محمدمهدی حسین زاده

Flooding is one of the most destructive natural disasters that causes loss of life and financial problems in urban and rural areas. In addition, this risk is a concern worldwide, and Iran, like many countries, faces flooding problems in urban and rural areas. Protecting people's lives and property from floods is a duty assigned to governments, and countries have enacted specific laws to manage floods and protect riverbeds and riverbanks. This research aims to determine the flood limit and flood margin of the Dinevar River using the one-dimensional HEC-RAS model. First, geometric data was prepared with the help of HEC-GEORAS extension in GIS software. To estimate the instantaneous peak discharge, the instantaneous peak discharge was calculated using the Hyfran software and the flood zone was simulated with different return periods. Then, based on 130 cross-sections, the area adjacent to the river was divided into two parts: the floodway and flood fringe zones, based on the 100-year flood level increase of 1 foot. Method 4 (the user specifies target water level increase) was used to determine the floodplain limit. The results of this study showed that in the first reach, the floodplain limit coincided with the old terraces of the Dinevar River. In the second and third reaches of the Dinevar River, due to the reduction of topographic restrictions, the riverbed has expanded and reached to an average of 300 and 500 meters in the second and third reaches respectively.

Alterations in river systems are inevitable and affect theenvironment. Rivers have played a very important role in creating and maintaining life on theearth since a long time ago. In other words, rivers are vital for sustaining life and ecosystems,providing essential freshwater for irrigation, drinking, and industry. However, humaninterventions including changes in land use patterns, construction near rivers, exploitation ofwater resources, and flood and storm management have significantly impacted on these crucialenvironmental systems. They can actually alter the spatial distribution and velocity ofgeomorphological processes such as sediment transport, erosion, and deposition, consequentlyleading to significant changes in river morphology. Therefore, assessing their morphologicalquality is important for their management and restoration. In this study, morphologicalassessment from the upstream to the midstream of the Talar River as a pilot has been conductedusing the Morphological Quality Index (MQI) to evaluate the morphological status.

First, Talar River was divided into two landscape units, three segmentsand 23 reaches based on the hierarchical approach and according to the physiographiccondition. Then, geomorphological functionality, artificial structure and Indicators of channeladjustment have been assessed by MQI which includes 28 parameters.

The results obtained from 28 MQI parameters in 23 reaches showedthat about 15% of the reaches have a "good" condition; almost 35% have a "moderate"condition, and more than 50% have "poor" and "very poor" conditions. Based on the assessmentalong the Talar river, the areas that are in the urban area due to the large amount of agriculture,urban development and road crossing have poor and very poor morphological quality class, andthe areas that are in the forest area are natural and have good morphological quality. Also, theresults of the assessment indicate that the average quality class of the investigated reaches is in"moderate" conditions.

The results show that most reaches of Talar River requires urgent measures for itsrestoration. In addition, although the MQI method can be appropriate and effective tool indiagnosing hydromorphological challenges. However, it is not still enough for an integratedmanagement and restoration, and it should be integrated with other indices regarding humanpressures i.e. water quality, hydrological and biological pressures.

The newly emerging and rapidly evolving technology of Unmanned Aerial Systems (UASs), covering a wide range of devices and enabling photogrammetric applications from user-driven platform, presents new possibilities for research in geomorphology by obtaining spatially accurate geographic data. The low-level altitude of flight allows researchers to obtain imagery at high levels of detail, which is necessary for a detailed analysis of even fine fluvial forms of the dynamic river channels or landslides. After the early 2010s, the use of UAVs equipped with an RGB camera has become widely applied in geomorphology. It has expanded the capability of low-altitude aerial photo shootings and subsequent SfM photogrammetry. The basic principle of SfM photogrammetry is the same as the conventional photogrammetry, but SfM enables automatic alignment of many (hundreds to thousands) images thanks to automated detection of numerous tie-points, and then produces dense point cloud and rasterized DEMs, as well as orthorectified mosaic images. One of the advantages of SfM photogrammetry is its flexibility across camera platforms. conventional aerial images, and ground-based images are commonly used platforms to 3D models by SfM.

The Vaz watershed is located in the northern slope of the Alborz Mountain range and in the south of Chamestan city, which in terms of political divisions, this basin is located in Noor city of Mazandaran province. First, using the library method, international and domaestic scientific literature was studied in order to examine the background and different methods of using UAVs in river studies and to prepare a study framework. After imaging, it was processed in Metashape software (Metashape 1.5.5) and orthophoto image and digital elevation model (DEM) were extracted in centimeters in order to prepare cross-sections and check the morphometric and hydrological characteristics of the river.

The lateral changes of the Vaz River were studied across 2 different sections of the river. The first level of analysis included building an elevation model based on imagery provided by UAVs and processed in Metashape software, with a pixel resolution size of 4.6 centimeters. Through measuring cross sections of the channel at different flows at the edges and bankfull discharge of the channel, data was acquired. This data included active depth and width of the channel, cross sectional areas, average depth, hydraulic radius and width to depth ratio. These data could be combined with hydraulic data to calculate flow velocity, discharge, stream power, shear stress and other parameters which enable the quantification of river processes. In the statistical comparison of 2 reach at channel edge discharge, some parameters such as cross-sectional area, hydraulic radius, flow velocity, maximum and average channel depth, width-to-depth ratio, channel width susceptible to flooding, channel depth ratio, discharge and Froude number, decrease at the downstream section comparing to the upstream section. However, shear stress and specific stream power of the river increase in the downstream. At the bankfull discharge of the channel, all parameters except specific stream power of the river decrease comparing to the 1st section. The specific stream power increases at the 2nd section. Afterwards the research investigated the change in cross sections across the 2 sections. At the upstream, sand mining, road construction across the channel and construction of a secondary channel had changed the composition and material of the right banks of the river. At the downstream, dam construction, had changed the flow and sedimentation regime of the river.

The data acquired from UAVs enables extraction of relevant morphometric and hydrological data regarding the channel and its transverse sections, due to geometric precision and high resolution. The high precision of this data provides an appropriate alternative for field works such as mapping and surveying with different cameras. Orthophoto images prepared using UAVs have enabled the more accurate identification of geomorphic features and landforms. According to data acquired from the 2 different sections of River Vaz, it was demonstrated that upstream and downstream sections are not similar and variation in morphometric characteristics causes difference in hydraulic characteristics such as flow velocity, shear stress and specific stream power. These varieties have led to different geomorphic forms at the studied sections.

Considering the importance of the subject, in this research, the factors affecting the hydrological changes of the Taleghan River have been investigated. Descriptive-analytical methods have been used in this research. The most important data of the research included Landsat 5 and 8 satellite images, the SRTM 30-meter height digital model, Taleghan synoptic station climate information, and regional discharge information. Also, the most important tools used in the research were ArcGIS, ENVI, and SPSS. According to the subject of the study, this research has been done in several stages. In the first stage, the evaluation of land use changes, in the second stage, the evaluation of changes in climatic elements, and in the third stage, using IHA indicators, has been paid to evaluate the hydrological changes of the Taleghan River. The results of this research have shown that during the years 2000-2017, the average temperature of the region has increased and the area covered by snow has decreased. Also, under the influence of population growth, the use of artificial areas has increased and the use of gardens and pastures has decreased. Also, the total results of this research have shown that the discharge of the Taleghan River under the influence of natural and human changes, in terms of all IHA indicators, has had a significant decreasing trend. Also, among the stations in the region, the Glink station, which is located downstream of other stations, has faced more changes, which can be considered as the result of human activities and climate changes.

Rivers in their path are always struggling with a phenomenon called erosion, which on the one hand causes many changes in the geometric shape of the river section, morphology and hydraulic characteristics of its flow, and on the other hand, it brings irreparable effects to the lands adjacent to the channel. One of the main sources of sediment production is the erosion of river banks. In this regard, investigating the amount of coastal erosion is one of the management strategies. The area under study is the banks of the Jajroud River, between Letian Dam and Mamlo Dam, with a total of seven sections. In this study, for the erosion of the river bank and estimation of the amount of sediment from the method or model of estimation of the bank and foot of the bank (BSTEM) in this model, the geometrical parameters of the channel (angle of the wall and height of the bank and the distance of the toe of the bank and its angle), the height of the layers And their species, flow information and vegetation cover and other side cover materials have been extracted and used. In this research, the depth of the flow in a spiral discharge mode and the flow duration of 12 hours were used to model the bank erosion. The model models the amount of bank destruction by calculating the shear stress and soil resistance. The results of the research showed that all sections except section 6 have high erosion. The difference in erosion values in different stages was mostly due to the type of bank sediments and bank slope angle. In terms of bank stability and safety factor (FS), the most unstable bank was in section 5 and the most stable bank was in section 6 of the river.

A flood is a natural disaster caused by heavy rainfall, which causes casualties and damage to infrastructure and crops. Trend of floods in the world increasing due to climate change, changing rainfall patterns, rising sea levels in the future, and in addition, population growth and urban development and human settlements near river have caused floods to become a threat to humans. One of the most important and necessary tasks in catchments is to prepare flood risk maps and analyze them. In recent decades, researchers have been using remote sensing techniques and geographic information systems to obtain flood risk maps in an area. Due to the numerous floods that have occurred in the Neka river catchment, it is necessary to conduct a study entitled zoning of flood sensitivity in Neka river catchment for more effective management in this area.

Study area: Neka river catchment area with an area of ​​1922 Km2 is part of Mazandaran province in terms of political divisions. This basin is between 53º 17´ 54 º44´ east and 36 º 28 ´to 36 º 42´ of north latitude. The highest point of the basin is 3500 m (Shahkuh peak) and the height of the lowest point of the basin in the Ablo station is about 50 m and at the connection to the Caspian Sea is -27 meters. The seven sub-basins of this basin are Laksha, Golord, Burma, Metkazin, Kiasar, Alarez and Sorkh Griyeh. Geologically, the basin is mostly of calcareous and marl formations. In the south and southwest of Neka River, the rock material is mostly clay and calcareous marl, which makes this basin has a high erosion potential To study the flood zoning of the area using a multi-criteria decision model, 1: 25000 maps of the surveying organization and a digital elevation model with a resolution of 12.5 meters (Alos Palsar) were extracted. In order to study the flood risk in Neka river, 4 criteria of height, distance from the river, land use and slope have been used. In the present study, modeling and preparation of flood risk zoning map in 4 stage including descending valuation, normalization of each class, normalized index weight and integration of criteria has been done by the following linear weighting method. Performing linear weighting operations depends on the weighted average of a number of selected parameters in the opinion of the expert. According to the weight assigned to each criterion based on the expert opinion, each of the criteria was multiplied by the assigned weight and at the end the criteria were added together and the final zoning map was obtained.

In this study, using a multi-criteria decision-making system model, a flood risk zoning map in the Neka river catchment was prepared. According to the weight assigned to each criterion based on expert opinion, the final risk probability map has a value between 0.02 to 0.2, which is ultimately divided into 5 classes in terms of flood risk. Value range 0.02 to 0.06 component of very low risk zone, range 0.08 to 0.11 component of low-risk zone, range 0.11 to 0.13 component of medium-risk zone, range 0.13 to 0.16 component of high-risk zone, and finally domain 0.16 to 0.20 components of the area with very high risk potential have been obtained. According to the final divisions in the flood risk zoning map of the catchment area, a safe area means areas where the probability of flooding is very low and close to zero, and in contrast, the area with a high and very high risk potential for flooding has the probability of high-risk floods. According to the final flood risk zoning map, about 982 Km2 (51%) has high and very high vulnerability, as well as about 510 Km2 (26.69%) has medium vulnerability in Neka catchment area.

The results obtained from the model indicates that the highest risk of flooding points are located in the western parts of the Neka catchment area and the end of the catchment area that reach the city of Neka. According to the research findings, the most important factors in increasing the risk of floods were the slope in this area and the distance from the drainage network. According to the results of the model, a large area of ​​the basin is a component of high risk zone, that means the Neka river watershed has a high potential for floods. Evidence and documented reports show that the Neka river Basin has experienced several floods in the last two decades. The major part of the occurrence of floods is due to the natural conditions of the basin, thus it is necessary to reduce flood damage by changing the locations of various land uses based on flood vulnerability maps. Using multi-criteria decision making method can be used to prepare flood risk zoning maps in basins that do not have hydrometric data; It is also a more cost-effective method in terms of time. One of the important issues in the final result of this model is due to the weight of the layers, which should be used by experts, who are familiar with the region and this method and adapt to field evidence.

The assessment of river patterns is necessary in order to understand current conditions and the potential of their possible changes in the future. Geographers, Geomorphologists, and geologists have used channel shape as an effective parameter in classifying, analyzing, and predicting fluvial responses. In recent years, the changes in river systems have led to increased environmental damage caused by river processes in many countries, therefore managers have had to pay more attention and be more sensitive and change as an integral part of all river systems. River classification is one of the most effective tools for solving these problems. Brierley and Fryirs (2005) categorized the channel pattern based on three interrelated characteristics, including the number of channels, sinuosity, and lateral stability, into five types, straight, sinusoidal, Meandering, braided, and anastomosing. For this purpose, changes in the braided pattern in Jajrud river have been studied.

The studied area is located on the east bank of the Jajrood river, which is 19Km long (17 reaches) and located between the Latian and Mamlu dams. The Jajrood River originates from the heights of Alborz (Klon Bestak) and its most significant branches are the Fasham, Damavand, Migun, and Ahar rivers. Mamlu basin covers 1772.82 square kilometers, including Latian dam basin (701.19 square kilometers). The study area is located on the main channel of the Jajrood river, where the Latian and Mamlu dams were constructed.Throughout this study, satellite images (years 2006 and 2019), aerial photographs (years 1957, 1973, and 1995), and fieldwork have been used as the main research methods. In order to conduct the fieldwork, the study area has been divided into 17 study subcategories, each subcategory being 200 meters long. Brace, Richards, and Warburden indexes were used to check the degree of braided pattern development. which are, respectively, the first index of the parameters of the length of barriers and islands (a) and the length of the study reaches (L), the second index of the parameter of the length of the sub-channels (l) and the length of the study reaches (L), the third index of the parameter of the active channel width ratio (b) the width of the channel (B) in the studied section. According to Richard’s and Brace’s Indices, the higher the output number, the more braided the river is. Brace and Richard indices are the reaches of investigation and the results of these two include the calculation reach. The Warburden index, however, is based on the ratio of the width of the branched channels to the width of the main channel which approaches Issue number one as branching increase.Richards and Warburton indices were used to check of braided pattern. For estimating the effect of dam on the braided pattern of Jajrud River, the Wilcoxon test was used and the paired t-test was used to check the difference in the braided pattern in different reaches.

The results based on the studies, conducted in 17 reaches of 19 km of Jajrud river for 5 time periods, show that these reaches did not have the same conditions in terms of the braided index.
These changes in the river pattern may indicate changes in environmental conditions along the river or the effect of the built dam on the river regime. The results of the study show that among the areas near the Latian dam, areas No. 1 and 2 have always had a single-channel state except in 1973 when it was low braided.The most important reason for the single-channel pattern in the first and second reaches is the location of the channel, which is limited inside the valley. For the year 1957, when the river regime is completely normal, except in reaches 1 and 2, all reaches have an braided pattern. The trend has been almost constant. This trend in 1973, when the Latian dam is in use, in all indicators for reaches 3, 4, and 5, the braided coefficient is zero or low values. The explanation of the above conditions can be the water extraction and launching of the Latian Dam in the same period of time and the limited output of water, which has finally led to the single-channelization of the mentioned sections of the river. In 1995, the values of the braided coefficient with all three methods in the studied reaches show the lowest value of the braided coefficient compared to the previous and subsequent years. Based on the discharge data of the available hydrometric stations, the high discharge values at this point in time compared to other times were the most important reason for the reduction of the sediment load of the bed and the reduction of the braided pattern index. In 2006, the average braided index increased compared to 1995. This year, the highest braided index has been created in the last reaches of 13 to 16. The most important reason for this issue would be the construction of the Mamlu Dam at a short distance.

Based on the average values of the braiding index in the Jajrood river, from 1957 to 1995, the values of the braiding index decreased and then increased until 2019. Assessment of the impact of the Jajrood dam on the braided pattern indicates the significant difference between the Brice and Richards indices values before and after the dam construction. Based on the results of the paired t-test in the Brace and Richards indices, the values of the braiding index in the studied reaches from 1973 onwards have significant differences in several periods. According to the findings, the Brace and Richards indices have been more effective rather than the Warburton index to study the braided pattern in this study area.

Bank erosion is one of the geomorphic processes caused by natural and human factors. This phenomenon, as one of the types of water erosion, can create several geomorphic effects in the river. The increase in river erosion also causes the instability of the river and as a result changes the type of flow, changes the pattern of the river and changes the course of the river. So far, several methods of rapid geomorphic assessment have been used to investigate river bank erosion, and one of the most common and widely used in these assessments is the Channel Instability Index (CSI). The aim of our study was to know the applicability of the channel stability index to identify erosion-sensitive and unstable banks in the Qaleh Rudkhan Fooman river in Gilan.

Qaleh Rudkhan river is located in the west of Gilan province in Fooman city. This river originates from the northeast heights of Sote village and flows into the Caspian Sea after traveling 40 kilometers from the Qaleh Rudkhan area. The area of the basin is 347.76 Km2. With the aim of studying the bank erosion and stability of the river bank of Qaleh Rudkhan, a part of the river path with a length of approximately 5 km was selected in near the city of Fooman. In this area, 8 reaches were determined based on river conditions (pattern and morphometric differences) and its sensitivity to bank erosion. Then, mapping of cross_sections, Channel morphometry, grain measurement of the bank sediments, state of compaction and stickiness of sediments, and examination of the vegetation characteristics of the bank and flood plain were carried out for each reaches. In eight reaches, using the channel stability index, the streambank erosion situation was investigated. In this model , the primary bed material ,bed/bank protection, degree of incision, degree of constriction, streambank erosion, streambank instability (percentage of mass movements), established riparian woody- vegetative cover, occurrence of bank accretion and stage of channel evolution model are scored.

Based on the findings of the channel stability index (CSI) on the left and right banks of Qaleh Rudkhan river, it showed that the index values ranged from 18.5 to 25.5. Based on these values, reaches one, two, three and four are in a very unstable state (high instability) in terms of channel stability, and reaches five, six, seven and eight are in a medium instability state. Based on the relative score method of bed sediments, bank protection and riparian vegetation are the most important factors affecting channel stability. Based on Pox-Whisker Plot diagram, the status of three variables of degree of incision, the available evidence of bank erosion, percentage of mass movements and occurrence of bank accretion are different in different reaches and as a result of these factors, the sensitivity of the river bank of Qaleh Rudkhan to instability is different.

The results of this research show that the three variables of the primary bed material, bank protection and established riparian woody- vegetative cover are the same in all reaches and are considered important factors affecting the stability and river channel stability. Based on the above findings streambank instability, occurrence of bank accretion, degree of incision and stage of channel evolution model are variable factors in each reaches, which cause differences and changes in the intensity of river bank erosion and river channel.

The U. S. Environmental Protection Agency lists sediment as the most common pollutant in rivers, streams, lakes, and reservoirs defined bank erosion as a natural geomorphic process or disturbance that occurs during or soon after floods. By producing sediment load, it causes pollution and reduces the quality of drinking water. In addition to that channel enlargement, bank instability, degradation of physical habitat and numerous other geomorphic responses accelerate the process of bank erosion Bank degradation is the result of a process that combines the erosive power of water and the effect of gravity. Bank erosion is one component of the natural disturbance regime of river systems and is integral to long-term geomorphic evolution of fluvial systems and ecological sustainability. Bank erosion is, therefore, a desirable attribute of rivers. In this study, Near bank stress (NBS) Rosgen shore for a part of Mereg Mahidasht river has been investigated. Mereg River Due to its location at high altitudes, high length and variable width, its meandering pattern and flood nature have been prominent features of this river. To suffer from general and localized erosion during floods and to reduce possible damages in the future by examining the erodible points

In order to conduct erosion studies, first a digital model of the altitude of the region, a 1: 1000 map of the region that covers the river and part of the flood plain has been used. The first stage was preparation of input data in ArcGIS using the HECGeoRAS extension. HEC-GeoRAS helps in creation of the data needed for the HEC-RAS model and the transfer of data between ArcGIS and HEC-RAS. The next stage was done within HEC-RAS (5.0.3) using the river geometry prepared in the previous stage. The final stage consists of analyzing the results from the HEC-RAS model within ArcMap. Three input parameters must be specified: stream geometry, flow data, and the model plan to create the flood and inundation maps of the Mereg river in HEC-RAS. In order to create the river geometry for HEC-RAS, elevation data were needed. High resolution digital elevation model was obtained from 1:1000 topographic map that was prepared by Navandish Water Processors Consulting Engineers Company Company. The HEC-GeoRAS extension was used to set up the necessary features that would be needed for the HEC-RAS model (i.e., stream centerline, bank lines, cross sections, etc.). In addition to elevations, Manning’s roughness coefficient values were applied to each cross sections using Cowan method. 44 sections of different river sections were selected and measurements were performed in HEC-RAS environment. And then , for bank stability from the Near bank stress (NBS) Rosgen NBS method is used. Two Rosgen methods have been used: (ii) Ratio of radius of curvature to bank-full width & (iii) Ratio of near-bank maximum depth to bank-full mean depth

According to the morphology and meandering pattern of the Mereg River, the total reach is 28 km and It is divided into four reach.
First reach: To study method of Near bank stress. In the first reach, 12 cross sections have been selected. In the first part, the river has a radius of curvature of 1.39. Bank Erosion of the Mereg River was low to severe in the first period.
Second reach: the average slope of the Merege River channel was 0.34%. The value of the radius of curvature is 1.64, which is considered as a meandering river. In this reach, 12 cross section have been selected to measure the degree of erodibility. Most arches were highly erodible.
Third reach: The slope of the canal in this part is 0.2%. The Mereg River has a radius of curvature of 1.7 and has a meandering pattern. And the rate of erosion of the shore in this section is estimated to medium or less.
Fourth reach: The number of cross section studied in the fourth reach is 5 and this reach of the river has a radius of curvature of 1.2 and has a straight pattern. The rate of bank erosion has been low and medium. 

Comparison of the two methods used to analyze the erosion of the Mereg River shows that the risk of erosion in all arches in the range of the river has been high erosion. And the reason is the intensification of hydraulic stress in these reaches. In the second and third reaches, the average bank erosion is calculated as medium to high. The reason for this is the reduction of the slope, which according to the longitudinal profile of the Mereg River, the average slope was 0.23%. In addition, there is a decrease in vegetation, an increase in the pattern of river winding and change of use and conversion of lands around the river to agricultural use in these periods.
Comparison of the results obtained from different methods of estimating the risk of erosion with field observations showed that Ratio of near-bank maximum depth to bank-full mean depth in the river Mereg Mahidasht was closer to reality and It is suitable for checking the degree of erodibility of the bank.

Floods, as natural and unexpected events, have occurred frequently in recent decades. To reduce the damages caused by floods and flood management, it is mandatory to assess the possibility of danger and prepare maps of possible danger zones. In recent decades, many destructive floods have occurred in the Nakarod catchment. Because of this, to manage floods, reduce damages, and properly use water resources, the flood potential of the sub-basins of the Nakarod catchment has been studied. Neka River is 176 km long, and it is one of the important rivers of Mazandaran province and one of the catchments of the Caspian Sea. In this research, to prepare a map of the sensitivity of the sub-basins to the flood risk of the basin, 11 influencing parameters have been used, which includes elevation, slope, distance from drainage network, drainage density, flow accumulation, rainfall, land-use, geology, stream power index, topographic wetness index and curvature of the topography. The layers were weighted using the Analytical Hierarchy Process (AHP); and eventually, by using the weighted linear combination method in ArcGIS software, the standardized layers were multiplied by the corresponding weight, and then the results of all the variables were added and accumulated together, and the final sensitivity map was divided into five classes. The results of the research indicate that flood sensitivity is different in the sub-basins of the Neka RiverAmong the effective environmental factors in flooding, the elevation and stream density were the most influential factors in the flood risk of the Neka catchment.

Changes in river pattern is one of the most important issues of river engineering that affects the activities and construction structures along rivers.Changes in the parameters of the meandering can be due to changes by humans, changes in the hydrological regime of the river, ecological changes or due to geomorphology of the region.Knowledge and understanding of the morphological changes of meandering patterns and the natural dynamics of river systems are very important for the purposes of planning, urban planning, dam construction, erosion and sedimentation, road construction and protection and reconstruction of river channels.By studying the amount of changes in river parameters, especially the length and width of the channel in a region, the future of the meandering patterns and rivers can be predicted.Channel form is a good initial guide to determine the morphology and channel form changes in alluvial rivers.In fact, the most obvious feature of a river is its planform or geometric form.A river plan is called a planform, which shows the characteristics of a channel and a floodplain in an alluvial river.The term river pattern describes the planimetric (two-dimensional) shape of rivers.In the new classifications, channel patterns are classified into straight, meandering, braided, and anastomosing.The purpose of this study is to investigate the trend of morphological changes in the Nekaroud River from the city of Neka to where the river joins the Caspian Sea for a period of 35 years between 1364 to 1399.

Neka river originates from Alborz mountains in the southern part of Gorgan city and passes through the southern part of Behshahr and flows into the Caspian Sea.The area of Neka Basin is 1902 km.The Neka River is 130 km long in the mountains and 39 km long in the coastal plains.In this study, the Neka River with a length of 39 km in the coastal plain from Neka to the Caspian Sea has been studied.At first, Nekaroud was divided into three parts: upper, middle and lower part and the changes were studied separately and together.With this method, the amount of displacement, change of dimensions and pattern of bends were determined.Using the method of historical changes, the river route map related to different periods based on aerial photographs of 1985 (National Geographical Organization of Iran) and satellite images (from Google Earth) of 2006 and 1399 has been digitized in GIS software.In order to study the changes of the river in three time periods, from three indicators including morphometry which includes (channel length, arc radius, central angle, wave amplitude, wavelength), morphology which includes (different models of lateral migration including retraction, new meander,migration, confined migration, cutoff, growth, meandering change, double heading) and morphodynamics (transect method) have been used.Finally, the changes of the left and right sides of the channel in the studied statistical period were statistically tested in SPSS software.

The results of the study of satellite images and aerial photographs show that the values of the curvature coefficient, the central angle, the angles of the arcs along the river have decreased from the upstream to the downstream.Based on these morphometric characteristics, the river is classified into three parts including the developed meandering pattern, the undeveloped meandering pattern and the almost meandering pattern in the third reach.Although the morphometric values of the channel show that the Neka River has changed,however, the statistical test in the section with a developed meandering pattern showed that no significant changes were observed in the right bank during two different periods.There were no significant changes in the left bank of the river during 2006 and 2016.The study of Yemani and Hosseinzadeh (2013) on the Talar River and Yemani et al. (2014) on the Babol River had similar results. In these studies, similar to the Nekarud River, at the beginning of the river's entry into the coastal plain, i.e., the alluvial fan  section (the first part of the Nekarud), there is more instability and changes are still taking place during large floods; However, in the second and third periods, due to human intervention and protection, the channel deepened and finally, the main river was divided into several branches in order to transfer water to the rice agricultural lands, which caused the degree of instability and changes in the channel pattern in the four The last decade is at a minimum.

According to the studies, it was found that the Nekarood River has had limited changes in terms of morphology, morphometry and morphodynamics during 35 years.Changes in the bed of the Nekaroud River during 2006 to 1399 have been decreasing. The reasons for these conditions are the existence of large-scale cultivation around the river and the protection of the river bank, the creation of storage dams and water diversion in the middle part of the coastal plain and the construction of dams on this river (Golord Dam and other dams).With the construction of these dams, many changes were made in hydrological parameters such as flow velocity and discharge. Also, the amount of erosion and the amount and method of sedimentation have changed.

River canal changes are natural river processes and part of the systematic functioning of rivers that cause the destruction of agricultural land around the river and damage to human facilities and roads. The purpose of this study is to investigate riverbank erosion using Oklahoma Ozark streambank erosion potential index (OSEP). Qaleh Rudkhan watershed is located in the west of Gilan province in Fooman city. This river originates from the northern slopes of the Talesh Mountains and after leaving the mountains in the Fooman region, enters the Gilan Plain and finally flows into the Caspian Sea. In order to investigate the erosion of the river bank, a part of the river with an approximate length of 5 km near Fooman was identified and in 8 reaches, the parameters in the Oklahoma Ozark streambank erosion potential index (OSEP) were examined. In this method, eight factors of bank height, bank angle, percentage of bank height with a bank angle greater than 80 degrees, evidence of recent mass wasting, unconsolidated material, streambank protection, riparian woody-vegetation cover and stream curvature are scored. According to the results of relative score, streambank Protection and Riparian Woody-Vegetation Cover have been the most effective factors in the instability of the left and right shores in Qaleh Rudkhan river. In general, it can be said that instability has prevailed in the banks of Qaleh Rudkhan river, which is due to human intrusion and occupation in this part of the river.

The annual loss of soil in the world is about 75 billion tons. In Iran, soil erosion is one of the most important environmental problems, and in Iran's catchments, soil erosion increased by 800% between 1951 and 2002. The significant decrease in the performance of Iran's catchments due to a large amount of erosion indicates the increasing necessity of monitoring and following up on this destructive phenomenon. Dendrogeomorphology is a technique that has been very successful in describing and determining geomorphological processes. Dendrogeomorphology is a very flexible method to assess soil erosion and can be used as a data source to determine the reliability of data obtained from direct estimation techniques. The purpose of this research is to investigate the state of sheet erosion in the Nachi watershed using the dendrogeomorphology technique on the oak tree's protruding roots as the region's dominant species. Considering the limited nature of such studies in Iran and the very fragile situation of the studied area, and the risk of filling up the reservoir of Zrebar Lake, which is very important from the point of view of the environment, it is necessary to study the situation of sheet erosion and soil wastage and sediment trans.

In order to achieve the research objectives, after collecting and preparing the primary information, including written information, statistical data, maps, and pictures, a preliminary area survey was carried out, and sampling sites were selected. The samples were prepared according to the program, based on the status of the catchment (according to the land use of the catchment and the direction of the range, the desired work units were selected in places with exposed roots). Based on this, different samples were taken in two different forests, agriculture uses, and western, eastern, and southern directions. All the samples were prepared from the oak tree species, which is the absolute majority in the study area. Finally, 64 samples were selected from the collected samples that could analyze the growth rings' anatomy. Discs harvested from the roots were used to reveal the vegetative rings of the discs by polishing and cutting the surfaces. Using a sanding machine, it was gradually polished with different grades to clear the growth ring border. Then, the disks were measured in the laboratory to determine the first year of root emergence and to determine the width of vegetative rings using a Lin-Tab 5 device equipped with a binocular microscope and specialized T-Sap chronology software with an accuracy of 0.01 mm.

This research showed that in the Nachi catchment, surface soil erosion in agricultural use (average erosion rate 2.43 mm per year) compared to forest use (average erosion rate 0.6 mm per year) is about 4 times. The results of the statistical tests also showed that the type of land use affects the average annual surface erosion rate in the studied basin. Also, this study found that different geographical directions do not affect the average annual surface erosion rate of the Nachi catchment. Comparing erosion values in agricultural and forest use shows the importance of natural covers' protective and important role in preserving the soil and preventing its erosion and wastage. Various studies in the world and Iran have shown that in recent decades, there has been an increasing increase in land use changes, that these changes have the basis of increasing runoff and affecting the amount of soil loss, comparing erosion in the agricultural area with the forest area, showing the protective and important role of the covers. Natural and forests have a valuable role in preserving the soil and preventing erosion and wastage of soil.

The results of this research reveal the necessity of paying more attention to studies on the possibility of modification and change of land use in these areas. The change in land use and the negative effects caused by human interference are not only in the basin itself but also in places outside the occurrence of erosion in the form of accumulation on high-quality agricultural lands, pastures, water storage sources, and irrigated canals. Also, the creation of pollution by sediments and heavy metals and accompanying chemicals, especially the threat to the very fragile ecosystem of Zrebar Lake, is more evident today than ever before. It is suggested to use another method parallel to this method in future works to validate the obtained erosion rate. In future studies, sampling should also be done from the northern slopes for a more detailed investigation of the effect of the slope directions on soil erosion.

Rivers face many morphological and ecological changes over time, and these changes are important in environmental and development planning. The Taleghan River in Alborz Province is one of the rivers associated with many morphological and ecological changes in recent years, and for this reason, this issue has been addressed in this study. The data used in the research included library information, information obtained from Google Earth images, information obtained from field visits, as well as the 12.5 SRTM digital elevation model. Research tools also included ArcGIS and Google Earth software, as well as RQI (description and assessment of environmental conditions in riverine areas) and MQI (morphological quality index) models. This research has been carried out in two general stages. In the first stage, the environmental conditions of the studied periods have been evaluated using the RQI method, and in the second stage, the river dynamics of the periods has been investigated using the MQI model. The results obtained from RQI method have shown that intervals 1, 2, 3, 4, 5 and 6 with 46, 67, 69, 64, 44 and 43 points, respectively, have a poor status and intervals 7 and 8 They also have an average position with 74 and 76 points, respectively. Also, the results of the evaluation of the dynamic condition of the river have shown that intervals 1, 2, 3, 4 and 5 with coefficients of 0.188, 0.156, 0.156, 0.117 and 0.242, respectively. Very poor morphological dynamics, interval 6 with a coefficient of 0.453 in terms of MQI index has a weak dynamic state and also intervals 7 and 8 with a coefficient of 0.477, have the highest coefficient and in terms of geomorphological dynamics have more dynamics than the other intervals.

Water flow is one of the earth processes that in addition to changing earth surface, affect human's life. Any change in channel properties affects other variables specially where human intervention disturbs the balance of the environment it can lead to hazards. Stream Bank erosion is very vital and important because stream bank erosion can result in loss of land, increased stream sediment load, diminishing water quality and aquatic habitat, threatens people's lives and property. Identifying and determining stable and unstable banks also determining their degree of stability can be a great way to manage fluvial environment. In this research the method of Rapid Geomorphic Assessment (RGA) has been used for investigate the stability and morphometric change in Haji arab river that located in south of Qazvin province. For this purpose 8 reaches were chosen. Field studies and mapping from all reaches were done. Based on channel stability index (CSI) that is one of the Rapid Geomorphic Assessment's (RGA) indicators. The parameters of this index (CSI) were scored during the field. In this research statistical analyzes such as correlation coefficient and Box & Plot diagram were used to determine the relationship between the parameters in the stream banks and data scatter. also relative score was used to determine the most effective factor in stability of stream banks, Results show that the highly unstable stream banks belong to reaches of 7, 8 and the most effective factor in the Haji arab river's bank ,based on Channel Stability Index(CSI) are stream bank erosion and riparian woody vegetation .

Humans alter river systems directly and indirectly. Construction of bridge and culvert is one of the anthropogenic interventions which take place. Road-stream crossing (RSC) is essential to be installed on the river lines for roadway transportation, while incorrect and structurally poor RSCs often negatively influence the geomorphology and ecology of river systems. Culvert and bridges can increase stream flow velocity, shear stress, turbulence of flow, degradation and aggradation, development of deep scours, channel braiding and downstream bank erosion. Jones et al., 2000; Wemple et al., 2001 & Blanton and Marcus, 2009, previously worked on the impact of roads on fluvial geomorphology with changing floodplain’s form and function. The difficult issue in survey study is gathering, up-to-date and easy to use data with high accuracy, therefore short-rang photogrammetry was used in this research.

In this investigation, the effect of bridge on river system was analyzed in Jurband village in Mazandaran province. Documentary references, remote sensing (UAV) and survey are 3 methods used. Longitudinal and cross-section profiles were drawn on digital elevation model. The model was generated from UAV with high resolution (pixel size: 4.6 cm). Longitudinal profile was obtained from survey along 400m from upstream to downstream and 8 cross-section sites were selected for detailed study in upstream (U) and downstream (D) of river channel (on bridge section, 25m, 50m, 100m, 200m).

The channel slope is smooth rend. After bridge cross section, the channel bed has collapsed at a rate of 8m gradually. In investigated reaches, all of cross sections had no change in width index except in 25U section. According to coefficient of variation index, parameters were 18.47% upstream and 2.8% in downstream. Maximum depth was in bridge cross section (1.40m) and in 200D (1.18m). The minimum amount of depth maximum and mean was in 25D (respectively 0.74m and 0.37m). There was a significant difference in W/d ratio in upstream to downstream, about 22m decrease in downstream. Cross-section area varies from 25D (65.7m) to bridge section (79.26m). The significant difference of bank-full area was 42% in all selected reaches. According to information, amount of flow velocity altered from 38.1 m/s in bridge cross-section to 18.4 m/s in 25D cross-section. Also, the maximum and minimum rate of Froude number and power stream were obtained at 25D and bridge cross-section respectively. Sinuosity index (SI) of cross-sections were equal with 1 except in 200U (1.30) , 50D (1.20) and 200D (1.10).

  Based on The principle of flow continuity, it can be stated that the amount of discharge was the same in reaches and variation in channel parameters is due to bridge construction. Because of scour in upstream over the time, altitude differences has changed in river bed and bank side between 3-4 m. After bridge construction, degradation in upstream has stopped due to local bed level foundation but sedimentation and widening of channel has increased about 2-3 meter lower than bank side. Nevertheless, degradation and scouring has increased in downstream and bed collapsing has occurred up to 8m after bridge section.

are connected at the end of the basin and form the Darbadam River. According to the results obtained for the central angle, in the first part between 2010 and 2021, the Meandri River pattern was developed and there was no change in the pattern class, but in the second and third parts in 2010, the river pattern is not developed meandering, which in 2021 has become the developed meandering river patternBased on the average curvature coefficients in all three sections studied, the Darbadam River has a meandering pattern. Due to the characteristics of the region, such as the presence of resistant rock layers, the high slope of the region and also the mountainous topography, has led to low transverse displacement of meander in the region. However, in some parts of the river, due to human activities, including land use change, vegetation degradation and overgrazing, there has been a change in the river pattern.

Human and natural factors cause the river to be out of equilibrium and this imbalance leads to changes in erosion and sedimentation. One of the forms of erosion in rivers is stream bank erosion which can change the plan and morphometry of the river and due to these changes, various hazards including : Change the morphometry of the channel and produce sediment may happen. Changing in river's pattern, longitudinal and transvers displacement of the river, occurrence of bank accretion, changing hydrological and geometric characteristics can be the results of change in river's sedimentation and erosion. Monitoring the variables affecting the stability of bank and stream characteristics can be effective in preserving human life and property also managing the natural environment. In this research the method of Rapid Geomorphic Assessment (RGA) has been used for investigate the stability and morphometric change in Haji Arab river that located in south of Qazvin province. For this purpose were chosen 8 reaches. Field studies and mapping were done from all reaches. The parameters of Oklahoma Ozark Streambank Erosion Potential Index (OSEPI) were scored during the field studies. In this research have been used statistical analyzes. Results show that the unstable stream banks belong to reaches of 1 in left side (down strem) and 7(up stream) in right side also the stable reaches are the reaches of 2(down stream) in left side and reach of 3 in right side. the most effective factor in stability of Haji Arab river's bank in both sides is riparian woody vegetation after that in left side stream curvature and in the right side Stream Curvature, Percentage of Bank Height with a Bank Angle Greater than 80 o, Unconsolidated Material equally are the most effective factor in stability.

The erosion phenomenon and sediment transport are the most important hydrodynamic processes that effect watersheds, rivers, coasts, ports, dams, bridges, roads, farms, and civil facilities. Waz is one of the main rivers on the northern slope of Alborz in Mazandaran province. This river has a morphological dynamic behavior and affected by various factors including geology, slope, land-use, and the condition of hydraulic flow. The aim of this study was to assessing the bank of Waz River stability using BANCS model, which is include NBS and BEHI indexes. To assessing the rate of bank erosion in the Waz River, in a three kilometer interval, eight cross-section were selected using field impression and mapping the parameters e.g. side height and angle, bank-full width, bank-full average depth, the maximum average-depth of bank in bank-full, the curvature radius, and bank material based on NBS and BEHI models. Regarding the results for each cross-section based on bank erosion risk index, near bank shear stress and comparing with field surveys, the banks with more risk of bank erosion and more stable banks were determined. Besides, comparing the results obtained from BEHI and NBS models with field surveys showing more efficiency of BEHI model for the Waz River.

The flow of water and rivers is the most important phenomenon in the crustal processes that not only plays a role in the overall appearance of the earth but also determines the form of human life on the planet. As a dynamic system, a river always changes its morphological location and characteristics according to time, geomorphic, geological-hydrological factors, and sometimes due to the human intervention. Bank erosion of rivers could cause a lot of damage to agricultural lands, buildings, riverside structures, roads, bridges, etc. every year. Inaddition, it could cause significant amounts of sediment to be transferred to dam reservoirs. The Haft Cheshmeh River basin is located in the Rozjerd region, in the northeast of Qazvin province and on the southern slope of Alborz. In the present study, the Haft Cheshmeh River in the area from Rozjerd to Shinqar villages has been studied for approximately 11 km. The pattern of the river in this sinusoidal range with an average curvature coefficient is 1.17.  

In order to obtain the required data, the Haft Cheshmeh River was divided into 4 sections and 10 cross-sections, and from these cross-sections, a cross-sectional profile of the channel was prepared during 7 field works. To investigate the erosion of the Haft Cheshmeh River using the near bank stress model (NBS), the estimation of the stress applied to the shore is related to the slope flow, in which seven methods can be used in accordance with the conditions of the region. According to the characteristics of the Haft Cheshmeh river, in this study, three methods of the ratio of the radius of curvature to the width of the bankfull (Rc/Wbkf), the ratio of the maximum depth of the near bank to the depth bankfull (dnb/dbkf), and the ratio of the shear stress of the near bank to the shear stress of the bankfull ) were used. After obtaining the data by field sampling and calculations, according to the measured parameters, the degree of lateral erosion in different classes was classified from very low to severe.  

To investigate the erosion of the Haft Cheshmeh River, the Near Bank Stress Model (NBS) was used. At the second level, which measures the ratio of the radius of curvature to the width of the bank, all sections, with the exception of cross-section 9, have severe erosion. Only in cross-section 9, very little erosion has been observed. At the fifth level, which is the ratio of the maximum depth of the near bank to the depth of the bankfull, low and very low erosion from the first to the eighth sections on both sides of the shore were observed. Only the ninth and tenth sections have high and severe erosion; however, even on the right bank of the tenth section, erosion is low. At the sixth level, which is the ratio of the shear stress of the near bank to the shear stress of the bankfull, the erosion has low and very low values in all cross-sections.  

The use of the ratio of the radius of curvature to the width of the bankfull is appropriate for a time when a narrow radius has the maximum effect on the bend of the river. Therefore, the results obtained from the cross-sections that were harvested at the site of the bend of the stream were consistent with the reality of the region and showed the instability of the sides. The results of the shear stress of the near bank to the shear stress of the bankfull did not correspond to reality. According to field observations and data obtained using the above-mentioned three methods, the ratio of the radius of curvature to the width of the bankfull is close to reality. Although the results of the near bank stress model show the erosive cross-sections with less intensity, if it is necessary to provide a quick and low-cost estimate of river intervals, it is reasonable to use the near bank stress model.   

River channel changes, bank erosion and sedimentation are the natural processes of the alluvial rivers that destroy the agricultural land and damage to human installations around the river. In the present study, the CAESAR model was used to assess the changes of the Kaleibar Chai River in order to measure the variation of 3 km of its main channel.CAESAR is a cellular automata model for river system evolution. CAESAR  is a cellular model  that uses a regular mesh of grid cells to represent the river catchment studied. Every cell has properties of elevation, water discharge and depth, vegetation cover, depth to bedrock and grain  size.  It  is  based  upon  the  cellular  automaton  concept,  whereby  the repeated  iteration of a series of  rules on each of  these cells determines  the behaviour of the whole system. CAESAR has a set of rules for a hydrological model, hydraulic model (flow routing), fluvial erosion and deposition and slope erosion  and  deposition.  For  every  model  iteration,  cell  properties  (e.g. elevation) are updated according to the rules, and the interaction between an individual cell and its neighbours. For example, the amount of fluvial erosion in a cell may depend upon the depth of water in the cell and the slope between that cell and its neighbours.For modeling, the input data such as topography (DEM), daily discharge (year 2012) and sediment grain size were prepared and then channel modifications were simulated. Channel changes were identified before and after the simulation by plotting profiles of each cross-sections and were analyzed sensitive to erosion and sedimentation.Six cross-sections were selected before and after simulation. Results showed that the channel geometry has changed. The width and depth and form of the channel have changed. And only the mean depth of the channels was changed in sections 1, 2, 6 and 4. The erosion was dominated in the cross- sections 1, 2, and 3 (the initial part of the main channel). Then the sedimentation was dominated in the cross- sections 4, 5 and 6.

Rivers have a lot of complexity and diversity in different environmental conditions, and various natural and human factors affect rivers and change their hydromorphological conditions. In fact, hydromorphological degradation is one of the most important types and causes of river changes which happens due to human interventions and consequently the adjustment of the river channel. Several methods have been developed to study the hydrogeomorphology of rivers. One of these methods is the morphological quality index, which has been proposed as a new protocol to assess the morphological quality of river flow. The present study aims to classify hydromorphological quality of the Haji-Arab River (which is located in the west of Bouin-Zahra city) by Morphological Quality Index (MQI). In this study, two main phases and three sub-phases are used for each phase and applied to eight spans. Various indicators such as: functionality index, artificiality index and adjustment index have been applied on this river. The results show that the amount of MQI in the studied intervals was between 0.82 to 0.74%. Among these, the maximum value was in the spans of 1,2,3,6 with a score of 0.82, while the minimum value was in the span of 8 with a score of 0.74.  In terms of quality, Haji-Arab River is on a good class and has good conditions. The functionality index in this river was zero, which was the result of non-intervention of human in the river. Therefore, it is suggested to protect Haji-Arab River appropriately by proper management.

Flood is the most common natural hazard in the world that affects many people every year. This study aimed to assess the probability of flood hazard in Gamasiab River of Kermanshah using Multi Criteria Decision Making Approach (MCDA). So, four factors such as height, slope, distance from river, and land use were prepared and each factor was subdivided into 9 classes in the form of descending valuation. Then Normalized Weight Index (NWI) was calculated according to the effect of each factor on the probability of flood and Weighted Linear Combination (WLC) method was used to provide the final map of the flood hazard risk zonation. The results of flood risk zonation showed that about 61 square kilometers (12%) on both sides of the Gamasiab River had high and very high vulnerability. The Bistoon City and the lower reaches of the Gamasiab River have the high and very high-risk probability due to the decreasing of slope and height downstream of the Gamasiab basin. According to the results, Multi Criteria Decision Making Approach is a powerful, fast and low cost method in basins without hydrometric information for preparing flood risk maps.

Bank erosion is a severe problem to any fluvial system as it can generate up to 90% of the total sediment yield from a catchment It is also considered a hazard because it causes loss of lives and properties. The bank erosion and displacement of river planform change, each year, large areas of agricultural land and residential areas and coastal installation are exposed to destruction. The Haft Cheshmeh river located in the village of Razjard in Rudbar Alamut region ( Moaalem kelaye), northeast of Qazvin province‚ with longitude 50˚10ˈ14 and latitude 36˚ 20ˈ27, experiences severe bank erosion in several parts of its course.. This area located on the southern hillside of Alborz and south of Alamut in the mountainous area. The study area is on the southern hillside of Alborz in the Alamot section. The length of the studied route of the river is approximately 11 km and it flows near the villages of Razjerd‚ Rashteghon‚ Mianber and Shengher.

In this research were used from the topographic map (1:25000) of National Cartographic Center of IRAN (NCC) and Google images for the demarcation of the Haft Cheshmeh basin boundary and flow path of the river. Meander curve, vegetation cover, and other parameters of the bank have been measured from from Google images and field observations. In this study, the method Bank Erosion Vulnerability Zonation (BEVZ) has been used for investigate the factors affecting (rainfall erosivity, lithological factor, bank slope, meander index, river gradient, soil erosivity, vegetation cover, and anthropogenic impact ) the instability and bank erosion of Haft Cheshmeh river. After collecting data and using from available parameters, the reaches and cross sections are selected. The base on six parameters data, general weightage values have been assigned to each of them.. this model Interprets data by weighting variables and It is actually a proposed model based on GIS. Finally, it prepares a map of the river zoning according to the parameters mentioned. Based on this zoning, the severity of the vulnerability is divided into 5 categories: very high, high, medium, low and very low. At the end when all cross sections are scored‚ map of cross sections is prepared and zoned based on weights assigned to areas susceptible to instability and bank vulnerability.

The bank slope map of the study area indicates that the most of the river banks of the Haft Cheshmeh river belongs to the moderate to gentle category of slope. The right side of reach 10 is in Very steep category in terms of side slope. According to the results, In the case of the meander index, the first reach is in the meander class and the rest of the reaches have straight pattern. In the soil erodibility factor, most bank river were in the class very gentle to gentle. Also in the left bank of reach 1, the right and left bank of reach 8 are in very high class. In the lithology factor, all reaches belong to the moderate category and only The lower part of the side of the reach 8 belongs to the very high category. There are also bed samples of all reaches of river in the low category.The river gradient is considered as the triggering factor of river velocity that controls river erosion. Longitudinal slope at all reaches in Haft Cheshmeh river ranges from gentle to moderate category. Although in the height of 1710-1720 and 1700-1690 are in high category. In the vegetation parameter, most reaches are in scattered class and also reaches 4, 5 and 9 have high vegetation. In the human activities parameter, reaches 1-5 and 8.9 are in the medium category due to agricultural and garden land use. In reaches 6 and 9, human activity is in high category. According to the results, all reaches except reaches of 5 and 9 have received average score. All of these reaches had moderate erosion vulnerability. According to the scores obtained and field observations, reaches 1 to 4 had a lot of vegetation. Also the soil erosion parameter in these reaches is in the gentle category and the meander index has the lowest score. The right bank of reach 5 has a slow erosion rate‚ but the left bank of this reach is high erosion. Because there is an bend at reach 5 that causes the left bank slope to increase and despite much vegetation, erosion has increased and the roots of the trees on this bank also show a lot of protrusions. But on the right bank, the gravely point bar has caused the wall slope to decrease and the amount of shear stress applied to it is low. As a result, it is less vulnerable to erosion. The right and left bank of reach 9 are very vulnerable, because in field observations, was observed in upstream of this reach a sedimentary barrier that caused the flow path to change and Channel walls on both sides become steep. At this reach, shear stress is high and also human activities have the most score.

The results showed that most of reaches in Haft Cheshmeh river are in moderate condition in terms of susceptibility to erosion. But in 8 and 9 reaches, due to high human activity in the river, they were in the middle to high class in terms of risk. Also, in all reachs except reach 10, are in the middle to high class due to the sensitivity of the side materials to erosion. A study of erosion sensitivity at different reach of Haft Cheshmeh river showed that more erosion occurs in areas where there is no vegetation or vegetation is scattered‚ also it is more susceptible to erosion. This study showed that vegetation and bank protection plays a key role in riverbank sustainability in this region . Evaluation of erosion using Bank Erosion Vulnerability Zonation method showed that vegetation is a protective factor along the river and human activities and meander index are two driving factors in the development of vulnerability and erosion.

The assessment of the ecological potential of the environment is to determine and measure the potential power and the natural use type of the land. Therefore, the environment power assessment is a tool for the management of geographical space and strategic planning for sustainable development and correct use of land sources. The aim of this study was to evaluate the ecological potential of agricultural and rangeland use in Kangavar city with an area of ​​883.9 km2 using Makhdoom ecological model. To this end, the required data and ecological resources were collected and generated. After creating and combining the maps in the ArcGIS system in a multi-hybrid way, the maps of environmental units were constructed and the ecological potential of the area was evaluated using the features of each environmental unit. To do this, the indicators and variables that could be involved in each of these models were examined. To classify the ecological potential of the area for agricultural and rangeland uses and to produce the map of different classes potential, 15 parameters were used as criteria for weighting and measuring the power. The results of Kangavar city ecological potential assessment led to the extraction of 58 environmental units in 7 classes with completely suitable, suitable, weak, and unsuitable power classes for agricultural and rangeland use. An area of about 356.79 Km2 was found to have suitable and completely suitable power for agricultural use. In addition, it was estimated that an area of about 72.23 Km2 would be appropriate for rangeland and rainfed agricultural use with suitable power. An area of about 483.26 Km2 of Kangavar city is currently allocated to agricultural use, while the optimal area for this means is 356.79 Km2. Thus, the land use of an area of about 126.47 Km2 has been converted to agricultural purposes. According to the results, the lands of the region have been exploited more than their potential for agricultural use (irrigated and rainfed) and the lands with rangeland use have been changed to agricultural use.