فصلنامه جغرافیای طبیعی
پیاپی 49 (پاییز 1399)

The aim of this study was to investigate temperature series trend in the southern coasts of Iran and its relationship with telecconections patterns. In this regard, the minimum and maximum monthly temperature statistics of the Persian Gulf coastal stations during the period 2019-1988 and the statistics of telecconections patterns during the same period were used. Homogeneity and commercialization of data were assessed using Chi-square and Anderson Darling tests and their trend was assessed by t-test and I-Kendall tests. Then, their correlation with remote linking patterns was determined by Pearson correlation test and multivariate regression. The results showed that except for the minimum temperature of Abu Musa and the maximum temperature of Bushehr, which were without trend in most months, there was an increasing trend in other months and stations. The maximum temperature in March and the minimum temperature in July have increased in all stations. In general, the minimum temperature shows a higher upward trend than the maximum temperature. The results of the relationship between tleconnection patterns and temperature series indicate a direct and significant correlation at both 95 and 99% levels and the high impact of WHWP and AMO patterns on the studied temperature series. In other words, the patterns located in the North Atlantic and the tropics have the greatest effect on the minimum and maximum temperatures of the southern coasts of Iran.

The purpose of this study was to estimate the level of deforestation in Astara county over a 24 year period and to prioritize the effective factors on deforestation in the area. For this purpose, the forest cover map of the study area for the years 1987 and 2011 was prepared and compared using Landsat 8 satellite TM images. In this study, 100 training samples for two classes of forest and non-forest were used and the images were classified according to the maximum probability method. The physiographic factors map of slope, direction, elevation and human factors of distance from road and distance from residential areas were also obtained using digital elevation model (DEM) and related objects map. Existing maps were matched and zoning map of destruction risk of the area prepared in GIS environment and finally correlation between levels of destruction and factors affecting the destruction were taken. The results showed that the forest area of the study area decreased over the 5744 hectares during 24 years. Distance from residential areas and distance from the roads were had the most correlation with the level of destruction. The direction and altitude factors had no significant relationship with degradation but slope had a moderate effect on degradation. As a result, human factors were identified as the main causes of deforestation in the region. Therefore, the restoration and protection of forests in the region should be prioritized through the control of human-made areas.

This study aimed to evaluate the potential effects of climate change on the phenological statges and yield of grape. First, the daily values of temperature (minimum, maximum) and precipitation based on HADCM3 model in the past and future periods based on the scenarios of RCP8.5, RCP4.5 for the future period of (2020-2050) has been downscaled using change factor method. Then, phenological stages and yield were analyzed using MATLAB2019 software using the observation data and downscaled output of the model based on the dynamic neural network.. Climate model output shows increasing of temperatures and decreasing of rainfall in the future periods when comparing to the baseline.The maximum RCP4.5 and RCP8.5 temperatures were increased by 2.7 and 3.2 °C, respectively, and at least RCP4.5, RCP8.5 increased by 1.8 and 2.9 °C, respectively. Results also showed that mean annual precipitation over the Golmakan station will be decreased by 34 and 49 percent under RCP4.5 and RCP8.5 scenarios. The phenological stages including bud flowering stage to fruit ripening under both scenarios will be completed at earlier time it is 15 days in RCP4.5 and 24 days in RCP8.5 in advance. Results showed that, grape yield under RCP4.5 and RCP8.5 will be decreased by 2.04 to 2.7 under RCP4.5 and 2.3 to 3 under RCP8.5 T/HK (as an average 0.54 to 0.86 T/HK). Results show that changing the date of growth period will change in all stages of phenology and reduce yield in the future.

Abstract In this research, the seasonal behavior of polar jet streem has been identified based on the cold season (autumn and winter) on Iran. General analysis of jet streem process based on what is mentioned in the methods section was done in order to find the behavior patterns of jet streem in GRADS software environment . The results of the analysis indicate the existence of two main medium nuclei, one above Europe and a wider nucleus over North Africa and Saudi Arabia. The prevalence of nuclei in Europe has been higher than in North Africa. In autumn, the incidence of North African nuclei was about 30% lower than in Europe, and in winter the frequency of both nuclei was similar. The core of the polar jet streem in the two seasons, is located approximately 35 degrees north latitude. According to the information obtained from the average speed maps in autumn and winter, it seems that the speed change has been more than before.

The purpose of constructing surface water collection networks is to provide the possibility of securing the city against unforeseen events (cessation) and improving urban health, etc. During the recent rains in Mahshahr port, most of the roads and streets were severely flooded due to the lack of canals and even streams. The purpose of this study is to manage and repel runoff using geographic information system in Mahshahr port. For this purpose, using the geographic information system, first the digital layers of the region including height, slope, slope direction and drainage network of the city were prepared. Then, using fuzzy logic method, spaces with runoff potential in the area were identified. The research findings indicate that the focus of these spaces is in the east, center and northeast and southeast of the region. Then, using the RiverTools technique and according to the map of the city's drainage network, the best routes were prepared for the construction of the proposed canals. These channels include sub-channels, main secondary channels and main secondary channels.

One of the methods of studying drought and its destructive effects is drought monitoring and zoning using meteorological indicators and remote sensing techniques. In order to determine the effect of droughts on vegetation changes, drought intensities were determined using annual SPI drought indices by rainfall data of meteorological stations. In this research, SPI drought index was investigated in short and one-month periods and the annual period for three stations which according to the results of the calculation of meteorological drought indicators in general in all stations in The 2001, 2003, 2005, 2007, and 2013 droughts have occurred from weak to severe, and also occurred in 2009 and 2014 in the region of Tarsal. Initially, the standard rainfall index (SPI) was calculated for three meteorological stations in Shiraz, Eghlid and Dorogozan during the years 2015 to 2001, and then, based on images taken from MODIS in October, August, September, the normalized vegetation difference index ( NDVI) and then the correlation between meteorological indices and vegetation was taken during the statistical period for dry and wet years. Accurately, the NDVI's statistical results have the highest correlation with drought and climatic variation with the Drooden Station, .

This study aims to investigate the spatial variation of extreme temperature events in Iran. The data used include daily minimum and maximum temperature of 77 Iranian synoptic stations for the period 1985–2017. To calculate the extreme temperature indices, 16 indices recommended by the CCL/CLIVAR Group were used. The indices were calculated by the RclimDex package of R software. The hot and cold indices showed that, in general, the frequency of occurrence and spatial variation of temperature in Iran depends on the geographical location, topography, and environmental conditions of different parts of Iran. Because, except for the northern coasts, in high altitudes and high latitudes, the abundance of cold indices exceeds the maximum and the extreme warm indices have the lowest values, and in lower altitudes and low latitudes the warm indices of the maximum event and the extreme indices Colds have minimal occurrence. Also, the results of this study showed that from 1985 to 2017, the high-temperature indices have a higher frequency and spatial variability than the cold-indices. Also, the warm extreme indexes are more elongated, which is why the frequency of occurrence of WSDI in Iran reaches up to 10 periods, while the frequency of the CSDI index reaches up to six periods. The results indicate that the temperature of Iran is warmer and increasing thermal events may continue in the future.

The first and most important step in assessing the risk of sloping movements is to prepare risk maps for the occurrence of sloping movements. These maps are a final product that can be useful for land use planning. The purpose of this study is to prioritize the factors affecting the occurrence of slope movements and zoning the risk of its occurrence using a new random forest algorithm in the topographic map of 1: 50,000 Lashkark in the northern part of Latian Dam. According to the hydrological, topographic, geological, geomorphological and climatic characteristics of the region, the most important factors influencing the occurrence of slope movements are 9 indices of distance from road, fault, river, lithology, rainfall, altitude, slope, slope direction and land use as the most important. Factors affecting the occurrence of this type of movement in the region were considered. The results show that the three factors of distance from the fault, road and slope are three important factors in the occurrence of amplitude movements in the study area, respectively. In order to evaluate the prepared model, the relative performance detection curve was used. Based on the results of the rock curve, the value of the area under the curve in educational points is equal to 0.826 and in evaluation points is equal to 0.839 percent. Figure 9 is a very good evaluation of the stochastic forest algorithm in zoning the risk of slope movements using this model.