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Rivers are natural systems that human pressures have caused severe changes in their morphology during the past decades.The factors influencing river morphological changes and their responses vary across different regions. Therefore, in the present study, morphological changes in a section of the Haraz River in of Amol city were investigated over a 53-year period (1968 - 2021). The changes in river width, planform, and fluvial landforms were examined using aerial photographs and satellite images. Subsequently, by calculating the specific stream power and conducting field observations, the hazards associated with the river channel were identified. In 1968, the average river width was measured at 141 meters, but by the years 2006 and 2021, it has decreased to 55 meters. The area of fluvial landforms, including the active riverbed and longitudinal bars, decreased by 50% and 95%, respectively, during this period. The river channel transitioned from a braided pattern to a single-channel pattern due to channel narrowing and significant reduction in longitudinal bars. These changes led to an increase in stream power and erosional processes, resulting in river incision and bank erosion. Key factors contributing to the morphological alterations in the study area included the reduction in base flow, irrigation channel diversion, and land use changes along the river floodplain. According to the process of changes, the construction of the new dam (Haraz), the continuation of the occupation of the floodplain and canalization can intensify the river channel hazards. [ABSTRACT FROM AUTHOR]

1-Introduction Landforms show different patterns over time and in different spatial scales and climates, knowing the temporal and spatial patterns of landforms in each region can provide the possibility of predicting and detecting the potential of Groundwater in a similar spatial situation. Due to Iran being among the dry and semi-arid countries of the world and the existence of inherent limitations of Groundwater water resources, proper location for exploring and maintaining the sustainable potential of Groundwater is of particular importance. The importance of these resources in the southern plains of Alborz is twofold due to the population density and location in a dry and semi-arid climate, which requires the exploration of Groundwater. A complete understanding of the system, forecasting the current and future conditions, as well as presenting the environmental indicators considered by geomorphologists by providing geostatistical methods, in addition to saving money and time, can determine the places where there is a higher probability of having desirable aquifers. Rivers represent to a great extent the geomorphic nature of any region. The appearance patterns of the river can be classified into four main groups, which are straight channels, sinuous meandering and severe meandering. The channel pattern is derived from a set of characteristics that can create a direct relationship with the state of Groundwater infiltration and, as a result, changes in the level of water stagnation. Factors such as changes in river flow, sediment conditions, land surface slope, river strength, vegetation cover, etc. cause changes in the pattern of the river along its path. These factors are considered to be the most important factors of Groundwater penetration in the plain and downstream areas of the mountain fault line (Kennik line). Therefore, it can be concluded that with the change in the river pattern, the status of the groundwater level should also change. In the field of investigating the real or actual potential of Groundwater, there have been scattered studies that based on the environmental changes during a certain period, it is possible to find out the probability of the existence of Groundwater in that area. The purpose of the current research is to find the potential of Groundwater resources according to the changes of river platforms in the western plains of Tehran, Alborz and Qazvin. In this present research, after identifying and mapping the river channels in the western and southern plains of Tehran, Alborz and Qazvin provinces, the sinuosity characteristics of each of the rivers were determined and the studied area was divided into 67 intervals according to the river patterns and calculated independently. Also, this article has tried to determine the influence of river parameters on the changes of Groundwater parameters by identifying the border of river pattern changes and its relationship with the clustering of Groundwater parameters according to statistical classification. 2-Methodology In order to evaluate the role of river platforms on water table changes, information on well discharge rate, electrical conductivity and water table depth of 23559 observation wells from Iran Water Resources Organization was prepared. Also, the morphometric characteristics of the rivers and the resulting patterns were identified and their relationship with the average, maximum and minimum depth of the water table, discharge and electrical conductivity were calculated. 26 rivers were used as the main rivers of the western regions of Tehran, Karaj and Qazvin provinces. Then, each river was divided into two or more parts by means of morphometric changes along the river course and according to the separated sinuosity. According to the pattern of rivers, the studied area was divided into 67 intervals and drawn. Arc Gis 10.5 software was used for digitization and data processing. The sinuosity coefficient of each river was calculated in terms of the ratio of the length of the main course of the river to the length of the valley or the linear length of the river. By determining the river's sinuosity coefficient (Figure 2), each river was divided into four straight, sinusoidal, meandering, and severe meandering patterns according to the average of the determined coefficient. Using SPSS version 23 software, hierarchical cluster analysis (HCA) was used to classify the characteristics of groundwater in 26 rivers and its tree diagram was drawn. Considering the non-parametric nature of the data of each cluster, the significant difference of the parameters was determined by the one-way variance and Kruskal-Wallis tests. Also, in order to determine the effect of river parameters on changes in the depth of Groundwater in each model, hierarchical cluster classification was done and its significance level according to the number of variables and parametric or non-parametric data using one-way variance, independent t, Kruskal-Wallis and Man-Whitney and Pearson correlation test were calculated. The coefficient of explanation and the graph of changes in Groundwater parameters were also estimated by Excel software. 3-Results The results showed that all three groundwater parameters have a strong correlation and a significant difference of 95% in straight, sinusoidal and Pichanrodi patterns. Also, the river sections that have a sinusoidal pattern with a sinuosity coefficient of 1.14 and an average flow rate of 12.6 liters per second have the highest amount of water flow compared to the other two patterns. The relationship between the sinuosity coefficient of the river and the amount of electrical conductivity and the depth of the sedimentation surface is linear and non-random, and moving from the straight pattern to the winding pattern, the amount of electrical conductivity and the depth of the sedimentation surface increases. 4-Discussion & Conclusions The results showed that each of the rivers, in addition to having an independent pattern, also had pattern changes along its course, which can be identified and separated. In addition, the areas under the influence of rivers can be separated into two classes or clusters in terms of the status of Groundwater parameters. In fact, the significant difference in the sinuosity coefficient of rivers in areas that have significant differences in terms of Groundwater changes can indicate the influence of both parameters on changes in environmental conditions such as the morphogenic state, topography, hydrology, lithology and morphology of the region. Therefore, the changes in the sinuosity coefficient can be considered as evidence of the changes in the Groundwater, and the results of the verification show the influence of the platform of each river section on the changes in the Groundwater. Also, the degree of correlation and significance of the twisting coefficient of the river with the changes in flow parameters, depth of water table and electrical conductivity also shows that all three Groundwater parameters have a strong correlation and a significant difference of 95% in straight, sinusoidal and meandering river patterns. In general, the results of this research showed that due to the great relationship between patterns or river platforms on Groundwater, this index can be used in large and small intervals to evaluate the quantitative and qualitative changes of Groundwater and it can be used for Other similar areas also extended. Also, the results of this study show that river geomorphic studies before carrying out implementation plans can be the basis for reducing the error in determining the appropriate place to feed the aquifer or dig an Groundwater well. [ABSTRACT FROM AUTHOR]

Soil erosion followed by sediment production is the most important phenomenon that causes soil and environment degradation in many areas and is increasing. Sediment fingerprinting is a method to identify sediment sources and determine the contribution of each source to sediment production. The present research was carried out to evaluate the relative erosion sensitivity of lithological units and to determine the contribution of each unit in bed sediment production using geochemical properties in the Vaz River located in Mazandaran province. The 33 soil samples were taken from the whole watershed and one sediment sample at the outlet of the watershed. Then, five tracers of B, Al, Sc, Mo, and Sn were selected as the optimal combination using three statistical tests range tests, Kruskal-Wallis, and discriminant function analysis. Finally, using optimal tracers and a combined multivariate model, the contribution of lithological units with very high (A), high (B), medium to high (C), and medium (D) sensitivity in bed sediment production were obtained using FingerPro statistical package and R software. The results showed that the contribution of lithological units with very high (A), high (B), medium to high (C), and medium (D) sensitivity in bed sediment production were 24.23, 50.77, 15.62, and 9.36%, respectively. Then, the specific contribution of each sensitivity class was also calculated to remove the effect of area on the results. The Qal lithological unit including the Quaternary sediments in the river bed and banks with very high sensitivity to erosion (A) and a specific contribution of 0.0807 % per hectare had the maximum contribution in bed sediment production in Vaz River. [ABSTRACT FROM AUTHOR]

The study of floods has always been important for researchers due to the great loss of life and property. Investigation of flood bed can provide appropriate solutions to reduce this phenomenon to managers and researchers. In this research, the compound channel (with flood plain on one side of the main channel) Been paid, Therefore, two experimental models of compound channel in laboratory flume were examined by considering dimensional analysis. With the goal Investigation of lateral slope of flood wall in laboratory model In the first model, transverse slope 0 And in the second model, a value equal to 50% Was considered. Also in order to investigate the effect of longitudinal slope of river bed sediments Longitudinal slope in three steps 0.00 2, 0.004 and 0.006 Was changed. Examining the ADV speedometer data, the results showed that with increasing the longitudinal and transverse slope (slope of the flood wall) of the channel, the maximum longitudinal velocity changes to the floor of the channel. In order to investigate the effect of average sediment diameter on the scouring process during experiments Mm was used. The results showed that increasing the longitudinal and transverse slope had a great effect on increasing the volume of washed sediments 3 and 0.9 of sandy sediments with a diameter Along the canal and with the increase of these longitudinal and transverse slopes in the channel, more sediment transport volume occurs. In the following, using Investigation of dimensionless numbers obtained from dimensional analysis, dimensionless weight landing number was introduced to evaluate this value value of other hydraulic parameters and Was introduced. A relationship based on nonlinear regression with correlation coefficient Acceptable was introduced at around 0.88. [ABSTRACT FROM AUTHOR]

Investigating dense flows containing cohesive sediments (turbidity currents) in the water environment has been the main interest for researchers in hydraulic and fluid mechanic science. This kind of flow streams at the bed surface because of higher density than water and penetrate to overhead water, which causes turbidness. In the present research, this kind of flow has been modeled using two-phase simulation with smoothed particle hydrodynamics Lagrangian method. A SPHysics2D code has been developed for modeling, in which pressure value is calculated using the equation of state. Also, Herschel-Bulkley-Papanastasiou single relation non-Newtonian viscoplastic model has been used for modeling the cohesive sediment phase. After that for investigating the amount of penetration of cohesive sediment mixture in limpid water, the advection-diffusion equation was used for developing code. Finally, one and two-phase results obtained from the present model were compared to experimental models. The study shows that the present developed model is able to model these flows desirably and could be utilized for studying concentration amount, dense flow penetration and their propagation in the water environment. [ABSTRACT FROM AUTHOR]

Rivers have different patterns along their path, and understanding these patterns could help researchers understand and predict the responses of human activities and natural factors of the river. In addition, in the morphological analysis, the flow power is one of the most important parameters. Therefore, the purpose of this study was to analyze the channel form and to evaluate the river power in different return periods as well as to estimate the shear stress in the Givi Chay River using Landsat 8 images, topographic maps, geology, hydrological, and field data. Morphological and hydrological indices, as well as methods for analyzing the total river power, river specific power, and shear stress, were used to achieve the purpose of the study. The calculation of the bending coefficient showed that the river pattern was sinusoidal in the first and third intervals and was meandering in the second interval. According to the central angle characteristics, the first and the second intervals were in the highlydeveloped meandering form and the third interval was in the developed meandering form. Also, according to the results of the study, the highest amount of the total river power was in the first interval at the 4th, 5th, and 6th sections. The specific strength of the river was high in the third intervals and the 2nd, 1st, 5th, and 6th sections. At present, due to the low strength of the lithological formations in these sections, the erosion of the riverbed is observed in these sections. The lowest specific power was due to the high river width and low bed slope at sections 12 and 13. The highest amount of shear stress was in the first interval in sections 5, 6, 2, and the lowest shear stress was in sections 12 and 13. In general, channel formation and channel dynamics in the Givi Chay River were influenced by discharge, lithological resistance of the riverbed, and human interference (encroachment on the riverbed, construction of bridges, and dumping of construction waste and debris). [ABSTRACT FROM AUTHOR]

Erosion under the conveying pipeline affected by river flow at the cross to rivers is one the important reasons for breaking the pipelines that can lead to leakage. While the mechanism of erosion under the conveying pipeline in steady flow has been studied by many researchers, studies have shown the importance of scouring research in flood times under unsteady conditions. So, this study has been concerned with the investigation of bed river erosion under the conveying pipeline at the conflict of river in unsteady condition. To achieve this aim, some effective hydrograph's parameters were changed in different scenarios and the results were compared to the steady condition. The result showed the erosion's ratio of unsteady condition to steady one was 34 to 69 percent. Also, the rise of flood hydrograph's peak led to increasing depth erosion from 7% to 22%. [ABSTRACT FROM AUTHOR]

Simulation of the hydraulic behaviour of the river basin boundaries is important for river engineering projects, prediction of flood damages in different conditions and economic feasibility studies, flood control, and other social programs related to the system of the river. In this study, river bed and flood zoning map in the range of over 155 km from the Zayandehrud dam to Nekouabad Diversion Dam were addressed by using the software's ArcGIS, HEC-RAS and HEC-GeoRAS extension. For this purpose, a digital elevation map in 1: 250,000 scale was provided and crosssectional area was divided in 1085. Manning roughness coefficient was determined by Cowan. Finally, data entered into the software HEC-RAS and was analysed. After determining the area of flood in the return periods of 2, 5, 10, 25, 50, 100 and 200 years in all cross sections, the results were entered into the ArcGIS environment and flood zoning maps were obtained. The results showed that of the 200-year flood lands, 96% of the land flood was related to the return period of 25 years. [ABSTRACT FROM AUTHOR]

In terms of geographical location, Mashhad metropolis has spread all over a wide alluvial plain. Locating between the Kopeh Dagh and the Hezar Masjed sedimentary heights and the Binalood igneous heights has led to the creation of specific morphology for the Mashhad alluvial plain. In the northern part of the city, the Kashafrood River drains all the rivers of Mashhad plain. And the Binalood heights drainage rivers run through the city of Mashhad and drain into the Kashafrood River. The city's physical development over the years has led to a change in the morphology of the city's rivers and in some ways, high-rise buildings are built on the abandoned river-beds and the probability of occurrence of geomorphological hazards has increased. In this research, the location of Mashhad and its physical growth, which led to the destruction and change of river's morphology, has been studied by using 1353, 1359, and 1390 satellite images and the old maps of Mashhad and geological and topographic maps in different periods. The purpose of this research is to investigate the comparative situation of rivers with urban built canals and the resulting risks. In this regard, it has been found that many urban canals are designed without regard to the natural morphology of the rivers and also regardless of the flow capacity of the water. The natural type of the river-beds has been sedimentary deposits including shale, clay and sand and rock along with the forms between the rifting of the rivers, but the canals have thick concrete walls and direct paths. [ABSTRACT FROM AUTHOR]