جمال محمدولی سامانی

Strategic plans approved by the competent authorities in the form of upstream documents are a suitable indicator for expressing the policies of any country including the country's strategies related to water and food security. In this research more than 50 documents were identified in the three main areas of water, environment and agriculture to examine the mentioned issues in Iran. The documents included the upstream documents in the field of water and agriculture and were explicitly or implicitly related to food and water security. These documents were examined using quantitative analysis on frequency. First, the counted upstream documents were analyzed for 4 axes, 14 sub-axes and 36 components. Then the amount of repetition of each was evaluated in the introduced documents. The highest level of attention of the policy maker has been given to the "political-administrative-legal" axis and then the "social-economic" axis. By using the analysis of the frequency, the sections that were important from the point of view of the law and the policy maker was identified. The results obtained from these sections showed the legislator's attention and the course of strategies in time which form three time periods of (a) first 1380-1358, (b) second 1381-1390, and (c) third 1391-1400 (Iranian Calendar). This showed the changes in the level of attention each axis received from the legislative and policy making authorities over time. The results showed that the attention of politicians and legislators has changed from a specific axis (organization administrative legal) to a uniform and one-size-fits-all attention to all the examined axes, which shows a positive evolution in the policy of water resources and agriculture.

In recent years, the issue of identifying polluting sources in rivers has been one of the most important topics in scientific researches in the field of water. In the main researches, the pollutant sources have been considered as the point sources and in order to recover pollutant concentration, it is necessary to have an observation point for each source. In this study, the places where groundwater enters to river are considered as several distributed sources with known location and length and goal is to recover the intensity of sources, using only one observation point. The sources which considered in this research are distributed sources with constant loading and significant distance from each other. The existence of significant distance among sources prevents the complete mixing of concentration at observation point. This matter and also the constant intensity of loading, makes it possible to recover several distributed sources using only one observation point. For this purpose, the inverse solution of the advection-dispersion equation is done using the simulation-optimization approach. To design the backward model, MIKE11, linked with genetic algorithm in MATLAB. Considering one observation point for recovering the salinity intensity of several distributed sources and providing a general framework to recovery of distributed sources are advantages of the present study. The performance of the developed approach is evaluated under different examples and measurement error conditions. The computational results indicated the backward model can recover the salinity intensity of several distributed sources with high accuracy using only one observation point, even with noise.

Even though dams have many social benefits, it also has caused social, economic, environmental and technical management risks along time. Due to the fact that the dam is considered a great phenomenon in nature, its effects on the environment are extensive. One of the issues that must be investigated during the operation of dams is the negative environmental effects in the dam construction area. The negative environmental effects of dams are including sedimentation in the dam's reservoir and lake, intensification of erosion in the downstream lands, inundation of agricultural lands due to rise of the underground water level. The effects of the mentioned risks for dam construction may be irreparable. The aim of this study is evaluating the effects of social, economic, technical management and environmental risks affected by the construction of dams on the watershed. Decisions related to the management of these dams require recognize the dangers and risks in the dam and prioritize them. Dam construction projects are more risky than other projects due to the high credits and time spent on their construction. Using multi-criteria decision-making methods is a suitable tool for evaluating different risks in these dams. In this study, the combined DEMATEL-ANP method is used to identify the relationships between risk criteria and sub-criteria and prioritize them. So, four criteria and 42 sub-criteria were determined to evaluate different risks in Mamloo, Taleghan and Lar dams and the network relationships between them were determined. The results show that the employment sub-criterion in economic criterion with a weight of 0.0720 has the highest risk and the land acquisition sub-criterion in management technical criterion with a weight of 0.0029 has the lowest risk compared to all sub-criteria.

Iran is characterized by a dry and semi-arid climate. The limited irrigated arable land in and the need for increasing food production due to the upward trend in population growth, coupled with water scarcity and Iran's heavy reliance on irrigation, have led to a heightened importance of water productivity in agricultural sector. In this regard, for the purpose of identifying and understanding the agricultural potential of farmlands, the analysis and estimation of physical water productivity can be utilized. The main objective of conducting this research is to evaluate various interpolation methods and to select the most appropriate method for estimating the physical water productivity of the sugar beet. Additionally, the study aims to investigate the spatial distribution pattern of sugar beet production in its major cultivation centers across Iran.

To accomplish this research, 108 field measured data obtained from selected sugar beet farms across Iran for the agricultural year 2016-2017 were used. Data on crop yield, irrigation water, and a ten-year average effective precipitation were collected, and the water productivity index of sugar beet was calculated for the selected farms.To achieve this goal, initially, the data was analyzed using the capabilities of the SPSS software. Descriptive statistical analysis was conducted, and similar regions were classified into independent and homogeneous groups (by drawing a dendrogram). Additionally, the spatial analysis of the data was carried out using the GS+ software. Furthermore, various interpolation methods were employed to create a classification map using the Geographic Information System (GIS) software. These methods encompass algebraic methods, including weighted inverse distance, radial basis function, global polynomial, and local polynomial methods, as well as geostatistical methods like ordinary kriging, simple kriging, and universal kriging. To assess the different interpolation methods, validation methods were employed, and accuracy index values such as Mean Bias Error (MBE), Mean Absolute Relative Error (MARE), Mean Squared Error (MSE), Mean Absolute Deviation (MAD), and Root Mean Square Error (RMSE) were utilized.

The results of the present study revealed that the water productivity index for sugar beet ranged from 2.60 to 13.11 kg/m³, with an average of 6.30 kg/m³. Despite the high standard deviation, the findings indicate a significant potential and high capacity for improving water productivity and crop performance in the sugar beet production hubs in Iran. Among the examined interpolation methods, the Radial Basis Function method with a completely regular spline model (CRS) exhibited acceptable accuracy (MBE=0.009) for generating the water productivity zoning map. The analysis of the generated map suggested that the western regions of the country, especially Kermanshah province, have higher water productivity index values compared to other parts of the country, making them more suitable for sugar beet cultivation. Furthermore, cluster analysis results for influential factors such as variety type, soil salinity, and irrigation water salinity indicated that within the study area, about 5% of the potential sugar beet cultivation areas could be divided into 23 distinct clusters. The minimum and maximum water productivity index were observed in cluster 11 (2.64 kg/m³) and cluster 3 (11.025 kg/m³), respectively.
Based on the low level of correlation coefficient according to the results of the Pearson correlation test, the physical productivity of water utilization can be influenced by various factors other than precipitation and climate parameters. These factors include salinity of water, soil salinity, total irrigation water, average effective precipitation (over a ten-year period), and crop yield. It can be concluded that, in addition to precipitation and climatic parameters, other constant factors including management factors have an impact on improving the physical efficiency of water utilization.

Given the high water consumption in agricultural sector and the need for increased production in cultivated lands, evaluating the water produvtivity of high-water-demand crops such as sugar beet in Iran is essential. Understanding its current state and obtaining comprehensive information from fields, as well as monitoring cultivated fields, are necessary for decision-making and macro-level planning to enhance and improve water productivity of sugar beet cultivation in Iran. However, due to the extensive cultivation area, costs, limited resources, and time constraints, this task is challenging and often unfeasible. To address this, the potential of interpolation tools can be utilized. These tools have the capability to extrapolate point-based information to spatial information (area-wide). Results have shown that the highest and lowest error values were associated with the kriging interpolation method and the radial basis function (completely regularized spline) method, respectively, for creating zoning maps. In conclusion, it can be stated that through interpolation, if there is a strong correlation between the data, a better understanding of the spatial distribution of water productivity can be achieved in the study area.

Evaluating the monitoring network and determining the main criteria in the stations is an effective step in improving the efficiency of the monitoring and measurement network. Consecutive assessment, pathology and optimization in long-term monitoring; Leads to proper management of output data, system efficiency and reduces costs. Of course, limiting factors such as: growing needs, limited resources, the consequences of unsustainable development and occasional human interference in the water cycle, etc., cause concern in meeting the water needs of human society. In this study, the evaluation of the quality monitoring network of the country's rivers was evaluated using a multi-criteria decision-making method and by selecting four main criteria. In management and technical criteria in water monitoring stations, data quality control and assurance sub-criteria, in social criteria sub-criteria of water quality parameters, in economic criteria sub-criteria of pollution detection and in environmental criteria sub-criteria of network optimization at a specific time and place have the most weight. Also, a comparative comparison of Iran's monitoring network with the monitoring network of selected countries was performed using Spearman correlation coefficient method. The Iranian monitoring network is most consistent with the Thai monitoring network with a coefficient of 0.9. One of the most important priorities of the US Monitoring Network is to optimize monitoring at specific times and places. Japan's monitoring network focuses more on regional monitoring than grade 1 rivers.

Due to the increase in population and the need for water supply, preservation and protection of surface water and groundwater resources has been considered by governments. One of the pollutant sources in rivers is entering salinity from groundwater into the river, that in this research is considered as distributed (non-point) sources. The goal is to identify the salinity intensity, location and length of sources by measuring the temporal distribution of concentration in one observation point. For this purpose, the inverse solution of advection-dispersion equation in the river was employed using the simulation-optimization approach. MIKE11 numerical model was used to simulate flow and transfer of salinity in the river, and genetic algorithm was employed for optimization. In the proposed model, considering only one observation point with some measured intensity data for recovering several sources, unknown location and length of the sources, in addition to their intensities is the most significant advantage of the present study. The model verified by using hypothetical examples, 40 km section of the Karun River and also by applying five and 15 percent noise to the observation data. The results confirm the ability of the model to recover the specifications of several distributed sources using only one observation point. With five percent of noise in the observation data, all three specifications of sources can be recovered with the desired accuracy. While at 15 percent of noise, the accuracy of the model in recovering the location and length of sources was decreased. Also, to recover the specifications of each source, employing only three points of the measured data in the ascending part are sufficient.

Today, most of the surface water and groundwater resources are exposed to contamination by different materials sewage. because most of the methods have been used to restore the pollution intensity function for groundwater, representing a method to restore pollution intensity function in rivers with more complex flow conditions is considerable. this research aim is to calculate the intensity function of the contamination source, by the numerical solution of group preserving scheme, which has not been observed in other researches done so far. Group preserving scheme is an accurate method to solve ill-posed problems. By implementing this method the one-dimensional advection-dispersion equation with variable coefficients has been solved. The principle of the introduced backward solution method is that by solving the dynamic systems in negative time steps, a general equation will be obtained, which can solve ordinary differential equations. The responses of this equation will lead to convergence of the equation and prevent the divergence of the data. three examples have been presented to show the accuracy of the forward and backward group preserving scheme, Firstly, using direct solutions of the river, the intensity of pollution concentration in the river is calculated, and the implicit finite difference method is applied to verify the accuracy of the direct solutions. In the direct method, the results of the two models were compared with statistical indexes in order to demonstrate the conformity of the two models. In the next step, by solving the backward group preserving scheme in two different examples, the concentration of pollutants upstream is simulated. Following the simulation and verification of the inverse model by direct solution, statistical indexes are used to evaluate the effectiveness of this method.

Due to scouring problems in impermeable spur dikes, which compromise structural strength and stability and as a result repair and maintenance costs increase, an alternative method of scouring is needed to protect the river bank. In this area, bandal-like structure can be used. This structure is a combination of an impermeable spur dike and a permeable spur dike. The upper part is impermeable causes the upper half of the flow run towards the center and the inner wall and the lower part is permeable enabling the lower half of the stream passes through it (Rahman et al., 2003a, b). The lower part causes the flow to slow down and reduces speed, and because the flow near the bed has a higher concentration, it leads to settling sediments in the downstream of the river near the coast. On the other hand, because of the flow through the lower half, the power of downstream flows are reduced compared to the impermeable spur dike and the horseshoe vortices are vanished. Therefore, the scouring rate in the bandal-like structure is less than the impermeable spur dike (Zhang et al., 2010; Teraguchi et al., 2011b)Regarding that the scouring rate, the bandal-like structure is less than an impermeable spur dike therefore, its use has been suggested by some researchers. Since the sedimentation rate behind the bandal-like structure is less than the impermeable spur dike, in the present study, a new structure called the wedge bandal-like is proposed to enhance the sedimentation of the bandal-like. Wedge bandal-like structure is constructed of a bandal-like structure and a repellent impermeable triangular spur dike. The purpose of using this structure is to use both the advantages of the bandal-like structure as well as the benefits of repellent impermeable triangular spur dike, for deviation of flow and sediment transport to the back of the structure and sedimentation. Both structures cause the secondary flow of the surface to move towards the outer arc before moving to the outer shore down the bottom and practically shore the coastal tail into middle areas.

In this study, the analytical solution of the pollution transport equation considering distributed source term and initial condition was performed by Laplace transform method for a general river network in a finite domain with constant coefficients for upstream and downstream using Dirichlet boundary conditions. Existence of the source term and initial condition increases the computational complexity to find the particular solution of the ordinary differential equation. To evaluate the existing analytical solution, two hypothetical examples were presented, that in each, modeling was performed on two branch and loop networks types considering a distributed source of pollution. Input data for modeling each of the desired river networks include values of velocity, dispersion coefficient, branch lengths, flow area, and input concentrations from boundaries and distributed sources. By calculating the diffusion and Laplace mass balance matrices (by influencing the distributed source) in the river network based on the connection and data matrix, a nonlinear equations system is created according to the Laplace s variable, which by solving it, the pollution concentration matrix and consequently the pollution concentration in each node is calculated by numerical inverse Laplace algorithm. The numerical solution used to validate the proposed analytical solution. The results showed that the statistical indices of R2, root mean square error, and mean absolute error in the best case were 99.86%, 0.0099, and 0.0067 kg/m3 for 1456 route and in the worst case were 95.20%, 0.0309 and 0.0194 kg/m3 for 23456 route of the loop network, respectively. The results showed that the two proposed solutions are well compatible together, indicating the good performance of the existing analytical solution and its replacement instead of numerical solution due to higher accuracy in the river network.

Hydraulic models are often used as a tool for the prediction of the hydrodynamic behavior of flow. But scale effects in the hydraulic modeling process due to deviations of the results from the prototype. This paper discusses to scale effect in the hydraulic flow model. The goal of the research is to investigate the effect of geometric distortion on the flow characteristics and the degree of deviation of the results of distorted models from the prototype, which is done using the two-dimensional numerical model MIKE21. First, the hydrodynamic conditions of the flow were simulated in four models of straight channel, convergent channel, divergent channel and curved channel with four degrees of distortion one (undistorted), two, five and 10. Then, assuming the similarity of the Froude number, the results of the models were compared with the prototype and the relative error in the result of channels was investigated. The results showed that the difference in depth and average velocity in distorted models with prototype is small, but the difference in transverse velocity profile of sloping model with prototype increases with increasing degree of distortion. So that the relative error in transverse velocity modeling in straight, convergent, divergent and curved channels with a degree of G10 was two, 29, 33 and 39 percent, respectively.

In this study, optimal designs with minimum costs are obtained for various storm return periods. Then the risk analysis is used to determine the return period in which the design cost plus the damage risk cost is minimum. SWMM software was used to handle the simulation and the Network optimization was performed by using the genetic algorithm. The non-linear reservoir model to convert the rainfall into runoff and the dynamic wave model to perform the network hydraulic simulation in this software are utilized as a complicated simulation model. The results showed that the 10-year return-period storm in which the summation of the design and the damage risk costs are minimum is the one that should be selected. Also, the rational method of the software was applied as the simplest method of rainfall-runoff and the hydraulic calculations were performed using a Manning equation without considering the flow travel time. The results show that the return period of the risk analysis is the same as the first one whereas the total design costs are greater by 16 percent. Afterward, the classical rational method in which the flow travel time is considered was used to design the same network. The peak flows of the pipes were remarkably reduced, causing the design costs to be only 5 percent greater than the complicated precise method. It can be concluded that the simple classic rational method considering the flow travel time may be used in the design of storm sewer networks due to its acceptable accuracy and costs.

In this study, by Laplace transform method, the analytical solution of the pollution transport equation in the limited domain for the river network to the upstream and downstream Dirichlet boundary conditions, and the initial condition of zero was extracted, and simulation was performed for two branch and loop networks with fixed and variable boundary conditions. After naming the nodes, by forming matrices of how to connect, flow characteristics and geometry of the river for each network as input to the problem, the diffusion matrix is created based on a function of the Laplace variable, which The value of the concentration in each node is calculated by solving the complex device created and using the inverse Laplace transform. Then, using the analytical solution extracted in a branch of the river for the pollution transfer equation, the analytical solution can calculate the value of pollution concentration at any desired location and time along with the river network. Finally, for validation, the analytical solution was compared with the numerical solution, and then the statistical error indices were calculated. The results indicate the optimal performance and high ability of analytical solution in modeling the two networks and its good adaptation to the numerical solution, which can replace numerical solution due to high accuracy and speed of calculations. Generally, due to common errors in numerical solutions such as numerical dispersion error, Round-off error, Truncation error of Taylor expansion mathematical sentences, analytical solutions, if any, for the river network are recommended over numerical solutions. Also, in the performed simulations, due to the change of the inlet flow and the flow cross-section to each, changes in the pollution concentration occur in the areas where the branches connect to each other, increasing or decreasing. The proposed analytical solution for river networks can model more complex river networks and can be considered a criterion for the validation of numerical solutions. Also, the existing analytical solution can be used as a tool to validate other analytical solutions in the river network.

The design of an urban storm sewer network is a costly task. Therefore, the design should be done so that the total cost becomes minimal. This requires modeling the problem in an optimization form. Floods are stochastic. Designing such a system is associated with risk. Thus, a project is optimal when both design costs and potential future risks are incorporated. This means that the selection of rainfall-runoff return period has to be based on risk analysis. SWMM software was used to handle hydraulic network simulation and the Network optimization was performed using a genetic algorithm in which the decision variables were the diameter and slope of the pipes. To calculate the cost of runoff damage, relationships for land uses, infrastructure and traffic, were provided. The accuracy of the simulation- optimization model seeking the optimal design of the storm sewer network was approved by a benchmark network evaluation. The developed model was implemented in a region of Tehran city to determine the optimal design return period with a risk analysis approach. The results showed that the 10-year return period with is the optimal return period with an annual damage risk cost of 508.68 billion rials, an annual design cost of 943.78 billion rials and a total cost of 1452.45 billion rials. Therefore, the developed method in which the genetic algorithm and SWMM model are combined in addition to the risk-based design approach is an effective tool for the optimal design of storm sewer networks.

Many countries throughout the world have a large population in coastal areas. Therefore, appropriate water supply in these areas is an important task. The increasing development of human societies has a major contributor to environmental pollution, especially in the water sector. Groundwater vulnerability mapping is used to conserve the quality of groundwater resources. In this study, a comparative evaluation of the vulnerability was performed using three GALDIT, SINTACS and AVI indices to determine vulnerable areas in the Lahijan - Chaboksar coastal aquifer. The GALDIT index offers better results than groundwater vulnerability to the intrusion of seawater in the coastal aquifer, especially in the flat areas, which cannot be identified by SINTACS and AVI. The results of AVI indicate a larger area that is highly vulnerable compared to the SINTACS index, but both methods show high vulnerability of groundwater in Lahijan - Chaboksar aquifer due to pollution from ground surface sources. In general, this aquifer has higher vulnerability to pollution in the coasts and the near zones to the Caspian Sea, particularly at the northern parts of the study area. It is needed to special attentions considered for the aquifer control and protection. The AVI and SINTACS indices can be applied to assess the vulnerability of no coastal aquifers and, in combination with GALDIT, is a useful tool for assessing the vulnerability of groundwater against any pollution at ground surface sources and the intrusion of seawater into the groundwater of coastal aquifers.

Groundwater in arid regions such as Iran plays a very large role in drinking water supply and agriculture. One of the threats to the future of groundwater exploitation, could be the contamination of these resources by harmful substances. At present, about 60% of the water consumption of Varamin plain region and the total volume of water consumption in the drinking sector is provided from groundwater sources. One of the best ways to prevent groundwater pollution is to identify vulnerable aquifer areas. The SINTACS model has been used to assess the vulnerability of the Varamin plain aquifer. This method consists of seven parameters that after combining the parameters, the vulnerability index map is obtained. The index of this method varies between 92 and 168.Results show that the north of the plain is very vulnerable and vulnerability is low in the south-eastern parts of Jalilabad village and downstream areas of the plain, while the rest of the plain has moderate vulnerability. A three-dimensional numerical model was used to evaluate the results of the model and the model was validated for a period of one year. The accuracy of the constructed model was evaluated as appropriate. In this model, nitrate contaminant was considered as an aquifer contaminant. In order to validate the inherent and special vulnerability of the SINTACS model, the nitrate output of the model was used, The correlation square of the results was about 65%, which shows a good agreement between the two models even thogh the numerical model is considered as micro- model compared to SINTACS one. Considering the role of the aquifer of Varamin plain in supplying the required water of the region, the quantitative and qualitative protection of this aquifer is a necessary and strongly recommonded. Also, in order to reduce the nitrate ion concentration in the study area, long-term solutions such as improving the agricultural structure and cultivation pattern of the area and constructing a collection network and wastewater treatment plant are proposed.

Rivers are one of the most important natural water resources in the world. Pollution transport modeling in rivers is performed by the partial advection-dispersion-reaction equation (ADRE). In the present study, using the Laplace transform, which is a powerful and useful tool in solving differential equations, the analytical solution of the ADRE equation was obtained in a finite domain with variable coefficients for the upstream and downstream Dirichlet boundary conditions and the initial zero condition in the river. To use the analytical solution in this study, three examples are presented, each of which, the river are divided into two, four, and eight parts, which, while the parameters of flow, pollution, and river geometry are variable in all three examples, for each of the examples, the accuracy of the analytical solution available when the segmentation of the intervals increases as compared to the numerical solution. By specifying the matrices of velocity, dispersion coefficient, cross-section, etc. as input to the problem, the diffusion matrix is calculated and, consequently, a complex system of equations is created that doubles the complexity of the work. The amount of pollutant concentration is calculated by solving the system of the above equations. The numerical solution is used to validate the existing analytical solution, the results showed that the greater the number of river divisions, the higher the accuracy of the solution, and the two analytical and numerical solutions will be well compatible with each other. Given the ability and performance of the existing analytical solution, it can be acknowledged that the analytical solution in this study can be used as a tool to validate and verification numerical solutions and other analytical solutions for the coefficients of the equation.

The optimal managment of pollutants discharged into the rivers plays a critical role in improving water quality. In this paper, a new method is developed for Cost-based waste-load allocation (C-WLA) modeling with trade-off between the cost of treatment at loading points and the loss of pollution at the points of withdrawal from the river system. For this purpose, the qualitative simulation model (MIKE11) is coupled with Particle Swarm Optimization (PSO) algorithm. The model is applied to the Karoon River system. At the first step, the sum of treatment cost and loading damage of TDS pollutant was estimated in the river system. Then, with insights into the impacts of the trade-off policy between treatment cost of dischargers and pollutant load loss, optimal treatment percentages and optimal concentration threshold limit were determined in a monthly base and for one year. The results demonstrated that the C-WLA model has the good efficiency in managing the TDS pollutant, so that, the sum of the costs and losses is minimized at $48.99 million with optimal concentration threshold limit of 2450 mg/l at the discharge points and with an average of 17.85% of the optimal treatment at the loading points.

One of the basic issues of that country is monitoring system. The monitoring process is carried out by considering the managerial and technical, social, economic and environmental indicators in the monitoring system. Consecutive assessment, pathology and optimization in long-term monitoring; Leads to proper management of output data, system efficiency and reduces costs. In this study, multi-criteria decision making methods have been used to evaluate the performance of the quality monitoring network of the country's rivers by considering various criteria. In this study, the total quality stations of the country's rivers with four main criteria including: economic, social, environmental, managerial and technical have been considered. The weight of the criteria is determined by experts. The weight of the options is calculated using mathematical standards and the network analysis process method. The network analysis process method is proposed in order to modify the hierarchical analysis process method based on the technique of sup matrices. Finally, the results of the method were controlled using the network analysis process method, compatibility ratio and sensitivity analysis. Most of the challenges in the managerial and technical criteria, then the environmental and water health criteria are considered important, and finally the next economic and social criteria are obtained. In the managerial and  technical criteria in water monitoring stations, the sub-criterion of data quality control and assurance, in the social criterion sub-criterion of water quality parameters, in the economic criterion sub-criterion of pollution detection and in the environmental criterion sub-criterion of optimization of monitoring network at specific time and place.

Predicting the transfer of pollutants in the water zones is of particular importance in the management and prevention of surface water pollution. The heterogeneity and non-conformance in morphology along the river, known to the Storage zone, will change the uniform Transport of pollutants to the downstream. The storage zones are actually places around the river where velocities are significantly slower than the rivers and are also famous as dead zones. The presence of these areas in rivers makes it difficult for them to use the classical equation of pollutant transport. To more accurate simulation of the transport of pollutants in natural rivers with storage zone, modifications should be made to the Advection- dispersion equation. In this research, a new approach to achieve more accurate simulation of transport of pollutant material by considering the changes of pollutant dispersion flux in a nonlinear method and considering the storage zone will be presented. To validate the model presented from the hypothetical example and actual data used. Based on the measured results, the output of the model is an acceptable adaptation with the observed data and shows that the proposed model is accurate and acceptable in simulating the transport of solute in rivers with the Storage zone and it can replace the classic model of pollutant transport in these type of rivers.

Considering the role of heterogeneous dams in flood control and also water storage, its very important to consider the flow hydraulic in them. On the other hand, proper design of Rockfill dams requires accurate study of flow behavior in these dams. In this regard by studying the concrete-face rockfill dam (CFRD) in the present study, by creating different cracks on the concrete face of the dam in the laboratory model, the water infiltration behavior inside the dam body was investigated. Transverse cracks of concrete slab on CFRD Dam and water flow and how to control it in CFRDs is one of the most important issues considered by experts in the design of dams. Determining the discharge coefficient of the groove to estimate the flow rate is important and unavoidable. The purpose of this study is to calculate the discharge coefficient of a rectangular groove located in the concrete surface upstream of the CFRD in both submerged and free conditions. Variable geometric parameters in this study include the height of the groove from the bed, the angle of the groove located upstream of the horizon and the variable hydraulic parameters include the height of the water head upstream of the CFRD. two equations were developed using dimensional analysis and nonlinear equation analysis, in order to predict the CD of the upstream groove of a CFRD dam in both free and submerged states. The equations are in good agreement (correlation coefficient of 0.988 (free ) and 0.984 (submerged )) with experimental results.

Horizontal layered dams and vertical layered dams are two types of the heterogeneous rock fill dams which can are employed by many engineers for attenuation of peak discharge of flood hydrograph. In this study a two dimensional (2D) computer model has been developed to investigate the flow through two layered rock fill dams. After development of the computer model, its validation has been confirmed using experimental data. Then a series of experiments have been designed to evaluate the flow discharge through two layered rock fill dams. In these experiments, four cases of layered dam have been investigated. The results of this study indicate that in the horizontal two layered dams when the lower layer is made of the finer grained rocks, the flow discharge is less than the other arrangments. Also, in order to demonstrate the model sensitivity to grain size in each layer, a sensitivity analysis has been conducted. Also, the results indicate that in the horizontal tow layered dam for each centimeter change in the rock size of the lower layer, flow discharge changes 9.96 percent, while each centimeter change in the rock size of the top layer leads to only 4.52 percent change in the discharge. In the vertical two layered dam, for each centimeter change in the rock size of the upstream and downstream layers, the flow discharge changes 11.72 and 12.04 percent, respectively.

The identification of potential pollution sources and their continuous monitoring is one of the most important measures in the quality management of groundwater and surface water resources. Since the relation between these two systems and the injected pollution pattern at the source is not easily discernible, inverse methods are recommended. In this paper, the inverse solution of the ADE equation is conducted using the simulation-optimization approach to identify the characteristics of a pollution source that is released in a confined aquifer and reaches a river, then moves along the stream to a monitoring cross-section where it is detected. The proposed case studies were not investigated before. The inverse method combines the forward model and an optimization algorithm. To speed up the computation, the transfer function theory is applied to create a surrogate transport forward model. The two approaches are compared in terms of accuracy and speed of solution for two hypothetical cases (The second example, considering the geometric dimensions of the Karun River in Iran). The result show transfer function methodology used to create a surrogate transport model is convenient, very fast compared to other existing approaches, and more accurate in the reconstruction of source characteristics even in presence of noise on observations. Moreover, each application of the transfer function to surrogate the transport process requires only 0.56 percent of the computation time of the complete simulation model. So due to its effect on significantly increasing the reverse resolution speed, it can be used for real scenarios of pollutant transport problems that generally face time constraints.

It is almost three decades that finding the release time and location of pollutant sources in rivers has attracted the researchers’ and pundits’ attention. In most of the current studies related to finding the release time and the location of pollutant sources, each of the researchers has considered their own specific circumstances in kind of hypotheses and problem solution methods. In a more general study, in previous studies researchers have used three approaches for solving the inverse problem of the pollutant transport equation. The first approach (simulation-optimization methods) includes characteristics such as combining an optimization algorithm with other numerical methods of solving transport and hydrodynamic equations. The need to use computers with strong processors for solving inverse problem is a type of computational costs that can be counted as a weakness for this method (Mazaheri et al., 2015). The second approach (probabilistic and geostatistical methods) focuses on using probabilistic and geostatistical distribution. Furthermore, using this method would assist to decrease computational volume for finding inverse problem answers, and finally would reduce number of simulations. So, that is an advantage for this method.

Pollutant dispersion in environment is one of the most important challenges in the world. The governing equation of this phenomenon is the Advection-Dispersion-Reaction (ADRE) equation. It has wide applications in water and atmosphere, heat transfer and engineering sciences. This equation is a parabolic partial differential equation that is based on the first Fick’s law and conservation equation. The applications mathematical models of pollution transport in rivers is very vital. Analytical solutions are useful in understanding the contaminant distribution, transport parameter estimation and numerical model verification. One of the powerful methods in solving nonhomogeneous partial differential equations analytically in one or multi-dimensional domains is Generalized Integral Transform Technique (GITT). This method is based on eigenvalue problem and integral transform that converts the main partial differential equation to a system of Ordinary Differential Equation (ODE). In this research, an analytical solution to two-dimensional pollutant transport equation with arbitrary initial condition and source term was obtained for a finite domain in the rivers using GITT. The equation parameters such as velocity, dispersion and reaction factor were considered constant. The boundary condition was assumed homogenous. In this research, the source term is considered as point pollutant sources with arbitrary emission time pattern. To extract the analytical solution, the first step is choosing an appropriate eigenvalue problem. The eigenvalue must be selected based on Self-Adjoint operator and can be solved analytically. In the next, the eigenfunction set was extract by solving the eigenvalue problem with homogenous boundary condition using the separation of variables method. Then the forward integral transform and inverse transform were defined. By implementing the transform and using the orthogonality property, the ordinary differential equation system was obtained. The initial condition was transformed using forward transform and the ODE system was solved numerically and the transformed concentration function was obtained. Finally, the inverse transform was implemented and the main analytical solution was extracted. In order to evaluate the extracted solution, the result of the proposed solution was compared with the Green’s Function Method (GFM) solution in the form of two hypothetical examples. In this way, in the first example, the initial condition function as an impulsive one at the specific point in the domain and one point source with the exponential time pattern were considered. In the second example, the initial condition was similar to the first example and two point sources with irregular time pattern were assumed. The final results were represented in the form of the concentration contours at different times in the velocity field. The results show the conformity of the proposed solution and GFM solution and report that the performance of the proposed solution is satisfactory and accurate. The concentration gradient decreases over time and the pollution plume spreads and finally exits from the domain at the resultant velocity direction due to the advection and dispersion processes. The presented solutions have various applications; they can be used instead of numerical models for constant- parameters conditions. The analytical solution is as an exact, fast, simple and flexible tool that is conveniently stable for all conditions; using this method, difficulties associated with numerical methods, such as stability, accuracy, etc., are not involved. Also because of the high flexibility of the present analytical solutions, it is possible to implement arbitrary initial condition and multiple point sources with more complexity in emission time patterns. So it can be used as a benchmark solution for the numerical solution validation in two-dimensional mode.

The inverse transport problem is very difficult and challenging to solve due to some special characteristics, including the lack of solution, non-uniqueness and instability. Regarding to these complexities, usually some simplifications are made in solution process, which ultimately leads to identification methods that cannot be extended for real-world applications. This study aims to develop a practical method for pollution source identification in rivers under realistic conditions, which considers irregular cross-sections, unsteady flow and both physical and chemical transport processes. The stochastic framework of proposed method provides the possibility of estimation of source characteristics in greater time instances than available observation data as well as consideration of uncertainty due to error in those data. Considering that direct solution is also required in the solution of inverse transport problem, at first flow and transport equations is solved by finite difference numerical scheme. Then, inverse transport equation is solved to identify active pollution sources using the geostatistical method. Results of application of the method to three hypothetical examples and two sets of real data indicated the great accuracy and numerical stability of proposed method in reconstruction of source characteristics even in complicated real-world condition and using sparse and erroneous observation data. Furthermore, the identification uncertainty was considered through 95 percent confidence interval.