Physical Geography Research
Year:2019 | Volume:50 | Issue:4 |Papers Count:14

Introduction Geomorphologists use different models to illustrate topography and geomorphic features. One of these common models is to use hillshading, as an effective tool to detect and represent morphological shape of the terrain. This model applys a light source to make a contrast between bright sections and the parts that fall in the shadows. Many researchers have worked on the hillshade modelling. Some of them work on the azimuthal and zenithal angle of light source illumination on the earth surfaces. Others focussed on the direction and the gradient of the earth and their effect on the quality of the shadows and bright areas representations. In this research new concepts called optical morphology is introduced which is considerred as a set of methods, models and technics for representing geomorphologic and topographic features more accurate and visible. We have employed 14 terrain curvature models and also 6 models for azimuthal and zenithal angle adjustmernt. For running these models, Digital Surface Model (DSM) extracted from ALOS satellite data was used on Iran diverse geomorphological landforms. Then, these models were scripted by python and Graphical User Interface (GUI)using Python Tkinter library. A GIS-Based toolkit named Optical Morphology was prepared to calculate all introduced models in the form of raster file format. Finally, numerical analysis, including statistical, morphological, directional and contrast analysis, were run for all the model outputs. The performances and some general applications of these models are described in the field of geomorphology. Materials and methods In this research, Digital Surface Model published by Japan Aerospace Exploration Agency (JAXA), with a spatial resolution, near 23m, has been used for the purpose. The data were obtained from ALOS satellite image. The database is based on the global 3-D topographical DSM, which is currently the most accurate elevation data on the global scale. Several hill-shade modeling is used to enhance terrain feature’ s representation. For this purpose, Python programming is used to prepare all these models. The main local terrain descriptors such as slope and aspect have also been used to enhance terrain morphology appearance. The 6 models were run based on changes of azimuthal and zenithal angles of light source position. The models for azimuthal and zenithal analysis are including Aspect Frequency Distribution Analysis (AFDA), Un-weighted Multi-Directional Light Source (UMDLS), Weighed Multi-Directional Light Source (WMDLS), Vertical Light Source Illumination (VLSI), Slope Shading Model (SSM), and Sinusoidal Light Source Fluctuation (SLSF). The 14 models run according to the terrain curvatures are including Profile Curvature Shading Model (PCSM), Tangential Curvature Shading Model (TCSM), Plan Curvature Shading Model (PCSM), Un-sphericity Curvature Shading Model (UCSM), Mean Curvature Shading Model (MCSM), Differential Curvature Shading Model (DCSM), Maximal Curvature Shading Model (MaCSM), Minimal Curvature Shading Model (MiCSM), Horizontal Excess Curvature Shading Model (HECSM), Vertical Excess Curvature Shading Model (VECSM), Total Gaussian Curvature Shading Model (TGCSM), Total Accumulation Curvature Shading Model (TACSM), Flowlines Curvature Shading Model (FCSM), and Total Ring Curvature Shading Model (TRCSM). All these models are programmed using python (V. 2. 7 and Tkinter for GUI programming). Results and discussion In this research, optical morphology of terrain has been performmed using basic geographic information system concepts. The python programming has been used to execute different hillshade models. Some topographical factors such as terrain slope and aspect have been considered with regards to light source directions (Azimuthal and zenithal directions). In general, 20 different shading models have been programmed for calculating optical morphology and prepared as GIS toolkit named Optical Morphology. This tool is able to uses Digital Elevation Model as an input to analyze its raster structure and then store results as an ASCII file format. Finally, we have explained results, applications, advantages and disadvantages of these models. Conclusion Light source direction modeling combined with the geomorphological attributes is a powerful tool to more accurately recognize and detect landforms and could help geomorphologist in different field of studies. In this research, optical morphology modeling was done using Python programming language to enhance representation of the geomorphological terrain features. The results of these efforts are abstracted in the GIS-based toolkit which is applicable in the quantitative geomorphology area. These models have different approaches against local topographic properties, local conditions of each place and shading properties. Some geomorphological factors such as slope and aspect, topographic characteristics, terrain curvatures and, pixel distribution are effective and suitable in running and performing and adjusting the models.

Introduction The activity of synoptic cyclones plays an important role in determining the local climate and forming large-scale atmospheric circulation through the vertical and horizontal exchange of heat, humidity and momentum, coupled with interaction with large scale circulation centers. The cyclones are generally transmitter of the bad weather conditions and also represent the initial mechanism of transmitter moisture and heat to the pole. Systematic changes in geographical location or in the intensity / frequency of cyclone activities will make significant disparities among other regional climate impacts. The effects of mountainous obstacles on synoptic systems, especially the cyclone systems, are recognized. The mountain range is one of the factors that in addition to disrupting the uniformity of the earth face, it also disrupts the climatic uniformity. The purpose of this study is to determine the influence of thermodynamics of Zagros Mountain on the changes in cyclones entering the country from the west. Materials and methods For this purpose, the daily precipitation data were obtained from 13 stations of the Meteorological Organization in west Iran. Also geopotential data were extracted from the NCEP / NCAR databases with spatial resolution of 2. 5 × 2. 5 degrees and ERA-Interim data from ECMWF databases with spatial resolution of 0. 125 × 0. 125 degrees, their framework is 0 to 80 degrees east and 0 to 60 degrees north. Using the Factor Analysis method, April 14th-18th, 2003 was selected as the best pattern. After selecting the sample day, sea level pressure maps and geopotential heights of different levels were prepared and analyzed. Results and discussion The results of the analysis of these maps showed that the cyclone reaching the Zagros Mountains are dynamically strengthened from the day it formed until it arrived in Iraq. When they approach the Zagros, the vorticity and its omega are reduced, but crossing Zagros, a positive vorticity increase happens. These types of cyclones call Zagros cyclones. The relationship between the amplified cyclone with the divergence region of the middle and middle levels were observed at all stages. The Zagros roughness, like a wall, initially weakens the cyclone reached Iran and makes them bipolar. However, the passage of the cyclones from the mountain make the thermodynamic conditions of the descending air in the lee mountain range. The condition makes them revival. As the air reaches the roughness, a weak core remains in the Zagros range, and another nucleus is formed by passing through the mountains in the central regions of the country, and is reinforced in the next hours. Finally, the cyclone is amplified and leaves its moisture completely on Iran. These cyclones can be called Zagros second cyclones. Conclusion Mountain barriers are considered as the factors destroying the homogeneity of the local climate. Sometimes they act in the planet scale like the Rocky Mountains. Iran has a heterogeneous environment in term of geomorphology and climatology. One of the most outstanding effects of roughness on the climate is the change in the structure of systems passing through these barriers. Zagros Mountains is one of the main mountain ranges of Iran, with an almost northwest-southeast direction and with a maximum height of about 4, 400 meters at Zardkuh Peak. It has a significant impact on immigrant systems to the country. A study on the cyclone on April 14th, 2003 showed that this cyclone was formed on the April 12th on the northwest Europe, moving towards the Mediterranean Sea. Its trough arrives in the country on the April 14th and it reaches the slopes of Zagros on the 16th. As it is approaching Zagros, changes in pressure in the back and the lee of Zagros are increasing. Vorticity and divergences are completely different in two parts. In the Zagros, during a few days when the cyclone pass across the range, there is a negative vorticity. The vertical velocity also demonstrates subsidence in Zagros altitudinal areas. The results vividly prove that the cyclone gets weakened in collision with the mountain, and its movement gets slow, but it does not disappear. It is re-reinforced on the Zagros lee in the central part of the regions, and continued its route to outside the borders of the country.

Introduction Blocking is one of the most protruding flow patterns and has received attention during the last decades due to its effect on seasonal weather characteristics. The first qualitative conditions for the blocked atmospheric flow was introduced by Rex in 1950 telling the atmospheric jet becomes divided into two separated parts with a considerable connected mass transport, the flow to be meridional at the splitting point and downstream, and the state to continue for at least ten days with a zonal width of at least 45 degrees. The new ideas formulated by Rex became the basis for several blocking indices. Most of the indices detect typical atmospheric patterns. For shorter time series, particular criteria have been used, although, the majority of the analyses are in the 500 hPa geopotential height. In the face of the differences between the index classifications, they draw similar conclusions regarding the patterns of the Northern Hemisphere blocking climatology. However, the blocking frequency is the percentage of time steps an assured longitude. It can be as low as 5% or higher than 20%. The main aims for this wide range of frequencies in automatic recognition are modifications of the Rex criteria and the use of different parameters. Due to its simplicity, the index of Tibaldi and Molteni (TM-Index) has become a standard in automated blocking detection analyses. An important problem of the TM-Index is that it cannot effectively distinguish between blocking and cut-off low patterns, since both fulfill the TM-Index criteria. The adapted TM-Index MTM has a higher rejection rate for cut-off lows. Limits in the Rex conditions can be measured as implementations of independent filters which show synergetic effects if they are used in run...

Introduction Daily average net radiation (DANR) is necessary for hydrological modeling, water resources management and planning, in particular for prediction of daily evapotranspiration (ET). Recently, some remote sensing based methods have been developed at watershed and regional scales to help researchers estimate DANR and ER under both clear and cloudy conditions. DANR is a critical variable linking estimates of instantaneous latent heat flux (satellite overpass time) from energy balance based models. Radiation modeling based on ground or station data is actually point scale estimation. On the other hands, application of geostatistical methods to produce radiation maps at watershed scale is often associated with remarkable errors due to the limited number of stations. In this study, net daily radiation maps were created based on newly developed geometric radiation model based on land and atmospheric MODIS data in the Urmia Lake Basin (ULB) under clear-sky condition for four selected dates in 2006 and 2007. Materials and Methods In this study, the ULB located in northwestern Iran was selected as the study area that extending in latitude from around 35. 67° to 38. 47° N and in longitude from around 44. 22° to 47. 89° E. The basin has an area of approximately 52700 square kilometers. This study attempts to estimate the DANR maps for four selected days under clear sky. Long et al. (2010) developed a geometric model considering slope and aspect effects to improve parameterization schemes to estimate daily average net shortwave radiation (Rns) and daily average net longwave radiation (Rnl). In present study, the same methodology employed a characteristics model (slope, azimuth and elevation) based on daily MODIS data products and the global ASTER DEM. The DANR is total of the daily net short wavelength radiation and daily net long wavelength radiation. Long wave radiation was estimated using MODIS products including surface albedo, Land Surface Temperature (LST), atmospheric temperature, pressure and emissivity. A four-observation based method using Terra-MODIS and Aqua-MODIS LST data was applied to estimate daily average LST in order to improve the accuracy of estimations of Rnl. In the study, we applied the 24-hour incoming direct solar radiation (Sin24) measurements of Tabriz and Urmia synoptic stations for validation. The RMSE and MAE measures were used for model evaluation. In addition, due to the lack of ground-based Rnl observations, we utilized the FAO (Penman) method to generate corresponding ground data for model validation. Results and discussion In order to compare the amount of incoming Sin24 on flat and slope surface, the whole study area was assumed as a flat and the Sin24 maps were produced. The differences between Sin24 on flat (Sin24, s) and sloping surfaces (Sin24, f) were calculated for all pixels. The histogram plot or frequency of Sin24, s-Sin24, f quantity at different intervals of slope showed that by increasing in slope degree, the frequency of pixels at all slope classes becomes greater. This reflects the importance of the slope for estimating Sin24. In addition, the values of Sin24 at flat are higher than sloping surfaces especially for where slopes < 30 degree. Aspect is another influencing factor on the amount of receiving and absorbed radiation. The RMSE and MAE for observed and estimated Sin24 values were 30. 29 and 19w. m-2, respectively. The models in average overestimate Sin24 about 10. 5%. The results showed that the eastern and western aspects receive more daily net radiation during day and sunshine hours or day length has its impact on radiation. For Rnl estimates, the RMSE was 36w. m-2 Conclusion In present study, the Sin24 was parameterized by taking into account the effect of terrain factors, such as slope, azimuth and elevation on direct solar radiation. The sunrise and sunset angles for a given sloping surface (pixel) are different in geometric radiation model. Results indicate that the model has the capability to characterize the variability in Sin24. The incoming solar radiation for flat surface is higher than sloping surface. We founded that southeast and southwest aspects receive greater net radiation. The DANR values decrease with an increase in elevation. The geometric model used in this research needs to be evaluated in different watersheds in Iran without data availability problem especially daily Rns, Rnl and LST measurements, a high number of meteorological stations with proper spatial distribution. This research was done under limited data in the ULB.

Introduction The increasing expansion of industries and the use of fossil fuels have led to an increase in greenhouse gas emissions and, consequently, global warming and the occurrence of climate change phenomena. Climate change is a change in the climate behavior of an area relative to the behavior that is expected during a long-term period of observed or recorded information in that area. The ET element is considered as one of the most important components of water balance in nature; it is strongly influenced by important climate components such as temperature and under the influence of climate change, it can exhibit various reactions. Therefore, in calculating the water balance of each basin, ET calculation is important. Because ET along with the surface flow and water penetration in the soil are considered as components of the water balance. Due to the temporal variations of climate variables and consequently ET, the use of remote sensing methods can consider these changes as more favorable. Using Landsat satellite imagery and energy balance model, using the NOAA, AVHRR and SEBS algorithms, Baba Jafari et al (2015) estimated monthly ETA values for agricultural use in the Akhole region in Tabriz. Comparison of the results of the algorithm with observation values indicates the accuracy of the model with a coefficient of 0. 8 and the mean square root error of 9. 64 millimeter per month (Baba Jafari et al., 2015: 1). Materials and methods In this study, for the analysis of the ETa of the East Azarbaijan province, we applied MOD16A2 remote sensing data in a time interval of 8 days in the period 2014-2000. Data on maximum, minimum and precipitation temperatures of 11 stations of the province were also used for the purpose. Since the relationship between temperature and ETa is linear, the correlation between the average of the maximum and minimum temperatures of 8 days in the stations of the province was calculated with the mean values of 8 daily ETa for representative cells. As the purpose of the current research is to estimate ETa for explaining the water balance of the province, the correlation between precipitations of the stations in the province with the ETa of the representative cells was also evaluated. Given the fact that the data of the MODIS are 8 daily scales, with programming in MATLAB software, the data of the maximum, minimum and precipitation temperatures of the stations was converted into eight days interval. Investigations showed that MODIS provides only ETa data of the representative cells of Ahar, Jolfa, Sarab, Sahand, Marand and Meyaneh stations, and for other stations due to the placement of the cell in the class of ground cover construction, ETa data has not been recorded. Results and discussion The findings of this study indicate that the average maximum and minimum mean and total mean of ETa data on 124546 pixels in the province for the period from 2000 to 2014 were 2. 3, 0. 5 and 0. 8 millimeter per day. The time series ETa of the cells within the boundaries of the province also showed the highest changes in 2003 and 2010, at 9. 1 millimeter a day, and the lowest in 2001, at 0. 1 millimeter per day. In this regard, the time series of the ETa of the stations in the study years showed that the highest and lowest values of ETa changes were in the Sarab and Sahand stations, and the value was 3. 3 (millimeters per day) in 2012 and 0. 01(millimeters per day) in 2001. Due to the fact that the temperature relationship with ETa is linear, the correlation between the average maximum and minimum temperatures of 8 days in the stations of the province with average ETa values of 8 days for representative cells of the station was calculated. Investigations showed that there was a negative relationship between the mentioned parameters. Basically, there must be a positive and direct relationship between temperature and ETa. The only factor that can disrupt this relationship is the lack of adequate water in the area. Regression analysis on min and max temperature data matrix with ETa of 8 days in the stations at 95% confidence level showed that with 1 degree increase in temperature in the province, the ETa decreases by 0. 02 mm per day. The ETa variation slope in relation to precipitation stations showed that at 95% of confidence level, with an increase of 1 millimeter of precipitation, the ETa would increase by 0. 9 millimeter per day. Conclusion In this study, was investigated the correlation between the average maximum and minimum temperature of ground stations with the mean values of 8 daily ETa of the representative cells of the stations. The results of the investigations showed that there is a negative relationship between the mentioned parameters. The existence of a negative relationship between the above mentioned parameters reflects the fact that when the warm season approaches, the water resources are decreasing as a result of decreasing water, and also ETa values decrease with increasing temperature. Because there is not enough water to evaporate in the area, the correlation between mean precipitation and ETa also showed a positive relationship. In other words, the higher the rainfall, the higher is the water available to the plant and the soil. Given that the average annual rainfall in the province is 267. 27 mm and the annual loss of ETa is 32. 4 mm. This amount of evaporation is significant compared with 267. 27 millimeters of annual rainfall. The climate condition of the province leads to desert and dry land.

Introduction Nebkhas are single dunes formed by accumulation of aeolian sediments on shrubs and single trees. They play an essential role in the stability of arid and hyper-arid ecosystems, mostly by preserving the vegetation. Moreover, they are very important in stabilization of moving sand in deserts and semi-arid areas, as well as in protecting human settlements and facilities from sand infestation. The spatial pattern analysis of natural or manmade effects provides useful information about the effects of competition between environmental conditions. The spatial point pattern analysis of every phenomenon and their impacts on environment is being considered as a basic criterion for decision making, especially in risk management. For instance, spatial pattern of plants is a context in ecological theory. A data-set consisting of a series of mapped point locations is a main example of a spatial point pattern. The methods for quantifying these characteristics of point pattern are known as summary statistics. From a statistical point of view, the methods are also appropriate for phenomena that represent various types of geomorphologic features. Thus, to better understand the factors controlling the pattern of Nebakas, univariate and bivariate summary statistics have been used. Moreover, a more promising approach in such analyses is to complement point position with quantitative size attributes and use mark point patterns (i. e., Nebakas with a quantitative characteristic such as physical and chemical properties of the soil). In fact, the spatial distribution of Nebakas in the semi-arid regions can be described and modeled by point pattern processes where the points are given by locations of the Nebakas. Given the importance of spatial statistics in obtaining useful information for better management in all fields, there are not remarkable investigations about the spatial analysis of the Nebka dunes. Materials and methods In the present study, we have selected an area of 197 hectare and produced a maps related to 147 Nebkas in the Sufikam plain, northwest of Golestan province, Iran. In order to study the distribution pattern of the Nebkas and also the factors influencing their spatial distribution, we have recorded morphometric characteristics of the Nebkas including length, width and height. The physical and chemical properties of the soil have also been assessed and the spatial pattern of Nebkas analyzed using R and Programita software based on Ripley’ s K and G univariate functions and Mark Correlation Function (MCF). Results and discussion Results showed that by using Ripley K function, the spatial distribution of Nebkas in Sufikam plain is clustered and most of them are located in the north part of the area of interest. Density of Nebkas and also their mean spatial distance (distance between Nebkas) was 0. 75 per hectare and 33m in turn. Regarding the results of g(r) in Sufikam plain, the significant aggregation of Nebkas was observed at all scales (0– 50 m). As the function failed to be in the bounds of respective 95% simulation envelope, the aggregation of Nebkas in all of the scales was a significant departure from random labeling at the significance level of 0. 05 (Fig. 8). Furthermore, regarding the results of mark correlation function (MCF), Nebkas and parameters of the length of the Nebka, sediment deposition, pH and organic matter of the Nebka soil, were highly correlated. Moreover, the parameters of width, volume and height of the Nebkas, EC, SAR, ESP, sorting and mean diameter of sediments did not affect their distribution pattern. Conclusion The results of the spatial analysis of the Nebkas helped us identify the factors affecting the distribution of these facies. In this study, it was also found that soil acidity has a significant effect on the distribution pattern of the Nebkas. In addition, greater organic matter content has a greater effect on the growth of the plant species, which can also affect the distribution pattern. Soil textures such as clay, silt and sand did not affect the neighboring Nebkas in the study area. The sediment deposition and the distribution of the Nebkas indicates a positive correlation; which means that the larger its value (or the symmetry of the sediments towards fine particles), the denser the distribution of the points. The results have indicated that the of Nebka landform play a positive role in reducing the effect of wind erosion. The investigation of their spatial dispersion and factors affecting their dispersion, development and natural processes, can be a guide for natural resource managers for controlling and reducing the wind erosion.

Introduction Kermanshah Province is one of the western mountainous provinces located in the middle Zagros Mountains. The rainfall in this province is similar to other mountainous regions in orographic and rugby. Forecasting rainfall in terms of severity, amount and continuity in the usual way is often not precisely possible and requires very expert forecaster and familiarity with local conditions. This leads to severe, destructive and sometimes catastrophic floods in the province. Today, weather radars can be a valuable tool for experts to forecast rainfall, provided that they are calibrated in accordance with local conditions and calibrated over time with climate change. If the calibration of weather radar is accurately conducted, the radar can estimate the amount of rain over the vast areas with good accuracy. Relationship between rain and reflectivity radar exponential show Z=aRb, where a and b are coefficients of radar. The amount of R depends on the factors such as the type of rain, rain season, latitude and topography. Variation is ranged of a in few tens to few hundred, and the range of variation b is 1 to 3. Drop size and distribution of rainfall, the coefficient of this. Materials and methods The purpose of this study is to calibrate the Kermanshah weather radar with the conditions of the province, so that the specialists be able to predict data using this radar before any hazard. By the way they can provide warnings to the people and authorities and reduce the damage to the dwellings, historic buildings, administrative centers, urban and rural facilities, farms, humans and animals. In this study, we have used rain data from November 17 to 18, 2015, and November 30 to December 2, 2016. These rain data have been obtained from the stations including Kermanshah, Eslamabad, Sarpol, Ghasre Shirin, Harsin, Javanroud, Tazabad, Songhor, Ravansar, Ghilan Gharb and Soumar. The stations are located in distance of 30 to 100 kilometers from Kermanshah’ s radar. Results and discussion For rainfall of November 17 to 18 2015 for all stations, we have different angles of radar beam and the reflectance. The radar beam elevation angle is optimized for each station; a separate line equation was obtained. Using the coefficients of the equation and radar, rain intensity level was determined by Surface Rainfall Intensity (SRI) and the total rainfall was an hour and finally total rain was estimated for each station. Radar estimated rainfall for the first part was more than that measured by rain gauges. Because the error was considerable in all stations, it is assumed that the size and distribution of rainfall in the first part of rainfall vary with the next step. To solve this problem, rain at all stations was divided into two parts. For the first part of the conflict between radar rainfall and gauge rainfall, we have used common linear equations and coefficients of a and b obtained again for all stations. The results showed that the amount of rainfall was estimated in this way better than before. Using this relationship, rain is estimated 31 percent to 96 percent and the average total rainfall by radar is estimated about 8. 9 to 32. 4 millimeters. The value is increased greater than that before calibration. Acquiring the optimum beam angle of the radar for any location is time-consuming and difficult. Therefore, when the time is not enough, it is better for each rainfall radar to obtain a relationship. Conclusion The results have indicated that the coefficients of radar for any location and at any time are different from those of gauge. To increase the accuracy of radar rainfall, it is better to obtain each separate equation. However, to obtain a separate equation for each location is the best. Finally, it is suggested that the radar equation coefficients for each region of Iran, which is covered by the weather radar, are calculated, so that they can accurately predict the precipitation and give warnings to the different centers.

Introduction One of the challenges in the 21st century is the issue of climate fluctuations. The increased average global temperature and its pursuing changes are part of the climatic changes that have been addressed in all ecological theories. In addition to this global increase in the air temperature, many of the phenomenological, meteorological and satellite-based studies have reported a surge in the length of the growing season caused by the augmented temperature in northern areas during the twentieth century. Any crop for its germination and growth requires a minimal temperature below which the growth process is impeded or stopped. This temperature is specific for each plant variety. One of the critical effects of this phenomenon (global warming) is a change in the degree-days of plants. A plant growth is a variable of the temperature. The growing degree day index and its availability for a crop plays a vital role in the process of the growth and enhanced productivity of inputs, including cultivation date and greater yield. Thus, the growing degree-days vary relative to the temperature fluctuations. Investigating the effects of temperature in different time periods on the growth and development of organisms, especially plants, is of paramount importance. The objective of this paper is to investigate whether there are specific trends in the number of heat units during the growing season using temperature indices to determine indicators, capacities and limitations of the agricultural climate in planting varieties with different adaptation styles. Materials and methods In this paper, daily temperature data (minimum, maximum and average) reported by 31 Iranian synoptic meteorological stations over a 25-year common statistical period were used to estimate the trend of heat units during the growing season for 1985-1986 and 2009-2010 periods. To calculate heat units, the length of growth season was initially extracted for temperature thresholds of 5 ° C and 10 ° C using Julian coding (January 21st with code 1 and January 20th with code 365) and then heat units of the length of growth season were calculated by subtracting average day temperature from base temperature. Maps of heat units have been prepared in GIS. The statistical defects have also been reconstructed using autocorrelation method, and the randomization of the data has been tested by the Mann-Kendall test. The series that had specific changes or trends at the confidence level of α =0. 05 were identified. Then, using Mann-Kendall test, it was determined how and when these trends were started and variations in heat units were estimated. Results and discussion To calculate the base heat units at 5 ° C, the start and end dates of 5 ° C and the length of growing season have been first extracted and then based on the length of growing season, the number of heat units during each season has been calculated for the stations. The average length of the growing season at a temperature of 5 ° C is varied in different stations ranging from 147 days at Shahrekord station to 365 days at Bandar Abbas and Bushehr stations. The heat units during the growing season also varied from 2218 to 4174 degree-days at stations under study, with the lowest number belonging to Shahr-e-Kord Station and the highest to Gorgan Station. The length of growing season at 10 ° C was variable from 67 days at Shahrekord Station to 348 days at Bandar Abbas Station. The number of heat units during the growing season for this base was 861 degree-days for Shahrekord station and 5664 degree-days of the Bandar Abbas station. The results of the Mann-Kendall test indicated that the average heat units in most stations under study over the past 25 years followed a specific trend throughout the growing season. That is, for a temperature threshold of 5 ° C, changes in most stations had an increasing trend, with the exception Sanandaj and Shahrekord stations, which pursued a negative or decreasing trend. For a temperature threshold of 10 ° C, most stations displayed a positive and incremental trend, except for Abadan and Ahwaz stations that had a negative and declining trend. The results of Mann-Kendall's graphic test on heat unit data with a temperature threshold of 5° C revealed that changes in all stations followed an incremental trend, except for Abadan and Bandar Abbas stations that had a dramatic and decreasing trend. Among the series of heat units at 10 ° C, unlike Abadan, Ahwaz and Bam stations, which have a dramatic and declining trend, the rest of the stations followed an incremental trend. Conclusion The analysis of the change trends of heat units during the growing season for temperature thresholds of 5 ° C and 10 ° C indicated that most of these changes were dramatic except few of them following a progressive and steady trend. For a 5 ° C temperature threshold, the changes in all stations had an incremental trend with the exception of Bandar Abbas station, which demonstrated a sudden and declining change. Considering the temperature threshold of 10 ° C for the analysis of heat unit series, it was observed that Abadan and Ahwaz stations had a sudden and decreasing trend whereas other stations such as Gorgan, Arak, Zahedan, Ramsar, Mashhad, Qom, Sanandaj, Anzali and Tehran followed a steady and incremental trend. Among the series of heat units for 10 ° C, unlike the Bam station, which displayed a sudden declining trend, the stations of Urmia, Bushehr, Birjand, Khoy and Sabzevar followed a sudden incremental event. The results of the research exhibited more significant changes in the series of heat units at a threshold of 10 ° C in comparison with heat units at a threshold of 5 ° C. At the base temperature of 5 ° C, the number of heat units for the length of growing season is increased from south to north and from west to east, and at the base temperature of 10 ° C, it revealed an increasing trend from south to north and from west to east of the country. According to the results, it can be suggested that in the areas where the length of the growing season declines, given that farmers struggle with low yields and crops that are not grown adequately, farmers would be better off cultivating crops with the low growth period or early plants to provide the heat energy needed by the plant during the growing season.

Introduction As a geomorphic hazard, landslide causes great deals of financial damage and casualties every year, and directly and/or indirectly contributes to large economic losses in different areas. Given that numerous factors contribute to the occurrence of a landslide, in order to prepare more accurate zonation maps, it is necessary to use more information layers and evaluate various factors possibly leading to the occurrence of the event before adopting the existing models to zonation the susceptibility map. This phenomenon is a natural hazard which is affected by the land surface shape (morphology). When it comes to susceptibility analysis of landslides in a particular area, not only common factors in zonation, but also morphometric features of ground surface are important and should be evaluated. Geomorphometric indices can be used for analysis of many geomorphologic events and natural hazards. These indices express quantitatively characteristics of hillsides which are susceptible to landslide. Materials and methods In this research, a total of 18 factors contributing to the occurrence of landslides in Fahlian watershed were identified and evaluated. These factors are including slope, aspect, slope length, altitude, distance to fault, distance to river, precipitation, lithology, landuse, general curvature, Plan curvature, profile curvature, Normalized Difference Vegetation Index (NVDI), topographic position index (TPI), Length and Slope Factor (LSF), Terrain Ruggedness Index (TRI), Stream Power Index (SPI), and topographic wetness index (TWI). In order to prepare the layers of the effective factors, we have used geological maps at scale 1: 100, 000, topographic maps at scale 1: 50, 000, Digital Elevation Model (DEM: ASTER), satellite images, and aerial photographs. The data have been analyzed by ArcGIS, Global Mapper, Surfer, and ENVI 4. 5 software packages. Given the focus of this research on the application of morphometric indices to optimize zonation map of susceptibility to landslide, the indices were extracted. Land surface characteristics, i. e., morphometric, hydrologic, and climatic properties, etc., and land features including watersheds, stream networks, landforms, etc. were extracted using digital models of ground surface (DEM) and parameterization software. Subsequently, using Dempster-Shafer probabilistic models and the morphometric indices, we have prepared zonation map of landslide susceptibility for Fahlian River watershed. Finally, using receiver operating characteristics (ROC), both models were validated. Results and discussion Based on the weights related to the role of each unit of factor layers and their order of priority and importance in the occurrence of landslide, factor maps have been combined to produce landslide distribution maps. The weights of each level have been calculated based on the relationships related to the Dempster-Shafer model in GIS environment. For example, in this study the slope > 40% in weight and imposes the largest contributions into the occurrence of landslide across the watershed. At lower slopes, other forces such as the friction between soil particles and other hillside material are usually dominant over driving forces such as gravity. In contrast, on highly sloping hillsides, due to the dominance of shear stress over resisting force, one may end up with increased probability of the occurrence of a landslide. Moreover, based on the obtained results, with a belief weight of 0. 77, TRI > 14 was the second most effective factor on the occurrence of landslides across the studied watershed. Other contributions are as following: Stream Power Index < 1. 2, precipitation < 750 mm/year, TPI <-4. 2, profile curvature of 0. 3 – 4. 2, TWI of-1. 5 to 2. 5, surface curvature of-5 to-2. 99, distance to fault from 0 to 500. The Pabdeh – Gurpi have belief function values of 0. 68, 0. 63, 0. 60, 0. 57, 0. 49, 0. 49, 0. 47, 0. 46, 0. 38, and 0. 37, in order. . According to the evidence of weight model, the class of TRI >14 (final weight: 2939. 32) was found to be the most effective factor on the occurrence of landslide across the region. Following a similar trend of reasoning, the class of slopes higher than 40% (final weight: 2611. 21) was the second most important factor, which are in agreement with the results of Javadi et al. (2014) and Teymoori-Yanseri et al. (2017). Moreover, in their research, Pourghasemi et al. (2011) referred to the slope as the second most important factor contributing to the occurrence of landslide. In this model, NVDI > 0. 6 (final weight: 400. 60) is identified as the third most important factor. Following the land use, Stream Power Index > 1. 2, TPI <-4. 2, TRI of 7 – 14, profile curvature of 0. 1 – 0. 3, NVDI of 04 – 0. 6, precipitation > 750 mm. The Pabdeh-Gurpi Formation imposed the largest impacts. The impacts are sorted in the order of effectiveness, from final weights of 2037. 60, 1925. 99, 1803. 48, 1793. 34, 1722. 40, 1494. 60, and 1340. 28. Conclusion Final results of the present research have indicated that, in both of the models, slopes higher than 40% and TRI > 14 exhibited the highest weights and played the most significant roles in the occurrence of landslide across the region. Moreover, based on the obtained results, 82. 59% of the landslides across the watershed in an area of 547. 82 hectare had occurred in pastures. Based on the results of Dempster-Shafer model, very low, low, intermediate, high, and very high susceptibility classes covered 23. 85% (961. 34 km2), 31. 82% (1282. 49 km2), 21. 72% (875. 63 km2), 16. 41% (661. 45 km2), and 6. 20% (249. 97 km2) of the entire region, respectively. Moreover, the results obtained from the evidence of weight model shows that zones of very low, low, intermediate, high, and very high susceptibility have areas of 25. 29% (1019. 59 km2), 30. 98% (1248. 82 km2), 21. 28% (857. 64 km2), 15. 68% (631. 93 km2), and 6. 77% (272. 90 km2) on the entire susceptibility zonation map, respectively. Results of evaluating the models using ROC documented that the Dempster-Shafer model provides higher prediction accuracy (0. 79) than the evidence of weight model (0. 76). Given quantitative results of validation, the combination of Dempster-Shafer model with morphometric indices is herein introduced as an appropriate model for landslide susceptibility zonation.

Introduction Land use and climate change and its impacts on water resources and hydrological regime have always been the most important problems in recent decades in Iran. These environmental risks will have direct and indirect impacts on health, economy and society by accelerating the hydrological cycle, drought and flood. Some researchers have examined the impacts of climate and land use change on extreme rainfall, runoff and flood events. Water resources have been investigated in different basins using hydrological models and GIS in arid and semi-arid regions via different scenarios and strategies. They have identified a serious increasing trend of extreme rainfall and drought intensity and duration due to land use change and climate change. Western Iran has experienced an agriculture growth and land use change that can alter evaporation patterns and affect the more frequent occurrence of drought and flood extremes largely due to climate change in this mountainous region. Definitely, there is an increasingly notable challenge in management of water resources, prediction of future changes in land use and climate variabilities, and human activities. In a watershed, climate change and human activities both contribute to the hydrological cycle, and this result has been supported by many researches. In this study, climate change scenarios and land use change models are coupled with a hydrological model to study impacts of these changes on runoff in a mountain catchment in western Iran....

Introduction Skiing is one of the branches of sport tourism in winter sports sector. This kind of tourism today has become a special trend in the mountainous regions of developed countries and is known as the "white gold", which has a great contribution to the economy of the local communities of these countries. From a global point of view, ski tourism has become an industry, but the industry is now threatened by changes in climate change. The results of general atmospheric circulation models indicate a rise in temperature and a decrease in summer rainfall in Europe. As global warming continues, some of the tourist destinations of skiing will be faced with the risk of decreasing in amount of snow and consequently loss of visitor numbers. Therefore, in such a situation, planning should be aimed at selecting the most suitable places for the construction of ski resorts with the least problem in terms of snowfall and other required parameters and the choice is made in principle and accurately. One of the problems that ski tourism in Iran faces is the installation of ski facilities and ski resorts in unsuitable places. Sit is important to specify proper location for construction of sports places and facilities for optimal and efficient exploitation in the present and future. Ignoring this issue in many cases leads to a lack of proper use of those places as well as spending too many to build them. One of the useful solutions in selecting and determining suitable sites for the construction of winter sports facilities and ski resorts is application of GIS to select the best cases. Therefore, in this study, the ArcGIS software is used to locate proper areas for construction of ski resorts. Materials and methods This is an applied research using a researcher-made questionnaire as research tool. The reliability of the tool was confirmed by calculating the incompatibility rate. The sample population of the study is 20 experts from the physical education and cultural heritage organizations of Chaharmahal and Bakhtiari province who respond to the questionnaire and have performed paired comparisons. In this research, the identification of suitable areas for the construction of a ski resort was carried out by weighting the criteria using the network analysis process and Super decision software. The network analysis process considers each issue and problem as a network of criteria, sub-criteria, and options. All elements in a network can, in any case, be linked together. In other words, in a network, feedback and interconnection between clusters are possible. Mapping is done by the ArcGIS software. In this regard, the most important measures affecting the location of the ski resort were studied. The combination of these standards with the experimental knowledge of experts in the field of sports helps to identify the proper locations for skiing. Results and discussion Sports tourism in our country is not well-developed and there is no systematic program for sport tourism marketing. Despite the huge costs of the physical education organization, the National Olympic Committee, federations and other relevant institutions for conducting national and international sporting events, the great benefits of tourism development cannot be obtained and there is always a loss of opportunities in this area. Assessing the environmental capability and determining the potential power and allocating appropriate funds to that can provide a logical and sustainable adaptation between the natural power of the environment, the needs of communities and human activities in space. In this way, while protecting biodiversity, we can be benefited from sustainable productivity of the land. Optimal locating attempts to help decision-makers and planners for regulating indicators and factors influencing decision making and finding logical solutions to choose appropriate places to carry out activities. In the site selection, it is necessary to see various parameters in relation to each other. In the present study, in order to identify suitable areas for the construction of a ski resort using the history of the research, interviews have been made with the experts. Three main criteria and eight sub-criteria have been obtained. It should be noted that due to the lack of snowflake network density in the country, the number of snow and frost days and the amount of precipitation have been used. After obtaining criteria and sub-criteria, the indices were weighed using ANP technique and by combining the results with the layers generated in ArcGIS software. The final map of the suitable areas for skiing in Chaharmahal and Bakhtiari province was produced. Conclusion After compiling the indices, the final score of each element was calculated using the ANP technique. In the next step, the layer has been combined considering the weights obtained in the layers. After obtaining the indices, the final score of each element was calculated using the ANP technique. In the next step, the required maps were drawn and, by combining the weights obtained in the layers, the suitable areas for the construction of the ski resort were located. According to the findings, about 4. 93 percent of the province has the necessary conditions for the construction of a ski resort with an area of 802. 77 square kilometers. The main part of the area is located in Koohrang city, the current most famous resort of Chahar Mahal and Bakhtiari province. Chelgaird is also located in this area. The specified level is considered appropriate in terms of technical conditions, which are considered as necessary indicators. If the research findings are combined with empirical knowledge of experts, the best places in the province for the construction of ski resorts will be located.

Introduction The background of spatial sustainable land planning is based on the proper position and establishment of the land use activities and their interaction. The suitability should be rooted in three main elements of sustainable development including economic, social, and environmental aspects. To the best of our knowledge, over the past 20 years, significant developments have been invented in the field of artificial intelligence techniques and the tools that can be used to solve many practical geographic problems. The present research aims to introduce a new and effective searching method in order to solve complex, multiple, and non-obvious problems existing in the evolution of land suitability using optimization algorithms....