فصلنامه پژوهش های ژئومورفولوژی کمی
سال سیزدهم شماره 2 (پیاپی 50، پاییز 1403)

Geomorphological indicators are useful tools in evaluating and identifying the effects of relatively sudden or gradual tectonic activities. The behavior of the drainage network is one of the parameters that is very sensitive to tectonic activities and shows the effects of duration and intensity of these factors. Among the geomorphological evidences of active tectonics of drainage networks and their related features such as drainage pattern, drainage density, drainage anomalies, connection method (connecting angle of networks) and direction of networks play an important role in identifying active tectonics and their spatial differences. Many studies have been carried out in the fields of the effect of tectonic factors on the ratio of branches, drainage density, hypsometric integral of river networks, response of drainage networks, and characteristic of hierarchical anomaly, branching index, to investigate the tectonic impact in four drainage basins and related fields. In addition to these parameters, by using the research results of other researchers and the reconstruction of the paleoclimate, it has been tried to analyze the effects of the Quaternary changes by using the mentioned factors as modeling and conceptual techniques.

The Kurdan watershed in Alborz province is located between latitudes 35 degrees 55 minutes to 36 degrees 6 minutes north and longitudes 50 degrees 49 minutes to 51 degrees 5 minutes east, its area is 336.5 square meters. The highest elevation is 4059 meters in the northern part of the watershed and the lowest elevation is 1427 meters in the area where the river exits the mountain. Therefore, the height difference between the north and south of the basin is 2632 meters. This height difference has affected the variety of weather and temperature and other geographical features of different parts of this basin.Watershed is a small part of the sub-basin of the Shur River of Qazvin, related to the Salt Lake basin. The rains of this small watershed arecollected by the Kurdan River and directed to the outside. The main branch of this river named Duran originates from the south of Kahar Peak in the rough northeast corner of the Qazvin basin and the neighborhood of the Karaj River watershed.Analysis of these changes using field evidence and sources such as aerial photos, satellite images, topographic and geological maps, and other physical tools of this research and based on the hierarchical anomaly index (∆a), basin asymmetry index(AF),Branches (R), horizontal topography symmetry index of the basin (T), hypsometric integral (Hi) and drainage pattern of geomorphic parameters have been done. Along with these parameters, by using the research of other researchers and simulating thepast climate, it has been tried to analyze the effects of Quaternary climate changes by using the mentioned parameters as modeling and conceptual techniques.In general, in this research, to detect the active tectonics of the area, it was measured from the topographic maps and aerial photos of the area, and to communicate between the tectonic movements and the drainage network, necessary geological and geomorphic data through the interpretation of geological maps. Topography, aerial photos, satellite images and especially frequent field visits were obtained. In the next stage of this research, evidence of new tectonics in the drainage network of the region has been obtained, and neo-tectonic analysis in the Kurdan basin has been analyzed using analytical-comparative methods and the use of geomorphological techniques. First, the information layers of topographic maps 1:25000 was transferred to the GIS information system in the ArcGIS environment and using it, layers such as drainage network, slope, digital height model were extracted and the results were analyzed using the geological map and according to the values of tectonic indicators. obtained, the morphology of the river in the studied area has been evaluated and analyzed in terms of the amount of new tectonic activity.

Based on the analysis of morphological parameters and branching index R, considering the branching conditions and the number of these branches, it shows the continuous presence of important tectonic activities in this basin. Also, the high figure of this index fully confirms the high tectonic activity in this basin. In terms of this index, the presence of dense branches in this region shows that it has experienced relatively high tectonic activities. Therefore, the results of this research show that: the studied area has been strongly affected by neo-tectonic activities and climate changes. Based on the obtained results, it shows the high tectonic activity of the drainage network of the Kurdan watershed based on the changes in river morphology and the youth of tectonic activities with high elevations. It can also be said that the documentation of scientific findings has confirmed the modification of morphological forms under the influence of climatic processes.

The results of the morphometric analysis and the analysis of the findings of the studies conducted in this basin show that it has experienced high tectonic activity, and considering the changes in river morphology such as the left deviations, it can be said that this basin from the perspective of tectonic activities It is active and has a young topography despite the high elevations. Also, the climatic evidence in this region confirms that this basin has experienced a sequence of cold/hot and wet/dry periods and has left evidence of glacial periods. Therefore, it can be concluded that the climatic activities in contrast with the tectonic situation of this basin have mainly gradually and at times suddenly and severely affected the basin, and adjustments have been made in the effects of these processes with the activity of climatic parameters. Therefore, the drainage network of the Kurdish basin of this basin is mainly gradually and at times suddenly and strongly affected by tectonics, and due to climatic processes, changes have been made in the forms.

The reconstruction of the past water level of the Caspian Sea has been carried out by many researchers throughout the Caspian Sea in its various parts, including shallow, deep marine deposits, as well as on the mainland. The study of palynology, magnetism, sedimentology and mineralogy, determination of absolute age, tectonics, and also the study of the Caspian fauna of the Caspian Sea shows now a better picture of the absolute sea level of the Caspian Sea in the past, but still there is no agreement on the sea level curve. (Rychagov, 1977, 1997; Fedrov, 1994; Boomer et al., 2005; Kroonenberg el al., 2007; Lahijani et al., 2009; Hoogendoorn et al., 2010; Leroy et al., 2013; Kakroodi et al., 2012, 2015; Naderi et al., 2015).The marine sediments recorded in different parts of the Caspian Sea indicate its drastic sea level changes of at least 50+ in the Early Pleistocene and around 20+ in the Late Pleistocene. From the Pleistocene to the Holocene, we are facing a sharp drop in the water level, therefore the expansion of the Khazar Plain. Its absolute level is not mentioned accurately, but in Russian sources it is reported up to -100 and in the Iranian part of the Gamishan area it is reported up to at least -50 (Kakroodi et al., 2015).

Study area The studied area is located in the southeast of the Caspian Sea and the northeast coast of Iran. It corresponds to the morphological features of Gorgan Bay and Gomishan Lagoon. The studied area is one of the vast areas of Iran's coastal plain, which has a very small slope towards the land and the sea. The southeastern shores of the Caspian Sea are very sensitive to the water level due to low angle coast, a suitable place to study the water level changes. The main sources of sediment for the south-eastern Caspian coast are the Gorgan and Qare Su rivers draining the Alborz Mountains, and the Atrak River draining the Kopet Dagh Mountains. The Gorgan River provides the most sediment supply and its annual sediment load is around 1.336 million ton (Mister, 2001). The Gorgan River has formed a cuspate delta, which has constantly changed its course during the Holocene

Figure 4 shows a log prepared from a part of the drilled borehole between 27.7 and 18.75 m, which includes a sequence from the pre-Holocene stage to the maximum water level rise in the Holocene (Figure 4). Each of these units is separated from the other unit by a specific fauna. Pleistocene ostracods with a homogeneous and oxidized sedimentary unit with gypsum crystals lead to the initial unit of the Caspian marine advance in the Holocene and a wetland environment, and finally to a deep environment with diatoms. In fact, in the Holocene, a wetland environment was first formed in the area and turned into a deep marine environment. The identification of these units is based on existing fauna and sedimentology (including texture, color and sedimentary structure).

The Late Pleistocene to Holocene Caspian Sea-level was retrieved by a multi-disciplinary approach from a 27.7 m long core in the SE corner of the Iranian Caspian coast in the Gomishan Lagoon. Pleistocene and Holocene sediments are distinguished by different structures in terms of fauna and intense oxidation. After a deep sea-level fall, the wetland system was identified at the beginning of the Holocene. The continued increase in the water level led to the movement of the marine system towards the mainland and a sharp increase in depth until the middle of the Holocene. This increase in water level continued until about 8400 years ago and probably the most effective level of the Caspian Sea in the Holocene. Its absolute level is still not clear, but its sedimentary evidence shows that this level has covered major parts of the coastal plain. Most likely, the existence of old wetlands such as Almagol, Alagol and Ajigol, which are now located at levels between -5 and -8, may be the evidence of this level, although to prove it, deep boreholes are needed in the bed of these wetlands.The study of Neo-Caspian sediments in the Holocene indicates cyclic changes in the water level. The two next and very important levels, whose sedimentary evidences exist in the studied area, are around -22 and -24, which covers a major part of the low-sloping coast. Finally, the last cycle of the Caspian Sea between 1929 and 1995, with a range of changes of about 3 m, has extensive impact along the coast.

Today, soil erosion is considered one of the most important problems in the world, and due to the long period of soil formation in Iran, the importance of this problem is more prominent in this country. This annual process causes the destruction of land, the reduction of soil fertility and the filling of reservoirs of dams. The best place for erosion control is catchment areas. It is necessary to pay attention to watersheds in the process of erosion, especially the basins whose rivers play an important role in providing drinking water for residential areas, agriculture and river treatment projects. In this research, using hydrophysical models (CSY), the sedimentation potential of the sub-basins of the Ruain River catchment area in the southern slopes of Aladagh Mountains in northeastern Iran was calculated. The results of this research showed that factors such as size, topography, erodibility, precipitation and vegetation cover in the sub-basins of this river basin have the greatest effect on the sedimentation potential of the sub-basins of this river, and the erosion and sedimentation potential is the same in all the sub-basins of this river. is not. Based on this, the sedimentation potential for Ruin sub-basin was 390.05 tons equivalent to 47.84%, for Mahmoudi sub-basin 182.04 tons equivalent to 22.32%, for Kalat sub-basin 143.91 tons equivalent to 17.65% and for Shiravieh sub-basin 99.27 equivalent to 12.17%. Therefore, the Ruin and Mahmoudi sub-basins are more sensitive to erosion processes than the other two sub-basins and should be properly managed by implementing soil protection plans and proper management of the erosion process.Erosion is the movement of soil from one place to another and in any possible way, the natural process of this process is necessary for nature, but a large amount of it will lead to unfortunate consequences such as the filling of lakes and dams, the reduction of soil fertility, the increase of the sediment load of rivers and the destruction of ecosystems. had Erosion occurs under the influence of various factors, and knowledge of these factors will have a significant effect on reducing erosion and sediment load of rivers. Today, the increase of sediment measuring stations in river catchment areas has made it easy to measure their sediment load, and most of the world's rivers are equipped with these stations, with all the possible improvements in this field, some catchment areas still lack this device. In addition, these stations cannot predict the amount of erosion in the future, and it is not possible to install measuring devices for all basins and their sub-basins, so estimating the amount of erosion and sedimentation of the watershed using the model Experimental studies can be considered as a suitable program to protect the soil and prevent the harmful effects of erosion and help to obtain reliable data in the stations.Due to the high rate of erosion and the slowness of soil formation, the study of this process gained more speed. With the presentation of the cycle of erosion by Morris Davis in 1884, the process of erosion attracted the attention of more researchers (Shahdad, 2009). With the passage of time and the increase of agricultural activities, erosion became more intense and the need for scientific studies in this field increased and became academic and many experimental methods such as USLE, MPSIAC, WEPP, EPM, SWAT, MUSLE, geomorphology, Hydrophysics, Musgrave and... were presented and researchers such as Gavrilovich (1988), Weiss Kamir and Smith (1978), Musgrave (1947), Gab Hart and Johnson (1982) (1982), Zonta in Italy and... in this field conducted studies (Maqami Moghim et al. 1402). In Iran, due to the long time of formation, the high rate of soil erosion and the lack of equipment and hydrometric stations, experimental methods of estimating sedimentation and erosion have attracted the attention of researchers, and researchers such as Mahmoud Abadi (1384), Naderi (1389), Khosravi 1390), Qadzavi (1391), Ahmadi (1396) and Haghi Abhi (1398). Conducted studies in this field. One of the new methods of experimental estimation of erosion among the methods proposed in Iran that has attracted the attention of Iranian researchers is The hydrophysical method is CSY, which has been used by researchers in Iran due to its ease. In a study conducted in the Nozhian watershed in Lorestan province, a jury concluded that the hydrophysical model is more accurate compared to the EPM and MPSIAC models. (Davari et al., 2014). In another study in the Kesilian basin of Mazandaran, compared to the geomorphological method, the results of the hydrophysical method had a greater distance with the statistics recorded at the hydrometric station of this basin (Mohsani et al., 2015). Damghan River used this method to estimate erosion potentials and considered it a suitable method to estimate sediment in a relative manner in this basin (Maqami Moghim et al., 1402). With this method, it is possible to identify the erodible points of the basin more easily, as a result, planning for high-risk points is done with more precision (Ahmadi, 2016). Ruin River is one of the watersheds of the southern slopes of Aladagh highlands in the northeast of Iran, which has received less attention from researchers. . The abundant accumulation of sediment in the alluvial cone of this river indicates severe erosion in its catchment area (Figure 1). Despite severe erosion, its sedimentation and erosion potential has not been studied. The only information related to the sediment measurement of this river is its hydrometric station, which is located in the southwest of Iraqi village which records the sedimentation of this river in general. For this reason, the information about the erosion potential in the sub-basins of this river is still unknown. This can cause many problems for the people living in this area, especially the industrial complex in the south of this basin as the largest industrial complex in northeastern Iran. For this reason, it is necessary to calculate its sedimentation potential for the principled exploitation of natural resources and reducing the harm of erosion.

Floods are among the natural disasters that, according to the United Nations Development Program's global report on the risk of natural disasters, floods along with earthquakes and droughts have the highest rank in terms of financial and human losses (Beheshti et al., 2018: 22). Inappropriate human interference in ecosystems, uncontrolled exploitation of forests and excessive livestock grazing are among the most important factors that aggravate floods, which reduce the storage capacity of watercourses, and waste fertile soils, and as a result, increase surface runoff and the occurrence of floods. (Chitti, 1382: 39). The increasing trend of floods in the last five decades shows that the number of floods in the 80s has increased almost 10 times compared to the 40s, and in other words, it has increased by 90% (Abdi, 2015: 20). Flooding in urban basins occurs at a high speed on flat and impermeable surfaces that have been created by man-made drainage systems. According to this factor, the urban state of finding natural areas causes an increase in the volume and intensity of runoff and the occurrence of floods in the downstream areas (Broumand Nesab, 2011: 2). One of the basic steps to reduce the harmful effects caused by floods is to know the flood-prone areas and classify these areas in terms of flood risk (Petial, 2008: 8) so that based on the results, it is possible to make decisions regarding the use of land and different land uses, including The future optimal development of cities and villages, service and production agriculture, made a decision. The catchment area of Izeh city due to its location on a mountainous plain is one of the areas at high risk of flooding, which causes great damage to this city and its surrounding areas every year. Flood risk potential and its zoning using multi-criteria models and geographic information system

The required data were collected in a library manner and the data analysis will be in the scale of the studied area in a comparative manner. The materials used in this research include the criteria of distance from waterway lines, slope, direction of slope, formation. , the shape of the basin, precipitation, land use, which were used to determine the vulnerable area against the risk of flood. Each of these criteria has its own characteristics and applications, which were extracted from the following data: 1- Land use map of the region 2- Topographical maps 1:50000 (Izeh, Kay Maghsoudi, Shahrak Shivand, Bagh Malik). 3- Geological maps (Mount Asmari, Taghdis, Kamestan with a scale of 1:100,000). 4- Map of digital model of elevation lines (DEM). 6- Rainfall data statistics (rain gauge stations: Izeh, Bagh Melek, Sosun, Dehdz, Barangard and Qala Tel, Water and Electricity Organization, 2014). - The map of the distance from the waterway lines. 7- Flood prone and problematic areas were controlled in the field, so that the accuracy of the action in prioritization and the conformity of the zoning results with the reality in the basin will be known more. Fuzzy standardization in Hydrasi software based on the degree of membership defined in the domain of fuzzy number and valued between (0 ≤ ud(x) ≤ 1), then weighted by the Analytical Hierarchy (AHP) method through Expert Choice software and Finally entered the model

In this research, seven effective layers in the occurrence of floods including: rainfall, slope, slope direction, land use, distance from waterways, geological formations and height were prepared and classified using the weighting method of Analytical Hierarchy Method (AHP). Expert Choice software (Table 1) in this method, after forming a pairwise comparison matrix related to each risk, in order to determine the importance of the relative weight, we transferred them to the Expert Choice environment. The most weight is assigned to the layer that plays a greater role in the occurrence of each. In this next step, a 7x7 matrix was created to compare, and different criteria were compared two by two, and the resulting values were assigned based on the hourly sieve.Based on Thomas L. Sati’s method to calculate the values and the special vector of the columns they are added together and each cell is divided by the sum of the corresponding column and normalized. Then, the average of the normalized table rows is calculated as the final weight. The resulting number for the compatibility index (CR) in the resulting matrix is equal to 0.07, which indicates an acceptable level of the weighting results, which is shown in the form of a diagram (Figure 1). Among the parameters It has been concluded that the most important factor in the flooding of this region is primarily the rainfall. Sudden torrential rains in the winter and spring seasons cause flooding in this region. The presence of steep slopes in the high mountain heights leads the runoff to the plain. On the other hand, this basin is a closed basin, and all the water flows into the basin to two lakes (Miangaran and Bandan). When heavy rains occur, the lakes overflow and the city is threatened by floods from the north and southeast.

The analysis of the Silber risk zoning map according to the WLC model shows that the main areas at risk are in the east and south areas, 79.17 kilometers of the basin are at very high risk of flooding and 58.52 kilometers are at high risk. Also, the results Of . The Vicor model map shows that 91.79 km of the studied basin is at risk of high flood, which mostly includes the eastern and southwestern areas of the basin. One of the main reasons for flooding in these areas is more rainfall in mountainous areas, high slope, impermeable formations; The presence of valleys and the high density of waterways in these areas have caused a large amount of runoff to be directed to the west and central areas of the plain

Tectonic activities along the strike-slip faults can result in the formation of various landforms such as shutter ridges, pressure ridges, linear valleys, offset stream, beheaded streams, sag ponds, pull-apart basins, scarps, offset fans, and asymmetric valleys. Alluvial fans are one of the most important landforms that obviously reflect the effect of tectonic activity of strike-slip faults. Active tectonics play an important role in the alluvial fan’s morphology, morphometry, geomorphological processes (aggradation, degradation), sediment thickness, and location of sedimentation. Dehshir Fault as a 350 km long right-lateral strike-slip fault is one of the most important structural features in the Central Iran structural zone. The formation offset fans, offsets streams, and fault scarps along Dehshir Fault implies that the mentioned fault has been active in the Quaternary Period. The aim of this study is to evaluate the effect of Dehshir active tectonics on the morphometric properties of alluvial fans including area, topographic slopes, length, width, width/length ratio, sweep angle, and revised fan conicality index.

To achieve the aim of this study, the borders of 28 alluvial fans developed along Dehshir Fault were delineated by Google Earth images. Then, the morphometric parameters of alluvial fans including area (A), topographic slope (S), length (L), width (W), width to length ratio (W/L), sweep angle (SA), and revised fan conicality index (FCIR) were calculated for each fan. The sweep angle (SA) of each fan was obtained by measuring the angle between the two outermost positions of the fan. Fan conicality index is a parameter to show that the shape of fan is conical or not. Normal or typical fans are conical in shape, but may be distorted due to the effects of parameters such as tectonic. Mukerji (1976) defined the fan conicality index as:AIF/ATF = FCIwhere ATF is the area of the fan, and AIF (area of equivalent ideal fan) is expressed as:AIF=(〖πr〗^2 ×dFA)/360where r (radius or length) is distance between fan apex and fan toe, and dFA is the sweep angle.In this study, we defined the FCIR (revised fan conicality index) as:FCIR=|FCI-1|The lower values of FCIR (close to 0) show the ideal or normal fans, whereas the higher values of FCIR demonstrate distorted fans by external factors such as tectonic.In this study, the means of morphometric factors were compared in two groups of large (more than 1 km2), and small (less than 1 km2) alluvial fans. To compare the means of morphometric factors in two groups of fans, the independent sample t-tests were applied. Correlations between the morphometric parameters were evaluated using Pearson correlation coefficients.

Data reveal that means of sweep angle (SA) and revised fan conicality index (FCIR) are higher in the large fans group (100.3° and 1.1 respectively), compared to the small fans group (83.1° and 0.69 respectively). Nevertheless, means of topographic slope (S), and width to length (W/L) ratio are higher in the small fans group (1.78% and 1.11 respectively), compared to the large fans group (1.3% and 0.73 respectively). Higher mean values of SA and FCIR in the large alluvial fans can be attributed to the higher discharge and sediment yield as well as to the lower topographic slope of large fans so that when larger discharges with higher sediment yield, produced by the occasional intense rainfalls, reach the large and low-gradient fan surface they are easily diverted across the fan, and hence increase the sweep angle and distortion of alluvial fans (increasing the SA and FCIR indexes). Results of T-test show statistically significant differences between the means of area, length, and width parameters in large and small fans. There are statistically no significant differences between the means of topographic slope, sweep angle and revised fan conicality index in large and small fans. Pearson correlation coefficients reveal that there are strong positive correlations between A-L, and A-W pairs, and strong negative correlations between S-SA, and S-W/L pairs, implying that fans with higher topographic slopes have lower values of sweep angle and width to length ratio. There is strong negative correlation between W/L and FCIR parameters showing that fans with higher values of width to length ratio have regular or more typical form. Data reveal that the mean sweep angle of study area fans is considerably high (92°) compared to fans developed around Danehkhoshk Anticline in the Zagros Folded Belt (with mean sweep angle of 49°). The high value of SA in the study area alluvial fans can be attributed to the lateral movement of Dehshir Fault so that continuous changes in the location of aggradation on fans surfaces have resulted in increasing the sweep angles of fans. Apart from the effect of lateral movements of Dehshir Fault in distortion of fans (high values of FCIR), the formation of presser ridges along Dehshir Fault and its impact on the flood diversion are also considerable.

Geomorphic evidence shows that Dehshir strike-slip fault as one of the most important structural features in the Central Iran structural zone has been active in Quaternary Period. In this study, 28 alluvial fans formed along Dehshir Fault were selected and their morphometric parameters including area, topographic slope, length, width, width to length ratio, sweep angle, and revised fan conicality index were analyzed. Results show that lateral movement of Dehshir Fault have resulted in increasing sweep angle, width to length ratio, and revised fan conicality index of fans. Larger fans are characterized by higher values of sweep angle and revised fan conicality index. Higher values of SA and FCIR in larger fans can be associated with higher discharge and sediment yield of large fans with lower topographic slope resulting in the fan distortion. It can be concluded that, in addition to the effect of lateral movement of Dhshir Fault in the morphometry of alluvial fans, development of pressure ridges along fault can also cause distortion of fans.

Geomorphological processes, by affecting the characteristics of sediments in alluvial fans, cause changes in soil resistance parameters, including adhesion and internal friction angle. According to the purpose of the present research, first through geological maps, satellite images and field visits, then based on the geomorphological evidence, two alluvial fans basins of Qaleh Shahin and Deira basins, which have old and new parts, were selected. Sampling has been done from the top, middle and downstream parts of the old and new parts of the conifers. The results of examining the shape of the particles show that from upstream to downstream, the particles affected by geomorphological processes are rounded, dimensional, fine-grained and have a smooth surface texture. According to the direct cutting test, the internal friction angle varies from 38.1 ˚ in the upstream to 27.4 ˚ in the downstream of the alluvial fans cones. As a result, the internal friction angle will decrease from upstream to downstream. Also, according to the results of the uniaxial compressive strength test, the adhesion of particles varies from 45 kpa in the upstream to 150 kpa in the downstream. So that from upstream to downstream, the amount of adhesion of soil particles in alluvial fans has increased. As a result of the present research, by examining the geomorphological and geotechnical characteristics of the accumulated soils in alluvial fans deposits, it can be considered from the relationships obtained in locating the best options for development plans and the implementation of construction projects, including the macro issues of urban management, industrial estates, and the use of environmental planners.

 Statement of the Problem: 

Landslides are among the most important geomorphological hazards in mountainous areas. Large-scale landslides often have significant social and economic impacts, making them one of the costliest natural disasters worldwide, causing considerable damage to individuals and infrastructure each year. Nowadays, due to climate change and human activities, the frequency, intensity, and impact of landslides have increased, posing significant threats to life and property. In recent years, with rapid socio-economic development, the spatial extent of human activities has also gradually expanded. The occurrence of heavy rainfall has increased the frequency of landslides in mountainous areas and the resulting economic losses have gradually increased, turning landslides into barriers to human environment development. Given the complex physics and diverse nature of triggering mechanisms (such as rainfall and earthquakes), dynamic landslide monitoring is vital for risk assessment and management. While small landslides constitute the majority of landslide events annually, large landslides are usually responsible for a significant portion of casualties and damages. In most parts of the world, identifying their locations and effects still faces many challenges due to the diversity of landslide types and morphologies, as well as the difficulty in collecting and updating survey forms. Therefore, the development of tools and techniques for identifying and monitoring these widespread gravitational processes is of great importance. Spatial assessment and preparation of hazard maps are fundamental strategies in landslide risk management. In the present study, spatial assessment and zoning of landslide risk in the Zemkan watershed in Kermanshah have been addressed. This watershed drains parts of the western slopes of the Zagros Mountainous area and has a high potential for landslides.

In order to assess the spatial risk of landslides in the watershed, studies of 13 factors affecting landslide occurrence were conducted, including elevation, slope, aspect, the Melton ruggedness number, surface convexity, length of slope, valley depth, TWI, precipitation, geological formations, distance from streams, distance from roads, and vegetation cover. In line with the research objectives, the necessary data were obtained from 1:25,000 and 1:50,000 topographic maps; 1:100,000 and 1:250,000 geological maps; Aster satellite images with a resolution of 27 meters; Sentinel satellite images (with a resolution of 10 meters) and Google Earth (GeoEye with an approximate resolution of 1 meter); climate data; field studies; and library resources. ArcGIS, ENVI, and SAGA GIS software were used for the preparation and preparation of thematic layers and the execution of research models. A catastrophe theory-based approach was employed for zoning and spatial prediction of landslide occurrence risk in the Zemkan watershed area. Functions of catastrophe theory were used in GIS environment to combine and overlay these factors. The model employed was used to address uncertainties associated with decision-making and data classification. In this model, the weight of criteria is determined by the internal mechanism of the system, which has a mathematical nature.

The results of the research demonstrate the satisfactory performance of catastrophe theory functions in zoning the risk of landslides. The model accuracy, calculated using field mapping of landslide zones and receiver operating characteristic (ROC) curves, was approximately 90%. Catastrophe theory-based modeling showed that slope factors with a coefficient of 1.3, precipitation with a coefficient of 1.2, elevation with a coefficient of 1.1, and geological formations with a coefficient of 1 are the most important variables affecting landslide occurrence in the Zemkan watershed. Over 32.4% of the study area fell into high and very high susceptibility classes. Several conditions have led to significant portions of the central and southern parts of the Zemkan watershed having a high landslide potential. In this regard, factors such as high elevation and slope, significant precipitation, the presence of landslide-sensitive geological formations such as marl, clayey limestone, and shale (Kazhomi formation), westward orientation perpendicular to westward winds, long slopes, high drainage density, and human interventions are noteworthy.

In the present study, a model based on catastrophe theory was utilized to mitigate uncertainties associated with decision-making and data classification. In this model, the weights of criteria are determined by the internal mechanism of the system, which has a mathematical nature. The results of the model are repeatable and generalizable, thereby reducing decision-making uncertainties and enabling the integration of multiple quantitative and qualitative data. The research findings indicate the effectiveness of catastrophe theory functions based on GIS in spatial assessment and zoning of landslide risk in the study area. The alignment of landslide field mapping with landslide risk zoning maps and receiver operating characteristic (ROC) curves indicates a model accuracy of approximately 90%. The model results show that slope, precipitation, elevation, and geology are the most important factors influencing landslide occurrence in the Zemkan watershed. A significant portion of the study area falls into high and very high susceptibility classes of landslides, indicating a considerable potential for landslides in the Zemkan watershed and the need for planning to mitigate the risks associated with landslide occurrence.

The studied area is located in the northwest of Sahneh city. The oldest variety of lithology in this area is related to the Mesozoic era and the Triassic, Jurassic and Cretaceous periods. Among the most important outcrops related to this period, we can mention the Biston limestone of Triassic-Upper Cretaceous age, Kermanshah radiolarites of Upper Jurassic-Lower Cretaceous age, as well as older Triassic rocks such as schist and marble. A huge part of the region has been affected by various types of faults such as thrust and reverse faults, normal faults and strike-slip faults. It is important to note that most of the faults in the region are of thrust or reverse type, which have sometimes caused the formation of a duplex structure in the area. Probably, these thrust and reverse faults have a greater role in creating the active tectonics of the region than strike-slip faults.

In order to investigate and analyze the morphotectonics of the study area, first the geological and topographical maps of the area were examined, then by using a digital elevation model with an accuracy of 10 meters (DEM), basins and drainages were extracted in the ArcGIS 10.8 software environment with the Arc Hydro extension.Then, by using Google Earth Pro software, the necessary corrections and proper basin were extracted from ArcGIS 10.8 software. In this research, in order to calculate the morphotectonic index, the study area has been divided into 23 drainage basins.

In the following, the introduction and analysis related to each index will be discussed. Drainage basin symmetry factor (AF) This index indicates the degree of tectonic tilting of the basin in relation to the main drainage and must necessarily be perpendicular to the main drainage. In this index, the amount of rise and fall on both sides of the basin (right and left side of the main drainage) is of particular importance. Transverse topographic symmetry (T) This index has been introduced to evaluate a river within the basin, which examines the amount of changes related to the asymmetry of that river in different parts of the valley. The calculated numerical value is between zero and one, and the closer this number is to one, it means that uplift has occurred on one side of the basin, and as a result, the degree of tilting is also increasing, and the basin is moving towards asymmetry and active tectonics.hypsometric curve(HC) and Hypsometric integral (HI) This index represents the distribution and dispersion of the height in a particular drainage basin, and the erosion and instability of the slopes are considered important factors in changing the height of the basin. Altimeter curve is a two-dimensional curve. According to the Hypsometric curves of each basin, it can be concluded that in almost all basins, the youth phase is ending due to factors such as erosion and the decrease in the height of the slopes, and the maturity phase is more visible in most of the basins. Stream length - gradient index (SL) This index is to investigate the active tectonics regarding the role of the river channel and the resistance of the rocks of the study area. Based on this index, three types of basins can be introduced in such a way that if the numerical value of this index decreases from upstream to downstream, that is, the slope of the waterway decreases from upstream to downstream, the basin has a low elevation. If the numerical value of this index is increasing from upstream to downstream, it means that the slope isincreasing from upstream to downstream, so the elevation of the basin is high, and if the numerical value of this index is fluctuating from upstream to downstream, is an indication of the average elevation in the basin.Drainage basin shape index (BS)This index refers to the study of the elongation of the basin. In this way, the more elongated the basin is, it indicates more tectonic activity in that basin, and vice versa, when the tectonic activity decreases or stops, as a result, erosion will overcome the basin and as a result, the basin will lose its elongation over time. and finally the circular basin is formed. The calculations of this index show that most of the basins are Inactive category. But According to Bl/Bmw index calculations, a number of basins are in active and semi-active category.Relief amplitude (RA) This index is between the highest height (maximum) and the lowest height (minimum) of the drainage basin, which is evaluated and is one of the parameters used to evaluate the level of activity of an active tectonic basin.Relative index of active tectonics (IAT)This index represents an average of the tectonic activities of each basin compared to the all measured indices. This index is also divided into 4 categories, respectively, category 1 means very high tectonic activity (1.0≤IAT<1.5), high tectonic activity (1.5≤IAT<2.0), moderate tectonic activity (2.0≤IAT<2.5) and low tectonic activity (IAT≥2.5).

The northwest of Sahneh city is located in the most dynamic part of Zagros orogeny. In this area, all typs of thrust, normal and strike-slip faults can be observed. The Sahneh fault as the middle part of the Zagros recent fault passes exactly through the central part of the region. There are many thrust faults in the region, including the Main Zagros Reverse fault. The Sahneh fault and the Main Zagros Reverse fault are far apart in this area, but they connect to each other in the southeastern part of the area. The connection of these faults has caused tectonic activity in this area, which shows this well in the measurement of the SL index. The effect of thrust faults can be clearly seen in other indexs, which have caused the tilting of sedimentary basins and their asymmetry. By examining the maps of the morphotectonic indexs of the region, it can be concluded that the thrust faults have had a significant impact on the morphology of the northwestern Sahneh.

Policy-making in the field of water resources management is usually based on climatic data and in the framework of statistical analysis, not knowing that these methods, Unaware that They will not be helpful without the support of environmental philosophy. Understanding the concept of climate identity in the field of water resources management can transform the view of policymakers.Although the concept of identity is mostly used in social studies, the recent studies of geomorphologists emphasize the point that territories also have a special identity that, like human societies, function based on these characteristics, and the lack of recognition and disregard for it to be the implementation of many policies fail. Recent reviews of geographic studies show that although the analysis of the same data can be done with several statistical methods, the results obtained are not always the same, and this issue can help us understand climatic identity.This article, which is the result of analyzing Iran's rainfall data over a period of time (30 years)And based on Harmonic Analysis And depending on the techniques Anomaly index, Cluster analysis, Run Test, Run Chart, and Maan-Kendal Trend Test for three components of average precipitation, Maximum rainfall in 24 hours and rainfall intensity of selected stations happened, suggests that: Iran's climatic identity from philosophical foundations Stochastic Thinking followed, which is referred to as catastrophic events in geomorphology And the condition of success in water policies is the recognition of such climate identity in Iran.

The main component of the climate of any place is precipitation, therefore, in order to achieve the goals of the research and the course of changes in the precipitation characteristics of the geomorphological zone of Iran, based on the analysis of statistical data and considering the importance of land use, based on the quantitative-phenomenological method It is mostly focused on the precipitation component. For this purpose, the research process is prepared as follows (Figure 2).

this research is presented in several steps. In the first step, 16 rainfall stations of Iran were selected and the type of climatic systems governing them was determined. In the second step, the average annual rainfall, maximum 24-hour rainfall and annual rainfall intensity of selected stations (1367-1396) were calculated in MATLAB software. In the third step (six steps), to review and analyze the rainfall data of 16 selected stations, in Excel, Minitab, SPSS and MATLAB software, Anomaly tests, cluster analysis, run test, run chart, Mann-Kendall and harmonic analysis have been performed. In the fourth step, the phenomenological method was used to infer and extract policy making propositions. The interesting point that can be obtained from these investigations is that the rainfall patterns of Iran exhibit two types of behavior: single-pulse and double-pulse or multi-pulse. For example, the stations of Rasht, Babolsar, Bandar Anzali, Gorgan, etc. have one pulse with a long mode, and the stations of Ramsar, Fasa, Bushehr, Bandar Abbas, etc. have two pulses or multiple pulses. Therefore, the following propositions can be extracted:- Iran’s rainfall events are dominated by three climatic systems that do not follow a specific order and each of them has irregularity and unpredictable chaos. Rainfall behavior has been different in each part of the country over many years. Almost all the heaviest 24-hour rains occurred in selected stations randomly and do not follow any particular order. And finally, Iran's rainfall patterns are mostly catastrophic in nature.Therefore, in the management of Iran's water resources, this feature of being random should be considered as the identity of our territorial climate and based on such identity, program policies should be formulated.

Although the measurement and study of precipitation data is considered as the main and most important element or input data to hydrological systems but many Iranian researchers have ignored the ruling spirit of these data and they have done their research on atmospheric data by resorting to averages, statistical medians, etc.; while the spirit governing statistical data in Iran, which has dry and semi-arid climates, triple climate systems, unique geomorphological forms, etc.; introduced the land of Iran as an exception and expresses the fact that the type of attitude, method of study, planning, type of management, etc. in the field of atmospheric precipitation, water resources and resource management must be changed. By considering the results of statistical analysis of rainfall data of selected stations, it can be concluded that Iran's rainfall events are catastrophic and do not follow a specific trend. As a result, the climatic identity of Iran is under the title of the proposition that climatic events are catastrophic as an inherent territorial principle and characteristic that defines Iran's climatic identity. Undoubtedly in a land where climatic events are random the way of making policies about water resources is different from other countries and it is not possible to adopt a specific policy for water resources management. The catastrophic nature of rainfall makes this principle clear to us that, firstly, we are faced with different periods of humidity and secondly, periods of decreasing humidity; Therefore, the following strategic propositions can be expressed in the field of water resources policy making:1- Water storage should be accepted and recognized as a principle;2- Due to the fact that sometimes some areas of Iran may receive more than their water needs and some areas may receive less than their needs therefore, it is necessary and mandatory to create a structure in the field of water resources management that is capable of territorial water maneuver in emergency situations.3- According to the country's development plans, it is certain to use new water sources in the long term (50 years).4- It seems necessary to create a nationwide water network in the country where the share of produced water (artificial, underground, surface water, floods, etc.) is known.

One of the challenges that many societies face is the occurrence of natural hazards. There are different types of natural hazards, and flood is one of the most important natural hazards, which is always associated with a lot of human and financial losses. In fact, floods are considered as one of the most destructive hazards that cause many human and financial losses every year, so that according to the report of the international database of hazards, floods along with earthquakes and droughts, have had the highest human and financial losses. Also, according to the statistics published in 2010, more than 40% of the natural disasters in the world are caused by floods. In recent years, due to the increasing trend of population and increase in human activities and misplaced human interventions in nature, the possibility of flood occurrence has increased and the risks caused by it have intensified. According to geomorphology, hydro climatic, land cover, etc., different areas have different potentials in terms of flood risk occurrence. Among the regions that have a high potential against flood risk are the southeastern regions of the country. These areas have a high potential against flood risk due to torrential rains, being located at high altitudes and low slopes, as well as poor vegetation, and this issue has caused many floods to occur in recent years. Let's be in this area. Considering the importance of the issue and the occurrence of floods in Esfand 1402 in this region, in this research, the identification of flooded areas and also the analysis of factors affecting its occurrence have been done.

In this research, Sentinel 1 and 2 radar images, Landsat 9 images, and a digital model at a height of 30 meters have been used as the most important research data. The most important research tools are the Google Earth Engine system (to prepare maps of flooded areas and land cover maps) and ArcGIS (to prepare the desired maps). Also, in this research, fuzzy logic model has been used to identify vulnerable areas against flood risk. According to the topic and objectives, this research has been done in several stages. In the first stage, using radar images before the flood and images after the flood, a map of the flooded areas has been prepared. In the second stage, the role of natural factors (elevation, slope, distance from the river, and ranking of the river and land cover) in the flood has been analyzed. In the third stage, based on the results obtained from the previous stages and according to the extent of the flooded areas in different floors, various parameters have been valued and standardized, and finally, by combining the desired parameters based on the fuzzy gamma operator, a map of the damage areas is created. It has been prepared against flood risk.

In this research, the Google Earth Engine system was used to identify the flooded areas in the study area. After preparing the desired images and also applying filters and specifying the threshold limit in Google Earth Engine system, a map of the flooded areas in the southeast of Sistan and Baluchistan province was prepared in March 1402. According to the prepared map, a large part of the southeastern counties of Sistan and Baluchistan province have faced floods, but Dashtiari county and especially its southeastern regions along the Pakistan border have faced the highest amount of flooding. After Dashtiari city, Chabahar city has faced the highest amount of flooding. The analysis of the effective factors in the floods has shown that the height, slope and type of land cover have the highest influence because in a general trend, with the decrease in height, decrease in slope and also decrease in vegetation density, the extent of flooded areas increased.

The results of the identification of flooded areas using radar images have shown that in March 1402, a large part of the region, especially the south-eastern areas of Dashtiari city, faced the risk of flooding. The results of the analysis of the effective factors in the floods have shown that a large part of the flooded areas were related to low altitude and low slope areas, which indicates the direct role of altitude and slope in the floods of the region. Also, the areas that were in the category of desert and barren lands in terms of land cover also had the highest percentage of flooding, so the type of land cover was also one of the effective factors. But the interesting point is that there was no strong relationship between the parameters of the distance from the river and the ranking of the river with the floods that occurred. That is, some areas that were far from the main rivers also faced floods, the main reason of which was the morphological condition of the rivers in the region. According to the mentioned cases, among the effective factors, the height and slope have the highest influence and the distance from the river has the least influence (among the studied parameters). Also, in this research, based on the condition of flood-affected areas and the influence of parameters, vulnerable areas against flood risk have been identified. Based on the results, the southern regions of the study area, including the middle and southern parts of Dashtiari city, the eastern and southern regions of Chabahar city, as well as the southern regions of Konarak city, have the highest flood potential.

Studying and measuring changes in snow levels is very important as one of the important sources of water supply. Due to the harsh physical conditions of mountainous environments, there is no possibility of permanent surface measurement to estimate snow sources and form a database. The use of satellite images and remote sensing due to their low cost, up-to-dateness, and wide coverage is a way forward in this field, and it can be a suitable method for identifying snow catchment areas and evaluating its changes to achieve this goal. The presence of snow in the basins affects the water resources that are stored in the form of frozen water on the surface Therefore, temporal and spatial monitoring of snow cover has been used for hydrological forecasts for years. Remote sensing images are a useful tool for estimating snow cover changes and analyzing the spatial pattern of this important environmental phenomenon, especially in high areas where there are few available ground stations or there are no stations

In this research, data from V006-MOD10A1 of the Terra satellite and V006-MYD10A1 of the Aqua satellite were used for snow coverage from 2003 to 2020, which have a spatial resolution of 500 meters and a daily time resolution. The Modis sensor data in both Terra and Aqua satellites were converted from HDF format to TIF format with a threshold of 0.1-1 to binary and ASCII and with a geographic coordinate system. These data were processed using Python coding language. Cloud effect was reduced by using three algorithms: data combination, spatial, and temporal filtering. For the digital elevation model (DEM), the data of the Japan Space Exploration Agency (JAXA) called ALOS World 3D (AW3D) was used. After preparing the snow cover database, average snow-covered days (SCDs) were calculated on a seasonal scale and maps of the spatial distribution of snow cover in this period were produced. Then, the relationship between the two components of SCAs and SCDs and the relationship between SCDs and altitude in the north-western geographical area were investigated and analyzed.

According to the pattern of winter SCDs, the flat plains around Lake Urmia, the plains around Zanjan City, Moghan Plain, and the lands around Sanandaj City show the lowest rate of SCDs (less than 10 days of snow cover). The maximum of winter SCDs corresponds to Sablan Heights with more than 60 days of snow cover. According to the average spring SCDs in almost the entire northwest area, the drop of SCDs compared to the winter season is evident. This reduction is much more evident in low and flat areas and plains than in high and mountainous areas. Spring SCDs are still high in the main altitudes such as Sahand, Sablan, Qandil, Bozghoush, and Qara Dagh and reach about 54 days in the spring season in Sablan. The decline of SCD started from the south and covered more areas of the northwest region. Summer SCDs are facing a sharp decrease in the northwest region. Except for the heights of Sablan, Sahand, and the heights of the western border including the Qandil range, the rest of the areas have snow cover for less than 2 days in summer. It is noteworthy about the heights of Sablan, which still can maintain snow cover for up to 55 days in the summer season. The average autumn SCDs in the northwest region show an increase again in the autumn season. The heights of Sablan, Bozghoush, Sahand, Qara Dagh, and Qandil all show a significant increase in SCDs in the fall season, and in the high parts of these roughnesses such as Sablan, the fall SCDs increase to over 60 days. In other areas, mainly the main body of the roughness has SCDs above 20 days. Investigating the phenological changes of SCAs and SCDs in the seasonal period showed that the highest SC levels in the winter season have SCDs of about 15 days. This surface is about 18000 square kilometers. In general, the areas and regions that have SCDs between 5 and 25 days have the highest SC levels in this season. In the spring season in the northwest region, the SC levels, which have SCDs of less than about 8 days, reach a maximum of 160,000 square kilometers. In the summer season, lands with SCDs of less than 5 days occupy the highest levels, reaching a maximum of 160,000 square kilometers. In autumn, the regions with SCDs of about 7 days have the highest SC levels with an area of about 50,000 square kilometers.

The findings indicate a decreasing trend of SCDs from winter to summer. Meanwhile, the average autumn SCDs in the northwest area again take on an increasing tone in the autumn season. Analyzing the seasonal changes of SCDs in the studied area showed that this phenological component of snow is strongly influenced by the two factors of altitude and latitude. Sablan mountain range has special conditions to maintain snow cover in the study area even in the summer season. The analysis of seasonal changes of SCAs with SCDs shows that the maximum extents of SCs in winter, spring, summer, and autumn seasons have SCDs of approximately 15, 8, less than 5, and 7 days, respectively. In winter, areas with SCDs of more than 40 days include significant SC levels of about 2000 to 8000 km2. On the contrary, in the autumn season, the areas with SCDs higher than 40 days have almost negligible SC extents, whose values reach below several hundred square kilometers. Analyzing the changes of SCDs with the altitude measurement in the seasonal interval, showed the obvious relationship of this snow phenological component in association with the altitude; In such a way that the highest values of SCDs in winter belong to the altitude band of 2500-3500 meters, in spring to the altitude range of more than 2500 meters, in summer to altitudes above 4000 meters and in autumn to the altitude belt of 2000-3500 meters.