عادل مرادی سبزکوهی

In order to reduce the amount of evaporation from water reservoirs, various methods have been proposed, which can be divided into two physical and chemical categories. In the physical methods, by using physical coverings, such as floating balls, metal and polymer plates, or tree leaves, and by covering the water surface, evaporation waste is greatly reduced. These covers reduce a large amount of solar energy reaching the water surface and reduce vapor transmission by slowing the air flow.

The present study was conducted with the aim of investigating the effect of the coverage and shape of polypropylene sheets on reducing the evaporation rate and the effect of meteorological variables on the efficiency of these sheets efficiency. This research was carried out in two parts, in the first part, the efficiency of square and triangular polypropylene plates was investigated in comparison with floating balls, and in the second part, the efficiency of 100, 70, 50, and 30% coverage of polypropylene plates was evaluated.

The results obtained from the tests showed that in the conditions of using floating balls, the reduction of evaporation was more intense and this coating was able to reduce evaporation to a greater extent compared to square and triangular floating plates. Also, using the square and triangular polypropylene plates and floating balls reduced evaporation by 30.71%, 14.86% and 48.7%, respectively, compared to the control pan.

The results of two-way ANOVA on different meteorological variables showed that the percentage of relative humidity, which was the most important factor in evaporation from the pan, lost its significance due to the presence of floating balls and polypropylene sheets on the water surface. The comparison of rectangular covers with different densities showed that by increasing the density from 30, 50 and 70% to 100% respectively, evaporation decreases by 2.3, 1.5 and 0.8 times.

The occurrence of phenomena such as surges in complex devices such as turbines, and problems caused by neglecting safety precautions, may result in significant economic damage and losses to the transmission system. On the other hand, electricity production is a key factor in the economic and social development for developing countries. Recently, institutions involved in electricity supply have recommended pump as turbine projects as hydroelectric power plant for supplying electricity to rural areas due to their economic benefits. The issue under investigation in this study is the effect of pump shutdown on surge occurrence and its effects on the water transmission line.

The case study project is the water transmission line to the city of Masjed Soleyman located in the northeast of Khuzestan province, Iran. In this study, by using WaterGEMS software, the route of the transmission line, the type and diameter of the pipes, pressure relief valves, tanks, etc., have been defined and modeled in steady state. After processing the line in steady state, in order to investigate the replacement of the PATs with pressure relief valves and its shut-down effect on the water hammer phenomenon created in the transmission line, the model created in WaterGEMS is called in the Bentley HAMMER CONNECT software to analyze the unsteady state condition. The phenomenon of surge has been investigated in three scenarios as follows: The first scenario involves studying the flow conditions in a steady state without any changes in the transmission line. The second scenario involves replacing the pressure relief valve at kilometer 054+0 from the Tang-e Mo reservoir with a reverse pump. The third scenario involves replacing the pressure relief valve at kilometer 700+3 from the Tang-e Mo reservoir with a reverse pump.

When the pressure relief valves are working, the flow velocity in the pressure relief valve in 3+700 km, equivalent to 2.07 m/s, and the pressure before the pressure relief valve is equal to 157.7 meters of water and reaches 20 meters of water. Also, in the pressure relief valve 0+054 km from the reservoir, the speed is 2.1 m/s and the pressure decreases from 104.77 m to 13.2 m of water, respectively. For second scenario, in the first pressure relief valve, 91 meters of pressure is wasted. In this case, the PATs with turbine flow and pressure have replaced the existing pressure relief valves. The inlet and outlet valves of the first PAT are closed in 20 seconds and the flow through it is reduced to zero. Third scenario considers the water hammer impact resulting from shutdown of the PAT (at 3+700 km) on the transmission line. 137 meters of pressure is wasted in the second pressure relief valve. Also, the flow through it is 580.189 liters per second. In this case, the inlet and outlet valves of the PAT are closed in 20 seconds. It is necessary to explain that if the valves of the PAT (at 3+700 km) are closed, the downstream flow will also decrease; But due to the bypass of the PAT, the input flow to the downstream pumps does not reach zero and the pumps do not exit the circuit.

The results indicate that the occurrence of the surge due to the failure of the PAT(s) installed in the transmission line, despite the creation of positive and negative pressure waves in the transmission line, does not cause serious disturbance in the pipeline. It is also concluded that the thickness of the steel material selected for the pipeline has the required strength to withstand the maximum and minimum pressures.

Rivers are one of the most important water sources that play an important role in providing water needed for various activities such as agriculture, industry, drinking and electricity production. Many of the water resources planning in the countries are based on the potential of surface water resources. Therefore, knowledge of the quality of water resources is one of the important requirements in planning and developing water resources and their protection and control. Used water considering the importance of the Shurbarik River for the use of the people of the surrounding villages, in this study, the water quality of the Shurbarik River was determined using water quality parameters. In order to achieve the objectives of this study, the parameters of dissolved oxygen, pH, biologically required oxygen, chemically required oxygen, temperature, phosphate, nitrate, ammonium, turbidity, total dissolved solids and electrical conductivity were investigated in four seasons. Based on the average NSFWQI index, the water quality of Shobarik River is in the bad quality category. The range of this index is between 29.9 to 35.4 in all seasons. The average of this index is the lowest in summer and the highest in winter. Based on the average IRWQISC index, the water quality of Shobarik River is in the bad quality category. The results related to the value of the Liou index also show that the numerical value of this index is in the range of 3.25-4.25, which indicates the relatively polluted quality of water from the point of view of this index in all seasons. Contrary to the differences in the parameters and methods used to calculate the indicators, the results of all methods are consistent and are very useful for evaluating water quality.

Electricity production is very important in developing countries. Undoubtedly, energy production is a key factor for the economic and social development of these countries. Institutions involved in electricity supply have recently recommended pump as turbine as an option for electrifying villages due to economic benefits. Electricity generation from transmission lines and water distribution networks is one of the new topics in the optimal management of water systems. In water transmission and distribution networks, despite the additional water load on the downstream equipment, which is often controlled by pressure control valves, a pump can be used as a turbine in electricity production. By taking energy from the pump and transferring it to the incompressible fluid, the pumping system increases the energy of the fluid and transfers it from a lower height to a higher level, while the reverse pump system works in the opposite direction of the pump. One of the most important factors in choosing the type of turbine for the construction of a power plant is the estimation of the initial costs of the project for the initial cost return in the shortest time. For this reason, according to the results of the investigations, one of the economic methods to replace the turbine is to use a reverse pump. These types of pumps have features such as lower maintenance costs than turbines and can be widely used.The case study in the present research includes the water supply plan to the cities and villages in the northeast of Khuzestan, which consists of a set of transmission lines, pressure relief valves, balance tanks and water storage tanks. The studied area in Khuzestan province includes the cities of Baghmalek, Izeh, Seydun and Ramhormoz. Seydun reservoirs in the east, Haftgel reservoirs in the west, Ramhormoz reservoirs in the south, and Izeh reservoirs in the north of the study area. According to the profile of the studied water supply line, there can be excess energy in the pressure relief valves, the inlet of the water tanks and the balance tanks. Based on this, eight points in the form of Helaijan branch, Seydon reservoirs, PRV6 pressure relief valve, RES5 equilibrium reservoir, RES6 equilibrium reservoir, Haftgel reservoirs, Ramhormoz reservoirs and Baghmalek reservoirs were selected as points with the potential of using reverse pump for energy production. Manufacturers of pumps usually do not provide the curve of pump behaviors in reverse operation, which causes problems in using the pump as a turbine. It is not easy to use the pump as a turbine, and the pump shows different behavior, which makes it difficult to predict the characteristic curve. For this purpose, it is necessary to convert the characteristic curve of the selected pump into the characteristic curve of the reverse pump. In this research, Sharma's method (1985) was used to determine the suitable pump for a small hydroelectric power plant. This method helps to select a pump with reverse operation capability according to the available line information so that it can be used as a turbine for energy extraction with the help of a generator. According to all the available methods for selecting the pump, this method provides the closest results to the user, and along with the practicality of its use, empirical equations are used in this method.Based on the amount of production power calculated for each of the points with energy production potential, it was determined that the maximum production power of RES6 balance tank and PRV6 pressure relief valve is 758.7 and 719.5 kW, respectively. The RES6 balance tank has the maximum head and the PRV6 pressure relief valve has the highest flow rate among all the studied points. The lowest production power is related to Helaijan branch with 32 kW, which is the lowest flow rate among all the studied points. Based on the obtained results, the proposed power plants are able to supply 1512 kilowatts of production power. In the next part, the proposed replacement of small hydropower plants on the transmission line with diesel generators with similar production capacity was analyzed from an economic point of view. In these calculations, the efficiency of the power plant is considered to be 75%. The total power produced by small hydropower plants with reverse pump is equal to 2717.29 kilowatts, which, considering 8000 hours per year for a period of 25 years, will be equal to 302400 megawatt hours. Considering that 10.96 kilowatt hours of power is produced per liter of diesel, the total amount of fuel required for a period of 25 years will be equal to 27600000 liters. Considering the world price of diesel, which is about $0.5 per liter, the cost of fuel required for energy production will be about $13,800,000.

Soil degradation is a phenomenon which destructs the soil structure and mitigates its capacity for production. Among several processes that cause soil degradation, soil erosion as one of the most common forms of soil degradation leads to loss of soil surface and including on-site and off-site effects. Although soil erosion is a natural process on the earth, but destructive human activities such as burning agriculture residue, deforestation, overgrazing, and lack of proper soil conservation practices; accelerate the soil erosion and enhance the negative outcomes of erosion. Selecting and implementing of management scenarios requires assessment of soil losses from different management operations. Generally, management practices consist of structural and non-structural methods that used to reduce erosion, prevent nutrient removal, and increase soil infiltration capacity. Application of simulation models is an appropriate technique to evaluate erosional conditions. GeoWEPP is a process-based, distributed parameters and continuous simulation model of water erosion in watersheds with the possibility to simulate hillslopes and hydrographical network. Locating problems in real world usually face with a large amount of information and decision space that need to be optimized using evolutionary algorithms due to the variety of aims considered. Considering diversity of evolutionary algorithms, NSGA-II is one of the most common and a usable multiobjective evolutionary algorithm (MOEA) which is very powerful tool for solving problems with conflicting objectives. Development of simulation models along with optimization algorithms that are capable of analyzing very complex systems, have found to be very efficient in real world problems. Simulation-optimization models are powerful tools for solving problems for least cost and best performance.

To predict sediment yield and runoff in the studied watershed, the GeoWEPP integrates WEPP model with TOPAZ (Topography Parameterization), CLIGEN (Climate Generation) and GIS tool (ArcGIS). The GeoWEPP model provides the processing of digital data including DEM ASCII file, soil ASCII file and landcover ASCII file. To generate climate file, the CLIGEN module which is a stochastic weather generation model was utilized. Furthermore in TOPAZ part the CSA (critical source area) and MSCL (minimum source channel length) to delineate streams and also the outlet point of studied watershed were defined using GeoWEPP linked to ArcGIS. Using the basic maps including DEM, slope, soil great groups and soil database the GeoWEPP model simulates and generates the hillslopes automatically; therefore this is an important advantage of GeoWEPP compared to WEPP model which is capable of performing the simulation of watershed components spontaneously. In this study in order to optimize the placement of Gabions, 118 channels and 5110 candidate sites for gabion construction were simulated and evaluated. For optimization process; regarding the number of objectives firstly the AHP technique was used to prioritize the effective factors on the placement of Gabions. Analytical hierarchy process is a structured technique for organizing and analyzing complicated decisions based on mathematical calculations. The AHP depicts the accurate approach for quantifying the weights of criteria and estimates the relative magnitudes of factors through pair-wise comparisons. The AHP technique includes creating hierarchical structure, prioritizing and calculating relative weights of the criteria, calculating the final weights and system results compatibility. The main criteria (objectives) for our study were minimum distance from road, minimum distance from residential area, maximum length of main channel, maximum sediment yield, maximum discharge volume and maximum volume structure. Indeed using the AHP technique it was possible to restrict the decision making space and the number of possible options, therefore simplify the optimization process. Then NSGA-II (Non-dominated Sorting Genetic Algorithm) was applied in order to find the best solutions, i.e. the Pareto front, of alternatives for optimal location of structures based on the two objectives with higher priority and distance constraint.

The results of paired comparison matrix and prioritizing showed that the length of main channel in the watershed is the main effective criterion in locating Gabion structures. The first priority is considered as the most critical channel which produces the highest sediment yield; therefore the most expensive structure is established on that channel. After channel length, the volume discharge was the second priority of effective factors for gabion placement. Using the results of AHP, based on channel length and discharge volume the non-dominated sorting genetic algorithm (NSGA-II) was performed and the priority of critical channels and the specific position was determined from 1 to 35 among 5110 candidate sites for Gabion construction. Using the ArcGIS, slope map and the lowest width of the critical channels the place for gabion construction as a point was determined. Moreover the main output of GeoWEPP is the spatial distribution of sediment yield and based on this map the sediment yield was classified in the watershed. Based on this map the red color was the highest amount of sediment yield (more than 4 ton) in the watershed.

Results confirmed that application of simulation-optimization techniques helps to select the best sites to construct the Gabion as structural best management practice therefore is a cost-effective technique.

In recent years much attention has been paid to the environment, especially river and lake pollution. Rivers and streams are usually receiving the outlet of sewage systems which may cause pollutant levels to rise. Pollutant dispersion is a key element in water quality modeling and the longitudinal dispersion coefficient is an important factor in stream pollution modeling due to its effect on pollutant mixing intensity. Various methods proposed to estimate longitudinal dispersion coefficient in natural streams based on different procedures and different set of data. The performance of the methods presented in previous research is mainly based on precision indices that alone cannot be used as a comprehensive index for comparing different methods.

In this study, in order to evaluate the performance of different methods, a combination of uncertainty criteria along with accuracy indexes were considered. First, the interval analysis approach was used to evaluate the uncertainty of different methods such as Deng et al. (2001), Kashefipour and Falconer (2002), Sahin (2014), Zeng and Huai (2014), M5 and Gene Expression methods. For ± 10% uncertainty in the independent parameters of estimating dispersion coefficient, for all 164 measured data, the probability bands of computational longitudinal dispersion coefficient was obtained for the 6 estimator methods. Then, by comparing the actual measured values with the position of the computational uncertainty bands, 10 uncertainty and accuracy indices were calculated for each estimator method. To determine the most appropriate method for estimating longitudinal dispersion coefficient with less relative uncertainty and greater relative accuracy, weighting was performed on 10 uncertainty-accuracy indices using the G1 weighting method, and then the performance of the methods was evaluated by three multi-criteria decision models including CUI, TOPSIS and VIKOR.

Based on the results, the M5 tree model has the lowest containing ratio among all methods and also has the lowest band, while the Kashefipour and Falconer (2002) model has the highest containing ratio and band values. In addition, for all methods except the method of Deng et al. (2001), the parameter of average deviation amplitude decreases with increasing containing ratio. Among the methods used, the M5 tree model has the lowest CR and the highest D. Based on the uncertainty and accuracy analysis, the method of Deng et al. (2001) was better than other methods and then the equation presented by Zeng and Huai (2014) with CUI = 0.717 had the best performance. The two data-driven methods of the M5 and GE are also ranked next. The results of TOPSIS method are completely in accordance with CUI method and there is no difference between the two methods. According to the VIKOR method, the two methods of Deng et al. (2001) and Zeng and Huai (2014) performed the best, followed by data-driven models. The only difference between the results of the VIKOR model and the two CUI and TOPSIS methods is the ranking of the two data-driven methods, so the GE model is more efficient than the M5 model in VIKOR method.

The results of the three multi-criteria decision-making methods were close to each other and in all the methods, the mathematical model of Deng et al. (2001) and the empirical model of Zeng and Huai (2014) were more efficient than the other methods. It is important to note that the uncertainties of decision-making models have not been examined in this study and the purpose of the present uncertainty study has been to quantify the inherent uncertainties of the methods and relationships for estimating the longitudinal dispersion coefficient.

Hydraulic analysis of pipe networks is generally done considering certain values for independent parameters of the system such as roughness of pipes, nodal demands, etc. Such analysis would inevitably lead to certain hydraulic responses of the system, i.e. nodal pressures, etc. This is while, inherent uncertainties associated with independent parameters as expected stresses, spread over the system and result in hydraulic stress in nodal pressure heads as dependent uncertainties. Using optimization tools, this study presents a reliable approach based on interval analysis to deal with these uncertain hydraulic stresses. In the proposed approach, the optimization problem is formulated in a manner that the nodal demands, roughness of pipes and water levels in elevated tanks would be the decision variables while extreme nodal pressures for unknown intervals are explored as the objectives functions. The large number of junctions in the case of real pipe networks, leads to inefficient iterative use of single objective optimization engine. In order to this problem, this study exploits a many-objective approach with an appropriate performance. Applying the proposed approach on a real pipe network shows that ±15% variation in nodal demands and pipes’ roughness in addition to ±1m in water levels might produce hydraulic stress in pressure heads from -13.7% to +10.2% with regard to the crisp values. In such a condition, it is possible for 125 junctions out of 128, to fail in satisfying the minimum required pressure head. It is demonstrated that the proposed approach has acceptable accuracy for analyzing hydraulic stress in real water distribution networks.

Evaluation of the short-term fluctuations in water demand and consumption is one of the most important consideration in design and optimization of drinking water distribution networks. According to necessity of system ability to distribute water during peak demand conditions، the capacity and pipe sizing of network are determined based on multiplying Peak Factor in Average Daily Flow. It seems that Diurnal Demand Pattern through which Peak Factor is obtained، regionally varies due to many complicated reasons، mainly because of the number of subscribers. So، most of standards and references have recommended their own specific Daily Peak Factor، Hourly Peak Factor and Peak Factor with emphasis on localization of these terms. Considering the importance of regional studies on Peak Factors، this research was conducted for a group of rural networks in north-east part of Khuzestan Province، Iran. After installation of electro-magnetic flowmeter with maximum error of 0. 3% and measurement of demand flow in 7. 5-minute time intervals by data logger، during one-year period، Diurnal Demand Patterns and Peak Factors were determined. The considerable difference between Peak Factors resulted in this research and those recommended by national and some international standards or references، makes the importance of peak factor localization more and more obvious. For example، in the case of the smallest investigated network، the peak factor proposed by national standard 117-3 is 27. 3% less than the actual factor acquired in present study. Also، the results show that calculation of peak factors without any notice on the negative effects of physical loss of unaccounted-for water can sensibly reduce peak factors 14. 5% to 24. 5% compared to reality.

Increasing the concentrations and emissions of greenhouse gases makes the weather warmer and affects land uses. Carbon dioxide emission is recognized as one of the most important factors in global warming. The objectives of this research were to investigate the amount of CO2 emission from soil to atmosphere during the wheat growth under two different tillage and irrigation methods. In this study, an experiment with a combination of tillage practices (conventional and conservation tillage) and two irrigation practices (flooding and furrow irrigation), using 45% surface residue, with 6 times of sampling from soil gases and 3 replications was done. The Statistical design of split plot in time with covariance analysis was used. A closed chamber method and gas chromatography were applied at Ramin Agricultural University research station. In order to measure the amount of water used, the submerged siphon method was used. The results showed that, the overall carbon gas emissions were influenced by soil moisture and tillage systems. Conventional tillage systems caused more fluxes because of mixing soils, the increase for CO2, was 67%. The amount CO2 gas emission for the flooding system was 33% more than of that furrow irrigation. Conservation tillage with furrow irrigation produced the lowest (p≤0.05) carbon dioxide emission. This value was 1143 mg/ m3 whereas the conventional tillage-flood irrigation, with an average of 2592 mg/m3 showed the maximum (p≤0.05) emission.

Drops are the most important and common hydraulic structures used as energy dissipators in irrigation networks and erodible waterways. Dissipation of energy occurs in two different ways. One portion belongs to the geometric form of the structure (briefly called loss due to structure), whereas the other occurs due to happening of hydraulic jump downstream of the structure. The dimensions of drop structure and downstream stilling basin can be optimized if geometric and hydraulic characteristics are recognized properly. In this research, the effects of drop geometry and hydraulic characteristics on the loss due to structure were investigated. At first, the effective dimensionless parameters were specified. 14 physical models of more common drops including straight, inclined and stepped drops were then built in 2 heights of 51.5 & 25.5 centimeters and 2 bed slopes of 26.6 & 33.7 degrees. The number of steps in stepped models was chosen equal to 3 and 7. With establishment of 90 flow rate, the energy losses were compared. The results showed that in the range of variable parameters, the straight drop has the maximum amount of energy dissipation.