Geomorphology of the river, a term used to check the river system. Zohreh river is one of the rivers in Khuzestan that consisted from 2 arm Fahlian and Kheyrabad it flow to Persian gulf at the end of Hendijan flat. To accomplish this study topographic maps, remote sensing data, including: Landsat satellite images, Landsat TM and ETM + collected from the Geological Survey of America (Earth Explorer), aerial photographs taken in 1334 of National Geography Organization is used. Next, aerial photos of 1334 as the base image and satellite image of Landsat 8 (2015) were selected as the data terminal. The future direction of the river in 2030 (1409) is plotted and compared with other periods. In this interval is 2 Meander complained. The findings suggest that during the period under review trends in three periods studied are quite different in the river, so in terms of reducing the length, intervals 7, experiences the lowest decline while interval 2 experience biggest decline in three visits. In terms of increasing the length, intervals 7, experiences the lowest increase and intervals 8, had the largest increase. The findings indicate that during the three periods under review, the river changes in the periods studied are quite different. The results show that in 1955 10 cases of amputation has occurred in the river channel and along the river has become 3, 653 km shorter. Even though at intervals of 1 to 5 we except villages along the way, there is no human factor; But in the interval of 6 industries are seen. Interval 7 in the northern part of the land is under irrigated agriculture. But in the southern part are bare. In the interval of 8, lands under the tide, and asphalt and dirt roads are important feature.

Introduction: An important characteristic of river is channel form and meandering rivers for active forms. Dams as barriers to water and sediment flow can create discontinuities in fluvial geomorphological conditions. The objectives of this paper are to assess the effects of reservoir on the meandering river morphology. The Gorgan River catchment is located in the southern part of Golestan province with a total area of 11، 380 km2. This river is originated from the Alborz Mountains into Caspian Sea. A reach of the river، 44 km long، that is examined in this research is situated in middle Gorgan River، between Gonbad Kaboos city and Digjeh. The construction of reservoir and changes in land use is effective on the main activities that potentially impact water regime، sediment transport and fluvial dynamics in the Gorgan River. Materials and method: The data of the flow discharge and suspended sediment load of Gorgan River are available in 1973-2015 at the Ghazaghli gauge station (73 km downstream from the Golestan reservoir Dam). The hydrological analysis was divided into two periods: before dam construction (1973-2001) and after dam construction (2001-2015). Sediment rating curves were created by daily mean suspended sediment discharge and daily mean water discharges by a power function. The fluvial changes have been measured using aerial photographs of 1967 at a scale of 1: 20، 000، Landsat satellite images (Landsat TM) 2001 and Google Earth images، 2015. The river was digitized from photographs and satellite images، after they were geographically referenced with the help of ArcGIS 10. 2. Meander morphology was described based on some of form parameters such as wavelength، amplitude and radius of curvature، and bank width of the channel. Lateral migration and channel activity was analyzed as geomorphic activity. The normality hypothesis was studied for each parameter and conducted with the Kolmogorov– Smirnov test. If the normality test was not rejected، an ANOVA test was applied. If the normality hypothesis was rejected، the Kruskal– Wallis test was used. In all cases، the significance level assumed was α =0. 05، as a threshold for rejecting the null hypothesis. The spatial distribution for these parameters was analyzed in order to change downstream the channel. Thus، the correlation coefficient of Spearman was calculated. Results and discussion: During the pre-dam period (1967– 2001)، mean discharge below the dam was 14 m3 s-1. These values were 10. 5 m3 s-1 after the dam was constructed (2001-2015). Power regression between suspended sediment discharge and water discharge data shows that suspended sediment load is reduced to 50 % after dam construction. The values of wavelength and amplitude show minor differences in the three records and do not show significant differences. The radius of curvature، the length in 1967 (124. 7 m) was reduced in 2001 (100. 6 m) and 2015 (103 m). The dispersion values show significant differences، with a maximum in 1967 and reductions in 2001 and 2015. Bank width shows significant variations in the three records. In 1967 and 2001، it reached the values of 31 and 33 m، respectively. This is decreased to 15. 7 m in 2015(-50% from 1967). Thus، bank width loses half of its value in the pre-dam. In pre-dam period (1977-2001) channel lateral migration was reached 39. 3 m and in post-dam (2001-2015) the displacement was recorded to 22. 2m. The channel activity during the time period 1967– 2015 reached 0. 65 m/y. The ratio between radius of curvature and the bank width (Rc/W) is changed from 4. 14 in 1967 to 3. 04 in 2001 and 7. 48 in 2015. These results have indicated that migration capacity is decreased. The stability state shows the spatial distribution of the values. There is no significant relationship between landuse and lateral migration. Conclusion: After construction of the three dams، upstream flow discharge is reduced (26%) and mean width of river is reduced (50%) from 2001 to 2015. Suspended sediment discharge has decreased (50%) after the construction of dams. Wavelength and amplitude do not show significant differences throughout the time period. The ratio Rc / Wb doubles from 1967 to 2015. The results show that geomorphological activity is decreased and a static equilibrium was obtained

A series of experiments was performed in a laboratory flume to determine the threshold of meandering and braiding of river patterns. For the 4, purpose, of modeling, an alluvial reach of Ghezol Ozan (a meandering river in central north of Iran) was selected and using reasonable values of  geometric, hydraulic and bed material properties of  this river, a physical model with horizontal scale of 1: 400 and vertical scale of 1:40 was constructed. After performing several laboratory tests it was found that discharge and slope were closely related to the threshold values of channel patterns. Also based on regression analysis of experimental, results a number of analytical relationships were obtained for determining the threshold of meandering and braiding patterns. The proposed relationships are between the channel longitudinal slope and discharge and between the non dimensional unit stream power (NUSP) and shields parameter. The later is a new and interesting relationship in river morphology. Several diagrams were made to show that under what initial" conditions the meandering and braiding patterns are established. The laboratory observations of this research have indicated that at very low NUSP, the 4.channel remains straight, but at NUSP of 5.5 to 6.5 a meandering channel is formed and as NUSP increases to 12-22 a braided channel is formed.

The Lateshur Watershed is a part of Central Iranian drainage basin located northeast of the city of Pakdasht in northeastern Tehran Province. This watershed has an elongate form and its surface area is more than 22.2 square kilometer. It is a part of central Alborz zone and geologically is composed of Neogen red beds units, Hezardareh Formation and Quaternary alluviums.Geomorphologic studies show that this watershed is within an anticline and surrounded by Dahaneh Mountains in the south and Gara-aghaj Mountains in the north respectively. Structural and lithological variability have a very important role in the formation of this watershed; therefore, the watershed has the same trend as structures (NW-SE). Based on this study, the Lateshur River has a braided pattern with gravelly bed. Sedimentological studies along rivers in Lateshur basin show that three basic factor (sudden changes in slope gradient, floods events and distributaries) are the main reasons for changes in texture of bed load sediments within the channel as well as the break in sedimentary links. Lithofacies identified in this watershed include gravelly (Gmm, Gmg, Gcm, Gt), sandy (Sp, Sm, St, Sh) and muddy (Fl, Fr). Based on lithofacies, Boundary surface and current direction architecture elements identified in main river of Lateshur basins include: (1) Gravel bars and Bed forms [Element GB], (2) Lateral Accretion deposits [Element LA], (3) Sandy bed forms [Element SB] and (4) Fine grain classtic deposits [Element FF]. Also, based an lithofacies and architectural elements, Facies models have been purposed for the Lateshur river from upstream toward downstream as fallows: Shallow gravel braided river, Gravel wandering river, Gravel bed meandering river, Sandy meandering rive and Fining grain meandering river.

The morphological and geomorphological characteristics of rivers are constantly changing due to their continuous nature. In this research, the geomorphology of a part of Karun River in relation to the changes leading to meandering has been studied using satellite data and with a "descriptive-analytical" methodology. For this purpose, first the cell values of different bands of TM images (related to 1991) and ETM (related to 2002 and 2010) were weighted using fuzzy hierarchical analysis method to detect the bands showing the most changes compared to other bands. Then, from the weighted bands, the main components of the corresponding bands TM 1991 and ETM 2010 (as the beginning and end years of the studied period) were extracted and finally, by defining the fuzzy membership of the changes, the regions with the highest amount and intensity of changes in five The floor is provided. The results show that bands 7 and 5 show the most weight changes (river area) among the other bands for the images of 1991, 2002 and 2010, respectively. On the other hand, the fuzzy membership function of the changes showed that the maximum changes with intensity of zero to 20%, with values of 149 square kilometers including 48.3% and also the minimum changes with intensity of 80 to 100% with values of 8.2 square kilometers including 2.6% of the total study area. Therefore, from the study area of Karun, an area of eight square kilometers (about 3% of the total area evaluated) has experienced the intensity of changes above eighty percent and about 20% of the area with an intensity factor of fifty percent or more, prone to meandering or about to.

Introduction: Meandering rivers, as prime examples of nature tendency to reach a regular form, have been the focus of many researchers. These rivers contain a series of alternating bends and curves, joined by short straight intervals across their plan and flow over gently sloping channels in which sedimentary load settles as point loads on the inner wall of the bend. River morphology studies the geometrical form of rivers in the plan, longitudinal profile (channel slope), cross section geometry and topography. Morphological analysis of meandering rivers is performed in two stages: determination of independent variables (flow and sedimentary discharge), calculation of geometrical parameters of river morphology through physical or experimental relationships. Such parameters are mostly studied using Euclidean geometry. Sinuosity, for example, has been calculated with Euclidean attitude in Cartesian coordinates. Quantifying geometrical parameters of meandering rivers morphology in a Euclidean approach arises problems such as inaccuracy or complexity in calculation. Instead, Fractal geometry is widely used in river engineering in recent literature, due to its more detailed perspective of an object and its non-Euclidean properties. In Fractal Geometry, the mathematical space classified into one-, two-, and three-dimensional spaces on the basis of Euclidean geometry, is expressed as is fractal spaces in which the irregularities of the shapes are expressed in terms of fractal dimension (a real dimension and not necessarily a natural number). Single-fractal analyses are mainly carried out using methods such as box counting, variation, scale change, and Brownian motion methods, while multi-fractal analyses include methods such as spectral or wavelet analysis. Methodology: Box counting is one of the fractal dimension calculation methods, widely used in rivers and shorelines. In this method, the set of points is meshed on a curve or a surface with squares (boxes) and the number of squares covering each part of the curve is calculated. Variation method also is one of the most accurate and popular method that can be used to calculate fractal dimension in various fields, however it is rarely used in river engineering up to now. In the present study, the fractal dimension in the Mond River was calculated over a 15-year period from 2000 to 2015. Mond River, with 685 km length is one of the most important rivers in southern Iran, originating in Fars province and flowing into the Persian Gulf through Bushehr province. Two fractal methods namely, box counting and variational methods were applied to calculate fractal dimensions in I) the whole river II) 3 longest bends III) 13 meanders. The results were then compared with those of sinusoidal coefficient. To calculate the fractal dimension by changes method, the area covered by different characteristic lengths is calculated in fixed intervals. Then, for different characteristic lengths the area covered by meander curve is calculated using code written in Matlab. The correlation coefficient values for the river coordinate data at each of the river intervals are obtained and compared in the bends. In the box counting method, different dimensions of the box and therefore different grids were considered. Then, in order to calculate the fractal dimension, the number of boxes involved was calculated for different widths using codes written in Matlab. Variations in the box width with the number of boxes in logarithmic scale are used to calculate the fractal dimension in the box counting method. Result and Discussion: The values for fractal dimension ranged between 1. 01 to 1. 09 and 1. 0027 to 1. 991 using box counting method and changes method, respectively. Additionally, the calculated fractal dimension values were compared with sinusoidal coefficients in three long meanders and fourteen bends of the river. Results indicated high correlations (R2 = 0. 940. 99) between fractal and sinusoidal coefficients in the meanders. The fractal dimension obtained in 2005 (1. 05) was larger than those in other years. The largest fractal dimension was met in the second meander, with a value of 1. 06. Highest sinusoidal coefficient was also found in the second meander indicating a direct relationship between these two parameters. There was a high correlation coefficient (close to 1) between the fractal dimension and the sinusoidal coefficient in the long meanders. Conclusion: A considerably high correlation coefficient of 0. 96 was obtained between the parameters of the sinusoidal coefficient and the central angle calculated from the morphological analysis, which indicates a direct relationship between these parameters. The correlation coefficient of 0. 85 between the fractal dimension parameters and the sinusoidal coefficient as well as the correlation coefficient of 0. 86 between the fractal dimension parameters with the central angle indicates that the fractal dimension parameter is an appropriate indicator for expressing the changes and complexity of the meandering rivers.

The Rapti River and its tributaries exhibit a predominantly meandering morphology, marked by annual spatial-and-temporal-variations in bend geometry and bankline position. Bankline modifications are most prominent during receding flow-stages due to the accumulation of excess sediment forming point and side bars. A detailed understanding of river behavior both upstream-and-downstream of hydraulic structures is crucial for effective planning, design, and long-term maintenance. This study utilizes remote sensing-and-GIS tools to analyze sediment deposition upstream of barrages and the impact of inefficient energy dissipation from skewed hydraulic jumps downstream. The minimum-sinuosity-index of 1.21 was recorded in reaches exhibiting two-phase underfit morphology, whereas the maximum-value of 2.73 was observed in single-phase reaches with irregular width variation. Prior to the barrage construction, the channel maintained a consistent width of approximately 1000 m both upstream and downstream. Post-construction, the downstream width reduced by nearly 400 m in 1998 and by 800 m in 2006; however, it is projected to return to 1000 m by 2024. From 1975 to 2024, the sinuosity index increased across all morphological types. The lowest average value (1.665) was recorded in partially bank-protected reaches, and the highest (3.139) in reaches with full bank protection. Overall sinuosity increased from 1.64 (pre-embankment) to 1.83 (post-embankment). Bankline migration declined from ~13 m (2006–2008) to ~10 m (2008–2010), stabilized at ~3 m (2010–2016), and reactivated to ~6 m (2018–2024). Sustained riverbank stability necessitates corrective interventions, strategic river training works, and coordinated policy support.

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.

In this research using finite volume method a two dimensional mathematical model is developed for predicting the changes of river morphology. The developed computer package can be used specially for calculating bank erosion and sedimentation in meander loops. In the prepared model first by solving the energy, velocity diffusion and momentum equations, flow parameters including main and secondary velocities, main and secondary shear stresses and critical velocity and shear stresses are determined. Then by comparing the critical flow velocity with the longitudinal flow velocity, the rates of sediment transport in longitudinal direction for each sub-section are computed. The transversally sedimentation (or erosion) rate is calculated, afterwards, through comparing the calculating bed shear stresses in the two main directions, together with determined sediment exchange among the subsections based on mass continuity equations. In this manner, the erodibilty parameter is calculated for each river section and by using periodic wave model the river plan changes is predicted. This investigation has indicated that: - The most suitable grid for dissolving the equations is 50*20 grid. - The finite volume method can be suitably used for analysis of natural river morphology problems. - To dissolve the questions, the point-by-point method, in spite of its simplicity, has shown a more suitable accuracy. - The best numerical methods for dissolving the equations (least time, accuracy of answer) are point-by-point (PBP) and line-by-line up to down (LBLUTD) methods, respectively. - Ghezel-Ouzan River has a parabolic velocity distribution and the exponent of the suggested equation varies between 3 to 8. - The maximum displacement of Ghezel Ouzan River is different in various places and it depends on discharge and slope. The prepared model is very sensitive to the variation of discharge and slope.

One of the most important engineering issues which greatly affects human activities is the Meandering of revers. Accordingly, studying this phenomenon in rivers is essential for accurate identification, identification of the resulting hazards, coping with them and optimal exploitation of natural resources. The purpose of this research is to investigate the characteristics of the riverside runways of the Gadar river route. The purpose of this study is to investigate the characteristics of the riverside meanderings of the Gadar river route. In order to achieve this goal, considering the size of the area under study, the use of satellite imagery and geographic information systems are considered as essential tools for processing. Based on this, satellite imagery ETM + was used for the years 2000 and 2012 and the IRS. The results showed that during the two surveys, the trend of river changes in the triple intervals is completely different. So that the first interval is the highest and the third is the least change over the two periods. The values of the central angle and the bending coefficient also indicate that, in all the intervals, the variation of the bending coefficient and the central angle, with the exception of a relatively small proportion in the mountainous regions, confirms the existence of roughly similar arcs along the path.