نشریه رویکردهای نوین در مهندسی آب و محیط زیست
سال دوم شماره 2 (پیاپی 4، پاییز و زمستان 1402)

Since chlorine is a highly toxic substance, if it is combined with organic elements in the wastewater, it causes the creation of odorous compounds and causes the creation of byproducts in the wastewater, and some of them are known as carcinogenic compounds. There are special parameters related to the use of chlorine for the treatment of waste materials and it can be said with certainty that the use of chlorine increases with the increase in the amount of BOD in the waste materials and changes along with the changes in the amount of BOD. Therefore, this research has tried to find the optimal amount of chlorine consumption, which is effective in disinfection and production of trihalomethanes, by conducting tests on several parameters of the effluent samples in different seasons of the year, including (temperature, pH, COD, BOD, total coliform and human excreta coliform, etc.) should be checked. Therefore, Arak Arak-activated sludge wastewater treatment plant was selected as a pilot. Then the results of the research using statistical methods (Pearson's correlation) showed that the amount of chlorine consumption in different seasons of the year changed with the change of weather conditions and microbial load, and in hot seasons chlorine consumption increased and in cold seasons it decreased and the amount of chlorine consumption It has a strong correlation and a significant relationship with the amount of coliform, and in this research, the optimal point of chlorine consumption was at the highest amount of coliform in the range between 15,000-20,000 kg.

The Darkhovein Water System was commissioned in 1969 for supplying water to the port of Bandar-e Imam Knomeini and the Mahshahr Petrochemical Complex via the Kut-e Amir Pumping Station in Ahvaz. In addition, it has been the sole source of drinking water for Shadegan County, including villages. In this research, using the Water Gems software, the flow pattern in the Darkhoin water transition line was modeled and the change in the diameter of the pipes and pumping and its effect on the pressure, velocity and losses were investigated. Based on the results, a 33.3% decrease in the pipe diameter resulted in pressure losses of less than 3 m throughout the pipeline. This low pressure drop was due to the normal flow velocity. Furthermore, a reduction in the pump propeller diameter from 500 mm to 460 mm in addition to the mentioned decrease in the pipe diameter led to a significant reduction in pressure. Moreover, the average pressure in Scenario 1 was found to be 75 m, while those in Scenarios 2-6 were 72 m, 65 m, 60 m, 55 m, and 40 m, respectively, indicating pressure drops of 3.3 m, 12.4 m, 19.7 m, 25.7 m, and 46.2 m, respectively, across the pipeline.

Socio-economic issues in watersheds around the world have become one of the most important issues in watersheds. In this research, first the sub-basins of Yazdanabad watershed were identified and then the socio-economic issues of Yazdanabad watershed were investigated and the gross revenues of the studied watershed and expenses and the net profits production of the watershed were determined. Consequently, the gross revenues of the watershed productions, as well as costs and net profit of the watershed productions were determined. Then, net revenue of production and household resources in Yazdanabad watershed was obtained in the Conventional Zone and the method and mechanism of practical solutions were proposed to solve the problems of Yazdanabad watershed. Considering that the existing agricultural exploitation systems are traditional in the studied area, it will lead to a series of problems that cause erosion, water shortage, income shortage and migration in the watershed.According to the economic studies done on the sources of production and income and according to the results the cost-benefit ratio of different sources of production in Yazdanabad watershed is 0.55 which is a low figure. Practical solutions for solving the problems of Yazdanabad watershed include establishment of watershed cooperatives, holding training classes, construction of semi-industrial livestock, construction of livestock health house, construction of tourism infrastructure and programs for cultivation and operation of medicinal plants are suggested. The results showed that in Yazdanabad watershed, the most common systems are related to the rural-nomadsand the lowest type of common systems is related to rural.

Dams play a key role in controlling floods and minimizing associated losses. They reduce downstream losses by lowering the flood peak and enable a safer flood stream. Despite the significant advantages of dams, dam failure may cause dramatic casualties and financial losses. Overtopping is a major dam failure that can be induced by one or more geophysical events, e.g., floods, landslides, earthquakes, and intense winds. Overtopping is particularly crucial for earth and aggregate dams as they are more likely to be destroyed due to the flow over the crest. Therefore, the overtopping risk evaluation of dams is important, and it is necessary to bring a trade-off between the reservoir level and overtopping risk.

The risk management of earth dams is complex since multiple factors are involved. System dynamics (SD) can be used to evaluate the effects of a set of complex, interrelated factors on the overtopping risk of dams under several scenarios. Floods and winds are the main causes of overtopping, with each being dependent on a number of variables. This paper used an SD model to evaluate the independent and combined effects of uncertainties with floods and winds of different return periods on the overtopping risk of the Vanyar Dam, Iran. This would help implement efficient measures to minimize the overtopping risk and maximize safety. To measure the effects of overtopping floods on the downstream of the dam, a hydraulic model was developed in HEC-RAS. The geometric parameters/data of the river and the non-steady stream data along with the initial and boundary conditions were introduced as inputs to the hydraulic model. The most critical scenario to identify the overtopping flood zone corresponded to the probable maximum flood (PMF), under which a broad area of the downstream lands would be flooded.

This study analyzed the overtopping risk of the Vanyar Dam, Iran, for different flood and wind return periods by modeling the dam reservoir through system dynamics (SD) under initial reservoir level and dam height uncertainties using the Monte Carlo method. The effects of floods and the combined effects of floods and winds on the overtopping risk were evaluated. The results demonstrated that the probable maximum flood (PMF) with a wind return period of 100 years under reservoir level and dam height uncertainties maximized the overtopping risk to 0.122931. The overtopping risk converged in 200,000 iterations. The analysis of the overtopping flood downstream of the dam showed that many villages and facilities would be completely flooded, and it is necessary to implement management measures, such as controlling the reservoir level, to minimize the overtopping risk.

Water is the most important factor limiting agriculture in the country. For this purpose, the effect of two irrigation methods (basin irrigation and tape irrigation) and three irrigation levels (50, 75 and 100 percent of the plant's water requirement) on the performance of edible onion plants in Aysk city, which has a relatively hot and dry climate, was studied. Was investigated. This research was done factorially in the form of randomized complete block design with four replications in two crop years 2017-2018. The results showed that the yield of onion under the influence of different levels of irrigation, the highest effect is in the yield related to the treatment of 100% water requirement and the lowest related to the treatment of 50% water requirement. Also, in terms of onion water consumption efficiency, it was found that Tape irrigation method with an average of 4.69 kg per cubic meter of water is 45.4% more than the basin method with an average of 2.56 kg per cubic meter of water. Also, the effect of different levels of irrigation on the efficiency of water use in 100% water demand with an average of 4.64 kg per cubic meter of water was not much different from the treatment of 75% water demand with an average of 17.4 kg per cubic meter of water. As a result, tape irrigation with a stress level of 75% of the plant's water requirement is the most appropriate method and irrigation water level for onion plants in this region.

Improving the mechanical properties of soil in order to build civil projects is one of the important concerns of civil engineers. For a long time, various methods have been recommended to improve the soil used in projects, and most of these methods have been the result of using past experiences, among which the use of different additives to the desired soil has been one of the most common methods. Today, by using high-tech laboratory equipment, it is possible to select additives needed to improve soil properties based on the type of minerals that make up that soil. Therefore, in the research, using scanning electron microscope and X-ray diffraction method, the type of constituent minerals and the morphology of the soils used in the channels of Azadegan Plain, which mainly had a chalky texture, were studied. The results of the research show that there are changes in the paste limit for all related samples, the lowest value for the sample with 5% lime is an increase of 7.65% and the highest value for the sample with 7% cement is an increase of 113.74%. The angle of internal friction for all samples shows, the lowest value related to the sample with 5% lime, 5% slag is equal to 22.2% and the highest value related to the sample with 5% cement is equal to 6.4% increase.

The Objective of this research is to provide a model to calculate flood discharge values with a certain return period by using the geometric features of the watershed and by providing multivariable models.To understand flood occurrence in the Gorganrood watershed, we studied 11 hydrometric stations in Golestan province. Various influential parameters, including physiographic factors, vegetation, land use, soil science, geology, and weather including 31 independent variables were selected in this research. Data analysis and flood modeling were done by the multivariate regression statistical method. In this way, flood regional models using the Enter method have higher accuracy and precision than the models obtained using the Forward method. In general, 13 variables out of 31 independent variables included in the multivariate regression test have been identified as the most important and influential factors in the occurrence of floods in the Gorganrood watershed. The effective variables include: Gravel's coefficient, percentage of the area of permeable formations, watershed slope, concentration time, watershed area, flow velocity, percentage of land area with a north direction, percentage of land area with a south direction, percentage of pasture land area, percentage of agricultural land area, percentage Waterway density is ranked 3, as are average annual temperature and maximum annual rainfall.

By using these relationships (models), it is possible to obtain the values of the maximum instantaneous discharge with a return period of 2, 10, 5, 25, 50 and 100 years in the basins without statistics under the sub-basins of Gorganrood.

In addition to soil water content, soil matric potential is also important for plant growth. Soil water characteristic curve (SWCC) or soil moisture characteristic curve describes soil water content and soil matric potential relationship. Many models have been developed to describe the SWCCs and their fitting to the experimental data. However, their fitting accuracies in different soil textures, have been rarely investigated. In this study, matric potential-moisture data of 16 soil sample of forest station in Finland use to fit SWCC models. Nine well known and frequently applied SWCC models were fitted to the measured data. The most accurate models of total soil samples, each textural group and each textural class were estimated using root mean square error (RMSE), coefficient of determination (R2) and mean error (ME). Result showed that van Genuchten-Mualem, van Genuchten, Gardner and Brutsaert models had most accurate and Brooks and Corey model had least accurate to predict SWCC.

Soil conservation requires a suitable model and framework to assess soil erosion and sediment yield based on land use scenarios. Therefore, the present study was conducted with the aim of investigating the sensitivity of the G2 model to the soil erodibility factor in the Kasilian representative watershed in the period of 2001-2021. Points such as the use of global soilgrid database and comparison with soil sampling data, removal of soil erodibility in rocky areas, and removal of outlier data created by systematic error were included in the current research. The results showed that qualitatively, the rate of soil erosion estimated based on each of the mentioned points was completely in the minimum category. The initial results of the soil erosion rate obtained from the global soilgrid database and the IDW method were 4.31 and 4.33 t ha-1 y-1, respectively, which were not significantly different based on the independent t test. But the effect of other changes, including removal of soil erodibility in rocky areas and removal of outlier data on the change of soil erosion estimates using one-way ANOVA and Duncan's tests were significant (P<0.01). The estimated average rate of soil erosion in the watershed after following the mentioned points was reduced by more than 65% compared to the initial results and became closer to the data of erosion plot.

Reforming the cultivation pattern is a program that the government pursues with the aim of achieving sustainable agricultural development and maintaining food security.Protection of basic production resources,self-sufficiency in the production of basic products and maintaining agricultural employment are among the goals of this program.In this regard,this research was carried out with an emphasis on the protection of water resources in the Kabudrahang plain of Hamadan province.Using linear programming modeling for the studied area, optimal patterns were determined. Water resource protection policies were examined and tested with two scenarios of reducing the use of underground water by 30 and 50% and the scenario of self-sufficiency in wheat production.The results showed that the water resource protection policy reduces the planned efficiency of the cultivation pattern from 2.44% to 24% compared to the current pattern.The area under cultivation of rainfed crops also increased and the area under cultivation of irrigated crops decreased.The area under cultivation of cucumbers and tomatoes increased, but the area under cultivation of fodder and water grains decreased.Self-sufficiency of wheat under the conditions of the existing and optimal cultivation pattern was achieved, but in the scenarios of water resources protection,self-sufficiency was not possible without applying the condition.Under the scenario of self-sufficiency of wheat, the planned efficiency and the use of labor decreased more than the scenarios of protection of water resources.According to the research findings, in order to protect water resources and sustainable exploitation of these resources,it is necessary to control and reduce their exploitation by 30 to 50 percent.

Traditional water distribution with Mirab is effective to a certain extent in the fair distribution of water, but it has limitations in terms of efficiency and productivity. While in modern networks, it is possible to try to optimize the allocation and distribution of water by using advanced technology and infrastructure. Of course, the implementation of a modern irrigation network, despite the high cost of its implementation, does not necessarily mean that it will be successful in the assigned operation, and its performance should be evaluated and analyzed by experts in this matter. water consumption efficiency in two villages of Shahkooh Sofla with traditional irrigation network and Mohammad Abad with renovated irrigation network and integrated lands has been done. The required data in this section included a questionnaire and field measurements of water flow in the network, and finally with the help of these data, the water productivity in the fields was calculated. performance per water volume unit (CPD), and economic productivity indicators, including gross profit per water volume unit (BPD) and net profit per water volume unit (NBPD) were calculated average CPD index in terms of fresh weight, BPD and NPBD in the Shahkooh, 7.54 (kilogram of wet matter per cubic meter), 12425, 10427 (tomans per cubic meter) and in the Mohammad Abad, respectively 0.41 (kilogram of dry matter per cubic meter), 1510 , 918 (tomans per cubic meter) has been obtained. Therefore, in Shahkooh , despite the traditional network of water distribution management, more economic productivity has been achieved

An experiment was conducted in order to evaluate the allelopathic effect of water extract from different parts of Eucalyptus on the germination characteristics and seedling growth of the benchmark plant and sensitive to allelochemicals of chickpea in both laboratory and greenhouse conditions in a completely randomized design with three replications, separately. At first, the dried samples were powdered by a mill. For bioassay experiment, a 2% suspension of Eucalyptus leaves and bark along mixture of them was prepared, and then different dilutions of the suspension such as 0 (control), 5, 15 and 20% of the resulting suspension were applied. In greenhouse condition, different amounts of plant residues including 0.5, 1, 2, and 5% by weight of each leaf organ, bark, and their mixture were prepared separately in three kg of loam soil in pots. The pots were kept for 60 days in order to rot and the activity of microorganisms in these conditions. Finally, for bioassay experiment, some characteristics of germination percentage, radicle and shoot length, allometric coefficient, seed vigor index, and in the case of greenhouse experiment, germination percentage, plant length, seedling fresh and dry weight were measured. According to the results, the effect of Eucalyptus organs, different concentrations or amounts of plant residues, and their interaction effect on the characteristics of germination and seedling growth of chickpeas were significant (p<0.05). The intensity of inhibitory and stimulatory effect in chickpea seeds depended on the type of organ and the concentration of aqueous extract or the amount of decayed Eucalyptus