mohammadmahdi hoseinzadeh

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.

 elevation factor, slope, Distance from river, Geomorphology, Drainage density, Flow accumulation, precipitation, land use, geology, SPI, TWI, curvature. SPI, TWI, curvature layers in SAGA GIS environment have been prepared and the other layers have been prepared in GIS environment. After preparing the criteria, the pairwise comparison matrix is prepared and then the value of the final coefficient of the layers is prepared with the help of Expert Choice software. Then all the factors are classified and fuzzy normalization is applied to them using fuzzy functions. Finally, all layers are merged using the WLC method and the final map is prepared. To determine the degree of correlation of layers using random points, the correlation coefficient of factors has been calculated. The results of this study show that in Sanghar catchment area, about 26% of the area is exposed to high and very high flood sensitivity and 59% have low and very low flood sensitivity. Among the geomorphic factors affecting the flood, three factors: elevation, slope, and drainage network density have a major impact on the flood sensitivity of the Sanghar catchment; In contrast, the four factors of Distance from river, SPI, Flow accumulation and curvature played a smaller role in the flood susceptibility map of Sanghar catchment.

The frequency and severity of floods has increased globally. However, in many parts of the world, especially in developing countries, there is no accurate data for estimating the probable of flood risk. In this research, flood risk zonation has been done for delineation of flood fringe in Gamasiyab River (south of the Sahneh city, east of the Kermanshah province).The simulation of the flood has been carried out based on the HEC-RAS (one-dimensional hydrodynamic model), and the geometric data has been processed in the GIS by the HEC-GEORAS extension. Also peak discharge in diffrence return periods has been calculated using SMADA software by Type III Pearson distribution. The study area has been divided to four reaches based on river patterns and then manning's roughness coefficient has been calculated for each reach. The results show that 23.78 km2 and 42.1 km2 of the river floodplain have been inundated by 25-year and 100-year return periods respectively, so that amount of damage from the 100-year flood was higher than the 25-year flood. Also the width of inundation area in the reaches 2, 3 and 4 indicated that 25-year return period was not good criteria for flood fringe. It is necessary to study the other features of the river, including bed morphology, river depth and river pattern.

River channel change, bank erosion and bank sedimentation are natural process of alluvial rivers that cause destruction of agricultural lands and destroyed of structures around the river bank. The aim of this research is estimation of bank retrogression rate and bank erosion in Galali river (the reach between Galali and Shirvaneh village) due to assessment of changes and estimation of potential changes in frequency of bank failures (Safety Factor) and sediment load from the river bank in two different scenario and 12 hours and three reaches by BSTEM model. The big floods can be caused bank erosion in this river and this issue is so important because there are some dams have been constructed in downstream of this river so estimation of erosion and sediment load is very important. Results show that total eroded areas in first scenario are 0.244, 0.372 and 0.054 m2 in reaches 1, 2 and 3 and the total eroded areas in second scenario are 0.272, 0.1 and 0.054 in reaches 1, 2 and 3 respectively. According to bank stability and safety factor, all of three cross-sections are unstable in first scenario and safety factor is less that 1 but safety factor increase in second scenario so that safety factor is around 1 in reaches 1 and 2 and in reach 3 is more than 1. Therefore, by protection works on the erodible banks can be reduced the total volume of the sediment load from eroded bank.

Snow avalanche is one of the snowy and mountenous areas phenomenons that may result in ‎hazzards and irreparable problems. The objective of this study is to determine the most ‎important effective factors in avalanche events in Meigoun-Shemshak road. Meigoun- ‎Shemshak road has been located in Shemshak drainage basin with area of 37.75 Km2 in ‎Roodbar Ghasran district, Shemiranat County, Northeast Tehran. To assest avalanche ‎corridors, effective enviromental parameters on avalanche including length of valley, width of ‎valley, azimuth, slope percentage, valley curvature coefficient, elevation, clay, silt, sand, ‎roughness coefficient, vegetation and rock cover percentage, precipitation, temperature and ‎snow were determined. In the studied area, three types of valley were identified: ephemeral ‎avalanche valley, permanent avalanche valley, without avalanche valley. The enviromental ‎parameters comparison between ephemeral avalanche valley and permanent avalanche valley ‎showed that slope percentage, roughness coefficient, clay, silt, sand, vegetation and rock ‎cover percentage are significant in the valleys and also in comparison between the sections of ‎them only valley curvature coefficient was significant. In comparison between three types of ‎valleys, parameters: Azimuth, valley curvature coefficient, slope percentage, surface ‎roughness, vegetation and rock cover percentage were significant. The results of comparison ‎between sections of the three types showed valley curvature coefficient was the significant ‎parameter. The most important parameters affecting the avalanche are Azimuth and surface ‎roughness coefficient.‎

  One of the subjects about alluvial fans is their sedimentary characteristics. The purpose of this study is to analyze and compare the Chitgar and Kan alluvial fans located in the southern slopes of central Alborz in Tehran province and the correlation between the sediment factors affecting soil resistance and determine the most important factor in soil resistance. The study area in this research is Kan and Chitger alluvial fans, located in the northwestern part of Tehran and in the basin of Kan and Chitgar rivers. At First, For better study and comparison of the parts, the Alluvial Fan were divided into three upper, middle and distal.Then the physiographic characteristics of each section were calculated. In the field operations, 24 trenches in the study area were excavated and all the layers were sampled and their position was recorded with GPS. After collecting samples, sedimentology studies, including classification and determination of particle size, determination of particle size parameters and clay measurements by pipet method were used. Finally, by using Excel and Gradistate soft wares, all statistical parameters and different charts for particle size by Folk method and morphometric analysis and particle size by pipet method were prepared and these two alluvial fans were compared in terms of sedimentary texture according to their basin. Finaly To compare geotechnical properties of sediments in two Fans, soil resistance factor was used.
Results and discussion
After examination of the sediment, two Alluvial Fans aggregates were observed in which both conifers follow from the exponential pattern of particle size reduction from top to bottom. So that in the upper parts the greatest concentration is observed in the coarse particles and fine particles are in abundance. Of course, in some trenches there are also thick and massive deposits of clay lenses with low thickness, which are due to sudden increase or decrease of energy in this part. There are no coarse particles in the bottom part, but fine particles become noticeable. Although this rule does not apply to the end of the cone, because there are even more than 2000 microns of coarse-grained sediments due to the interference of the Alluvial Fan sediments of Karaj. In both Alluvial Fan, the sedimentation in the flood plain is more mass and the diameter of the sediments is reduced from the vertex to the end of the Alluvial Fans. The relatively good sort, especially in the upper parts and the small amount of clay, represents the sediment deposited by water in the flood plain.
The results of sediment compaction in two conifers from top to bottom resulted in the following - The range of upward/downward ratio changes in both fans shows a downward trend.
- The range of sphincter changes in both Alluvial Fan from top to bottom of the Alluvial Fans shows an incremental trend.
- The magnitude of the factor shape, from the top down to both cones, shows an incremental trend.
- The range of rounding changes in both cones from top to bottom shows an incremental trend.
- The range of three-axis size variations in both cones shows a decreasing trend from top to bottom.
- Investigating the correlation between particle size and Particle form to soil resistance indicates that the average factor of particle diameter and rounding dimension shows the highest correlation with soil resistance, which is the first positive and the latter negative Based on the results of the laboratory tests and the analysis of the above data, general results of the research are as follows. The Chitgar Alluvial Fan in the middle diameter of the particles from the upper to lower parts shows a gradual decrease, although the cone-shaping from the upper to mid-point shows a decreasing trend, but in the end part due to interference with the intermediate sediments of the cone This is the order of Karaj. The variation of the three dimensions in both cones is normal and with increasing distance from the river's origin, the trend is decreasing. Also, in both fans, the form of sediment changes from top to bottom from the plate and the bar to the sphere and cubic. In general, it can be said that the sediment deposited in both conifers is due to coarse-graining, mass sedimentation (which indicates a sudden decrease in the energy of water), and the insignificant amount of clay from flood-river type. . The results of correlation showed that: sediments with coarse-grained and angular particles are more resistant to soil resistance in terms of construction

The process of precipitation – runoff of each basin, is influenced by hydrologic, geomorphology conditions, geological formation and vegetation. There are different methods in drainage basins. One way to estimate the runoff height is Curve Number (CN) method. That reperesents the hydrological behavior of basin. data were collected for statistics of climate and then topographic map of 1: 25000 and geological map of 1: 100000 by GSI was used. Smada software for calculate the short – term rainfall at different return periods. As well as Arc GIS software for mapping Curve Number by combining maps of land use, soil hydrological groups and moisture of soil with using the table of America Soil Conservation Service (SCS). And then modeling related in the GIS mappings of runoff height of Hesarak catchment was prepared. The aim of this study, was to determine Curve Number and estimate runoff coefficient and maximum discharge runoff with SCS method in various units catchment is. The results showed, hydrologic condition and soil hydrological groups are the most important parameters to determine the CN and affect on runoff. The most potential for runoff is in downstream of basin that specified with urban land use. Also average weight of Curve Numbers those obtained for each sub catchments, Chapdareh sub catchment (S2) with 88 Cure Number and mean of runoff 28.15 mm had the highest volume of runoff, Dochenaran sub catchment (S3) with 89.3 Curve Number and mean of runoff 24.54 mm and sub catchment of the twin branches (S1) with 90.1 Curve Number and mean of runoff 17.36 mm had The lowest amount of runoff probability and spill potential. But in general potential runoff in this basin is relatively high. The maximum amount of runoff Curve Number in condition of high humidity is 99 and 78 is the lowest.

The river is a dynamic phenomenon that is constantly changing. Estimating the resistance of sediment particles against erosion will identify stable and unstable points in different areas of the bed. Study area of this research was of Masiel Mouchan River in the Astaneh city. In this study, we investigated threshold of (transformation and deposition of bed sediments, in 4 cross sections. the critical shear stresses and the critical unit discharge calculated for four particle sizes D16, D50, D84 and D95 in all sections, and results shows, sediments in D16, D50, D84 and D95 diameter moves at bankfull discharge in sections 2 and 4, therefore sedimentary conditions of the river bed will change at bankfull discharge. At cross sections 1 and 3, particles with a diameter of D84, D95 will remain stable in bed, and other particles smaller than this size was unstable. Sediment particle are unstable in cross section of 2 and 4, because Slope of cross sections 2 and 4 are greater than 1 and 3 cross section. Finally, the results of both methods (critical shear stresses and the critical unit discharge) have high confection and confirms these methods are useful for stabilization studies in other rivers.

The initial step of each phenomenon is complementary recognizing and understanding of its relationship with other effecting and affecting phenomena. Runoff yield and flood occurrence are affected by complex factors. Therefore, defining these factors recognizing their effect on the runoff generating in the catchment can help the better planning for decreasing losses of runoff and increasing the flood in the catchment. There are several factors that affecting runoff and flood generating such as non- fundamental the exploitation of nature by man, physical and hydrological properties of the catchment. Determining the effective factors may be useful to achieve optimal models and methods for champion and reducing runoff and flood. The aim of this study was to evaluate the influence of these factors on production runoff in Hesarak catchment. In view if this, runoff of the catchment were measured using SCS method and HEC- HMS model based on five groups variables including physiographic characteristics (seven parameters), geology (three parameters), sediment types (three parameters) , land use (seven parameters) and the maximum daily rainfall and twenty one parameters. So The required layers and informations includes layers of land use, geology, Maximum daily rainfall and runoff were calculated for each subbasin. Then The informations collected after transformed and standardized, The most effective factors were determined using principal component analysis. The results showed that geology and land use are the most effective factors on runoff yield in the study area.And due the large number of variables that 2 factors justified 100% of the data variance.

Islamic management represents different notions, concepts, and definitions; each researcher has approached the issue from his own perspective. What have been neglected in these studies are the issues, aims, and methodology. This article tries to investigate the issue in terms of definition of management, Islam, science and knowledge, the necessity of the relation between Islam and management from the two perspectives of expectations of the religion and management science. Moreover, based on the selected definition of Islamic management the interdisciplinary nature of the issue is elucidated. The findings revealed that this knowledge, on the one hand, is based on rational knowledge, and on the other, is taken from experimental science. The focus of the issue is on the organization and the aim is productivity in the course of creation and the methodology is identified in the dialectics between knowledge and experimental science. Japanese management is a successful model of implementation of the proposition of a cultural and thinking doctrine into experimental and scientific propositions. The results revealed that styles and methods which are based on school can construct theoretical, applied principles of Islamic management and achieving such identity requires reciprocating from the Islamic management school (subjective aspect) to Islamic management science(objective aspect) . The collection acquired in this reciprocity can be called Islamic management science. This paper, therefore, is, generally, an elucidation of the Islamic management science which has been deeply considered from the perspective of science, knowledge, and the school.

Mountain regions are increasingly endangered by a variety of disaster, including avalanche, debris flows, and rock slide. Some characteristics such as elevation, angle of slope, vegetation and climatic elements could affect the avalanche event. Indeed, avalanche is the second factor in soil erosion that causes demolition; therefore, it threatens the food safety. Iran has two main large mountain ranges of Alborz and Zagros with risk of avalanches. In mountains and snow routes, avalanche is an inevitable event and due to special geomorphological condition, Meigoun- Shemshak road is significantly highlighted. Meigoun- Shemshak road has been situated in Shemshak drainage basin. The objectives of this study are to identify the role of effective factors in avalanche events and its zoning in Meigoun- Shemshak road and to find high risk regions.
Material and Meigoun- Shemshak road has been located in Shemshak drainage basin (51º26'49˝ to 51º31'39˝ E; and 35º57'28˝ to 36º3'15˝ N) with the area of 37.75 Km2 in Roodbar Ghasran District, Shemiranat County, Northeastern Tehran. The minimum and maximum elevations of the study area are 2200 and 4200 m, respectively.
Figure 1. Geographical location of Shemshak Basin
In order to prepare the effective factors in controlling the avalanche events, the primary data and maps including topographic maps in 1:25000 scale and geological maps with 1:100000 scale as well as Google Earth images were used. Independent variables including elevation, aspect, slope, curvature, outcrop rock and geological were prepared based on the basic maps. The snow accumulation area were found using Google Earth along with the researcher’s knowledge of the region, and then converted to polygon layer by GIS software. Since the area of avalanche zones is so smaller than the total area, the Rare Event Logistic Regression was used to find the effective factor in controlling the avalanche events. ROC index was used in order to evaluate the validity of the model, accordingly. Finally, the susceptibility map of avalanche events was prepared using the factors resulted from RELR.
Figure 2. Variables used in logistic modeling
The RELR was applied to find the relationship between the snow accumulation areas as dependent variable and independent variables, including slope, aspect, geology, elevation and other similar elements. The results showed that depth stratum, curvature, elevation, outcrop rock, slope, and aspect were selected as final factro in controlling the avalanch event. The susceptibility map of avalanche events resulted from controlling factors were classified into three classes, including low risk (67.35% of total area), medium risk (24.9% of total area), and high risk (8.06% of total area). Since the area of avalanche regions is less than total area; therefore, we considered 10 % of one and zero regions for the validity model and executed it in half of the basin. The area under the curve is 0.75, and it is reliable for being close to one.
Table 1. Rare event logistic regression Parameter Coefficient ᵦ
Fixed coefficient -6.247
Curvature -6.936
Elevation 4.436
Outcrop Rock 1.521
Slope 1.254
Aspect 1.079
Figure 3. Regional distribution map affected by avalanche
According to the results of the rare events logistic model, curvature, elevation, outcrop rock, slope and aspect layers were known as effective factors in the snow accumulation area, respectively. 61.49 % of the snow accumulation area is related to convex footslope and 38.51 of density in the concave area. The highest snow accumulation area ranges from 3200 to 3400 elevations and 13% of the basin total area is appropriate for snow accumulation. The slope map indicates that 58.22% of density is in the slope 30 -40º, which is the best slope for the occurance of avalanche. The most snow accumulation area is located in the southern part of the region (49.85% of the total area) and the western part with 29.14 %. 99.97 % of the region, which have no outcrop rocks prone to the snow accumulation area.

One of the most important measures in flood management project to determine the contribution of different components of flood basinswatersheddetermineoutput of basin. Due tolack of hydrometric stations in all outlets sub - basins, achieving this objective requires simulation of rainfall-runoff process in sub-basins using hydrologic models is. Routing and location of sub catchments influence on outlet flood basin. for performance programs flood control in upstream catchments should evaluate the on basins flood and prioritized them according to share of sub catchments in outlet flood of basins. In this study, first for appointment partnership of sub catchments in flood discharge, Hesarak catchment divided to three sub catchments. sub catchments of Hesarak drainage basin ranked due flooding with performance HEC-HMS model. The aim of this study was to estimate the runoff height and outlet flood in sub catchments of Hesarak basin. Results showed rate of sub catchments in peak flow of the basin dosent only on one factor and intersections between factors that determining share of sub catchments in flooding. With performance HEC-HMS model was observed junction of two branches sub catchment had the lowest share and Chapdareh sub catchment had most share in catchments discharge and placed in first priority.

The objectives of this study were to investigate and to zoning desertification in a semi-arid region، khomein city using MEDALUS model. In first the study area was divided into four homogeneous land unites based on geomorphological facies. Then، based on input data in MEDALUS model، effective indicators in desertification including climate، vegetation، soil، erosion، groundwater resources and land management were selected. Then، the indices were weighted and the geometic mean was calculated and the map of each criteria was provided. The final map of desertification was prepared based on combination of all maps of each indicator. The results showed that 4. 15%، 12. 8%، 19. 52%، 11. 37%، 11. 1%، 26. 33%، and 14. 7% of the study area are in vulnerable، low-intensity fragile، moderate intensity fragile، high intensity fragile، low-intensity critical،، moderate intensity critical، high intensity critical types، respectively. Also، investigation of desertification، relate to land use and land units exhibited that bared land and 1 and 2 land units، that has the most percent of critical type of desertification، is more capable to desertification comparing to other land use type

Exploring the changing processes of land forms is considered to be one of the key topics in geomorphological studies. Nowadays, geomorphological studies analyzes and clarifies geomorphic forms and processes at ground level. This shows the dominance of a systematic view in this field. In systematic view, geomorphic analyses are performed based on the relation between land form and process. Geomorphologic threshold is one of the key concepts in systematic theory and thus is of significant importance in geomorphology. It indicates borderline situations during the occurrence of changes and shows temporal changes. The present article is based on secondary research and exploits theoretical and applied concepts related to thresholds, seeking to reach a balanced systematic analysis. It tries to study geomorphologic thresholds and classifications using different Persian and English resources. Moreover, we propose a short overview of some geomorphological issues, such as gully erosion, alluvial fan and river systems. Results indicate that geomorphic thresholds separates different situations of a system and are thus distinguishable. In fact, occurrence of a threshold changes the dominant processes in a geomorphologic system. This concept shows the situation in which a process operates to establish a new balance in the system. Siyum classifies geomorphic thresholds into two categories: 1) Internal which is related to the inside of a geomorphic system and 2)external which is under the influence of external variables such as climatic and tectonic changes.

The gravel extraction from the bottom of rivers constitutes an important source of aggregate for the construction of buildings، roads and other structures. The problems of fluvial erosion generated by these activities can affect properties and human works located near the river، and have become a severe problem in many regions of the world. The environmental costs of instream gravel extraction have generally not been factored into production costs، making instream sources more economically attractive than alternatives such as dry terrace mines، quarries or distant sources such as reservoir deltas. Gravel extraction can have both immediate and long-term consequences for channel stability. Changes to channel morphology are initiated through the lowering of the riverbed during extraction. As geomorphically effective sediment transporting events are infrequent in many gravel-bed rivers، instream mining activities may operate for several years without obvious effects upstream or downstream. However، responses may be manifest during high flows many years later. Study area: This paper examines the significance of within-channel gravel extraction on the morphometery of the River Lavij in northern Alborz. The study site at Khashpel Park is 2 km in length، and is located in the lower River Lvaij catchment in Nour Township، Mazandaran province. The altitude of the Lavij catchment varies from a maximum of 3359 m to 90 m on the valley floor. Mean annual rainfall in the catchment is around 650 mm. Mean daily discharge is 1. 7 m3 s−1 with a maximum mean daily discharge of 175 m3 s−1. The River Lavij is a gravel-bed channel dominated by cobble size material in the study reaches. The upper study area reaches to an altitude ranging between 120 m and 90 m with a mean slope of 0. 02m/m. In this study different types of data have been collected: (a) hydrological data، (b) channel morphometric data concerning the time evolution of the longitudinal profile، cross section and planform (c) bed grain size distributions of the study reach. The discharge records at the Aghozketi gauging station and discharge-area relationship are appropriate for the study reach. Regional catchment area-discharge plots are produced for a range of flood recurrence intervals (2، 5، 10، 50، 100، 200 years). Study area divided into two reaches. The first reach A has been mined before 2008 and the reach B has been mining to present. The data of reach A was surveyed in 2012. Then a comparison is made between the river character (longitudinal bed profiles، cross section and planform) of the intact reach and the reach A. Information on the recent evolution of the river character was collected from surveys made along the reach B at scale 1:1000 between 2008 and 2011. The grain size distribution of the gravel surface was obtained from Wolman pebble counts sampling of bed. An estimate of annual sediment delivery from the catchment to study reach calculated using an empirical regression equation of river suspended load. Then، we calculated gravel extraction on the fluvial sediment balance by comparing the extracted yield with an estimate of the catchment sediment yield. Long Profile: a general tendency towards incision four main changes observed in reach A. The changes in bed elevation were locally greater than 6. 5 m، 3. 3 m and 2. 5 m below river’s normal slope. Three drops were built in order to limit regressive erosion، reduce channel slope، and dissipate fluvial energy. The average river slope is greatly decreased from 0. 02 m/m to 0. 003 m/m between drop1 and drop 2. Local slopes increased to 0. 027 m/m between drop 2 and drop 3. The average river slope shows low changes in reach B، except reach 3. Cross section: the average river width shows a 10 m change between 2008 and 2011 in reach B. The bankfull depth increased up to 0. 5 m in this period. A decrease occurs in amount of stream power in both reach A and reach B. This apparent decreasing trend in stream power is not surprising because we observed a decrease in slope and increase in width. Planform: Channel planform analysis has revealed that both the reaches A and B are changed. The straight planform formed where the river has been artificially transformed in a series of steps and Gradient is steepened as flow follows a shorter path. Braided pattern has observed in reaches A2 and A3 that river gradient decreased. In reach B، river pattern has been straight or meandering. Sediment: the sediment average size in upper reach is 32 mm and it decreased in lower reach (B and A to 25 mm and 8 mm، respectively). A sediment budget by comparing the volume of sediment supplied from the catchment، which an estimate of that released during extraction. The volume extracted unallowable have estimated 80000 m3. Gravel extraction in study reach has changed the slope، width، depth، stream power، planform، and sediment size of channel. Comparing to reference conditions، reach A river altered irreversibly direct human disturbance and a wholesale shift in the geomorphic unit structure، planform، and bed material texture، so that the river has operated in a fundamentally different manner to its former state. In reach B، river altered reversibly direct human disturbance. Channel geomorphic analysis indicated that management interventions، such as Drop، only delay morphological adjustment.