نشریه کاوش های جغرافیایی مناطق بیابانی
سال سوم شماره 2 (پاییز و زمستان 1394)

In many parts of the world, wind has a main and powerful role in displacing soil particles and eroding the earth surface. Khuzestan province is among the regions in Iran where the wind is a powerful factor of soil erosion and transportation. In the current study, in order to evaluate the erodibility and transportation of soil by wind in Khoozestan province under dry conditions, the data were obtained from 58 stations during the period 1987-2010. Due to the effects of humidity and precipitation on soil erosion, wind thresholds were used for erosion of different particles, e.g. silt, clay, and sand, during non-rainy days. The findings, illustrated in maps, indicate that most of the wind erodibility has happened in the southern, southwestern, and western parts of the province where the wind speed is high, its variability is low, and precipitation is low.

Soil salinization is one of the problems in arid and semi-arid areas, and its control requires the adoption of proper management. Using up-to-date soil data and remote sensing technologies is a good way to evaluate soil salinity in different regions. In this research, with the aim of evaluating soil salinity in Chah-Afzal area of Yazd, a comprehensive map of different salinity levels was proposed by combining remote sensing and statistical methods. For this purpose, at first, 50 soil samples from the study area were taken randomly, and their electrical conductivity was measured. Then, Landsat 7 satellite images were prepared at the same time as the field harvest date in August 2007. The pre-processing steps were performed for visualization using salinity indicators. From the 14 variables, six different soil salinity indices and eight satellite image bands were used to obtain the best equation for soil salinity. In order to reduce the number of variables in providing the best salinity estimation equation, factor analysis and backward regression analysis were done, and three equations were introduced to indicate soil salinity. On the basis of the results obtained from the soil salinity maps and the verification of the maps, NDSI salinity indices with the highest correlation coefficient of 0.6 could serve as the best soil salinity model. The study area was classified into five soil salinity classes, which showed that about 90% of the area had a salinity of more than 50 dSm-1. According to the results, preparation of soil salinity maps by combining remote sensing techniques and statistical methods save time and costs and increases the accuracy and speed of studies.

This study aims to assess the results of settlement projects in arid and semi-arid areas of Ferdows city. The main hypothesis of the study was that new residential districts would bring more satisfaction to residents and have better conditions as compared to old neighborhoods. The study was conducted with a descriptive-analytical methods. The required data were collected using library research, field surveys, and a questionnaire. The data collection tool was confirmed before use, based on experts’ opinions and tests of validity and reliability. The data were then analyzed using the SPSS software. The findings show that new residential areas have not been able to provide higher life satisfaction than in older neighborhoods. Indeed, the overall satisfaction with residential neighborhoods was not at a high level; only 48 percent of the respondents were satisfied with life in their neighborhood. In the case of the quality of buildings, there was a satisfaction of 49 percent. It seems that, among the affecting factors, disregarding the climatic and environmental conditions plays an important role in creating dissatisfaction. For this reason, it is recommended that, in future projects, these factors be taken into account more emphatically.

Dust storms are one of the common phenomena in arid and semi-arid areas of the world. With regard to the heavy impacts of these storms on socio-economic issues, human health and environment preservation have turned into universal concerns. Dust storms mainly stem from powerful turbulent winds and air fronts or desert surface erosion. Through a storm, huge amounts of dust rise from the soft and fine surface of deserts, and visibility falls below 1000 meters. Due to the prevalence and the high frequency of dust storms in Khuzestan province and other eastern areas of Iran, the present study aims at the synoptic analysis of the pressure and humidity patterns in those places during dusty days with a visibility of less than a kilometer in an 11-year statistical period from 2000 to 2010 as well as an experimental seasonal (hot and cold) period. The corresponding data were provided from the meteorological office of Khuzestan. They included information about horizontal visibility, relative humidity, precipitation, and wind speed and direction. Also, satellite images were used to determine the source and the direction of dust on the day when the phenomenon culminated. To identify the sustainable and non-sustainable atmospheric patterns, unsustainability indices were analyzed according to skew T graphs. Analysis of the maps indicated high-altitude patterns of the mid layers of the atmosphere, a Mediterranean ridge stretching to the east, an increase in the western high-pressure gradient along with a reduction in humidity, and an increase in the high-speed nuclei. This played a role to intensify the reduction of horizontal visibility in the first period. In the second period, dust pressure patterns, eastern African ridge, and anti-cyclonic circulatio led to a stable atmosphere. In the third step of the study, the pressure declined at certain times during the day, and some stations recorded precipitation. It was attributed to a relative in the southwest of Iran. Satellite images showed the direction of the dust moving from the southern Iraq and northern and central Arabia.

Wind erosion and influx of quicksand into infrastructures, settlements, communication ways and industrial and agricultural installations is considered as one of the most important environmental issues in some parts of Iran, especially in the northeastern part of Toroud. Therefore, proposing a management approach for quicksand stabilization is necessary. In this research, a composite method of AHP-TOPSIS is proposed to select the best sand arrow species for quicksand stabilization. The research is of a descriptive-analytical type. The studied area was investigated by the satellite images of Google Earth, and its limitations were determined. Then, descriptive and analytical methods were used to study sand arrows. In addition, the morphometrical characteristics of the selected sand arrows were measured during the fieldwork. In the next step, the best species was detected using the AHP-TOPSIS method, a hierarchical structure was designed, a questionnaire was prepared, and finally the species were ranked. The results indicated that a composite method is more effective that the TOPSIS method. The results also showed that Zygophyllum eurypterum with the weight of 1 has the best effect on the stabilization of quicksand. Seidlitzia florida, Reaumuria turkestanica and Alhagi ManniferaNebkas with weights of 0/187, 0/080, and 0/028 were less important. The findings of this research will be fruitful in the systemic management of deserts as well as quicksand stabilization projects.

Water, according to the climatic conditions in arid and semi-arid, in most areas of our country, the most vital matter. Humidity is an important factor in a rain Therefore, identification and knowledge of how to transfer moisture, vibration and affecting rainfall is in a critical area. Therefore, in this study re-analyzed data of precipitation ERA interim, geopotantial, not special and components (u,v) the wind in the period 1981-2011 with a spatial resolution of 1 arc in the first grade level climate prediction center of the mid-term Europe (ECMWF) were obtained. Using the Standardized Precipitation Index (ZSI) periods of drought and wet extraction, and moisture flux entering the area during this period were calculated. For comparison, circulation patterns and changes in the flux of moisture in dry and wet samples were taken. This variability makes changes in a rain storm and the subsequent occurrence of drought and wet years in the region. The amount of moisture flux and the total thickness of all layers of the atmosphere in the wet than dry years, respectively.

In many parts of the world, wind has a main and powerful role in displacing soil particles and eroding the earth surface. Khuzestan province is among the regions in Iran where the wind is a powerful factor of soil erosion and transportation. In the current study, in order to evaluate the erodibility and transportation of soil by wind in Khoozestan province under dry conditions, the data were obtained from 58 stations during the period 1987-2010. Due to the effects of humidity and precipitation on soil erosion, wind thresholds were used for erosion of different particles, e.g. silt, clay, and sand, during non-rainy days. The findings, illustrated in maps, indicate that most of the wind erodibility has happened in the southern, southwestern, and western parts of the province where the wind speed is high, its variability is low, and precipitation is low.

Occurrence of frosts can cause a lot of damages to economic, cultural, and political sectors. In order to avoid financial losses, it is necessary to identify the characteristics of this phenomenon. This research aims at the synoptic patterns at the level of 500 hPa and the sea level in a freezing period of 30 years. To determine the synoptic patterns of the frosts days, the days with a temperature of 0 degrees centigrade or below zero reported from at least five stations were selected. Then, the geopotential data of the 500hpa level and the data of the sea level pressure were extracted at 10°-100°E and 20°-80°N in a matrix of 312 by 925 based on the widespread frost days from NCEP/NCAR daily data. In the following, the frost phenomenon was analyzed by the synoptic method. In this regard, Principle Components Analysis (PCA) and Clustering analysis (CA) with Euclidian distance and Ward linkage were used too. The results showed that a high-level system building up in the north of the Caspian sea and the east north of Europe (polar vortex) in the original pattern of 500hpa causes cold air with anticyclonic circulation from the east and brings about frosts. Also, the influence of a low-height front from the Caspian Sea with a northern Siberian focus leads to cold air with cyclonic circulation from the west of the region.

In this study, meteorological data and remote sensing were used to investigate the effect of drought on vegetation in Semnan province. At first, the Standard Precipitation Index (SPI) for the years 2006-2015 was calculated at Semnan station. In the next step, based on 30 Aqua MODIS images from the platform in April, May and June, the normalized difference vegetation index (NDVI) was calculated. Considering this index, the vegetation was classified into four groups including lack of vegetation, thin vegetation, semi-dense vegetation, and dense vegetation. Then, the area of each class was calculated. Finally, the NDVI and SPI indices were compared. The results of the study showed a reverse relationship between NDVI and SPI on one hand and the rainfall in the thin and semi-dense vegetation on the other hand. During all the three spring months, with an increase in the amount of rainfall and the SPI value, the vegetation on the thin floor grew to be semi-dense. Conversely, as SPI and precipitation reduced, the area of semi-dense vegetation reduced and turned into thin vegetation. This is what usually occurs in the case of droughts. With regard to the considerable size of these two vegetation areas, which account for 93 percent of the whole province area, droughts can cause irreparable damages. As it was found, the desertification process invariably turns semi-dense vegetation into poor vegetation. If this process is not stopped, desertification will go on in the region.

Coastal tourism has been rapidly growing in recent decades and is, thus, known as the fastest part of the tourism industry. Beach areas, as one of the aspects of ecotourism, have gained great achievements in attracting tourists and are now popular natural tourist resorts. Kaftar lake in Eghlid is one of the beautiful beach tourist attractions that attracts many tourists annually, especially on holidays. It is considered as a potential region for developing beach tourism, but, unfortunately, there are no facilities and services required by tourists. Buildings and other requirements should be placed at a special spot in a tourist complex with maximum efficiency. Since a lot of standards and indexes need to be analyzed to set up a tourist complex, this research aims at choosing the best location for this purpose by using Boolean logic and AHP technique. After using Boolean logic in a GIS environment, three places of Kaftar lake were examined as potential regions where to establish a tourist complex with such standards as domination of the ground, availability of the beach, flatness of the ground, reasonable construction costs, enough sunshine for sunbathing, and acceptability and originality of the ground. Finally, the best place was decided to be on the northern side of the lake.