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In the summer of 2001, an intense thunderstorm in southeastern Caspian Sea triggered a catastrophic flood in the Madarsoo basin . Use of methods including high-resolution aerial photographs and satellite images interpretation, multi-date mapping, hydraulic calculations and field observations made possible the documentation of the geomorphic impacts on the Madarsoo River and its tributaries. Geomorphologic effects of this catastrophic flooding included: trees up to 2m in diameter were scoured from the main river channels and locally as much as 80% of trees crown cover was removed from riparian zones. The scour of trees exposed the underlying flood plain to macro turbulent scour, leading to extensive removed of flood plain sediments that had accumulated over centuries. Other hydro-geomorphic impacts of this flood have been drainage network modifications create new alluvial fans, new meandering pattern and gully development that all of them have been documented by authors. Subsequent to the mentioned flood two other extreme floods also affected the basin in the August of 2002 and 2005. In addition to causing further landform modifications, It wiped out the infrastructure which was reconstructed posterior to 2001. All three floods were in the same conditions on the basis of their time, climatic and triggering characteristics. The peak flood was estimated 700m3s-1 in August 2002, and also 1060 m³s^-1 August 2005. the occurrences of the two above mentioned catastrophic floods and related processes were result of triggering variables, forming a new dynamic environments by the main event (August 2001 flood), Which prolongs the required time for recovery of stream channels. Geomorphic instabilities lead to consecutive Crises in this new environment. This Condition accelerates geomorphic hazards in combination with the effects of recent climatic

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Past decades damage by floods in Iran and on the other of the world has shown that we have still much work to do to cope with this problem. Hence, the study of these events and development of more effective adaptation and mitigation policies has become a priority, in other parts of the globe. First step in achieving flood risk assessment is data collection. Availability, suitability and quality of hydrological, meteorological, topographic and management data is discussed. This study combines a hydrologic and geomorphic data with aim of geographical information system to delineate the extent of a flood event in the Ojan Chay basin (98,227 km2), one of the river system draining into the Aje Chay River. For This purpose, the 16- information layer has been prepared for overlaying ​​using fuzzy sum and classified using Fuzzy C mean on the geomorphology data. The main objective of this research is to assess the flood hazard that affects Ojan Chay river basin, in order to develop a basis for further vulnerability and risk analysis.

Flood hazard risk presented in the map because that give a more direct and stronger impression of the spatial distribution of the flood risk than other forms of presentation. The results of this study show that more than 70% accuracy (Kappa coefficient 0.7502459) compared with reference data, indicating the acceptability of this method is the mapping of flood hazards.

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The use of new methods of Remote Sensing (RS) and Geographical Information System (GIS) in zoning the flooding potential and its variations in a particular geographical area (Tang-e-Bostanak Catchment Area) constitutes the main subjects of this study. In this regard, the production, combination, and composition of effective information layers such as K index and run off in identifying these zones have been noted, highlighting the capacity of GIS. Theaim is the identification and percent of flood zoning and their variations within an 18-year period by RS and land use variation maps. In this study, we have observed excess rainfall under the curve number (CN). According to the results, the above mentioned area isexperiencing a 15% increase in flooding during the 18-year period.

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Considering the most of country have no gage station, in recent year one method can be proposed with the involvement of other information, which will affect hydrology condition. It can estimate flood water level. In this study, considering relationship between geomorphology and hydrology, using little information, flood hydrograph were simulated. This method is named geomorphological instantaneous unit hydrograph (GIUH). At first, the drainage basin was ranking using Strahler method. Then, the quantitative geomorphologic parameter concluding ratio of bifurcation (RB), ratio of area (RA), ratio of length (RL) and length of last order (L&Omega) were calculated considering this ranking. Then using these parameters and the peak flow velocity in outlet, peak discharge in outlet and time to peak of instantaneous unit hydrograph were calculated. For model evaluation, five events were selected from hydrometry station in outlet of basin, compared with computational hydrograph using GIUH model. Result show that, this model is suitable for this area, and little difference between observed and computed hydrograph was due to construction of earth dams in upstream, which affect hydrology conditions.

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Flooding is a natural hazard events and Survey data from the annual losses due to flood in Iran and the world show the extent of the flood damage caused on natural and human resources. To estimate height of the runoff and discharge maximum in basins and stream erosion, there are various experimental methods and mathematical models that one of these models, SCS model is. Thus, the aim of this study was to estimate the Runoff coefficient and Maximum discharge by Curve Number method with different units forming the Fyruzkla Kojoor basin and zoning maps of potential runoff and stream erosion in the drainage basin is. After mapping the watershed CN and S, to calculate the volume of runoff produced in the region, short-term rainfall for different return periods were calculated using Pearson distribution of type III. According to the map of potential runoff in the basin, forest land has the lowest runoff potential and pasture lands have the greatest potential to generate runoff and erosion is occurring and also has the lowest penetration. The middle part of the basin, the most prone to runoff and erosion and gully formation in the region are. After determining the height of the basin surface runoff, peak discharge was calculated for various hydrological. The highest values of maximum flow rate are based on rangeland with hydrologic group D.

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Floodwater spreading (FWS) has an important role in floodwater control, groundwater recharge, restoration and enhancement of vegetation and desertification control. Since the flood causes the transporting of soil particles including organic materials, the floodwater spreading project can be a suitable place to sequestration of organic carbon in sediment yielded by flood. The knowledge of soil organic carbon stock (SOCS) changes affected by different process can be important in realizing of these process roles in world carbon cycle and consequently in greenhouse gases effects mitigation. Therefore, the objective of this study was to evaluate SOCS in floodwater spreading project in the Zahab Plain. In view of this, 9 FWS strips based on random block design divided into three higher, middle and lower strips as well as each strip divided into three initial middle and final sections and sampling carried out in 0-20 cm depth. Soil organic carbon concentration and bulk density in 42 samples from FWS project and control areas were measured and SOCS were calculated. The results showed that SOCS in the three divided strips of floodwater spreading and control area as well as three sections of each strip with control area was significantly different. But the SOCS within divided strips and sections were not significantly different. The mean of SOCS in 0-20 cm depth in the three sections and control area were 1.29, 1.02, 1.53 and 4.61 Kg m^-², respectively (P < 0.05) and  the mean SOCS in three sections of strips initial middle and final sections was 1.04, 1.16 and 1.64 Kg m^-² respectively (P > 0.05). Overall, transported sediment with low organic carbon concentration from upstream catchment or exporting of organic carbon as dissolved organic carbon have been caused to low increasing of SOCS in Zahab Plain floodwater spreading.

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The dimensions, shapes and the patterns of natural rivers change according to their dynamic properties. These unavoidable changes cause the rivers imbalance and a new balance will be formed.  The around lands will be affected by this dynamic and dangers such as instability of the bed. In this research we used chronological inference method to study Kashkan River morphology. Kashkan river is located in a region between Lorestan province and Gavmishan bridge in a reach of 25 kilometers. The aero photos of 1334, 1376, the sensing images of liss3 obtained from IRS P6 satellite in 1385 and the Geo Eye image of the land were digitized in Arc GIS software. In the second step geometrical parameters such as wave length, valley length, sinuosity, central angle and radius tangent on the river arch were calculated. Then these geometrical parameters were statistically analyzed and were compared in 4 stages. We Using HEC-RAS investigated flood zonation as an important factor in river bed changes. The results of this study and comparing these parameters during the 4 reaches showed that in the abovementioned year s kashkan river pattern was meandering in the reaches of 1, 4 and 5 and also it was developed meandering form in the reaches of 2 and 3. Those river’s arcs which had the most changes in those years were located in the reaches of 2 and 3. At the end it was concluded that the geology factor and the river’s flood in the reaches of 2 and 3 were the most important factors in forming the bed’s changes and bank erosion. Topography factor was the most important factor in causing the most changes in the reaches of 2 and 3 which were located in floodplain.

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Flood spreading is among preventing method from damage of deluge, especially perishing of water and soil in latrine basins of arid and semiarid regions. Accumulation of sediments on the flood spreads regions lead to changes in soil fertility, revival and support of plant covering and controlling of desertification and change in physicochemical properties of soil in these regions. In order to measure of soil changes in the station of flood spreading Hashtbandi, Minab, Hormozgan, were dipped 12 cavities in two regions: flooded and control. Sampling was done from 0-30 cm and 30-60 cm depth. Physicochemical properties were evaluated in the samples. The obtained results indicated that the average of organic carbon, total nitrogen, amount of potassium and phosphorous, EC as well as sand percent significantly increased in the flood spreading region than control region and clay percent, pH and saturating percent (SP) decreased in the flood spearing region than control region. Beside, silt amount non-significantly decreased in the flood spreading region than control region. Generally, can be said flood spreading system changes the soil texture during the time and has positive effect on soil fertility. Increasing amount of macro elements such as N, P and k as well as reduction of pH are positive effects for enhancing soil fertility, although increasing EC may be limited planting of some sensitive crops.

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Extended abstract
 
1-Introduction
     The purpose of this research was evaluating the effect of the 120 -day's winds on flood flow entering deposit to Sistan region. At first, it became clear that flood flow path to Sistan area after the floods and droughts, according to the file work is randomly sampled from the flood deposits accumulated for a period of 3 years. Also, high deposit was measured with filed work in two periods before and after the begining of 120-days winds. In order to study the graded sediment samples and granulometry, the parameters were determined middle (D50), Mid-average, Kurtosis, Skewness and sorting. For analyzing the winds of the region WRplot view 8 and the harvest sand rose Software were used. In statistics study parameters of graded flood flow deposit entering to Sistan shows that the average particle size of sediment is 88 microns and mainly were fine-grained sediment. By determining the threshold of peak flow deposits, the frequency of prevailing winds and also draw sand rose of stations points of study, data shows that the high cumulative flow of sediment erosion affected by winds of 120 days of Sistan region. As the frequency of winds over speed ​​threshold is 100 percentages to study station. In study of sediments height, the results showed significant differences at 0.01 levels (p < 0.01) between the heights average of sediment before and after the beginning of 120 days winds in Sistan region. Therefore, according to analyzing Granulometry of Sediments transported by floods, determined threshold and the capability of carrying particles by local winds as well as field measurements, these deposits are the main resources harvested with starting 120- days winds along with flood flows intering Sistan region each year, eroding and causing a lot of problems in that region.
 
2- Methodology
   In this research we have provided data about the direction of rivers in Afghanistan country watershed. We used accessible images of Google Earth for determining peak flow path in the Sistan area and according to the luck ontinuity of flow in the region, areas that have been affected by flood flow was determined. In the following, it was found rods of Sistan region.  After the floods and droughts, during field operations, accumulated flood sediments samples were collected randomly. Also, the sediment level in scale (Sediments transported by floods and depth of drilled by wind sediments carried by wind) of the 14 points were measured. The above steps have been done during each incoming flow to the Sistan region during 3 years (2016-2018). To evaluate the constituent particles of sediment in granulometry, 60 samples were selected and analyzed in Sistan Agricultural, Natural Resources Research and Education Center lab. In the study of granulometry of sediments taken with respect to deposits collected by 20 sieves. The estimation depth of accumulated flood sediments for two stages before and after the 120-day winds flood in summer. Selected by accumulated flood sediments and high measured sediments. In order to study the graded sediment samples and granulometry, parameters were determined middle (D50), Mid-average, Kurtosis, Skewness and sorting. For winds of region analysis, we used WRplot view 8 and the harvest sand rose Software. In statistics study parameters of graded flood flow deposit entering to Sistan shows that the average particle size of sediment is 88 microns and mainly were fine-grained sediment.
3- Results

               By determining the sediment in granulometry, frequency curve of particle was drowning for each of the study samples. Drawing on sediment size distribution for each sample, the results of the study analysis parameters, were estimated the peak flow of sediment into the Sistan region. Based on the results, the median and mean values ​​of accumulated sediment on the bed river (Sistan River) and Hamon wetland were phi 6.2 and 6.4, respectively. Changes in these parameters are almost identical, but in some areas, the median value is greater than the average value which is due to finer grain particles. The general trend changes two parameters; the mean and median separable in study terms. In the first year, medians index was more than the average value of the samples taken which indicates that the presence of fine particles is more than coarse particles percent (the average size of silt). Whereas in the second year, the average of sediment samples taken increased the size of the fine silt particles coarser grain and reduced the fine silt particles in much finer grain. In the third year, the mean and median values ​​are almost identical and fine silt was deposited as sediment size. The result shows that the tilting parameter values of sediment samples of peak flow was from very good tilting (0.22) until very weak tilting (2.86). Study of parameter values ​​tilting this parameter indicates the rate of change between 0.14-0.76.

4- Discussion & Conclusions
In this study, for the first time has survey graded sediment input peak flow in Sistan. Then determine particle size and analyze the wind of the region, was estimated attrition of the sediments. In examining sediment samples in granulometry, during study period and the overall changes under the influence of mean and median and existence fine and coarse particles was perceptible in the overall trend analysis of these two parameters. Fluctuations in hydrological and hydraulic conditions prevailing in the bed of peak flow to Sistan area includes Sistan and Frahe rivers are determining particle transport in flood deposits. In support of this important Morphometry properties including sorting that reflects that the energy levels in sedimentary environments and energy situation is stable over time shows that the natural sediment sorting peak flow is not formed under the influence of hydraulic and dynamic conditions governing the flow of the river. In the other hand, because the rivers are seasonal and alluvial transmitter rivers transfer flood flows in the Sistan region, decrease the sediments have been sorted turbulent flow conditions along the river and rapid changes in river flow and erosion phenomenon over time. The results showed that sediment in granulometry of sediments transported during peak flow is always fine which has a low threshold velocity and due to the frequency and intensity of wind in the region, this has eroded sediments which effects of like phenomena dust and endangering the health of residents. Therefore, according to the analysis in granulometry of sediments transported by the floods and determined threshold, capability of carrying particles by local winds and field measurement, these deposits are the main sources of harvest starting with 120 days winds.

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Extended abstract
 
1- Introduction
An examination of the number of floods in recent years shows that floods are no longer a rare sudden disaster, but a growing phenomenon that, at any given time, causes a lot of damage, including life and death. As a result of interference in natural environments, the presence of multiple structures, and the lack of appropriate measures to protect these environments, flood conditions are provided. Also, with the rapid growth of urban development and the creation and development of infrastructure, floods in urban areas have become more and more severe. In our country, especially in the southern regions of the country, due to climatic conditions, floods are frequent and harmful. The growing trend of floods in recent years suggests that most of the country's southern cities are at risk of flooding. According to studies, about 40 large and small floods occur in different parts of the country every year. Experimental and managerial experience of different countries shows that the first step in reducing the harmful effects of floods is to identify flooding areas and zoning of these areas in terms of flood risk so that based on the results obtained with integrated management. And comprehensive urban planning prevented the harmful effects of urban floods as much as possible. This study aims at identifying potential flood areas of Bandar Abbas and Bandar Abbas strategic city using GIS, and adapting this map to the development plan of residential areas obtained from LCM model in remote sensing of satellite images as well as determining the flood risk areas.
2-Materials and methods
In this study, two steps have been taken to achieve the desired goals. In the first stage, using five height parameters, slope, land-use, lithology, and river mile have been used as effective parameters in identifying flood-prone areas. After preparing the information layers for each parameter, the layers are standardized using fuzzy logic. After standardizing the layers, a hierarchical analysis model (AHP) was used to weight the layers. After determining the weight of each layer, in the ArcGIS environment, the weight obtained is applied to that layer, and finally, using fuzzy gamma, the information layers are combined, and the final map of flood-prone areas is prepared. In the second phase, satellite imagery from the 1990s, 2000s, 2010, and 2019 was used to assess the development of residential areas to prone to flood-prone areas. After preparing the images, in the ENVI software, first the necessary pre-processing on the images, including radiometric and atmospheric studies, has been done, and then by using the maximum probability method, land-use maps of the study area related to the 1990s, 2000s, prepared in 2010 and 2019, were presented. After preparing the land use maps, IDRISI software and the LCM (Land Change Modeler) software were used to evaluate the trend of land-use change in residential areas.
3-Discussion and results
Evaluation of the final results of flood-prone areas indicates that a large part of the study area has a high flood-rising potential, so based on the results, the class has a very high potential for floods, 88 km² (equivalent to 28.7% of the study area). The study area includes mainly areas close to the river, low-slope, and low-lying areas. Also, the class with a very low potential for flooding includes 24 km² (equivalent to 7.8% of the study area) of the study area, which mainly includes the highlands and the northern slope of the study area. In addition, the results of the assessment of land-use changes indicate that land-use has undergone many changes during the study period, and the use of residential areas has increased. Assessing the trend of changes, shows that the increasing trend of use of residential areas has been due to population growth and construction development. The decrease in the use of vegetation and water area is also due to the development of the use of residential areas, which has caused the destruction of vegetation and the progress towards the coast. Also, the trend of changes in the use of weak pastures and salt marshes has been affected by the development of residential areas and climate change.
4-Conclusion
The results indicate that the study area has a high potential for flooding, so that about 170 km² of the study area (equivalent to 55% of the study area) have a high and very high flood potential these areas mainly include low-slope and low-lying areas of the urban area and the suburbs of Bandar Abbas. Therefore, in terms of used parameters, the city of Bandar Abbas has a high potential for flooding. Also, in this research, the trend of land-use changes and residential areas of the study area has been evaluated. According to the results, the use of residential areas (including residential areas and man-made areas) has grown so much that in 1990, this area was 32.2 km², which in 2000 to 42.9, and in 2010 it increased to 55.7 km² and in 2019 to 77.4 km². Assessing the spatial trend of land use changes indicates that a large part of the residential area has moved to areas prone to flooding. According to the results, in 1990, 14.2 km² of residential areas were located on the potential floor of many floods, which in 2000 to 16.4, in 2010 to 21.9 and in 2019, it has increased to 28.1 km². Therefore, it can be said that in recent years, a large part of the residential areas has moved to flood-prone areas.

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Extended abstract
1- Introduction
Floods are one of the natural events that cause human casualties and damage to buildings, facilities, gardens, fields, and natural resources every year. Urbanization disturbs the balance of slopes through indirect intrusion within watersheds, kills vegetation, soil compaction, and changes in the profile of waterways, increases the severity of floods, and increases the amount of sediment generated. At the foot of the mountain, which includes the city's physical fabric expansion area, the natural drainage pattern disrupts and increases the risk of urban flooding. On the one hand, because of its geographical position and the heavy rainfall regime over a short period of time, and on the other hand, because of its significant growth and development, especially during the last decade, and because of its location, the town of Bandar Abbas faces flood problems. On the other hand, flood risk zoning has not been considered so far in order to be used in the planning and management of flood protection and control in Bandar Abbas, and not much work has been done in this area in the form of research and even studies. Flood risk zoning is therefore important in order to forecast the degree of flood damage under various circumstances and the economic and social basis for flood control and containment systems. Risk modeling and flood vulnerability mapping will play an important role in future decision-making, flood management, and land management in the area of the study in some cases.
2- Methodology
In general, the first step in the implementation of research in watershed management, environmental, natural resources, agriculture, etc. projects is the preparation of the data used in that project. The data needed to investigate the hazard, vulnerability, and risk of urban floods in Bandar Abbas in the first stage are: 1- Height 2- Land slope 3- Distance from water table 4- Water transport capacity of canal 5- Distance from river 6- Distance from collection network of surface runoff was obtained from Iran Water Resources Management Organization and city demographic data Bandar Abbas was prepared by the Statistics Center of Iran. A map of four key factors, including building quality, urban density, population density and, socio-economic status, has been prepared to examine the vulnerability. Two models of Maximum Entropy (MaxEnt) and Support Vector Machine (SVM) were used to investigate the risk, vulnerability, and risk of flooding and urban flooding in Bandar Abbas. Then, the Area under Curve (AUC) obtained from the curve ROC was used in order to test the model's efficiency. After estimating flood hazard, a hierarchical analysis model was used in order to estimate flood vulnerability in this report. Finally,  the map of flood risk was obtained based on hazard and vulnerability maps.
3- Results
Based on the Maximum Irregularity Model, the results obtained from the flood risk prediction map showed that the southern parts of Bandar Abbas had a greater likelihood of flooding. It is also likely that parts of Bandar Abbas city center will be flooded. Bandar Abbas western and eastern areas are less likely to be flooded. Support has also shown that the southern, eastern, and southwestern regions are listed as likely to undergo urban flooding in order to help control urban floods. Using the SVM, the flood prediction map shows that the southern, eastern, and southwestern areas are more likely to flood; however, the northern and northwestern parts of Bandar Abbas are less likely to flood. The AUC was used in order to prepare the models. In the two phases of training and validation, the accuracy of the model suggests the highest irregularity. The Maximum Entropy Model, based on these curves, was 99.7% accuracy in the training phase and 94.2% accuracy in the validation phase. Therefore, in both the training and validation phases, the MaxEnt had excellent performance (area under the curve about 90%). The findings of hierarchical analysis have shown that the most important effective criterion for vulnerability is population density. The standard of construction, urban density and socio-economic status were ranked second, and fourth, respectively. Finally, on the basis of the risk map review, it can be claimed that there is a higher degree of risk in the southern parts of Bandar Abbas and parts of Bandar Abbas city center.
4- Discussion & Conclusions
The results of the model accuracy evaluation show that SVM has accuracy in flood probability spatial prediction and in identifying areas vulnerable to flooding. It can also be seen that the SVM had better performance than the model of the support vector machine. Since most urban areas such as Bandar Abbas lack reliable hydraulic and hydrological knowledge, a new approach to flood management and urban flooding may be the use of machine learning models and historical urban flooding events. Machine learning models are highly capable of spatial analysis of flood events and urban flooding, as well as extracting the relationships between environmental variables and flood events, based on the tests conducted. The flood risk map revealed in this analysis that the central and southern sections of Bandar Abbas are more susceptible to flood. Prioritization and expert studies have shown that among the factors influencing vulnerability, the population density factor is the most significant. The map of vulnerability based on different factors also showed that there is a greater degree of vulnerability in the central and coastal areas. Comprehensive flood risk analysis has shown that there is a high risk of flooding in the southern and central parts of Bandar Abbas and these areas have a high priority for urban runoff and flood control.

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1- Introduction
Over the past few decades, a variety of methods have been developed to study flooding, including the most important flood risk estimation methods proposed by researchers such as maximum possible flood risk and flood frequency analysis. In addition to the mentioned methods, that are methods which are mainly based on the use of GIS and remote sensing technologies and seek to investigate the flood situation using environmental parameters. It seems that the study of flood risk beyond natural phenomena is also related to human factors. In this regard, studies conducted on multiple floods show that despite the high efficiency of software in assessing hazards, none of these cases in practice has been able to prevent the occurrence of re-floods and the resulting losses. Human factors are also effective in the occurrences of floods. Considering the mentioned cases and the necessity of investigating the possibility of occurrence of floods and also the great importance of investigating the role of human elements along with environmental factors in the happenings of floods, the present study was conducted with the main purpose of investigating and analyzing the role of environmental components and humans in the occurrence of floods in Qaleh Chaie, which was taken from the experiences of floods in 2017.
2- Methodology
The present research, in terms of method, has an applied purpose and a descriptive contextualized nature.  To collect the required data for the research, the library and field methods (researcher-made questionnaire in a five-point Likert scale) as well as the experts' questionnaire (Delphi), were used. The implementation process of this research has been done in two general stages: in the first part of the research, the parameters affecting the risk of flood occurrence were environmental. The software used in this section was ARC GIS and ENVI software. Components used in this section include land topography (height), land slope, slope direction, distance from the river, vegetation density, flood characteristics, rainfall, and land use. Also, in the environmental component section, economic, socio-cultural, structural-institutional, and infrastructural variables have been used. The collected data were analyzed using statistical tests.
3- Results
The results of the analysis of satellite images in the field of topographic parameters of the land slope, slope direction, height, and distance from the Ghaleh Chaie River and others show that there is a big difference in different villages. The first group of villages that are located in the direction of Ghaleh Chaie are prone to floods due to the mountainous type of the region and also the steep slope, and the other group that is located at the end of the Ghaleh Chaie watershed has a very gentle slope due to its plain location and villages are less prone to face floods. Also, the results showed that from 1971 to 2017, 9 floods were reported in the area. In other words, the return periods of the floods are about six years. Also, since 1971, three floods have been reported, which killed four people in 1979, eleven people in 1990, and twenty casualties in 2017.
The results of one-way analysis of variance showed that the difference between 36 villages in terms of four indicators affecting flooding was significant at the level of 0.000, coefficient of 0.05%. Among these, the variables related to economic effects with the value of F = 13.524 have the highest level of expectation from the other three groups, followed by infrastructure, cultural-social and structural-institutional variables, respectively.
The study of the spatial distribution of the villages indicated that the villages near the Qaleh Chain River are vulnerable due to the high slope of the land, the mountainous nature of the region, the melting of snow, and the flow of water due to rainfall on the slopes of Sahand Mountain. Most of these villages are prone to be affected by environmental factors like slope, proximity to the river, mountainous topography, and so on.
 
4- Discussion & Conclusion
As it has been examined in this study, given that floods are recognized as one of the most destructive natural disasters in the world, the identification and investigation of areas vulnerable to floods as well as the identification of all natural and human components that might influence the occurrence of this this phenomenon can be the starting point for practical and effective planning in the field of flood prevention. Accordingly, in this research, the role of environmental and human factors in the occurrence of floods have been investigated simultaneously. The results show that villages located in mountainous areas with high slopes are very vulnerable to flooding. Since environmental parameters are beyond human control, their effects can be reduced by taking preventive measures. The results also showed that there is a relationship between human parameters and the degree of vulnerability of villages to floods, so it is suggested that to manage flood risk in rural areas, human and environmental components be taken into account and studied simultaneously.

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1- Introduction
Floods and their consequences, with the intensification of human exploitation of nature in the early twentieth century, have had negative effects on vital ecosystems. Also, adverse effects of erosion, while destroying the harvest site, lead to reduced production capacity and degradation of physical and chemical properties of soil in lands. To manage this phenomenon, the factors of production and flood must be identified and then areas with high potential in flood production must be identified to enable the possibility of executive and corrective operations at smaller and risky levels. The level of flood areas in the country is estimated at 91 million hectares, of which about 42 million hectares have moderate to very high flood intensity. Therefore, knowing the flood situation of the regions is a necessity to prepare strategic plans for sustainable management of basins. The purpose of this study is to estimate flood potential and determine the priority of flood areas by physical factors to combat erosion in Hajilar watershed by using a combination of data and information based on the CN-SCS method and also to determine critical flood areas.
2- Methodology
In this study, in order to investigate the potential and zoning of flood risk in the basin, at first, by studying and examining the foundations and theoretical background of the subject, the physical factors affecting the occurrence of floods were identified.Then, the required information was collected and layers of each of the proposed factors were prepared in Arc GIS 10.7 software and Arc-Hydro and Arc CN-Runoff extensions. In this regard, the information layers of the waterway network, level lines, and elevation classes were prepared using a digital elevation model with a scale of 1: 120,000. Lithological information layers were obtained using the geological maps of Siah Rud, Tabriz, belonging to the Geological Survey of Iran. The precipitation map of the basin was prepared using data from meteorological stations within the study area and also adjacent stations using IDW interpolation method. Land use layers of the area were obtained using the area land use map and monitoring using Sentinel 2 satellite imagery. The soil map of the region has been prepared using studies of natural resources of Arasbaran basin prepared by the Forests, Rangelands and Watershed Management Organization of the country and controlled with lithological conditions and other environmental factors. Vegetation of the area was prepared through NDVI index. Then, by extracting the number of curves (CN) and the amount of penetration (S), the layers were combined and the runoff height of the basin was estimated by the runoff curve number (CN-SCS) method, the units were classified by SPSS software and the priority of areas in terms of floods in the basin was determined. In order to determine the peak discharge of flood through the obtained data, first based on the proposed Schwab relation, the water accumulation time of all sub-basins was prepared separately and, finally, the maximum peak discharge obtained from this runoff was obtained.
3- Results
The results of the SCS-CN model which was intended to determine areas with different flood potential in the basin and compare it with environmental factors such as slope, lithology, land use, rainfall, etc in the basin indicate that this model is highly capable of estimating the flood potential in different areas of the basin. Results of changes in the number of curves based on effective environmental factors were also presented in Table 1.
The potential for runoff production was high in high altitudes with poor pasture landuse or dryland agriculture with poor permeability soil, as well as in residential areas where the city surface consists of impermeable or low permeability surfaces.Also, there was a high flood potential in the  dense and medium pastures with hydrological group B. Irrigated and rainfed agriculture with hydrological group A has the lowest runoff potential and thus has the lowest amount of flooding in the basin.By obtaining the runoff height in different parts of the basin and determining the levels of changes in the values through quartering, it was found that mainly the central and lower parts of the basin are in the first priorities in terms of flood potential. Poor coverage, low permeability, and low rainfall in this area are some of the factors that increase flood potential. The southern and central regions are areas marked by low sensitivity to flooding. By prioritizing areas in terms of floods and mapping them, the results can be used in watershed management operations at the level of high-sensitivity units to reduce erosion and damage. Taking into account the values of runoff height relative to the sub-basins and water accumulation time obtained based on the Schwab estimation method, the results showed that the flood volume and maximum peak discharge in the basins have a good relationship with each other and the highest maximum peak discharge is related to H33 and H18 sub-basins with volumes of 51.44 and 48.67 and the lowest is related to H12 and H29 sub-basins with volumes of 3.77 and 3.86 m3/s.
4- Discussion & Conclusions
Floods are among the most important environmental hazards that cause human and financial losses every year. In the meantime, using the SCS-CN experimental model, as a method for estimating floods in basins with different environmental conditions, and the inter-environmental approach in it can be a useful solution in watershed management studies. Considering that human intervention has caused an increase in floods in all areas, providing methods for accurate flood estimation is one of the basic needs of the relevant responsible organizations. Accordingly, the present study was conducted to determine the priority of areas in terms of flood potential and the results showed that 9% and 51% of the basin areas are in the very dangerous and high-risk flood categories, respectively. According to the final map obtained, Areas with very high risk and high risk are mainly located in residential areas and in the lower areas of the basin, which are the first priority in programs related to water resources, especially flood control and watershed management in the upstream units. Also, according to the results, areas with medium risk potential occupy 23% of the area and 17% of the area has low risk potential. The results of the study confirmed the high potential of the studied area in terms of flood risk, so lands with very high and high risk are lands that should be protected and appropriate watershed management measures must be conducted to control the speed of floods and reduce soil erosion.
 

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1-Introduction
Rivers are considered as the main sources of water for humans and other organisms, and sometimes this source of life causes destruction and irreparable damage. Predicting the hydraulic behavior of rivers in the face of potential floods to reduce damage to urban and rural areas, facilities under construction, farms and other existing uses around the river is of particular importance (Askari et al., 2014) because they can be used to provide measures and solutions to control floods and minimize the damage caused by it. One of the key topics in geomorphology, engineering and river management is the morphology of river canals, which provides useful information about the geometric shape, bed shape, longitudinal profile, cross sections and their deformation and location over time (Yamani et al, 2012). ). Hejazi et al. (2020) zoned for flood risk in the Varkeshchay catchment using the HEC-RAS model. The results of these researchers showed that 110 km of the total catchment area is affected by floods with a return period of 50 years and 63 km of it is affected by floods with a return period of 25 years. Shafiei Motlagh and Ebadati (2020) used HEC-RAS software (Case study: Maroon River - southwest of Iran) to perform zoning of the flood and simulating the hydraulic behavior of the river. They concluded that the flood area for different return periods of 5, 10, 25 and 50 years is equal to 1265, 1651, 2334 and 4450 hectares, respectively, and the number of endangered villages is equal to 5, 3, 2 and 9, respectively. In a study aimed at producing flood risk maps in Kazakhstan, Ongdas et al. (2020) stated that the village of Volgo was flooded during a 100-year flood event. Aynalem (2020), in a study on the Muga River, reported floodplains for 5, 10, 25, 50, and 100-year return periods of 18, 21, 26, 34, and 43 km2, respectively. Therefore, the aim of the present study is to morphologically simulate the occurrence of floods in the Nooranchay River using the HEC-RAS hydraulic model.
.2- Methodology
Geological maps 1: 100000, topographic maps 1: 50000, and 1: 2000, data of synoptic stations, rain gauges, and flowmeters are among the most basic data of the present study which were prepared by Ardabil Regional Water Organization. HEC-RAS software or software river US Army Engineering is a set of tools that allows the user to perform river hydraulic calculations in steady-state and non-steady-state flow. The HEC-RAS system includes three components of one-dimensional hydraulic analysis to perform water level profile calculations in steady-state flow, non-steady-state simulation and sediment transport calculations at the moving boundary. These three components share a common geometric representation and use the same geometric and hydraulic calculation process is set of tools that can be used in the GIS software environment. This add-on creates a link between ArcGIS software and HEC-RAS software, and is specifically designed for spatial data processing for use in RAS modeling and for processing RAS results in the GIS environment. Processing ground data and other GIS data in ArcGIS software using GEO-RAS allows the user to create and export a geometric file for RAS analysis. To perform hydraulic calculations using the HEC-RAS model, first the cross sections must be defined, for which the desired layer of the TIN map is extracted in the ArcMap software environment. After forming the TIN layer, different layers such as center flow line layer, river bank line layer, flow range layer and cross-section layer are drawn and after processing by ArcMap software, it is ready to be extracted for HEC-RAS hydraulic model work. The HEC-RAS model can perform water level profile calculations for Gradual variable steady flow in rivers and artificial canals in subcritical, supercritical and mixed flow regimes.
3- Results
The TIN layer is the basis for extracting the alignment lines and the required RAS layer, and the more accurate the obtained river elevation figure, the closer the 3D model will be to reality. In this study, due to the use of topographic map 1: 2000 and also the adaptation and casting of existing maps on the ETM satellite image of the region, it was found that TIN obtained from digital maps is able to significantly simulate floodplains and plains around Nooranchai River. The basis can be a good reference for conducting research and creating flood simulation layers of the Nooranchai River. The minimum altitude is 1220 meters and the maximum altitude is 1530 meters above sea level. According to the flood zoning map (Figure 11), the flood area with a return period of 2 years along the Nooranchai River is about 122 hectares. These zones mainly correspond to the bed of Nooranchai river, which locally surround the river channel. The average width of areas exposed to floods with a return period of 2 years is about 160. In general, such floods do not pose a threat to human communities living in urban and rural areas. Finally, the highest flood zone with a two-year return period covers the lower part of the Nooranchai River, which has entered the Ardabil plain, and the lowest flood zone with a two-year return period can be seen upstream of the Nooranchay River. However, these floods are of great importance in the formation and morphological changes of the Nooranchai River duct due to their high frequency and potential for shaping the channel platform. Also, the average flood width of 50-year-old floods is about 307 meters. These floods cover flood zones with return periods of 2, 5, 10 and 25 years. As a result of this increase in area and width in areas (3), (4), the areas leading to the Ardabil plain, which are lower than areas (1), (2), has led to more flood zones in the above areas This has caused the flooding of agricultural lands around the Nooranchai River, and even damaged some residential areas of Ardabil and the villages through which the Nooranchai River passes, and even resulted in casualties. In general, such floods can pose a threat to human communities living in urban and rural areas. Finally, the highest flood zone with a return period of 50 years is downstream of Nooranchai River, which flows through Ardabil, and the lowest flood zone with a return period of 50 years can be seen upstream of Nooranchay River. The impact of floods with a return period of 200 years along the Nooranchay River increases by about 329 hectares. Also, the average flood width of 200-year-old floods is about 500 meters. These floods cover flood zones with a return period of 2, 5, 10, 25, 50, 100 years. As a result of this increase in area and width, more can be seen in all parts of the upper, middle and lower reaches of the Nooranchai River. In other words, during the return period of 200 years, the flood zone of Nooranchai River has covered all parts of the river. Due to high discharge and the participation of discharges of different tributaries, such floods can affect a large part of the floodplain area of ​​the river and in addition to human and financial losses and destruction of agricultural lands, have many morphological consequences such as shortcuts, and so on. Floods with a return period of more than 200 years affect the residential areas of the villages around the Nooranchai River and even the riverbed in the part entering the Ardabil plain; they can also affect part of the residential areas of Ardabil.
4- Discussion & Conclusions
Considering the flood simulation of Nooranchai river using HEC-RAS hydraulic model, it was concluded that it shows a very high spatial variability of flood risk along Nooranchai river. This variability stems from variable geomorphological conditions along the river. The results show that floods with a return period of 2 years do not pose a serious threat to human communities living in the vicinity of the Nooranchai River. These floods mainly affect the agricultural lands along the river. The risk of floods also increases with increasing return periods. Floods with a return period of 50 years due to the inclusion of a large area of ​​the river and affecting residential areas will lead to property and human losses. These floods can also lead to morphological changes around the river, as well as extensive damage and loss of life and property. Rather similar findings were obtained by scholars such as Rad et al. (2018), who conducted a study in Khorramabad watershed located in Lorestan province and indices such as flow boundary conditions, maximum instantaneous flow with different return periods, cross sections and their distance and manning roughness coefficient for each section in HEC-hydraulic model RAS implementation and water level profile were obtained in different flood return periods. In addition, Shafiemotlagh & Ebadati (2021) used HEC-RAS software to zone the flood and simulate the hydraulic behavior of the Maroon River. They concluded that the flooding area for the return periods of 5, 10, 25 and 50 years is equal to 1265, 1651, 2334, 4450 hectares, respectively, and the number of endangered villages is equal to 5, 3, 2 and 9, respectively.
 

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1- Introduction
      Flood is defined as an unconventional increase in river discharge. Complete protection from flood hazards is rather impossible. For those living next to floods, implementing new policies is necessary regarding land use management and development of residential areas along rivers to reduce the effects of destruction. One of the basic steps to reduce the harmful effects of floods is to identify flood-prone areas and grade these at risk. For this purpose, one of the solutions against floods is to prepare for a zone. By using zoning maps in watersheds, flood preparedness can be created. The purpose of this study is to perform the zoning of flood-prone areas in Talar drainage watershed and to calculate the damage in areas eroded and destroyed by floods in 20 meters of river, which due to the geographical location and weather conditions in recent years, this region has been faced with various floods and in this regard, the importance of risk zoning and management and planning of the region intensifies.
2- Methodology
In order to conduct this research, input data including digital geological file, digital vegetation file, digital soil file, digital elevation model (DEM) with a spatial resolution of 10 meters, satellite image, and flood event statistics and information were used on 19 July 2015. HEC-1 model in WMS  was used to estimate the hydrograph of SCS unit in Talar basin and Kasilian sub-basin.To determine the flow and boundary conditions, the peak flow number for the flood of 19 July 2015 is 163 cubic meters per second. In order to zone the flood, software WMS and HEC-RAS models have been used.  Since the upstream and downstream slope of the river have a significant impact on the flooding process, the upstream slope is 0.02, and the downstream slope is 0.01. Water elevation points were imported from HEC-RAS program in WMS, and cross section profile plots were prepared at the location of sections located in rural and urban areas, and finally, water depth maps were prepared and compared for the event on 19 July 2015. The Kruger Method was used to determine the maximum instantaneous discharge for 50-year and 100-year return periods. In order to calculate the damage in flooded and eroded areas, a 20-meter area of the river has been considered. Then, the monetary values in each square meter of the covered uses have been estimated according to experts, and finally, the flood damage has been calculated. Duncan-Tukey and ANOVA tests were used to assess the hazard.
3- Results
    In the SCS unit hydrograph, the peak time is 390 minutes for the Kasilian basin and 555 minutes for the Talar basin. The height of the current water level and the height of the water level at the critical level in some cross-sectional profile plots have coincided, which indicates the dangerous situation in these areas. The largest area of ​​flood zones in the flood of 19 July 2015  in Shirgah, Zirab, and Pol Sefid cities at a depth of  0.6  meters, Do Ab villages at a depth of  0.3  meters, Lerd and Rudbar villages at a depth of  1.2 meters, Darzikola, Vazmela and Sangdeh villages at a depth of  0.6  meters. The highest area of ​​flood zones in the 50-year return period is in Pol Sefid and Shirgah cities at a depth of  0.3  meters with an area of ​​181 hectares, and the 100-year return period in Shirgah with an area of ​​292 hectares at a depth of  0.3  meters. Also, the largest area of flood zones in the 50-year and 100-year return period in rural areas is located in the villages of Valik Ben Sang Deh, Darzikola, and Vazmela, with an area of 276.9 and 188.6, respectively, at a depth of  0.3  meters. The results of statistical tests in the risk assessment section showed that in total, two uses of rangelands with an average water depth of   0.57 meters have the lowest average water depth and urban residential areas with an average water depth of  0.84 meters have the highest average water depth.
4- Discussion & Conclusions
According to the flood zoning on 19 July 2015, it was determined that the highest areas of water depth zones of  0.3 meters,  0.6 meters,  0.9 meters,  1.2 meters, and  1.5  meters are located in Pol Sefid city. The zoning of the 50-year and 100-year flood return period also indicates an increase in the area of ​​water depths of 0.3 meters,  0.6 meters, 0.9  meters, 1.2 meters, and  1.5 meters compared to the flood of 19 July 2015. Considering the area of ​​flood depth zones in the flood of 19 July 2015 and the area of ​​land uses covered by flood risk, it was determined that the most damage is related to the Zirab city in residential use with a damage of  266,482,744,183 Rials. Then the city of Pol Sefid with agricultural use with damage of 96,979,434,983 Rials and the city of Shirgah with garden land use with damage of 78,544,366,182 Rials. Finally, flood risk assessment with Duncan, Tukey, and ANOVA tests showed that residential land use has the highest average depth of  0.84 m, and Lerd rural area with an average depth of  1 m has the highest flood potential.
 

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1- Introduction
 The water flow that is higher than the river level and penetrates the surrounding lowlands is called flood. In urban environments, due to high human density and its economic importance, the occurrence of floods is important and can lead to a lot of human and financial losses. In the metropolis of Karaj, in the floods that occurred in 2018, in addition to the damage to urban infrastructure, 8 individuals were dead, 10 injured and 12 missing and this phenomenon damaged 40 vehicles as well. Karaj metropolis from a geomorphological point of view, according to the physical characteristics and form of waterways, is characterized by hydrological coefficients of sub-basins, high rock outcrop, and high intensity of storms. Due to the importance of preserving lands and gardens along rivers, and its agricultural status and existence of gardens within its basins, and most importantly, the establishment of Karaj metropolis at the river outlet from the mountains, conducting flood estimation and management and water storage in this basin is necessary.
Therefore, due to the importance of floods in urban issues, a lot of research has been done based on data from 1: 50000 topographic maps and 1: 100000 geological maps, lithology, digital land model, land use, aerial photographs, satellite images and Google Earth in order to obtain flood-prone areas. Therefore, in this study, the hydro-geomorphological features of Karaj metropolitan basins with emphasis on flooding are investigated by estimating and studying the physiographic characteristics of watersheds leading to Karaj metropolis and calculating the probability of floods in different time periods and spatial analysis. In order to manage possible floods, appropriate scenarios and locations should be identified according to the landform characteristics of the basin for storing and maintaining excessive water and floods.
2- Methodology
In this research, the research steps are as follows:
Required data collection:

• Preparation of remote sensing data including:
• Digital terrestrial model data (altitude, slope and waterway data),
• Landsat 8 OLI sensors (land cover data, vegetation density index and FCD index),
• Ground data preparation including:
• Karaj Municipality data (absorption wells, drainage canals and urban lands),
• Geological Survey (fault and lithology) data,
• Regional water organization data (hydrometry and groundwater),
• Meteorological organization data (climate data),
• Data from ground observations

3- Results
 The upstream basins of Karaj metropolis consist of 5 sub-basins named Klak and Hesar (in the east of Karaj metropolis), Azimiyeh, Taleghani, Siah Kalan and Delmbar (in the north of Karaj metropolis). The flow of surface water in the Klak and Hesar basins, which is directed to the Karaj River, and due to the construction of the Karaj Dam upstream of this river, practically possible floods in this basin are directed out of the urban environment by using the mentioned river. Therefore, there are no flood hazards in this basin. However, the northern basins of the city, due to the diversion of all surface water into the urban environment of Karaj metropolis, and the location of this city in its waterway bed, such as Taleghani Street, has faced high flood risks. Therefore, the northern basins of the city have been studied in detail. In Azimiyeh, Delmbar and Taleghani basins, protection measures including diversion canals and water storage ponds have been constructed to control floods, but due to lack of protection and proper management, they have lost their function.
Drainage networks located in the city of Karaj are transferred using two canals and a metro collector, which are located in the bed of the old streams of Kamalabad (Beheshti canal) and Hosseinabad (metro collector). These two old streams have irrigated the lands of Kamalabad and Hosseinabad using the water of Karaj River, so the slope of these canals is from east to west, which collects surface water from the city and through Haftjoye leads to the Shore River.
 The results of flood simulation in different return periods using HecRAS model show that in a 20-year return period, 0.27 cubic meters per second flood is produced in the largest waterway located in Azima, which affects 14 hectares of surrounding land. Also in Taleghani, Siah Kalan and Delmbar waterways, 0.3, 0.58 and 1.91 cubic meters per second of floods are produced, respectively, which affect the area equivalent to 15.82, 22.65, 85.51 hectares of the surrounding lands, respectively. In addition, by using the TOPSIS model and hierarchical weighting systems, the areas with flooding potential were identified. For this purpose, 9 criteria were used and normalized using fuzzy logic model and straight and inverse linear functions, and then using the AHP model, the effective weight of each of them was obtained. The results of zoning show that 56.8% of the area of ​​Karaj metropolis and its upstream basins are exposed to flooding and the potential for flood production, to the extent that north of Karaj and the slopes overlooking the city of Karaj due to he highest slope, height, rainfall and poor in terms of vegetation, are categorized with high and very high flood potential. On the other hand, the southern part of the city, due to the slight slope and rainfall compared to the northern part and the slopes overlooking the city of Karaj, and the density of gardens and vegetation and agricultural lands, has the lowest risk of flooding potential.
With the aim of flood management and by using 14 criteria and a combination of weight assessment (WASPAS) locations to store flood water were identified:  4 locations (end of North Taleghani Boulevard with water storage volume of 4620 meters³, northern part of Azimiyeh slope with 8400 meters³ of water storage, northern part of the Atomic energy street with a storage volume of 8400 cubic meters of water and the northern part of the Epsino Valley with a storage volume of 3000 meters³ of water. Assuming a depth of 2 meters in each of the proposed zones, a total of 20 thousand cubic meters of flood water is self-sufficient through which flood water can be managed. Location of deep and semi-deep well drilling site is another way of managing surface runoff and flood that was located using 10 criteria and MCE model and the result is the identification of 16 sites for construction and drilling of absorption wells. Another measure for surface runoff and flood management is to increase vegetation density. The result of examining the relationship between surface runoff and vegetation density percentage obtained from the FCD distance sensing algorithm, shows that zones with maximum runoff have lower vegetation density. 25% of the area has the most runoff, So, according to the cooficit correlation (%98) between runoff and vegetation density, increasing the area of ​​green space and vegetation density from 25% to 75% reduces the runoff to less than 25 mm which prevents the area from causing floods.
4- Discussion & Conclusions
The results show that despite the construction of transmission canals and absorption wells in the city of Karaj, in some northern streets such as Tarbiat Moallem Boulevard, Bouali Gharbi and Nawab Safavi Street located in District 8 of the municipality, as well as Goodarzi and Nedaye Shomali streets in the south, no measures have been taken to control the flood, and due to the impermeability level, heavy rainfall compared to the southern part of Karaj and a steep slope (more than 15%), there are conditions to increase runoff on the street. Also, despite the construction of Taleghani, Moazen and Delmbar canals, which direct the surface water from the Taleghani, Siah Kalan and Delmbar sub-basins to the Beheshti collector, due to the lack of transmission capacity of the artificial canals implanted in at the metropolitan area, excessive surface water enters urban streets and generates floods. In order to manage floods and surface runoff in the city of Karaj, the identification of suitable locations for digging absorption wells and water storage pools has been considred, according to which 16 suitable locations for drilling wells and 4 suitable locations for constructing artificial pools had been identified for storing a total of 36,800 cubic meters of water. Also, increasing the surface infrastructure and vegetation from 25% of its density to 75% will reduce the amount of surface runoff by 75%, which leads to flood management.
 

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1-Introduction
The main problem in river engineering is to investigate the mutual effects of water, soil and plants in the river and to identify and introduce compatible tree species and the appropriate patterns of its stabilization for different climatic conditions of the river in terms of water quality and quantity, the type of river bank and its hydraulic characteristics. River erosion reduces sedimentation and increases the efficiency of surface water reservoirs, and the stabilization of riverside lands creates social and work security in relation to the displacement of the river. Vegetation on the margins and wide plates of rivers slows down the flow. From the hydraulic point of view, the slowness of the flow caused by vegetation in natural channels is an important factor in the flood design of the plain and the management of the river and natural channels. The role of vegetation in the protection and stabilization of river walls and banks has been widely studied by researchers in all parts of the world and they have all recognized it as an economic and environmental option. This method has the power and capability for regeneration in a natural way (Agha Razi, 2002). The results of a study that investigated the effect of vegetation on the protection of the banks of the Qara Chai River in the central provinces showed that the amount of erosion and destruction of the river bank, in the direct route and in the winding route, is far more in places without vegetation cover than in places with vegetation (Morgan, 1999). For a better understanding of erosion, effective factors in its occurrence have been identified and the practical natural and biological methods for controlling erosion along waterways have. In the book on river management techniques, while studying the effect of vegetation cover on manning flow roughness and flow speed distribution, the author has provided recommendations about the type and location of planting various tree species (Schiechtl, 1997).
2- Methodology
 The purpose of the present study was to identify and record the geographical locations of suitable points and the required numbers for each of the design treatments, including tree stands, shrub stands, bush stands and parts without vegetation along the river. Tree vegetation (alder), shrub cover (willow), and grass cover (three drip washes and swamps) have covered most of the rivers of Guilan. At each selected point in the field operation, 6 metal pins are hammered at distances of 2 meters from each other and perpendicular to the direction of flow. These pins must be fixed during the execution of the design and no movements must be made in them. The numerical analyses conducted based on vegetation conditions (tree, shrub, and herbaceous) indicated the amount and extent of erosion resulting from changes in soil surface at the location of pins in each layer at different temperatures. Based on the design of the study, the collected data, which are both numerical (i.e., number of species) and in the form of ‌percentage (i.e., percentage of canopy cover of plant species) are compared by t-test, and the relationship of vegetation ‌(trees, shrubs, and grasses) with erosion had been examined by using bivariate regression equations.
3- Results
The executive works of river engineering, especially in Gilan province, should be carefully considered in the current weather conditions. The conditions of Gilan province in terms of the stability of river walls are different from the provinces of arid and semi-arid regions; Because the water regime is very high in spring and autumn, and its frequency is also associated with a large volume of water. Therefore, the cultivated seedlings will not have much resistance against a huge amount of water and most of the seedlings will die in the first year. Also, the right opportunity in the first year is not enough for the root to strengthen the walls and stabilize at least 50%; Therefore, it is recommended to stabilize the walls with natural structures and unnatural mechanical structures such as rip-rap at the base of the wall and gabions and other structures after planting the desired species. The research showed that the grass cover in the surface part has little erosion. This does not mean that the presence of grass cover has been able to provide good protection against erosion; Because there was no flood. Therefore, the erosion is also less, but in the tree and shrub cover, the roots of the plants are exposed to the washing of the lower floor, therefore, the recorded statistics show a high number of erosion. But during severe flooding - during the removed statistical period, it was observed that the grassy cover is destroyed in a blocky way, but in the tree and shrub cover, the walls maintain their stability, and in general, the protection of the river walls that It flows in the whole region, subject to changes in land use, upstream destruction, changes in the morphology of the river bed, and the cutting of tree cover along the river's walls, all played a role in lateral erosion. Therefore, the authorities should pay attention to the important points of watershed management and river engineering in order to create stability of the river walls in order to prevent erosion.
4- Discussion & Conclusions
First of all, it should be noted that in order to maintain the river bank and its On both sides of the river stability, the pressure on the wall should be reduced as much as possible. Having tall and heavy trees can increase the force in the form of a lever and thereby can increase the pressure on the wall bed. Therefore, it is possible to use short stature with very low weight in these places (Davoodi, 2013) grass cover and alder roots are shallow and deep and are suitable for preventing soil erosion along the river (Ghobadian,1989). It is suggested that in this area or in areas with similar ecological conditions, in order to control surface erosion along the rivers, plants such as watercress, grass should be used. The important issue in this project is that the method of breeding branches will be suitable for the establishment of tree species in the walls and along rivers. And in some areas, the walls must be accompanied by mechanical operations in the first 5 years of wall protection. The use of non-woody (herbaceous) native plants such as watercress, grass cover to protect topsoil from water erosion can be very effective.
 

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1- Introduction
Erosion is the main cause of wasting water and soil resources and causing natural damage. According to geological characteristics of erosion and sedimentation, it is very important to study the erodibility of the geological formations of the watershed to determine their constructive effects on sediment and runoff. Many factors affect soil erosion and one of the important factors is the erodibility of geological formations. Sediment that moves with water is called suspended sediment load, and the amount of suspended sediment material that passes through a river section in a certain period of time is called suspended load. The suspended sediment load (SSL) of a watershed, which passes through a certain section of the river, depends mainly on the climatic characteristics, the characteristics of the watershed and the capacity of carrying sedimentary materials. The input suspended load is one of the important and influencing factors on the amount of sediment input to reservoirs of dams and lakes. Determining the amount of sediment carried by rivers is important in many aspects. The calculation of suspended load is very important because of various reasons, one of the most important of which is the role of suspended sediment load in the quantitative and qualitative management of surface water resources. Therefore, the distribution and transportation of suspended sediment load (SSL) in rivers have a significant effect on the water resource management, design of hydraulic structures, river morphology, water quality, and aquatic ecosystems.
2- Methodology
The present study was carried out to evaluate sedimentation and runoff production of Asmari and Gachsaran Formations in Ghaleh Gol watershed around Khorramabad city, from Lorestan province, Iran, located between 48° 21 '2" and 48° 33 '1", and between 33° 15 '43" and 33° 21 '15" N with an area of 10.76 km². The studied area has a semi-arid climate with a mean annual rainfall of less than 500 mm.  This study aimed to measure suspended sediment load (SSL) and surface runoff during the November 30^th, December 2^th and 16^th 2020 and also on the 12^th of March 2021; for this purpose two square meter plots were used. A tank was installed at the plot outlet to collect sediment and surface runoff. After the rainfall finished, the volume of water and sediment collected in the tank installed at the end of the plot was measured.
3- Results
The results showed that during the mentioned rainfalls, the average volume of water output from Asmari and Gachsaran Formations were 1.802 and 1.345 liters, respectively; the average output sediment for these two formations were 1.133 and 1.048 g /l, respectively, ant the total output of suspended sediment load (SSL) was 3.083 and 2.227 gr, respectively from Asmari and Gachsaran Formations. Finally, the obtained results suggest that the Asmari formation has the highest erodibility. Also, according to the results, the Asmari formation has the highest flooding level in the study area.
4- Discussion & Conclusions
According to the results, considering erodibility and flooding features, Asmari Formation has higher sensitivity compared to Gachsaran Formation in the study area. In fact, the obtained results showed that Asmari formation based on the prioritization of erodibility and flooding has the first rank, which must be prioritized for conducting management operations in the Ghaleh Gol watershed.

 

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1- Introduction
  Land use and land cover (LULC) is a complex set of changes caused by the interaction of the natural environment and human activities, which has an important impact on the global environmental changes and sustainable development (Li et al., 2020). Changes in land use can occur due to population growth and the development of regional activities (Prayitno et al., 2020). Many of the problems caused by this development can be soil erosion, soil degradation, and the reduction of forest areas and biodiversity (Hu et al., 2019), which have had a major impact on the regional and global environment (Chen et al., 2020). Changes in LULC can not only directly affect the quantity and quality of land resources in human life, but also indirectly cause climate change, which is one of the important factors of global warming (Baoying et al., 2008), so it can change the hydrological regime and rainfall-runoff mechanisms of a region (Li et al., 2007). Factors such as land use changes, rainfall intensity, and degree of soil saturation, etc. cause the balance and natural flow of rivers to be disrupted (Ghanavati et al., 2014). The expansion of urbanization leads to an increase in impervious areas and a decrease in rainfall absorption in the watershed, causing changes in the river's hydrology, creating runoff after rainfall, and as a result, reducing the recharge of the aquifer (Quan et al., 2015). Around the world, flood includes almost one-third of natural hazards and harms people more than any other types of disasters (Asinya et al., 2021). Change detection of LULC is possible by comparing the changes that occurred in a certain area according to the images taken at different times. Today, satellite data on land resources are available and are relevant and useful for LULC studies (Shanmugapriya et al., 2016) because of having some features such as high temporal frequency, accessibility, showing global land cover for consecutive years, being suitable for calculations, and having a wide range of uses which make them have a high potential for analyzing spatial and temporal changes (Kantakumar, 2019). In recent years, due to climatic reasons, the occurrence of floods has increased in the world (Ghanavati et al, 2013). Golestan province is no exception to this rule. In the recent floods in Golestan, natural factors such as the wet winter have led to the wetting of the soil, the filling of storage channels, and the rise of the stagnation level, and as a result, the runoff coefficient has increased. In terms of human factors, it is possible to point out the impact of non-observance of the principles of land preparation and improper land use allocation, deforestation, encroachment on river boundaries, and insufficient dredging of the main channels especially the estuary, which have increased the possibility of occurrence of natural hazards. Hydrological models are the basis for understanding the cause-and-effect relationship between hydrological changes and land use changes (Shokouifar et al., 2022).


2- Methodology
  In this research, Landsat TM, Landsat ETM+, and TIRS OLI satellite images from 1986, 2006, and 2020 have been respectively used to classify and investigate land use changes in the Gorgan River basin. ENVI 5.6 software was used for image processing and data analysis, and ArcGIS 10.7 software was used to obtain output from image processing. ENVI 5.6 software was used to classify the desired images using the Random Forest algorithm and using the EnMap-Box 2.2 plugin. TERRSET2020 software was used to model the changes. The Kappa coefficient was used to evaluate the accuracy and precision of the classification as well as to compare the classification result with the ground reality. For land cover classification, six land use classes, including forest, urban areas, agricultural lands, water areas, pastures with good vegetation cover, and land with poor cover (pasture and barren land) were considered. In this study, the effect of land use on runoff potential was also simulated through the semi-distributed SWAT model. Model implementation was done in Arc GIS 10.7 environment. After preparing the required maps and preparing the input data, three different SWAT models were designed for the Gorgan River watershed. The first model was used from 1985 to 1996 from the land use map of 1986, the second model was used from 1999 to 2009 from the land use map of 2006, and the third model was used from 2010 to 2020 from the land use map of 2020. In the first stage, by entering the Dem map and producing the flow network by the model itself, based on the threshold limit of 14,000 hectares as the minimum drainage level and entering the Agh Qala hydrometric station as the outlet of the basin, the Gorgan River watershed was divided into 32 sub-basins. After drawing the boundary of the basin, sub-basin, and flow network, the physical parameters related to the basin and each sub-basin, including area, length of the main waterway, slope, height characteristics, etc. are calculated. In the next step, the soil and land use maps must be entered into the model and the slope classes must be defined by the user, and by combining them, hydrological reaction units (HRU) are produced in each sub-basin. The number of HRUs can be changed multiple times for each land use, soil, and slope by determining a minimum percentage of the watershed area that is defined by the user. In the next step, climate data including daily precipitation and temperature information are entered into the models and the appropriate method for calculating potential evaporation and transpiration is determined based on the type of climate data available. In this study, the Hargreaves-Samani method was used to calculate potential evaporation and transpiration. The method of variable storage coefficient was used for trending the flow. Also, management information such as planting, fertilizing, irrigation time, and harvesting of the dominant crops of the basin were introduced to the models. In the final step, the model was run to simulate monthly runoff, considering 3 years of training for all three models.
3-Results
The analysis of annual runoff in three scenarios shows that under the second and third scenarios, the surface runoff has increased by 20.47 and 46.45%, respectively, compared to the first scenario According to the investigations, it is clear that water efficiency has been increasing from 1986 to 2020. This increase can be attributed to land use changes, including the reduction of forest area and the increase of agricultural land, pastures, and residential areas. An increasing trend is observed in the northeast sub-basins compared to the southwest, which is due to the reduction of forest land and its conversion to agricultural land in the northeast. In 1986, the water yield of most sub-basins (45.98% of the basin area) is less than 194 mm. While the water yield in 2020 has increased by more than 290 mm in most of the basins (56% of the basin area) and in sub-basins 10 and 12, which are mainly degraded forest areas and are at a higher level up to 378mm, the variable of agricultural land with an average participation rate of 43.63% has had the highest change in runoff from 1986 to 2020. And after that, forest lands increased by 37.25% and played an important role in creating runoff in the Gorgan basin.
4- Discussion & Conclusion
The results show that urban land has increased from 3.20% of the total land of the region in 1986 to 4.66% in 2006 and this number has reached 5.60% in 2020. According to the investigations carried out in this research, it can be concluded that the area of forest land decreased by 45.56% between 1986 and 2020,The largest increase in the area of built land occurred in the second half of the period between 2006 and 2020. However, the decrease in the area of forest land from 1986 to 2020 is very impressive. These changes show the process of destruction in the region by replacing these uses with pastures, barren lands, and forests. To evaluate the effect of land use change on runoff, three SWAT models were implemented using three land use maps for the study area. The simulation results of the flow in the region were acceptable in all three models, so the coefficient of explanation between the observed and simulated data showed acceptable results. After the SWAT model simulation, three optimal values of the parameters of each period were placed for the defined scenarios. The results showed that with the change in land use, the value of the curve number in the second and third scenarios increased by 0.79 and 1.50%, respectively, which was due to the increase of barren lands and the decrease of vegetation in the region. The annual study of runoff in three scenarios shows that in the second and third scenarios, surface runoff has increased by 20.47% and 46.45%, respectively, compared to the first scenario. According to the studies conducted on the impact of each land use in increasing the runoff, the highest impact related to agricultural lands has increased by 12.38% in 2020 to the amount of 43.63% compared to 1986. The subsequent use of forest lands with a decrease of 34.73% has caused an increase of 37.25% of runoff in 2020. As a result, the water output volume has increased by 6.89% of the basin. Also, the rate of evaporation and transpiration of the second and third scenarios was reduced by 2.07 and 7.59%, respectively, compared to the control scenario. The reason for this is the reduction of vegetation including water lands (gardens and agriculture) in the basin in the second and third scenarios.