نشریه پژوهش های حفاظت آب و خاک
سال بیست و هشتم شماره 3 (امرداد و شهریور 1400)

Human encroachment in rivers, such as the construction of a structure (bridge) or deformation of the bed, has affected its natural flow, which leads to the phenomenon of scouring and the creation of holes in the natural bed river. After deformation of the bed due to sedimentation and erosion, these holes can move in the longitudinal direction of the river and cause various damages to the structures and facilities in the riverbed as well as the bridge pier. Bridges are one of the most important access structures whose failure has irreparable social effects, so the effect of mining material holes on the bridge piers can be very important. The extension of mining material holes along the riverbed and its movement towards the bridge piers and accompanied by the scouring phenomenon and turbulent flows formed around the piers causes the destructive effect of erosion and overturning of the pier. Therefore, in this study, the effect of mining material downstream of the cylindrical bridge pier on the surrounding scour profiles is investigated with changes in the depth and distance of the mining material hole from the pier .

For this purpose, on an experimental model and in clear water conditions and constant flow, changes in the profile of the hole and the effect of the depth of the hole and its distance from the pier to the scour profile around the bridge pier were evaluated, by mining holes with H/D= 0.8, 1.6 (ratio of hole depth to pier diameter) and with I/D= 10, 20, 30 (ratio of hole distance from pier to pier diameter) downstream in sediment bed with depth 0.1 meters.

The results of experimental observations showed that in the case without mining hole, the lowest maximum scour depth related to the experiment was obtained with a Froude number of 0.26 at 9 mm; While the highest maximum scour depth was related to the experiment with a Froude number of 0.46 of 60 mm. Compared to the case without a mining hole at the Froude number of 0.43, the lowest maximum increase in scour depth in the hole harvesting experiment was with H/D=0.8 and at I/D=20 by 8%. While the highest increase in maximum scour depth in the experiment with hole removal was 26% with H/D=1.6 and I/D= 10. In order to find the optimal distance for mining materials downstream, experiments with I/D=30 show the maximum values of scour depth equal to the case without mining material holes. Therefore, by increasing the distance from the pier I/D=10, 20, and then 30, the maximum increase in scour depth compared to the case without a mining hole decreased from 26% to 15% and then to zero%.

By observing the general results, it is possible to comprehend that mining material from the channel bed downstream, affects the amount of scour depth and increases it, and by increasing the mining hole depth and reducing its distance to the pier, the scour depth around the pier increased. Also, in order to predict the maximum scour depth, relationships in the case without mining hole and also for the case with it have been proposed using the obtained data based on regression analysis. The accuracy and also the scope of application of these relationships are mentioned with statistical indicators.

There are various methods to prevent the entry of suspended sediments into the irrigation canals, one of which is the construction of sedimentation ponds at the beginning of the irrigation network. Sediment efficiency, which is the ratio of the concentration of outlet sediments to inlet, should be determined before designing the sedimentation pond according to the geometric dimensions of the structure, hydraulic properties and characteristics of inlet sediments to be planned for management and operation. The purpose of this study is to present a one-dimensional model of sedimentation in the sedimentation pond by considering the sedimentation of inlet sediments, which in addition to estimating the trapping efficiency in the pond, also calculates changes in the pond floor, sedimentation of sediment outlet and sediment concentration in each section.

n this study, in order to simulate sedimentation in the sedimentation pond, first a numerical model was developed and then the effect of the geometric factors of the pond on the sediment trapping efficiency was investigated. In the developed one-dimensional numerical model, the governing equations of flow and sediment were solved, respectively. To validate the results of the numerical model, El-Baroudi (1969) laboratory data were used, which include a rectangular sedimentation pond with a length of 1.2446 m and a width of 0.4572 m. For different discharges, El-Baroudi deposited 200 mg/l of sediment with a specified diameter into the sedimentation pond and after a certain period of time measured the concentration of the effluent from the pond. Also, field data of Nekoabad sediment catchment area of Isfahan (Shetab-Boushehri et al., 2010) were used for validation.

The results of trap efficiency verifications showed that the mean value of the square root of the mean square error of the numerical model for El-Baroudi (1969) experiments was 6.15% and for the left and right sedimentation ponds were 8.13 and 6.77%, respectively. Also, the trapping efficiency was investigated for all sediment particles and for each group of particles in relation to the length of the pond. The results showed that with increasing the distance from the beginning of the pond, the amount of sedimentation efficiency increases so that at the end of the pond The sediments are deposited in the left and right basins, respectively. The floor level of the sedimentation pond also changes due to sedimentation of sediments. The rate of these changes in the floor of sedimentation ponds at the beginning of the structure is higher than the end due to the high concentration of inlet sediments. The amount of these changes in the bottom of the left and right sedimentation ponds using the numerical model simulation of the present study after three months was about 23.4 and 20 cm, respectively.

After developing and validating the numerical model, the performance of Nekoabad sedimentation ponds and El-Baroudi laboratory model were investigated using the numerical model. The results showed that the average sediment trapping efficiency for the left and right sedimentation ponds was 36.5% and 27.3%. Therefore, a large amount of sediment enters the irrigation network. In order to improve Nekoabad sedimentation ponds and increase sediment trapping efficiency, the length, width or depth of the pond can be increased. For this purpose, by increasing one of the above variables and keeping the other parameters constant, the numerical model was executed and the trapping efficiency was calculated. The results showed that increasing the length of the left sedimentation pond and increasing the width of the right pond of Nekoabad Dam has the greatest effect on the trapping efficiency.

The most common methods used to estimate and spatialise precipitation data are geostatistic methods and satellite images. Today, satellite rainfall products have become very popular in preparing rainfall maps. These products use satellite imagery to estimate precipitation in places with no observed data and are usually associated with a large error and require calibration. Interpolation methods also estimate precipitation data using recorded data. It seems that the combination of interpolation methods and satellite images can be effective in increasing the accuracy of rainfall maps, especially in areas with complex topography such as Mazandaran province

In this study, in order to evaluate different methods of estimating precipitation in Mazandaran province and combining satellite images with interpolation methods, precipitation data from 21 synoptic and rain gauge stations and 24 monthly images and 2 annual TRMM satellite images were used in 2012 and 2015 that the spatial resolution of this satellite product is 0.25 * 0.25 degrees. The studied interpolation methods included Kriging and Inverse Distance Weighting. Also the accuracy of rainfall products of TRMM satellite was investigated. In addition, to increase the accuracy of rainfall maps, multiple linear regression were used to combine satellite images with latitude, longitude and altitude covariate. The investigated methods were evaluated using the Root Mean Square Error and Mean Bias Error indices and regression analysis. Also the annual rainfall maps of the province for 2012 and 2015 were drawn and analysed.

In this study, 5 theoretical semivariogram models were fitted to the data, that the spherical and exponential models was selected as appropriate models. Also the coefficient of determination of selected variogram model and the ratio of structured part to total variation showed a relatively strong variography anlysis and the effective range of precipitation data wasobtained about 80 km. Correlation coefficients of covariates and precipitation in most months provided acceptable results and were significant in almost more than 50% of the studied months. As a result, the coefficients of determination of four-dimensional gradient regression equation also showed satisfactory values, so that the used covariates explained between 10 and more than 70% of the precipitation variations. evaluation of investigated methods showed that interpolation models and TRMM satellite network data are not efficient in estimation of precipitation in the province and the use of covariates in the gradient method could reduce the error estimation of rainfall data by 20 to 40 percent. Investigation of Bias error showed that TRMM precipitation network data, despite good correlation with observational data, has about 5 times more underestimation error than other interpolation methods, but the combination of TRMM network data with other covariates in the 4-dimensional gradient method has reduced the MBE to zero. Regression analysis of the studied methods showed a significant advantage of the 4-dimensional gradient method that the slope of this method is 3 times more than the geostatistical methods, which shows the performance of this method in detecting low and high rainfall rings in Mazandaran province.

The results showed the superiority of the 4-dimensional gradient method in spatial rainfall estimation of Mazandaran province and showed the role of covariates in increasing the accuracy of rainfall maps, that use of the selected method reduced the estimation error of geostatistical methods and TRMM network data by 30% and 40% respectively. The results of this study showed that the combination of satellite raifall products with interpolation methods will lead to more accurate estimation of precipitation in highlands and the points with no recorded rainfall data.

Iran is one of the countries with the highest production of greenhouse gases in the world, which according to estimates is a significant part of these effects are related to agricultural activities. There are various methods for assessing the environmental impact of agricultural activities. Life cycle assessment is one of the methods for assessing the effects of sustainability that has been developed based on the product production process. Existing methods for assessing the effects of life cycle and determining the effects of agricultural activities are determined by classifying and modeling the evaluation and possible changes in soil quality indicators as a result of agricultural activities in the field. The main purpose of this study is to investigate the environmental effects of the forage maize production system using the Life Cycle Assessment (LCA) method in order to better manage and control these effects.

The study area is an educational farm of the University of Tehran with an area of 260 hectares. The required information was collected through interviews with field experts. The amount of inputs used and the emission of pollutants in several groups of effects including global warming, eutrophication, acidification, surface water poisoning and ozone depletion, classification per functional unit (one ton of forage corn) are determined and their effect on the exchange life cycle. Life cycle evaluation calculations were performed by Sima Pro software.

The results showed that (1): The most environmental degradation due to forage maize production is related to surface water pollution with a value of 1.94×10-13 kg, 1,4-DBeq that chemical fertilizers and irrigation have the most effect on this pollution 1.33×10-13 and 4.96×10-14, kg 1,4-DBeq, respectively: (2): The value of the environmental index is 2.19×10-13 points or 0.219 picopoint. It was calculated that the normalized values of the effect groups are due to the production of fodder corn, which is calculated by multiplying the total amount of contamination of each effect group by the normalization and weighting factors, specific to each effect group. The lower the value and the closer it is to zero, the less environmental impact of the product is less.

Using different methods of crop management such as the use of organic inputs, rotation, nitrogen-fixing plants, and tillage, at least based on the using of low input principles to reduce these environmental effects and also by selecting appropriate methods of irrigation yield and optimal crop yield management environmental degradation reduced these operations. The solution that can be proposed and implemented to reduce the effects of this operation is to use different methods of crop management such as the use of organic inputs, rotation, nitrogen-fixing plants, and tillage at least, based on the use of minimizing principles to reduce these environmental effects. By selecting appropriate methods for irrigation and optimal management of water consumption while increasing crop yield, the environmentally destructive effects of this operation were reduced.

Soil erosion is one of the factors that can reduce soil permeability in watersheds and thus increase the risk of floods. Plant biodiversity is weakening and the sediments pollute the surface water and fill dam reservoirs. In recent decades, various watershed management measures have been taken, including the construction of sediment dams and conservation measures such as exclosure in watersheds to reduce the effects of erosion throughout the country. The present study was conducted to investigate the effect of watershed management measures on vegetation, sediment and phosphorus content, organic carbon and sediment granulation in Zidasht Taleghan paired watershed.

The study area is Zidasht Taleghan paired watersheds located in Alborz province, which includes control watershed and treated watershed with an area of 92 and 104 hectares, respectively. Using 1: 25000 topographic maps and field survey in rangeland areas, vegetation types were identified and studied. Also, percentage of canopy cover, rocks and, biomass and bare soil percentage were measured in 35 plots in sample and control watersheds and the average of each factor was calculated. The amount of sediment was also measured by measuring the total volume of sediment accumulated in the reservoir tank of both areas. Three samples were taken from the sediments of each outlet of the watershed and the amounts of total phosphorus, organic carbon and particle size distribution were measured in them. The total amount of phosphorus and organic carbon output from the watersheds was also calculated.

The results of vegetation assessment showed that the percentage of vegetation in the treated watershed (53.9) was about 8.7% higher than the control watershed (45.2). The results of evaluation of outflow sediments showed that the amount of outflow sediment in the treated watershed (520.5 tons) was about 72% less than the control watershed (34.06 tons). In other words, the portion of the control watershed was 86.05% and the treated watershed was 13.95% of the total reservoir sediments in the output of the watersheds. The results of particle size distribution also showed that the percentage of particles with a diameter less than 0.5 mm in the treated watershed (26.8) was 18.6% higher than the control watershed (8.2). Also, the amount of total organic carbon (40.26 kg) and total phosphorus (13.44 kg) in the sediments of the treated watershed were 11.81 and 70.88% less than organic carbon (51.9 kg) and total phosphorus (78.82 kg) of control watershed, respectively.

Watershed management measures have prevented the transfer of sediment and fertile soil to downstream, especially in the reservoir of Taleghan Dam. Although these elements in the watershed increase soil fertility, improve plant nutrition, increase soil permeability and create strengthening conditions for plants and soil, if they enter the downstream and the main river due to erosion, they will have the opposite role and cause pollution and reduction. The cost of improving water quality will be compensated with implementing watershed management measures, due to the low cost of implementing watershed management measures.

Development of agricultural lands, the occurrence of droughts, and climate change have made the Maroon-Jarahi basin to become one of the most stressful basins both quantitatively and qualitatively. Due to the existence of numerous irrigation and drainage networks in this basin, it is very important to investigate the effect of returned drainages on the river. Due to having suitable water potential, the study basin has always been suitable for the development of irrigation and drainage networks, also Shadegan Wetland at the end of the basin has increased the importance of quantitative and qualitative water resources management. Therefore, in this study, the effect of drainage from irrigation and drainage networks and traditional agriculture on the quantity and quality of rivers, and more importantly, the endpoint of the Jarahi River and the entrance to Shadegan wetland was investigated. Quantitative and qualitative simulation of the basin for a period of 60-year was performed by the WEAP model. Considering that none of the studies conducted in the Maroon-Jarahi basin has comprehensively and accurately examined all agricultural drains and critical points of the basin from a quantitative and qualitative perspective, so the study was conducted in this regard.

In this study, the WEAP model was used as a comprehensive tool for quantitative and qualitative Modeling and their effect on downstream. First, the WEAP model was calibrated and validated in a period of 5-year (2012-2016) using the observed data. In order to evaluate the results of calibration and validation of the quantitative model, the statistical indices of root mean square error (RMSE), squared correlation coefficient (R2), and NASH model efficiency coefficient were used. The model was implemented for a 60-year simulation period (2017 to 2077) under the control management scenarios of network drainage in terms of quantity and quality to determine the effect of each drainage on the river system of the basin.

The results of the model showed that the amount of salinity in the reference scenario is 3.6 (dS m-1) which in comparison with other scenarios only in Matbag drainage transmission scenario with a decrease of 34% (1.2 (dS m-1)) salinity compared to the reference scenario. This rate of salinity improvement is very important at the end of the Jarahi River and the entrance of the Shadegan Wetland and will have an excessive effect on the environment. Also, according to the reliability values of the environmental node of the Jarahi River, the difference between the reliability in the two references and the Matbag drainage transmission scenarios is 0.4%, which shows the minor effect of the Matbag drainage on the flow of the Jarahi River and also the reliability of other scenarios is equal to the reference scenario.

According to the results of quantitative and qualitative modeling in the Maroon-Jarahi basin, the Matbag drainage transmission scenario (left drainage network of Ramshir) has the maximum effect in terms of quality compared to other scenarios. If this drain is transferred, the salinity at the end of the basin during the simulation period will decrease by 1.2 (dS m-1) (34%).

The groundwater level of Silakhor plain has decreased significantly with the occurrence of successive droughts, industrial growth and increasing water needs. In addition, the cultivation pattern of the region in recent years has tended to cultivate water crops, and the combination of these events raises the need for efficient management in the allocation of limited water resources in the region. In this study, in order to sustainable management of groundwater resources, the optimal cultivation pattern of major crops in Silakhor plain has been determined, with the aim of maximizing farmers' net income and available water and land constraints. In this regard, two approaches to using Linear Programming (LP) and using Multi-Objective Meta Heuristic Algorithms in different exploitation scenarios have been investigated and the performance of different penalty functions in algorithms has been evaluated. Also, how to change the optimal cultivation pattern by increasing groundwater exploitation has been studied.

In the first step, after modeling the rainfall of the last 10 years using Artificial Neural Network (ANN) and Genetic Programming (GP) and selecting a better model in terms of accuracy, rainfall for the next three years was forecasted and groundwater recharge was estimated. Then, for each crop year, 100 different exploitation scenarios were considered according to the groundwater recharge and water exploitation in previous years. In the second step, using LP with the aim of maximizing farmers' incomes and available water and land constraints, the optimal cultivation pattern was obtained in the determined exploitation scenarios. Finally, in order to unbound the problem, the mentioned constraints were implemented as static, dynamic and classified dynamic penalty functions in MATLAB software. Then, the performance of three algorithms NSGA-Ⅱ, SPEA-Ⅱ and PESA-Ⅱ with the objective functions of maximizing farmers' incomes and minimizing penalty functions, to achieve the optimal cultivation pattern obtained from LP was examined.

The results of this study indicate that although with the increase of groundwater exploitation, farmers' incomes increase in the optimal cultivation pattern; However, in the exploitation of more than 223.5, 222.2 and 225.1 million m3 for the cropping years 2020-2021, 2021-2022 and 2022-2023, respectively, the limitation of the total arable land in Silakhor plain prevents the increase of crop cultivation and the area under cultivation of crops remains constant and consequently the income of farmers does not change. The results of the study of algorithms and penalty functions also show that in this problem, the best performance among the algorithms belongs to SPEA-Ⅱ, PESA-Ⅱ and NSGA-Ⅱ algorithms, respectively, with an average number of iterations of 12.1, 14.5 And is 17.8. Among the penalty functions in all three algorithms, the best performance belongs to the classified dynamic, dynamic and static penalty functions with an average number of repetitions of 13.1, 13.7 and 17.5, respectively.

In general, it can be seen that the optimization of the cultivation pattern in different exploitation scenarios provides a comprehensive view to the authorities for the sustainable management of valuable and limited water resources and its optimal allocation. In this regard, the use of SPEA-Ⅱ algorithm with classified dynamic penalty function in determining the optimal cultivation pattern leads to desirable results.

The formation of jumps in relaxation ponds plays an effective role in the depletion of flow energy at the bottom of aquatic structures. Hydraulic jump is a type of fast variable currents that changes from supercritical to subcritical mode if the channel conditions downstream are suitable. In this research, a new method has been proposed to reduce the conjugate depths and jump lengths, in which the characteristics of a fast free rectangular jet and floor roughness have been used to influence the jump characteristics. The fast jet hits the jump and the amount of motion transferred to it affects the jump characteristics and position.

In this study, a laboratory study was performed with a set of experiments in a channel with glass walls 10 meters long, 0.3 meters wide and 0.5 meters high. In order to investigate the effect of flow rate, jet angle, inverted slope and floor roughness at 2, 2.5 and 3.2 liters per second on the hydraulic jump profile of three flow rates, the angle with a maximum displacement of 90 degrees, 60 degrees per second for Jet and four angles were used for the horizontal direction of the jet, including the displacement of the beginning of the jump and the angle without changing the beginning of the jump and three types of roughness.

The experimental results showed that for a given jet angle, at different discharges, the hydraulic jump has no displacement, which was named as the inert angle. With the increase of the jet angle, the jump moved upwards and from one angle onwards, the jump did not move upwards, which was also named as the maximum displacement angle of the jump. Changing the angle and flow rate of the jet reduced or increased the secondary depth, jump length, relative energy loss and shear force of the bed. The reverse slope and roughness reduced the hydraulic jump characteristics. At a slope of 2.25 and a distance of d and a jet angle of 3.2, the most changes were observed in the hydraulic jump characteristics.

Experimental results showed that by increasing the shear stress, it intensifies the effect of reverse slope and increases the roughness of the channel floor due to increasing shear stress, intensifies the effect of reverse slope on the length of the jump. In these changes, the effect of the downward component of the weight force on the reverse slope and the increase in shear stress on the rough bed can be considered as the main cause of the changes. Inserting the jet into the jump at an angle greater than the inert angle reduces the ratio of conjugate depths, jump lengths, and increases energy loss and floor shear forces.

In recent years, many coastal areas have been exposed to the pollutant threats. The occurrence of pathogenic bacteria in recreational beaches has made difficulties in these areas. Resistance of these bacteria to antibiotics has also worsened the situation. Therefore, this study aimed to investigate the occurrence of coliforms and antibiotic resistant Escherichia coli, as an indicator bacterium, in the swash zone of Caspian Sea, Guilan province.

Nine popular coastal areas in Guilan province including Rudsar, Chamkhaleh, Aminabad, Jafroud, Sahele-Ghou (Anzali), Rezvanshahr, Gisum, Sahele-Zomorrod (Haviq), and Astara were selected for this study. The sand beaches were sampled in three replications from 0-20 cm depth in the swash zone. The coliform number was counted on the EMB medium. pH and EC were also measured in 2:1 sand:distilled water suspension. Then, E. coli as an indicator bacteria was isolated and its resistance to antibiotics was determined by disk diffusion method on Mueller-Hinton agar medium. Broad spectrum antibiotics including cephalexin, gentamicin, doxycycline, ceftriaxone, ciprofloxacin and trimethoprim were tested. Data for pH, EC and coliform number were analyzed in a completely randomized design and for the zone of inhibition (ZOI) test a factorial arrangement experiment in a completely randomized design was adopted. Also, mean comparisons were done by Tukey test (p<0.05).

In all sampled areas, the pH was alkaline and its highest value was obtained in the Jafroud beach sand. The highest EC value was obtained in Aminabad beach sand which was significantly different from EC values in other sampled sites (p<0.05). The highest number of coliforms was obtained in Sahele-Zomorrod sand beach (5.8 Log CFU g-1). The effect of sampling site and antibiotic interactions on the ZOI of E. coli showed that in three sampling sites including Astara, Gisum and Rezvanshahr the isolated E. coli was resistant to none of the tested antibiotics. In the other six sites except Sahele-Ghou (Anzali), it showed resistance to cephalexin. The isolated E. coli showed resistance only to cephalexin in Jafroud. While it also showed resistance to ceftriaxone in Rudsar, Chamkhaleh (eastern beaches), Sahele-Ghou, and Sahele-Zomorrod.

Overall, the beach sand of the western coastal areas had a lower pH and EC values and higher total coliform number compared to the eastern and central coastal areas. In all studied places, the coliform number was above the standard level for recreational sites. In eastern coastal areas; Chamkhaleh and Roudsar, isolated E. coli showed resistance to both cephalexin and ceftriaxone antibiotics. Thus, the management of microbial contamination especially those that are resistant to antibiotics needs more attention in the eastern coastal areas in Guilan province.

Nowadays, decision-makers consider the integrated management of crisis and risk management in the face of drought. So far, the North Khorasan Province has suffered a lot of damage due to the drought risk. Therefore, in this case study, determining drought vulnerability and type of meteorological drought risk condition are major research problem in the last three decades, especially.

In this research, the Deciles Index (DI) was used to determine meteorological drought conditions. Firstly the monthly rainfall statistics were collected and tested for accuracy, precision and homogeneity of data from 27 selected meteorological and rain gauge stations during the period from 1990 to 2015. Accordingly, the factor of percentage of droughts occurrence and were determined with yearly time scale for each station, and then the Drought Hazard Index (DHI) was extracted for each of the different intensities. Then, the drought hazard index was extracted by assigning weights and degrees to each drought class based on drought severity. Meteorological drought vulnerability was also calculated using physical and socio-economic indicators. Subsequently, vulnerable areas of drought were identified. Finally, drought Risk quantification was calculated based on two factors: potential drought hazards and vulnerability rate, and then drought risk areas were specified.

The results of research on drought conditions showed that the most severe droughts occurred in the region in 1990, 1995, 2001 and 2008. Based on the drought hazard index, the results showed that the south western area and part of the northeast of the region, equal to 41.13% of the province, is a region that is prone to severe droughts. The largest of area (64.36% of the area) that located in the eastern part of the province has had severe drought vulnerability. Generally, about 85 percent of the total area of North Khorasan province has been affected by severe to moderate drought vulnerability. Also, about 75 percent of the entire area of the province has a moderate to severe drought risk.

The results of this study indicate that the hazards and vulnerabilities caused by meteorological drought seriously threaten North Khorasan province. The meteorological drought risk maps can be a helpful alert tool at risk reduction plans for all policy makers, managers and stakeholders in the research area. This issue is of particular importance in the planning of agricultural activities, the optimal use of water resources and green water management, especially in this province, where the livelihood of its agricultural also depends on rain-fed agriculture.

The city of AqQala has been constantly exposed to floods in the Gorganrood River in the past, which is determined by examining the general characteristics of water structures, especially the historic bridge in the city center. The flood of March 2019 was one of the most destructive floods in this region, which left very bitter memories for our compatriots. In the management of this flood, a series of previous studies using different flow simulation models, past experiences to deal with floods and using the experiences of previous floods should increase accuracy, speed and reduce costs. At the time of the flood and the entry into the city of AqQala, in order to drain the water, those involved in the ring road and the railway line that was located in the flood route were considered to be the main reason for the large flood in the northern part of AqQala and the persistence of floods in the city. Destroyed in several places. Therefore, in this study, the effect of the ring road and railway line on the flooding rate of AqQala city has been investigated.

This research was conducted using HEC-RAS, GIS software and HEC-GeoRAS add-on. In order to investigate the effect of the ring road and railway line on the flood rate of AqQala city, this effect in three scenarios (absence of ring road and railway line, existence of ring road and railway line with coils installed in the route and existence of ring road and railway line It was discussed along with the embedded culverts and the cracks created in the path during the flood) was discussed.

Examining the three scenarios discussed in this study, it was found that in the first scenario, we see flooding of a large area of the city of AqQala, so that 1.38 square kilometers of the city has been flooded. The second scenario shows an increase in flooding and intensification of floods in the city compared to the first scenario, which causes flooding of 2.53 square kilometers of residential land, and the third scenario shows the positive effect of cracks created during floods to reduce flooding in the city Which has reduced the amount of flooding to 1.98 square kilometers.

Although the low level of ground level in some areas of AqQala city such as Eidgah, Moallemabad and Hakimabad, the flooding of these areas is obvious, a comparison of the first and second scenarios showed that the location of the ring road and rail line Railway in the direction of flood movement has increased the extent of flooding and submergence of some other areas and neighborhoods and the persistence of flood flow in the city of AqQala. On the other hand, by comparing the second and third scenarios, it can be concluded that the lack of procrastination and rapid decision-making regarding the gap on the ring road and railway line, could have reduced the relative flooding of the city and the persistence of floods and submerged some Avoid areas.