نشریه هیدروژیومورفولوژی
پیاپی 16 (پاییز 1397)

The drinking water of about 50% of the world's population is supplied by groundwater whereas it includes only 4% of water of the Earth. (Taheri Tizro, 1384:3). Iran with an average annual rainfall of 250 mm is one of the arid countries in the world (Masodyan & Kavyani, 1386:82). Determination of new groundwater potential and its management in arid and semi-arid regions is a temporal solution to encounter water crisis. Indeed, it includes the identification of the potential areas for water abstraction according to the aquifer capacities. In order to explore groundwater potential in Mehran Plain, several data including climatic data, regional stations, geological, vegetation map and topographic maps, and satellite images of the area were prepared. Using the RS and GIS technologies, several layers were developed and combined to obtain the final zoning map. The main factors that were used to prepare the layers included lithology, climate (precipitation and temperature), hydrology (drainage density and distance from the drainage), vegetation, topography (elevation and slope of the land), faults (fault density and distance from fault), geological maps, topographic maps, and precipitation data which were processed in the Geographic Information System (GIS) to provide a groundwater potential map. The weight of the different layers was assigned from 1 to 9 based on the judgment and field survey. The priority of each layer was rated based on their potential for groundwater using the Analytic Hierarchy Process (AHP). Using the fuzzy approach, the layers were transferred to Idrisi Software and standardized. In order to perform groundwater potential zoning in Mehran Plain, standardized and weighted maps were combined using AHP-OWA and AHP-WLC methods to produce its final groundwater potential zoning maps. Weighing the parameters was carried out by a paired comparison method and the weights were calculated based on an analytic hierarchy process. The amount of calculated weights of lithology and distance from fault parameters were respectively 0.31 and 0.02. Next, the fuzzy maps were produced and were overlaid. The final map of the groundwater potential for the study area was prepared using AHP-OWA, AHP-WLC overlaying methods. In these methods, the weight of each layer was determined based on its importance in the groundwater potential and a map was produced which showed the groundwater potential in different parts. It showed five zones with very low, low, medium, high, and very high potential zones. The zoning map was verified using data of wells location and their catchment area. The effective parameters which cause potential for groundwater are varied in literature, but in most studies, hydrological, geological, climatic, and topographic parameters have been employed. In this research, the effective parameters on the potential of groundwater resources included lithology, climate (precipitation and temperature), hydrology (drainage density and distance from the drainage), vegetation, topography (elevation and slope of the land), fault layer (fault density and distance from fault). The final map of groundwater potential in the study area was prepared using AHP-OWA, AHP-WLC methods. Five zones with various groundwater potential included very low, low, medium, high and very high. The areas with high groundwater potential are in accordance with the alluvial deposits and the zones bearing low groundwater potential are matched with the clayey and marly sediments and with relatively high slope. The verification of the final zoning map showed that the employed methods had a high efficiency in groundwater potential determination. The results of this research can be used in the management of groundwater and prevention of over abstraction of groundwater resources, especially in Mehran Plain bearing low groundwater potential.

Rivers are considered as one of the main sources of water and energy supply for humans, due to their special effects on human life and the formation of different civilizations. Therefore, their behavior should be considered. Flood flow is very complicated in natural rivers, especially in Meanderi Rivers. Therefore, the present research uses a numerical model to evaluate river floods characterized as different return periods of 10 and 50 years. The study area is located on the Kor River. In this study, the geometry model and a numerical mesh system were calculated by taking advantage of topographic surveys and the required parameters for running CCHE2D were collected through filed works.
The CCHE2D model, a two-dimensional hydrodynamic model of flow and sediment transportation for unsteady flows, is able to simulate and analyze sediment transportation flows and morphological processes. It contains two parts: 1- CCHE-MESH generation for meshing the studied area
2- CCHE-GUI for applying the resulted mesh to simulate flow and sediment.
Finally, the model outputs including flow depth were obtained for the considered river reach in different return periods. In this study, using the numerical model CCHE2D, changes in the depth of the water in two return periods of 10 and 50 years in different sections of the river route were obtained and the diagram of these changes was one of the outputs of the model. Discussion and Conclusion: Study shows discharges with different return periods. In the Meander range of the study area, centrifugal force gradient flow of flow on the center and cross slope caused at the level of the water was so high, but the water level in the upper arch cross external and internal were decreasing. This phenomenon caused peripheral gradient pressure within the cross section which resulted in an imbalance of the local effect between the centrifugal force and gradient pressure flow, the secondary flow forms in the transverse section.
Once flooding occurs in the river (50-year return period), water level exceeds the main river channel and enters the surrounding floodplains. Under such circumstances, due to the differences between flood plains roughness and the main channel, flow rate (velocity) on flood plain is much slower than the main channel. Consequently, such difference leads to some shear layers in crossing points of the main channel and floodplain in the entrance, resulting in greater water turbulence. The comparison of the water flow velocity in different reach sections indicated that the highest water velocity was related to the first meander so that in return periods of 10 and 50 years it respectively reached 2.7 m/s and 3 m/s. The results of the study confirmed the applicability of the numerical model to predict river changes using flow parameters. Therefore, it can be said that the present numerical model is capable of analyzing the river changes in the wind tunnel channels in a desirable manner.

One of the most important factors in the development of a region is the availability of sufficient water resources and its quality status for various uses. Due to Iran's arid and semi-arid climate and water shortage, it is essential to pay attention to the water quality of its rivers. Pishkooh-Taft Basin is an important watershed inthe east of Yazd province and located between 54º 15’- 53º 40’ east and 31º 50’- 31º 30’ north. Tezerjan fault of Taft Continues to the west with the northsouth trend. There are 3 gauging hydrometric stations in this area. TM images13 October 1991 and ETM+ 15 October 2011 of Landsat 7 were used to change the detection of the land use. In addition, to examine the physical and chemical properties of water in Taft, Islamiyah and Feyz-abad stations during 1361 to 1390 years were used. First of all, the method which was performed included geometric correction for fixing errors and adapting the images by the Digital topographic map scale of 1: 25,000. Then, land use was extracted by supervised classification, training samples, and maximum likelihood techniques. Next, to report the physical and chemical properties of anions and cations, TDS, conductivity and pH of the water, the stations were investigated during 1361 to 1370 and 1371 to 1390 years, and the data was evaluated using Mann-Whitney statistic. The finding of land use showed that the wasteland and pastures were dominated and there was an increase in pastures compared to 1370, but there was a decline in covered meadows in 1390. To examine the relationship between land use changes and water quality, the elements of the water was dealt with. For this purpose, the physical and chemical properties of anions and cations, TDS, conductivity, and pH of the water between the years 1361 and 1370 and 1371 and 1390 were studied. The results of Mann-Whitney statistic in different elements and three stations showed that the difference between these two periods was significant in Taft station. Discussion and conclusion: The effect of land use on water quality change over the period of 30 years showed a relative decline of water quality in Taft station and to some extent in Islamiyah station. This can be attributed to the increase in land occupancy and the existence of agricultural lands in Taft and Islamiyah Stations. However, in Feyz-abad station, due to the lack of habitat and agricultural lands and an increase in water flow, there was no decrease in water quality. On the other hand, the examination of the changes in the height of the stations showed that Taft station was in the outlet of the basin and had the minimum height which could affect the quality of the water. Several researchers (Townsend & Popcorn, 2009; Kazi et al., 2009; Travka, 2004; Orion, 1390) have studied the effect of reduction of water quality on increasing agricultural lands and urban areas which are in line with Taft station.

Introduction: Changing the environmental conditions of a natural ecosystem influences the hydrological responses such as flooding and the extent of erosion and sedimentation of the area. One of the models used to investigate the effect of land use change and climate change on runoff is SWAT model which is a hydrological simulator and a continuous and semi-distributive time-space model with a physical base. Understanding the relationship between land use change and its causative factors and its secondary effects on hydrologic regimes provides essential information for land use planning and sustainable management of natural resources. Investigating the amount and trend of the changes and its effect on the hydrological processes in the basin is a way to predict the state of future changes and provide more effective plans for the sustainable development of the water resources in the basin. The construction of the Garin Dam in the Garin Basin, the risk of filling the sediment reservoir with sediment, reducing its useful life due to seasonal floods, and the effect of basin land use and climate change were the reasons for choosing this area for this research. The purpose of this study was to study the land use and climate change in the studied watershed and determine the effect of these changes on the runoff rate of this watershed in order to better it correctly.
Garin Dam is located in the Zagros in the province of Hamedan. It includes the catchment area of the Sarab Gamasiab River to the Garin Reservoir Dam and its area is up to the 22,000 m2. The Garin land basin is mainly mountainous and its range of height ranges from 1833.9 to 3429.2229 m above sea level. SWAT model input data included climatic and hydrological data (daily precipitation, maximum and minimum temperature, relative humidity, wind speed, dew point, and solar radiation). In this study, the ten year data of Nahavand synoptic station was uased. Topographic maps, digital elevation model (DEM), soil and land use were also used as the input of the model. A digital elevation model (DEM) was extracted using a topographic map of 1: 250,000 of the Garin River basin. SWAT CUP software was used for the calibration and validation of the SWAT model. The calibration data was from the years 2002 to 2007, but the validation data was from 2008 to 2010. In order to determine the degree of the sensitivity of the flow parameters in the SWAT model, SUFI2 software SWAT CUP were used and the sensitivity of the selected 24 parameters were measured. The Elimination of the parameters which had less sensitivity, was based on the calibration process. According to the P-value and T-Stat criteria, the sensitivity of the parameters were determined. The land use maps of 1986, 2000, and 2014 were prepared at the previous stages, and the Markov chain and the CA Markov filter were used to map the land use in 2042. In this research, the outputs of the Hadcm3 model were used to predict Garin's future climate.
In addition, the SDSM statistical method was used to fine-scale the output of the general atmospheric circulation models. The SWAT model was also used in the range of calibrated parameters to simulate runoff caused by climate change in Garin basin under two A2 and B2 scenarios. After micro-sampling, the SWAT model was converted and t analyzed for the scenarios. Then, the results of the model implementation with different scenarios and the results of model implementation with the current climate conditions were compared Results and Discussion : Regarding the results of the statistical indices, NS index was 0.95. P and R factors were respectively 0.47 and 0.03, and the coefficient of determination (R2) for observed and simulated floodguns was 0.6. Accordingly, the results were confirmed in the calibration phase. The validation phase was conducted to verify the correctness of the selection of the parameters during the calibration period between 2008 and 2010. Given that the Nashatcliff coefficient for Garin's catchment area at the calibration and validation stages were respectively 0.95 and 0.66, , the results were satisfactory and the SWAT model was able to simulate surface runoff in Garin River Basin. In general, due to an increased forest use, an increased permeability and water drainage to the surface and deep water aquifers, and an increased evaporation and transpiration, the amount of runoff has decreased. Regarding the results of temperature, rainfall, and runoff of the next period, it can be seen that in months when rainfall is reduced and the temperature increased, the amount of runoff in the coming period also decreases. The main reasons for this discrepancy can be attributed to the difference in the intensity of land use change as well as the extent of the altered land area, which, given the mountainous nature of the area in the Garin land basin, can be compared to other areas with flat lands with agricultural uses. It is concluded that the effect of climate change in the Garin dam basin is greater than the change in land use due to its mountainous nature. The results of the study of the effect of land use change on runoff in the Garin basin indicated that there was a daily and monthly decline in the amount of runoff. The results of the study of the effect of climate change on runoff in the Garin western basin also indicated that there was a daily and monthly decline in the amount of runoff. In both A2 and B2 scenarios, the monthly average temperature, especially in the first and last months of the year, had an increasing trend and rainfall decreased in the spring and winter. It can be attributed to the increased temperature and evaporation, and decreased rainfall. It can also be seen that there was a decline in the average monthly runoff in January, February, April, May and December, with a decreased rainfall, but there was an increase in the average monthly runoff in June, July, August and September, with an increased rainfall. In addition, the effect of land use change on the reduction of runoff in the upcoming period is lower compared to the change effect under A2 and B2 scenarios. It will affect the climate change of the runoff more flatly and the reduction of runoff is more affected by climate change. According to the information obtained from these predictions, it is possible to properly manage the watershed and adopt appropriate management measures in accordance with the conditions of this watershed, prevent unauthorized land use changes, and reduce the damage caused by the phenomenon of the climate change.

Rivers' pattern is seldom stable and is always subject to change. Rivers' banks have long been the most important areas of population settlement, especially in the semi-arid regions of Iran. This has made the recognition and assessment of the geometric deformation of rivers an important applied topics. Alluvial beds of a river are divided into two groups of stable and unstable. While in a stable bed, the walls and the floor are stabilized, in the unstable bed, the walls and the floor are not constant and have a changing state. Zanjanrood is regarded as the natural bio-economical artery of Zanjan province. In the present study, by recognizing the temporal and the spatial hydro-geomorphological changes of Zanjanrood during the years 1955 and 2011, and in the western part of the river, which is more important for agriculture, the amount of morphological changes is calculated and presented in the form of a map. The method of the study was analytical by spatial-local comparison based on the direct and the indirect observations using satellite images, aerial photos, and maps.
In this method, the intervals were classified into distinct parts based on the morphology-hydrodynamic similarity. Then, by applying spatial analysis on the raster maps, the pattern and variation of the changes were estimated by plotting tangential transects on the extension and restriction areas in the right and left sides. By determining the extension and restriction areas in river sides, the type and amount of stream’s variation in various reaches was determined. Afterwards, the total areas of extension and restriction on both sides of the stream were computed. Transects are rectangles with constant angles whose area variations indicate the changes of the river banks in different time ranges. This technique was used to determine the area dominated every progression and regression area in order to analysis and assess of the main factor(s) affecting this change. The results of the study showed that the outcome of the action-reaction of the factors affecting Znjanrood changes in the studied area had been a stable trend over the past 56 years. The most important factors involved in this trend were the development of the agricultural activities, the increase of management actions to stabilizing the river for agriculture and infrastructure proposes, and dam construction. However, the effect of slope and geological conditions (neo-tectonic) should not be neglected as well. Discussion and conclusion: The results indicated that the overall trend was to reduce the width of the channel to its axis. However, the process has increased from the first period (1955-1985) to the second (1985-2011) and the third periods (1985-2011), so that at the end of the given time intervals, there was an increase in the relative stability of the stream. The change in flow to the outlet reduced the erosion power of the river flow and increased the stability and relative stabilization of the bed. The development of the fairly stable gardening activities dispersed on the flood bed played an important role in the stability of the stream in the studied area, so that the gardens and fields on the stable river main bed sides exhibited great changes in the images and photographs.
The role of the human factors in the Zanjanrood Basin due to its relative geographical position (east to northwest transit), has been the basis for the development and launch of several road construction projects (railways, roads and freeways) during the period of 1955 to 2011 in Zanjanrood and caused the change of Hydro-geomorphological-Hydrodynamic systems. A quantitative assessment of the Zanjanrood river bed changes shows that the rate of change, overcoming the general trend of stability and stabilization, has increased from the first period to the last period. Indeed, while the stabilization rate in the first period was 0.16 km2, in the second and final periods, it was respectively 1.91 and 2.01 km2. Progressions are concentrated in the beginning and end of the research (Transects 1, 2, 6, and 9 to 13), which affects the lands of the villages of Nikpey, Darelik, Dolanab, Naji, Idalou, and Baghloja and Saifabad. The recessions are also focused on transects 3 to 8, excluding transect number 6. Based on the results, Zanjanroud shows the overall stability trend. The adjacent area of the upper and lower parts of the studied research (the areas around the villages of Nikpey and Baghloja) are among the most sensitive areas of the research.

Continuous simulation of rainfall-runoff is very important in many hydrological studies, including the effect of climate change on river flow, flood forecasting, and water resource planning. This phenomenon requires the identification of its components and formative variables. One of the most important hydrological calculations for a basin is the determination of the relationship between rainfall and runoff. The amount of water conversion from rainfall to runoff volume depends on the climatic and the physical parameters of the basin. In the hydrological calculations of a basin, determining the relationship between rainfall and runoff is very important. Accurate calculation of precipitation and runoff at the basin level depends on the identification of its components, form-providing variables, and the use of an appropriate dependent model. The HEC-HMS software is a simulation-based hydrologic modeling software (with parameter optimization capability) developed by the US Army Hydrological Engineering Center whose first edition was presented in 1967 (Hydrologic Engineering Center, 2000: 4). In addition, in order to increase the accuracy of the input information entering into the HEC-HMS software, the HEC-GeoHMS has created an add-on called HEC-GeoHMS. One of the most important applications of this software is calibrating and estimating hydrological parameters in catchment areas. Due to the importance and the extent of using this software, many studies have been done. The catchment area of ​​the city of Uremia is located in the western part of Lake Urmia. Its approximate area is 167.75 km2 and its geographical location is between 82 ° 44 'and 58 ° 44' eastern longitude and 32 ° 37 'to 48 ° 37' northern latitude. The height of the altimeter station is 1591 m and the maximum height of the basin (located on the border between Iran and Turkey) is 3574 m. Figure 1 shows the location of the Urmia Shahirchay basin in the watersheds of Iran and Lake Urmia. In this study, the HEC-HMS model was used to simulate surface runoff. In addition, the HEC-GEOHMS integration was used to map the basin model. For this purpose, the data of the temperature and the precipitation data of the synoptic station of Urmia and the daily flow rate of the river flow at the hydrometric station of the Bardesour (located at the outlet of the basin) were used. By obtaining the basin model by the HEC-GEOHMS add-on in ARCGIS software and creating climatological models, controlling and entering other necessary parameters of the model was implemented. In simulation of rainfall-runoff of Chacha basin by HEC-HMS model, in the period of 2004-2013, the best calibration and validation period was selected to minimize simulation error. The base course was divided into two calibration (2004-2010) and validation (2010-2013) periods. The calculation of this parameter is necessary for simulation in mountainous basins, which are mostly snowfall. In this study, the temperature index method, one of the complementary methods of day-to-day modeling of snow modeling, was used. One particular way is to consider the specific amount of snow melting for any temperature above freezing point. For this purpose, the catchment area was divided into altitudinal classes and the percentage of area of each sub-basin in each altitude region was introduced into the model. Discussion and Conclusion: Based on the results of the simulation in the calibration and validation periods, as well as the evaluation criteria of the model, it was found that the HEC-HMS model had a high probability in rainfall-runoff simulation of Shahrchay basin. It should be noted that the use of the HEC-GEOHMS in the design of the basin model has played a large role in increasing its accuracy in rainfall-runoff simulation. In Yacoby's (2013) study, the accuracy of this model in the simulation of runoff was weaker than other models. It was probably due to not using the HEC-GEOHMS add-on and the lack of a synoptic station in the study area. Nevertheless, in other studies (e.g., Verenden et al., 2013; Borhani Daryan et al., 2016), the HECGEO-HMS add-on was a good result of the model's work, which is consistent with the current study. The results of this study indicate the ability of the HEC-HMS model to simulate the hydrologic behavior of the Chacha basin. In addition, the ability to use the GIS to accurately provide input for the model and view the output shows the efficiency of their integration. The present integration, with proper hydrometric data and precipitation, is able to accurately simulate rainfall-runoff phenomena.

Saymarreh landslide is one of the known largest landslides in the world that is located in the southwest of Iran. The purpose of this study was to compare the characteristics and geomorphological influences of this landslide with the largest landslides of the world. Saymarreh landslide is one of those large landslides that have undergone significant geomorphological, historical, and cultural changes during the Holocene era. The evolutionary trend of this landslide is highly complicated; in fact, it is one of the most important characteristics of large landslides. This landslide formed several dam lakes, and their formation were frequently repeated. However, it is not clear that whether the formation and evolution of the lakes were due to the river erosion sequences or the repetition of Saymarreh landslide. A large number of researchers believe that Saymarreh landslide is the largest landslide in the world, but some researchers do not believe so and introduce other landslides as the largest ones. Thus, by performing detailed investigations into the region, the geomorphic features of this landslide and its evolution was probed. To achieve this goal, ETM2002 satellite images, IRS of PAN and LISS III satellite images of 2004 and 2006, topographic maps, geological maps of SRTM DEM, and ArcGIS software were employed. The research method was empirical and it was based on the analysis of the field data. In this regard, the process of the landslide formation, its causes and morphometric characteristics in three classes of slide area, mass movement and displacement parameters along with deposited materials in Saymarreh Dam lakes were studied. The results relevant to the morphometry of the landslide indicated that various factors were involved in the occurrence of Saymarreh landslide. Among these factors, undercutting of the Asmari limestone layers made by Saymarreh and Kashkan Rivers, particularly in front of the landslide, was the most important cause of the landslide occurrence. The landslide had formed a large lake behind the slide mass and had formed sequential terraces due to repeated slides. The results of the morphometry of the lake, particularly through the estimation of its water (45.642 Gm3) and sediment volume (23.422 Gm3), and comparison of the time taken for filling of the water volume (19.8 years) with the time required for deposition of the whole sediment volume (1888 years) showed that the sediments have not been deposited only during one stabile period of the lake and the lake has been renewed at least at several stages. As a result, the reoccurrence of Saymarreh landslide at several times led to the obstruction of the Saymarreh River. Stratigraphy studies on the lake sediments and the age of its terraces clearly implied the renewal of the lake at least at 4 stages. The sequences of the lake terraces and other evidences confirmed the different scales of the reoccurrence of the large Saymarreh landslide. Discussion and conclusion: This landslide obstructed the Saymarreh and Kashkan rivers and led to the formation a large lake in that region. The lake depleted after destructing the landslide mass, and there was a change in the direction of the Kashkan River.
The main triggering factor for this landslide was undercutting of Saymarreh and Kashkan rivers. Other factors included the direction and the angle of the slope, steep structural slopes, and gravity. The results obtained from the morphometry of Saymarreh Lake and stratigraphy of the lake sediments demonstrateed that Saymarreh landslide had been reactive several times and led to formation of the lake at several stages.

Due to population growth and human activities and increasing water demand, water availability will be critical and water resource assessment and planning for sustainable use become more complex. The dynamic and long-term laws of runoff are important and have practical value for the sustainable development and planning of water resources. On the other hand, the traditional methods of runoff estimation should be improved regarding the accuracy and spatial variations. The application of GIS extensions is needed to provide water resource assessment data. Therefore, the application of such new techniques has greatly increased in recent years to estimate the runoff characteristics. The SCS method is the most commonly used method for estimating surface runoff, whose accuracy has improved through employing advanced GIS-based tools. The applicability of Arc-CN Runoff tool was tested in different internal and external studies which emphasized the quantitative evaluation of the model results. In this study, the accuracy of runoff estimation by Arc-CN Runoff tool was evaluated based on the land use map in two different time periods (1996-2011). The Landsat satellite images of 1996 and 2011 were processed and analyzed for land use mapping. Map of soil hydrologic groups was prepared in GIS environment using slope and soil texture maps. The annual rainfall calculations were done using rainfall daily data of several years for stations within the basin. The curve number map was used to estimate runoff using SCS method within ArcCN-Runoff tool in GIS environment. The runoff observations of Karehsang Station were calculated using daily flow data and the base flow was separated. Finally, the accuracy of the estimated runoff was assessed by estimating the percent relative error. According to the accuracy assessment of land use maps using the ground-based map, the best overall accuracy and kappa coefficient were respectively 90% and 88%. The results showed that the maximum likelihood algorithm and the combination of main and synthetic bands, classified the land use classes of the study area with an acceptable accuracy. The highest percentage of the area was classified as range and dry farming (62.74%) in 2011. The percentage of rangeland, dense forest, and water zones decreased in 2011 compared with 1996.The map of the hydrological groups shown in this study, consisted of groups B, C and D, respectively covering 15.5, 44.5 and 40% of the study area. The average CN in the years 1996 and 2011 was estimated to be around 79.6 and 81.6.
The average estimated rainfall of the study area using the arithmetic mean, inverse distance weighting, and kriging methods in 1996 were respectively 486.24, 424.4 and 486.1 mm. The estimated annual rainfall values were equal to 521.5 (arithmetic mean), 514.6 (inverse distance weighting) and 521.5 (kriging) mm. Runoff height was the highest in bare lands and residential uses, and the minimum of runoff height values were estimated in good and medium rangelands. The mean values of total runoff, base flow, and surface runoff have increased in 2011 compared to 1996. The highest CN values in both periods consisted of bare lands and residential area. The runoff height in different land uses and the total runoff height increased in 2011 (11.38 mm) compared to 1996 (8.8 mm), which can be partly due to the degradation and land use change. The results of this study showed that the ArcCN-Runoff tool improved the accuracy of potential runoff estimations, while the relative error of runoff estimation in both periods was relatively low and acceptable. Thus, the implemented tool can be used to assess and estimate runoff height. The results showed that the relative error of runoff estimation in both periods was in agreement and the error amount was relatively low (10%). In addition, the used methods and tools were evaluated with 90% accuracy in both periods and can be used for runoff estimation in data-scarce watersheds.

Global warming has profoundly changed the climatic regions of the earth and the time and the place of snowfall, which has caused a lot of damage to humans, especially in recent decades. Indeed, depending on the nature of the climatic regions, these changes are diverse and varied. Mountains and valleys play different roles in the uneven distribution of the temperature and snow. The effects of different directions can be very important in snow coverage on the northern and southern slopes. In this research, using statistical models and satellite images in the Alvand, the role of the elevation, the direction of the slope, and the effect of temperature changes on snow cover in the recent decade (2015-2006) have been investigated. In this research, based on Landsat satellite 5, 7, and 8 imagery, the data from the visible and infrared bands were used to extract snow data based on the NDSI index. The NDSI index was applied using relationship (1) to produce snow maps on images. Indeed, the use of relative indices such as NDSI reduces the effect of the topography on the result.
(1)
To investigate the role of the Alvand in snowfall in both of its northern and southern slopes and the snowfall regime changes in its windward slope and windsurf, the harmonic analysis was used. For this purpose, to analyze the snowfall co-ordinates and periodic behaviors and time variations, the monthly mean snowfall per cm with harmonic analysis was used. This analysis is given as a substring using a time series. Resultsand Discussion: According to the findings of the NDSI index, Tuyserkan area receives less snow (62%) than Hamadan (69%). The moist air mass ascending the western slopes of the Alvand's heights causes more rainfall than its eastern slopes. However, the temperature of Hamadan station is lower than that of Tuyserkan due to its northern slopes in the Alvand and the less energy it receives from the sun, which has made the snowfall on the northern slopes be more visible than it is on the southern slopes. The minimum and maximum temperatures have increased in the winter. This steep trend of increase in the winter temperatures along with lower snowfall indicates the effects of climate change and global warming on Hamadan and Tuyserkan regions. The value of the variance in the second harmonic reflects the effect of elevations on the region's climate. The value of the second harmonic variance in the northern slope which is 28% and significant shows the impact of topography on snowfall in the area. Indeed, the snowfall up to 28 % is related to the height and topography of the northern slopes of the Alvand.
While at Tuyserkan Station, this amount is reduced to 20%, meaning that the northern altitude of the Alvand is more effective in the snowfall. The Alvand is a branch of the Zagros mountain range that passes through Hamedan province and has high peaks. The climatic phenomena of this mountain range are abundantly observed in the province. Severe winds and snowfall of the Alvand altitudes are among these phenomena. The mountainous cities of the province, including Hamadan and Tuyserkan, are among the most affected by the Alvand. This study by examining the hidden features of the climatic data by harmonic analysis and satellite images showed that the northern slope shared more than the southern slope in snowfall which was a significant amount in the second harmonic and a relative decrease in the temperature and snowfall. The northern slope was colder in the northern hemisphere and the sunrise of southern slope got more heat than those that were not exposed to the direct sunlight. The percentage of snow in the NDSI index on both sides of the Alvand confirmed this geographic reality. In general, the results showed a hidden feature of the rise in temperature and snow loss in the data and satellite imagery also recognized this fact. Considering the fact that the Alvand is a climatic region of the country's cold and mountainous regions and the sustainability of the natural environment depends on the relative stability of the climate, in order to achieve sustainable development and land use in the region, it seems that regional climate change should be considered in the context of climate change and the reduction of snowfall in the long time.

Geomorphometry is the science of quantitative land-surface analysis (Pike, 1995, 2000a; Raseman et al., 2004). It is an interdisciplinary field that has evolved from mathematics, the Earth sciences, and most recently computer sciences (Pike et al, 2008, 3). It is well to keep in mind the two overarching modes of geomorphometric analysis first distinguished by Evans (1972) as specific, addressing discrete surface features (i.e. Landforms), and general, treating the continuous land surface. The morphometry of landforms per se, with or without the use of digital data, is more correctly considered part of the quantitative geomorphology (Thorn, 1988; Scheidegger, 1991; Leopold et al., 1995; Rhoads &Thorn, 1996). The shape of terrain, i.e. landforms, influences flow of surface water, transport of sediments, and soil production, and determines climate on local and regional scales. Furthermore, natural phenomena like vegetation are directly influenced by landform patterns and their relative position across the landscape (Blaszczynski 1997; Blaschke & Strobl, 2003).
The Earth’s surface is structured into landforms as a result of the cumulative influence of geomorphic, geological, hydrological, ecological, and soil forming processes that have acted on over time. Landforms define boundary conditions for processes operative in the fields of geomorphology, hydrology, ecology, pedology and others (Dikau, 1989; Dikau et al., 1995; Pike, 1995, 2000a; Dehn et al., 2001). In this study, using MRS algorithms and Ecognition software, landforms in the northern slopes of Mount Sabalan have been extracted and the effects of Landform morphometry on its hydrology have been investigated The semi-automated methods refer to the automatic procedures of extracting a landform based-process. This is mainly relying on unsupervised isodata classification, pixel-based classification (supervised /subpixel classifier based on training material), the analysis of digital elevation models (DEM), algorithms, hydrological modelling, and object oriented analysis (Nabil and Moawad, 2014:42).
In this study object-oriented methods and Ecognition software were used for the classification and the extraction of landforms. The object-oriented classification was used as an alternative to traditional pixel-based classifications, to cluster grid cells into homogeneous objects, which can be classified as geomorphological features (Seijmonsbergen, 2012). In addition, the DEM and its derivation (Slope, Profile and plan curvatures, maximum and minimum curvatures), were used in order to extract landforms. Then, using fuzzy logic method, the landform, land use, NDVI index , precipitation, density of river, and lithology layers were Overlaid and the potential flooding area was obtained. In the object-oriented method, determining the scale parameter is a very important factor in the separation of different objects in an image. Scale parameter is a crucial threshold that determines the maximum allowed heterogeneity for segmentation and has a direct influence on the size of the objects to be obtained. The scale parameter, after a trial and error process, is recognized to be within a particular range (Gerçek, 2010:115). A novel method that was introduced by Dragut et al. (2010) and the ‘Estimation of Scale Parameter (ESP) that built on the idea of ‘Local Variance’ (LV) were employed to obtain the optimum scale out of a range of scales. By interpreting thresholds and prominent peaks in the ROC-LV graph, characteristic scales relative to data properties at the scene level could be found. This curve in 100 scale level was produced for the study area by using the ESP software and with respect to curve, the scale of 25 was selected for the segmentation. After segmentation, using the morphometric differences between the landforms, the landforms were extracted. After this stage, the landforms along with three layers of NDVI index, land use, and lithology was fuzzy. Finally, using gamma 0.8, they were combined and the zoning map of the potential flooding was estimated. Flood zoning map was classified into 5 classes and the percentage of each zone risk was calculated in each landform. In this research, using an object-oriented model, landforms were extracted as plain, peak, pit, ridge, channel, nose, shoulder slope, hollow shoulder, spur, planar slope, hollow, spur foot slope, and hollow foot. An assessment of the effect of landforms on the hydrology of the area revealed that three landforms of hollow, shoulder and planar slope which were respectively 67.3%, 62.9%, and 53.2% had the greatest impact on flooding and their area were zoned as high and very high flooding. On the other hand, plain and pit landforms were zoned in the form of low and very low flooding areas.