1. Prelude Surface water, especially Rivers are the most important sources of water for drinking and agricultural purposes. The parameters involved in the ecosystem of the River covers a wide range and since the rate of elimination, some commonality, decrease and increase of pollutants and the factors influencing them is different, and there is in some cases, addressing all the features and parameters of water quality is not possible. In this regard, water quality parameters such as DO, BOD, COD, NH4, NO3 and PO4 in the Abbas Abad River of Hamedan were evaluated. The purpose of this study, was to simulate water quality parameters of Abbas Abad River with the QUAL2KW models and estimate the amount of pollution entering Abbas Abad River, without making environmental problems of Rivers with the River enjoying self-purification capacity. Also, it is noteworthy that no research has been done using this model in Abbas Abad River, so the results can be used in developing control programs pollutant load (TMDL) for Abbas Abad River, and in the related organizations for similar applications. 2. Materials and Methods 2. 1. Study area Abbas Abad River is 18 km long from the slopes of Mount FakhrAbad of a height 3312 meters 12 km southwest of Hamedan flowing to the north. The River in its path (between regions Ganjnameh and Abbas Abad), gets branches, and after passing Hamadan Abbas Abad village garden pours in to, in Grachqa Lands into the River (Gishin) khaku. Abbas Abad River, because is a mountainous basin, and the steep, has a swift flow. Due to the snow catchment, this River has a permanent origin. 2. 2. Research Methodology In this study, was used QUAL2KW model to simulate DO, BOD, COD, nitrate, ammonium and phosphate and calculate parameters of self-purification capacity of the Abbas Abad River. To calibrate the model, the necessary information for the years 2012-2013 was obtained from the Environmental Protection Agency Hamadan. In order to test and validate the model, data collection was carried out in May, June and August 1394. In order to determine normal flow of the River, two patterns of the three-year River flow continuity and moving average of the River flow. And according to the 43-year period (1971-2013), the normal flow for months of the study was determined. 2. 3. Collecting data According to the field observations and determination of the locations of wastewater disposal into the Abbas Abad River, water harvesting (dividing the water 1 and 2), lateral branches (Tarykdrh) added, were selected in 5 stations sampled on the Abbas Abad River from the Ganjnameh to the Natural History Museum (behind Faculty of agriculture), 7. 43 kilometers long. These stations were sampled and analyzed in the months and required quality tests were conducted. To model, the River was divided into 16 pieces. Since the water quality of the River is influenced by flow and temperature, to determine the critical month in terms of water quality, based on 3-year moving average and Discharge River was 43-year-old took place, who was selected in August as dry months. 2. 4. Self-purification capacity and TMDL process In this study, given Abbas Abad River plays apart to supply water to Hamedan city and another part is used as water right of farmers to irrigate gardens and agricultural land, to use drinking water and agriculture standards in the examination of self-purification capacity River, two interval were considered. First interval, the range of Ganjnameh up to water division 1, to harvest drinking water and second interval of the division of water up to the water withdrawals for agriculture in behind the School of Agriculture (water division 2) were selected. In this regard, Iran's water quality standards were used. And the standard in order to apply the water used in agriculture FAO standard was used. To determine self-purification capacity of River and total maximum of daily load, the TMDL process was used and according to the type of use (agriculture and drinking), in compliance with the respective standards safety margin was considered. For phosphate, the entering load pollutants was reduced up to standard. 3. Results Based on these results, levels of dissolved oxygen in the range of one kilometer beginning to change is not considerable, but with the continue the path up to km 4. 100, relative to the initial state, the average level A drop in 1. 5 percent relatively minor exists, and then up to the end of the path was increased to 5 percent. According to the charts of ammonia and nitrate, with the increasing River discharge and dissolved oxygen, process of nitrification taken place and oxygen caused the conversion of ammonium to nitrate. This increase of nitrate, in the interval (3. 500 km), an average of 15 percent, but is not the index. Also the flow increased that is combined with the relative increase oxygen, enhanced the quality of River water, and dropped amounts of BOD and COD an average of 45 percent. This also causes the status of phosphate to improve in the River. Self-purification capacity of River: For drinking purposes, if the values of BOD, COD, NH4 and NO3 increase up to level 1, 0. 3, 9. 3 and 10, fold respectively, they are still acceptable In terms of drinking water standards. It should be noted that this is accordance with position and place of harvest of the River for drinking purposes (the first interval). If in future, the harvesting place of drinking water is changed, the assessment will not be valid. It should be noted that the amount of Phosphate River is always higher than the standards for drinking purposes and thus should be reduced to the initial value of 0. 64. Also, for agricultural purposes, if the values of BOD, COD, NH4, NO3 and PO4 respectively up to 35, 28, 25, 46 and 40-fold increase, still will be accepted in terms of agricultural standards. As already stated, this would suit position and harvesting of water from Rivers for agriculture (second period) is valid. If the relative increase parameters, examined compared to relevant standards, we find that the BOD further increases other elements, although significant difference cannot be observed between respective elements, also, there was determined the lowest level of self-purification in the first interval of COD and the second interval of NO3. 4. Conclusion and recommendations The aim of this study was to determine assimilative capacity of the Abbas Abad River of Hamedan, in compliance with the standards and quality criteria such as parameters of DO, BOD, COD, NH4, NO3 and PO4. In this regard, QUAL2KW one-dimensional model and the measured data in May, June and August 2011, 2012 and 2015 were used. Was applied the TMDL process for to determine the self-purification capacity of the River and total maximum daily load. The results showed that due to the mountainous and steep area, re-aeration is properly done so that although the values of BOD, COD, NH4 and NO3 increase up to 1, 0. 3, 9. 3 and 10-fold respectively, they are acceptable in terms of standards for drinking. The River PO4 is always higher than the standards for drinking purposes and it is necessary to decrease the initial value of 0. 64. For agricultural purposes, if the values of BOD, COD, NH4, NO3 and PO4, respectively, and up to 35, 28, 25, 46 and 40-fold, they will be accepted in terms of agricultural standards. Based on these results, self-purification capacity of the River in the first interval (drinking) is more than that in the second interval (agriculture). Also pattern of behavior of DO, BOD, COD, NH4, NO3 and PO4 parameters in River follows a normed probabilistic distributions, normal, Pearson, log normal, Pearson and normal respectively, and this information can help in the prediction of variability in this quality index.

Background and Objective: Increasing population growth and the need to develop agricultural products have increased the use of pesticides and thus the pollution of water resources as one of the environmental problems. Therefore, this study was conducted to determine the residual concentration of diazinon pesticide in the water of AbbasAbad River in Hamedan in 2014. Method: Water samples were collected from four stations along the Abbas Abad River. In the laboratory, after sample preparation, diazinon residues were determined using a spectrophotometric method. All statistical analyses were performed using the SPSS software. Findings: The maximum mean concentration of diazinon residues (μ g/L) in samples of spring and summer seasons were 97. 0 ± 10. 2 and 202 ± 13. 7, respectively. Also, the mean contents of pesticide residues in the water samples in both seasons were higher than the maximum contaminant levels (MCLs) established by WHO and EPA. Discussion and Conclusion: Due to exceeding the average residual concentration of pesticides in the evaluated water samples, it is necessary to pay attention to issues such as training gardeners in order to use pesticides correctly and in principle. Also, measures should be considered in order to use the water of this River for drinking or farming cold-water fish.

Introduction: Rivers are considered as one of the main sources of water and energy supply for humans, due to their special effects on human life and the formation of different civilizations. Therefore, their behavior should be considered. Flood flow is very complicated in natural Rivers, especially in Meanderi Rivers. Therefore, the present research uses a numerical model to evaluate River floods characterized as different return periods of 10 and 50 years. The study area is located on the Kor River. Methodology: In this study, the geometry model and a numerical mesh system were calculated by taking advantage of topographic surveys and the required parameters for running CCHE2D were collected through filed works. The CCHE2D model, a two-dimensional hydrodynamic model of flow and sediment transportation for unsteady flows, is able to simulate and analyze sediment transportation flows and morphological processes. It contains two parts: 1-CCHE-MESH generation for meshing the studied area 2-CCHE-GUI for applying the resulted mesh to simulate flow and sediment. Finally, the model outputs including flow depth were obtained for the considered River reach in different return periods. Result: In this study, using the numerical model CCHE2D, changes in the depth of the water in two return periods of 10 and 50 years in different sections of the River route were obtained and the diagram of these changes was one of the outputs of the model. Discussion and Conclusion: Study shows discharges with different return periods. In the Meander range of the study area, centrifugal force gradient flow of flow on the center and cross slope caused at the level of the water was so high, but the water level in the upper arch cross external and internal were decreasing. This phenomenon caused peripheral gradient pressure within the cross section which resulted in an imbalance of the local effect between the centrifugal force and gradient pressure flow, the secondary flow forms in the transverse section. Once flooding occurs in the River (50-year return period), water level exceeds the main River channel and enters the surrounding floodplains. Under such circumstances, due to the differences between flood plains roughness and the main channel, flow rate (velocity) on flood plain is much slower than the main channel. Consequently, such difference leads to some shear layers in crossing points of the main channel and floodplain in the entrance, resulting in greater water turbulence. The comparison of the water flow velocity in different reach sections indicated that the highest water velocity was related to the first meander so that in return periods of 10 and 50 years it respectively reached 2. 7 m/s and 3 m/s. The results of the study confirmed the applicability of the numerical model to predict River changes using flow parameters. Therefore, it can be said that the present numerical model is capable of analyzing the River changes in the wind tunnel channels in a desirable manner.

Abbas-Abad Garden located in Behshahr county is a garden belonging to the Safavid era that is expanded in the suburban area representing a gorgeous bride in the heart of the forest at a height of about 400 meters above sea level. Its natural beauty with a picturesque landscape was so great that, despite being hard to reach area and the difficulty of operating construction, persuaded Shah Abbas Safavi to undergo building this garden in this area, as he kept it hidden from many people`s eyes after completion. In confirmation of this idea, it can be mentioned that there is no specification or description of the garden spaces available in the historical documents. Its vicinity to the untouched and natural forest next to the built-in garden according to the geometry of Iranian gardening and the existence of a lake in the southern part of it, similar to a precious gem, has increased the inexpressible beauty and calmness of the garden. After the reign of Shah Abbas, the garden was abandoned, and consequently, due to the dominance of natural events, the built-in garden was buried in the heart of the forestry area, as the precious lake of Abbas-Abad and the remains of Chartaghi in the middle of it were the only representatives of the garden, so that there was no request for this place except the residents of the neighboring villages. The garden was registered in the list of national monuments in 1967 despite the construction of a hydraulic dam in the area, and the presence of a building between the lake and the dam wall, with no trace of the remains of the built-in garden. The story of the garden did not end with this issue, and after the Islamic Revolution of Iran, by facilitating access to the area, new requests1 for this area gradually appeared, as each of the interested organs took possession of the property. In the 90s (70s SH) following the initiation of excavation operations around the lake, the built-in area of the garden appeared and came out of the ground, as this gorgeous bride thoroughly presented itself again, and the reputation of the garden became more and more popular. Despite of all the adversities that occurred to this magnificent area, eventually, it become possible to be registered in the UNESCO World Heritage List in 2011 together with eight other Iranian gardens. Following the registration, it was expected that all kind of organizations whether public or private, from national or domestic corporations, take their actions to protect the values and aesthetic aspects of this work, however, each organization was merely thinking about its interests to benefit from it, And meanwhile, it is only the Cultural Heritage of the country that has not benefited from it. Lowering the position and value of this unique garden to a place for vulgar2 or ‘negative tourism’, exploiting it for trade purposes, benefiting specific groups from it merely for short-term profitable targets, and requesting their share will eventually turn this gorgeous bride into a crone, old woman over time, which increases the risk of removing it from the list of the world works, the level of vulgarity in this area is so high that even the domestic cultural tourists who come to this place for the fame of Abbas-Abad Garden, have no desire to get off their cars, and leave the place regretfully for the careless approach is applied to this place. From the beginning of 2015 onwards, by disclaiming the cultural heritage organization of the country from the tourist areas of the place and around the lake, known as the forest park (Park-e Jangali), unfortunately, the situation of the garden as a registered work has been depreciated along with many intrusions in the location, inattention to the rules of the World Heritage, all have given an unpleasant appearance to the cultural landscape of the area and greatly destroyed the historical monuments in the area. The final shot was fired at this place following the approval of the Behshahr Master Plan by the ‘Supreme Council of Urban Planning and Architecture’ in August 2022, without consulting the Ministry of Cultural Heritage, as a result of this action, this sub-urban area was transferred to the jurisdiction of Behshahr city and its management was given to the municipality. The collection of unpermitted activities, unregulated authorizations, and unorganized presence of tourists coupled with harmful activities are the adverse outcomes of the two mentioned decisions. Certainly, the persistence of these activities, diminishing the power of Cultural Heritage, and the position of this world garden bring destruction to the Abbas-Abad Garden and this gorgeous bride will be lost forever. What would happen, if Shah Abbas was alive today! ! .

Introduction: Chlorination is the most common and successful method for disinfection of drinking water, especially in developing countries. However, due to the probability of formation of disinfection by-products especially Trihalomethanes (THMs) that are known as hazardous and usually carcinogenic compounds, this study was conducted to assess the investigation of THMs in drinking water of Abbas Abad water treatment plant in 2015.Methods: In this study, 81 water samples were gathered during autumn season of 2015. Temperature, pH, Ec, turbidity, and residual chlorine were measured on site. After samples preparation in the laboratory, THMs concentrations were determined using gas chromatography. All statistical analyses were performed using the SPSS statistical package.Results: The results showed that the minimum and maximum mean concentrations (mg/l) for bromodichloromethane were 1.47 ± 0.57 and 1.90 ± 0.26, for bromoform were 1.47 ±0.35 and 2.36 ± 1.10, for dibromochloromethane were 1.47 ± 0.42 and 1.53 ± 0.55, and for chloroform were 3.40 ± 0.70 and 7.53 ± 1.00, and all compounds were determined for stations 1 and 3, respectively. Also comparing the mean concentrations of assessed THMs with ISIRI and World Health Organization (WHO) Maximum Permissible Limits (MPL) showed significant differences (P<0.05). Thus, the mean concentrations of all Trihalomethanes compounds were significantly lower than the maximum permissible limits.Conclusion: Although the mean concentrations of THMs were lower than MPL, yet due to discharge of restaurants and gardens’ wastewater into the Abbas Abad River, prechlorination process of water in Abbas Abad water treatment plant, high retention time and increasing loss of foliage into the water, especially in autumn season, the formation of Trihalomethanes compounds could increase. Therefore, periodic monitoring of THMs in drinking water distribution network is recommended.

Introduction Rivers are always faced with erosion and sediment transport. Sediment transport in Rivers is one of the most complex topics in River engineering and is always the focus of experts and water engineers. This phenomenon is one of the important hydrodynamic processes that affect many hydraulic systems and water facilities and is considered one of the basic problems in the exploiting surface water resources globally. Estimating the sediment load of Rivers is one of the important and practical issues in the studies and design of water engineering projects, such as the design and development of irrigation and drainage networks, water extraction from Rivers, etc. Sediment concentration can be calculated by direct or indirect methods, which are usually expensive and time-consuming direct methods. Various factors affect this phenomenon, which makes their analysis difficult. Therefore, they cannot model the sedimentation phenomenon with acceptable accuracy. Hydraulic models cannot always be trusted due to the need for a lot of data, unavailability of the required data, and the inaccuracy of the data due to human error for simulating sediments. Nowadays, fuzzy and neural intelligent conductor systems, due to their ability to solve complex and nonlinear phenomena, have found many applications in various water engineering problems, including sedimentation. The purpose of this research is to evaluate and compare adaptive neural fuzzy models (ANFIS), support vector machine (SVM), gene expression programming (GEP), and group model of data handling (GMDH) in estimating the sediment load of Tirah River, Markazi Province.   Materials and Methods In this research, first, the long-term daily statistics of temperature, rainfall, average flow rate, and sediment concentration of Hasan Abad hydrometric and sediment measuring station located on the main branch of the Tirah River were collected. Then, the data sufficiency test for analysis, checking the correlation between parameters of River discharge, precipitation, temperature with sediment discharge, and determining the long-term average of suspended sediment in the studied stations were performed. In the next step, a suitable combination of input variables was selected. The design of the input parameter pattern can be based on the relationship between flow and sediment flow parameters, rainfall, temperature, flow, and sediment flow. Of course, considering that the mentioned parameters have a historical course, therefore, the design of the input patterns of soft computing models should be done based on time delays (like what is discussed in the analysis and forecasting of time series). Determining the most appropriate time delay of the input parameters in the modeling of discharge, sediment, temperature, and rainfall, then the appropriate design of the structure of the used soft calculation models was done. In the next step, the estimation of sediment discharge using an SVM, GEP, and ANFIS group method of GMDH data control and comparison of three data mining methods, and also with the sediment rating curve and observational data. About 70 % of the research data was used as training and between 20 to 30 % for validation and testing.   Results and Discussion Based on the statistical indicators of optimal model selection, the best performance of the SVR model has been obtained for model number one. In this model, the R2 and RMSE obtained from the model are 0.96 and 0.0047, respectively. Besides, the R2 and the RMSE error of the models in predicting suspended sediment values in the test stage are 0.95 and 0.014, respectively for the ANFIS model, and 0.50 and 4.97, respectively for the GEP model. The best performance of the ANFIS model has been obtained for model number one. In this model, the R2 and the RMSE obtained from the model are 0.95 and 0.014. The R2 and RMSE of the models in predicting suspended sediment values in the test stage are 0.96, 0.0047 for the SVR model, and 0.50, 4.97 for the GEP model, respectively. The best performance of the GEP model has been obtained for pattern number nine. In this model, the R2 and RMSE obtained from the model are 0.99 and 0.010, respectively. The R2 and the RMSE of the models in predicting the amount of suspended sediment in the test stage are respectively equal to 0.70, 0.015 for the ANFIS model and 0.78, 0.0185 tons respectively for the SVR model.   Conclusion It can be seen that the performance of the GEP model was better compared to other models. SVR and ANFIS models are ranked second and third. In the next step, the best-selected pattern of ANFIS, SVM, and GEP models was used as the input of the GMDH model. First, input pattern one, which was selected as the best pattern for ANFIS and SVM models, was introduced as the input of the GMDH model. In the training and test, the values of R2 statistical indices are 0.94 and 0.99, respectively, the RMSE error value is 0.0079 and 0.0038, respectively, the MSE value is 0.000062 and 0.000015, respectively, and the MAPE values are respectively 0.007 and 0.003. In the next step, input pattern nine, which was selected as the best pattern for the GEP model, is introduced as GMDH input. In the training and test steps, the value of R2 is equal to 0.95 and 0.98 respectively, the RMSE error value is equal to 0.0077 and 0.0045 respectively, and the MSE value is equal to 0.0006 and 0.00002 respectively, and MAPE value is equal to 363 and 502. The results showed the acceptable performance of the GMDH model with the highest R2 equal to 0.99 and 0.98 and the lowest RMSE equal to 0.0038 and 0.0045, respectively.

To prevent distribution of recessive alleles in dairy herds all bulls used for AI (Artificial Insemination) have to be tested. In this study 26 blood and 4 semen samples were supplied from Iranian Holstein bulls used for AI. Genomic DNA was extracted from 100 ml of blood and 200 ml of semen. Samples were tested by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method. PCR reaction was performed for amplification of polymorphic region of the CD18 gene on chromosome 1 and exon 5 of ASS gene on chromosome 11. We detected one Bovine Leukocyte Adhesion Deficiency (BLAD) carrier and no carrier for bovine Citrolliemia in this study. Hardy-Weinberg test confirmed the equilibrium of BLAD locus in this population

The Abbas Abad area is one of the most significant natural and historical landmarks in Tehran. It has been developed and utilized over the past 17 years to establish a tourism and cultural hub for Iran's capital. However, with new activity areas being introduced, changes in leisure patterns and citizens' needs, and management conflicts arising from independent organizations established in the region, it is crucial to manage the complex's activities effectively. This requires attention to changes, a review of requirements and capacities, and consideration of present situations. To address these challenges, this study employed documentary research, field observations, in-depth interviews with stakeholders, and questionnaires to survey different visitor groups during various months and seasons throughout the year. The results offer appropriate solutions to improve the utilization status of the complex. These solutions include increasing diversity and functional mixing within the complex, particularly emphasizing the private sector's role in cultural activities. Additionally, providing basic comfort conditions in open spaces, improving communication methods, and upgrading management infrastructures in accordance with exploitation are essential steps towards enhancing the complex's management. Keywords: Abbas Abad Area, Optimal Exploitation, Urban Space, Cultural Space, Tourism Space.     Introduction Urban spaces have played a crucial role as the physical platform for civil life and social interactions amongst citizens. The relationship between urban spaces and various forms of civil life has a long-standing history in cities. These areas witness a diverse range of activities encompassing cultural, tourism, social, economic, and political domains, facilitating most contacts, communications, and interactions between people. Among the significant ecological capacities of Tehran city, Abbas Abad district holds a prominent position, further amplified by its strategic location within the capital. Today, Abbas Abad is one of the most important tourist destinations in Tehran, featuring an array of cultural, scientific, recreational centers, green spaces, and natural areas. However, certain sections of this complex encounter issues of unbalanced population distribution concerning space or time. Additionally, due to its strategic location, some lands of Abbas Abad have been allocated to independent cultural and administrative institutions, contrary to the approved plans, resulting in challenges in the effective utilization of this area. Literature Review This research paper summarizes studies on the management of urban spaces globally, emphasizing tourism and cultural spaces. Carmona highlights user regulation, maintenance, and investment as fundamental dimensions of urban management. Barakpour and Asadi (2011) categorize the dimensions of public space management into five fields: integration of planning and policy-making, functional, territorial, governmental-political, interested stakeholder groups, and management contexts. In 2020, García Henche proposed a sustainable management model for creative, cultural, and historical tourism spaces in the article titled "Sustainable Management Model for Creative Cultural and Tourism Ecosystems." This innovative model supports the coexistence of both public and private sectors while integrating residents of city centers with economic activities generated by urban tourism, promoting a culturally rich, sustainable management approach. Therefore, cooperation among cultural organizations, hospitality industry, and retail businesses is vital to foster successful cultural, creative, and sustainable management practices in urban cultural spaces. Methodology The present study was conducted using a variety of methods, including library research, field observations, questionnaires, and interviews. The statistical population for this project included tourists and visitors to Abbas Abad lands, and the study focused on examining the patterns of people visiting the area, the problems they experienced, and their suggestions regarding various factors affecting environmental quality in the area. To determine the necessary sample size, Cochran's method was employed. Given the lack of extensive studies regarding the number of people who visit the area, as well as the large research area encompassing regions 3, 6, and 7 of Tehran Municipality, the highest sample size recommended by Cochran's method was used, requiring 384 questionnaires per season, totaling 1536 questionnaires overall. On average, 128 questionnaires were distributed each month, on different days of the week (both working and non-working). The questionnaires were distributed across different areas according to the population density of each section and were completed at various times during the day and night, on different days of the week and month. Discussion and Results One of the most significant findings of this research is the proposal of tourist routes for Abbas Abad's area. The proposed tourist routes in the cultural complex of Abbas Abad lands consist of five thematic axes: health and recreation, myth and history, exploration and research, knowledge and philosophy, and culture and art. Each of these axes was developed based on the issues and challenges facing the area, as well as the potential of different spaces to support tourism. For each axis, a tourist tour program is presented, including the origin and destination, the duration of the tour, and the proposed activities and programs in the areas of the Abbas Abad complex. Given the importance of using Abbas Abad lands for cultural and tourism purposes, improving the quality of content and activities, as well as infrastructure and background conditions, are crucial. This will enable the complex to fulfill its functional position as outlined in urban, national, and transnational documents. To address the identified challenges, solutions can be classified into two main categories: policy-making, planning, and activity establishment, and conditions, requirements, and supporting fields for activities. Proposed solutions include increasing diversity and functional mixing in the complex, enhancing the role of land in cultural activities (particularly with the involvement of the private sector), providing basic comfort conditions in open spaces, improving information dissemination and reputation building, and enhancing management infrastructures consistent with exploitation. Conclusion Improvement of management infrastructure is one of the most crucial steps towards optimal utilization of the complex. Given that exploitation is more important than construction measures with regards to activities of AbbasAbad Land Renewal Company, it is necessary to align the organizational structure, human resources, strategic documents, and legal frameworks of the company to facilitate private sector involvement in the complex. Furthermore, changing the position of the company from sub-committee of Urban Development and Architecture Deputy of Tehran Municipality to Tehran's Mayor Office can enhance the management ability of the company due to its critical role in Tehran city performance. It is noteworthy that the proposed shifting of the company's position does not involve changes in the existing personnel structure and administrative framework, thus avoiding additional financial costs for the municipality.

Background and Objectives: River water temperature has both economic and ecological significance when considering issues such as water quality and biotic conditions in Rivers. This parameter affects directly other water quality parameters and plays a major role in the quality of aquatic life and habitats. Consequently, with wide application of water temperature for conducting environmental impact assessments as well as for effective fisheries management, it is important to understand the thermal behavior of Rivers and related heat exchange processes. Numerous deterministic and statistical models have been used for prediction of River water temperature by researchers. So far the modeling of River water temperatures has generally been based on air temperature. However, the River hydraulics and metrological parameters may have their special effects on River water temperature. Furthermore, there are limited researches undertaken by novel and intelligent algorithms. Hence, in this study, gene expression programming has been used for estimation of the water temperature of the Mohammad Abad River located in Golestan province. In addition to the air temperature, the River hydraulics and metrological parameters were also accounted for modeling River temperature. Materials and Methods: Gene Expression Programming (GEP) is an evolutionary algorithm that uses a population of individuals and selects individuals according to fitness and introduces genetic variation using one or more genetic operators. For the water temperature modeling, the River hydraulics and meteorological parameters including River flow discharge, flow velocity, air temperature, humidity, wind speed and cloud cover during 7-year statistical period (2006-2012) were considered as input parameters and River water temperature was selected as output parameter. Results: Based on the comparison of the results of different GEP models with 1 to 6 input variables, it was concluded that the GEP model with 6-parameters has the highest accuracy in terms of the coefficient of determination and the root-mean-square error. These values were obtained 0. 92 and 1. 8 ˚ C for training data and 0. 90 and 2. 3 ˚ C for the testing data. The mean absolute errors of this model were obtained as 14. 67% and 12. 80% for training and testing phases, respectively, while the error of linear regression model was obtained greater than 38%. Results showed that in comparison with the multiple-linear regression model, the GEP model has better performance for River water temperature estimation. Conclusion: According to the results obtained in this paper, one can use the GEP model for prediction of River water temperature with acceptable accuracy. It is concluded that in addition to the air temperature which has the highest impact on the River temperature, the River flow discharge also has considerable impact.