromatography-mass spectrometry. The highest and lowest total amount of these compounds (∑PAHs) was observed in the surface sediments of the riverbed at the estuary and Darkala stations (903.8±144.30 and 51.71±19.33 ng/g) respectively. The trend of accumulation of PAHs in the surface sediments showed that the ∑PAHs concentration increased from the upstream to downstream in the river. Determining the origin of PAHs in surface sediments of the riverbed using isomeric diagnostic ratios showed that the origin of PAHs in the river was a mixture of petrogenic and pyrogenic sources with petrogenic dominance. According to the NOAA sediment quality standard, the sediments samples were in the range of moderate pollution in the studied stations, except at Darkala station, located upstream of Chalous river and had low pollution. The influx of agricultural effluents from the surrounding farms, the increase in population and vehicles in the area has led to an increase in the composition of PAHs in river sediments.

The formation of the secondary flows is caused by the non-prismatic nature of the main channel and floodplains in the compound channel and the intense interaction of the low-velocity flow of the floodplains in passing over the high-velocity flow of the main channel. So far, comprehensive studies on changing the divergence angle of floodplains have not been done as a numerical and physical model, and due to the effectiveness of this parameter, its study is necessary. In the present study, using the three-dimensional Ansys-Fluent model, simulation was performed based on the standard k-ε turbulence model and VOF method for the hydraulic flow in compound channel with divergent floods for five divergence angles of 3, 6, 9, 12 and 15° and in three sections of 2, 8 and 14 m. The boundary conditions used in this research were the input limit of the mass flow rate, the output boundary as a pressure outlet, the solid boundaries as a non-slip wall without roughness and the upper boundary of the channel as a non-slip wall without roughness. The results of accurately predicting the average depth velocity in the section Z = 14 m of the channel showed that in all sections of the channel, the modeling results were within the allowable error range defined for numerical models, indicating the appropriate matching of laboratory and simulation results. The results showed that the maximum velocity in the channel occurs with a divergence angle of 3° and the higher the divergence angle, the lower the velocity. Moreover, the maximum shear stress in the channel is with a divergence angle of 3° and the minimum shear stress is in the divergence angle is 15°. The lower the water angle, the higher the divergence angle, and the higher the divergence angle, the lower the water height.

Agriculture is the largest user of freshwater in the world. One of the practical solutions for managing agricultural water resources in arid and semi-arid regions is to calculate the amount of water consumption in the process of agricultural crops through the virtual water index. The aim of this study was to use virtual water to manage water consumption in the agricultural sector of the Hirmand catchment. The need for irrigation of agricultural crops in the catchment was obtained using CROPWAT software. Then, the current and future status of water supply and demand was investigated using the WEAP model for agricultural crops in the catchment in the current cultivation pattern of the region. After calculating the virtual water content of the crops, the cultivation pattern was presented based on it and with emphasis on the need for irrigation. The water demand for crops in the virtual water scenario of the cultivation pattern was investigated using the WEAP model. The results showed that the need for irrigation of crops in the Hirmand catchment was 7847 m3/ha and the virtual water content of crops was 2.353 m3/kg. The agricultural sector consumes 70.10% of the total water supply in the Hirmand catchment. In the current situation, the total annual demand of water for crops is 1011×106 m3, of which 67.13% is supplied and 32.87% is not supplied. If the current situation continues for the next 15 years, the agricultural sector will face water shortages of 6099×106 m3. By applying the virtual water scenario, the demand for agricultural water could be decreased by 180×106 m3/yr. Finally, it was found that if the priority of water allocation between the agricultural sector and the drinking sector be the same, the drinking sector will face an annual water shortage of 18×106 m3.

Due to the high volume of oil activities, there is a possibility of groundwater oil pollution, which requires extensive source identification, remediation, management and monitoring. In Rey industrial area, despite widespread oil pollution, the source identification of groundwater oil pollution has not been carried out before the present study, and previous studies were limited to exploration and extraction of petroleum products. The purpose of this study was to determine and separate the sources of oil spills to groundwater in the Rey industrial area. For this purpose, subsurface geology and hydrogeology of the region were studied by digging exploratory wells and data analyzing, and a conceptual model of the region was prepared. Then, all potential sources of pollutants and monitoring wells in the area were sampled and distillation and gas chromatography-mass spectrometry and hydrogeological analyzes were performed. Based on the results of this study, five main contaminated plumes were identified. The research results show that if the contamination is single product, the distillation method is the fastest and cheaper method of identifying and separating the plumes of contamination. When the contamination is a combination of different compounds, the use of gas-mass chromatography analysis and different ratios of the compounds along with hydrogeological analyzes is required. The main leaks in the study area were from the transmission lines of petroleum products buried in the underground, which usually transport petroleum products with high pressure.

Accurate estimation of dam lake evaporation is of great importance in reservoir water management. This factor has led to the installation of meteorological stations in most dams. At the meteorological station, the rate of evaporation from the lake surface is measured using an evaporation pan. Remote sensing methods are cost effective and can be generalized to the whole area. In this study, the daily evaporation rate from the surface of Suleiman Shah Lake was calculated using a combination of SEBAL algorithm and meteorological data and using five Landsat 8 satellite images. The obtained results were compared with the evaporation rate obtained from different methods. The results showed that among the combined methods, Penman Kimberly 1996 method, among other methods, Blanche-Kridel method had the highest agreement and Hafner method had the least agreement with the measured data indicated with R2, RMSE and MAE equal to 0.96, 2.78 and 5.66, respectively. The results of this study can be used to estimate evaporation in other regions with similar climates.

To prevent the occurrence of floods, it is necessary to identify areas having high potential for this phenomenon. The aim of this research was to estimate runoff coefficient, understanding the effective factors in flooding, and the flood hazard of Arasbaran forests (Sotanchai basin). For this purpose, first, the required data, including the maximum daily precipitation, soil, slope, land use, vegetation density and drainage density layers, were prepared in geographic information system (GIS) environment. In the following using the analytic hierarchy process (AHP) method, an effective weight was assigned to each of the six factors influencing the flood hazard of the basin. Through applying the weight of each layer and combining it, the flood hazard zonation map of the basin was prepared with different return periods (10, 25, 50, and 100 years). The results showed that 15 - 19% of the basin area had a medium flood potential during the period of 10 to 100 years and 1-13% had a high flood hazard. During the 10- and 25-year return periods, no area of the basin was in the flood hazard category, but in the 50- and 100-year return periods, 0.32 and 0.96% of the basin area were in the very high flood hazard category, respectively. Generally, it can be concluded that due to good forest density and vegetation, flood hazard was low in the region, instead areas with high flood hazard were located in areas, where forests have been destroyed.

Emphasis on water resources based on adaptation to water scarcity makes production adaptable to climate conditions. In this study, after identifying the educational resources, the educational needs of greenhouse owners were determined prioritized with reference to water scarcity conditions. For the educational needs assessment, three-dimensional model and Delphi method were applied. Data were analyzed using mean and standard deviation indices and Kolmogorov and Smirnov, one-sample t, one-sample Sign, Kruskal-Wallis, and Yumen-Whitney tests. The findings of this study showed that the operating status of irrigation systems from the three perspectives of "greenhouse owners", "experts" and "trainers" were 4.34±0.95, 2.83±1.04 and 2.86±0.64 (out of 5 points), respectively. The status of exploitation of educational resources from the three points of view were 2.26±1.23, 2.46±0.99 and 2.56±1.10 (out of 5 points), respectively. Moreover, the knowledge and skills of greenhouse owners regarding educational needs from the three perspectives were 3.61±0.9, 2.50±1.09 and 2.48±0.9 (out of 5 points), respectively. Evaluations showed that greenhouse owners are not aware of the principles of proper operation of irrigation systems and do not have sufficient knowledge and skills regarding educational needs. It is necessary to change the content and use of educational resources according to the greenhouse owner's conditions and interests. In addition, the most important educational needs of greenhouses owners based on the three views were "time management of different stages of irrigation", "how to use irrigation systems" and "introduction of different irrigation systems and their disadvantages and benefits".

The proper combination of cutoff time and lengths of border are among the criteria for high efficiency in surface irrigation. The objective of this study was to determine cutoff time and the optimal distance and flowrate in closed-ended border systems. The basic assumption in this method is that the point along the field, where the lowest water depth permeates should receive water equal to the required depth. For this purpose, the data applied were consisted of 18 vegetated and non-vegetated borders, and bed slope of 0.001 to 0.005, Maning's roughness of 0.017-0.211, border length of 100 m and flow rate range from 0.08 to 0.16 m3/min.m. After determining the cut-off time, the application efficiency obtained using the method presented in this study was compared with zero inertia (WinSRFR 4.1) model. The highest similarity of results was observed in closed end border for R-6, R-13, R-14 and R-17 border with 0% difference and the highest difference was for R-1 border with 8.67% difference in efficiency. Maximum efficiency was obtained in some border with decreasing length and in some border with increasing length. Generally, it can be concluded that the application efficiency obtained from both methods was close to each other.

Among different industries in each country, tourism industry is directly related to the environment. Tourism is not a clean and non- destructive industry, so that tourists’ behaviors in addition to positive effects can also have many negative consequences on the environment. The purpose of this study was to analyze factors affecting environmental behavior of tourists in Susan Plain, Izeh county. Statistical population of the study consisted of tourists traveled to Susan Plain during Nowruz Holidays in 2019. The sample size was determined by available sample and they were randomly selected (n=150). The research tool was a questionnaire, which its validity was verified by a panel of academics and its reliability was approved through Cronbach's alpha coefficient. The data were analyzed by SPSS (Ver. 22) and LISREL (Ver. 8.80) software. The results showed that variables of environmental knowledge, attitude, and values had positive and significant correlation with variable of environmental behaviors. Furthermore, according to the results, variables of environmental knowledge, attitude, and values could describe 83% of tourists’ environmental behavior changes. As a recommendation, it is worthwhile to use environmental topics in the textbooks from primary school to university.

GharehGheshlagh wetland is one of the most important wetlands in Iran in terms of having a variety of plant and animal species especially birds. In recent years, agricultural development and land use change in this region has reduced water areas of this wetland. The present research was conducted due to the necessity of the assessment of the variations occurred during last years and forecasting the future status of this unique ecosystem in order to make decisions about the land use management. For this purpose, Landsat 8 satellite images were used as a reliable tool to investigate the trend of changes. In this regard, the images provided in three different years were classified to cover two periods of 12-year and 15-year using Support Vector Machine and Random Forest models. Then, considering the existence of land uses including barren landscapes, saline fields, water areas, and also vegetation and agriculture in the region of GharehGheshlagh wetland, their changes were evaluated. The results represented the immethodical development in agriculture area over a 15-year period from 2001 to 2015. The land use changes had a negative impact on the wetland water areas and it had caused remarkable reduction in the water level of the wetland, which necessitates for agricultural management and prevention of its future development in the region of the wetland can be mentioned as the most important result of the present study.