نشریه کاوش های جغرافیایی مناطق بیابانی
سال سوم شماره 1 (بهار و تابستان 1394)

Drought prediction, in many regions of the world, is critically important for strategic planning of agriculture and water management. The occurrence of droughts cannot be predicted with certainty and, thus, must be treated as a random variable. It is the main purpose of this paper to develop a new concept of drought and assessment of its features based on triple drought-related hydro-meteorological and meteorological variables, namely rainfall, solar irradiation and sunshine duration. At first, the scatter diagrams of rainfall, solar irradiation and sunshine duration are drawn as prescribed by the Dual Graphic Method (DGM). Then, the monthly drought conditions that are observed are compared together on the basis of the SMP values table. Also, equal standard rainfall lines are drawn as a map with two reference variables including solar irradiation and sunshine duration. These are referred to as the triple graphical method (TGM). It furnishes rich features of drought behavior variation based on the rainfall, solar irradiation and sunshine duration. This analysis and the solar irradiation estimation method are applied to Kermanshah stations in the Republic of Iran based on monthly data obtained within the period of 1970–2005. The linear relationship between drought and the variables of the Angstrom equation is found to be 0.80. Also, in severe drought conditions, the irradiation variables of H/Ho and S/So are found to be varied in the range of 0.66-0.79 and 0.71- 0.86 respectively

This study aims at the change of the land usage around the city of Yazd from 1994 to 2013 and the prediction of these changes until 2020. To this end, multi-temporal Landsat satellite images taken in three years of 1999,2006 and 2013 were studied and analyzed. The corresponding classified images were used to detect and characterize changes from a cross-tab. In order to predict the changes during these years and in future until 2020, two different models including CA-Markov and LCM were used. The results of this study showed that during these intended 14 years, the CA-Markov model could present a land use map with a 70% accuracy, and the final map for 2020 displayed the maximum usage of the land for residential purposes at the rate of 51.11%. On the other side Wasteland may decrease around 29%. The accuracy of the LCM model for the prediction of the land use map was estimated to be around 83%, and the final plan for 2020 exhibited a 68% increase of residential land and a 24.8% decrease of wasteland. However, the results demonstrated a better accuracy for the LCM model as compared to CA-Markov, which is the consequence of the use of independent variables as the input parameters in the LCM model. In general, it can be concluded that both models have almost the same accuracy and they are powerful methods for predicting the development of the city of Yazd in the intended period until 2020. Finally, the physical development of Yazd to the suburbs through the west, west-south and south regions is expected. This expansión tends toward the neighboring towns like Hamidia and Shahedieh.

In tourism studies, sustainable development should be placed at the center of investigation so that no problem would be created in the field of environmental planning through any incorrect operation of attractions. In the city of Shahrood, despite the existence of geomorphosites with tourism potentials of desert and desertification, no systematic research has been done yet on evaluating the geological sites in order to introduce the attractions associated with them. This study aims to evaluate these geomorphosites using geomorphotourist methods of Pereira and phasilus. For this purpose, at first the geological sites are located using aerial photographs and field operations. In the second phase, geological evaluation of the site is conducted by using appropriate evaluation models. The results show that the employed methods are capable of considering many different variables and serve as useful models for assessing geomorphosites. It is also shown that the Toroud desert in both of these methods has earned the highest score. The won 15 points by Pereira and 37.45 points by phasilis, hence the most suitable site for development of tourism. Overall, the results show that the desert areas of this city have strong potential in tourism development. Unfortunately, so far, these places have been ignored by planners and decision-makers. Actually, there are no infrastructures in order to attract tourists to the region.

Housing as a key component of a built environment plays a very important role in the sustainable development of cities. This study aims at the factors affecting the social sustainability in the residential district of historical texture in the city of Kashan. The researchers have sought to measure and evaluate the impact of social sustainability indicators of housing. The study population consists of 45,552 inhabitants from six quarters of the historical texture of the city. Therefore, using the formula sample and a questionnaire, the perspectives of 364 inhabitants in the historical texture of Kashan were collected and analyzed. Using factor analysis, the results showed that two factors, namely "Identity and Belonging" and "recognition and identification with the place" are the most important factors affecting the social sustainability of housing in the context of the historic city of Kashan. Also, the results of a correlation analysis showed that the period of residence in the historical texture can also affect the resident's satisfaction, and this satisfaction, in turn, can have a positive impact on the sense of belonging to a place and on encouraging the residents to usefully participate in the affairs of their historical residence.

Drought has occurred as a natural disaster and an inevitable phenomenon across many parts of the world, especially in arid areas for a long time. To monitor draughts and to determine their extent and indices, meteorological data, such as those obtained from precipitation, can be of use. In the absence of these data, techniques of remote sensing are useful tools in monitoring droughts. The city of Yazd located in the central plateau of Iran is surrounded by deserts, and the deserts have a great impact on the occurrence of severe droughts in the region. The present study is based on the data obtained from 25 synoptic stations in Yazd province within a 20-year period (1990-2010) to determine the weather SPI and the RDI index in long series in 3, 6 and 18 months. For this purpose, satellite images were used in the form of bands of MODIS images from 2000 to 2010 to assess the remote sensing parameters of VCI and LST. After interpolation of the meteorological indices, the correlation between them was investigated. As the results show, the correlation was relatively low. Therefore, to verify the initial results, the calculation of the correlation indicates was repeated using the station points. The final results showed a good correlation so as for SPI and VCI to be found approximately 0.5 to 61.3 % and for RDI and LST to be between 25.7 and 82.1 respectively. Based on the results, distance sensing indices can be appropriate alternatives for meteorological indices in drought studies.

The city of Zabol with a population of 130000 is located in the zone of 120-day wind. There are many rural emigrations, and the city is, thus, faced with many problems including site selection for garbage dumping. In this article, attempt is made to find a place that conforms to standards criteria for gathering and burying garbage in Zabol. For this purpose, the GIS software and the AHP model are used. Analytical hierarchy process is one of the most widely multi-criterion decisions. In the site selection process with the AHP model, after determining hierarchical levels including purposes, criteria, sub-criteria and alternatives, paired comparisons have been made to weigh the sets against one another. The results show that locating a place for garbage dumping and burial in Zabol is not in accordance with the standards criteria.

In heterogeneous spatial distribution of rainfalls and the formation of deserts, geographical conditions and, especially, elevation have an influential role. The Loot desert, as one of the driest areas of the Earth on the global desert belt, is dominated by the subtropical high pressure for some time in a year and is located in the rain shadow of Kerman province mountains. Accordingly, in this study, using station and networked (ERA-Interim/ECMWF) precipitation data and the required data for running the regional climate model (RegCM4.1) from ICTP, attempt is made to detect the effectiveness of heights in formation of the Loot leeward desert. So, in order to detect the effect that mountainous dams on the rainfall of the region, topography was removed from the RegCM4 climate model. Simulation was performed in the original state, and topography was removed for the farming years of 2006-2007. The results showed that the model rainfall estimation is 151 mm, which is close to the observed average of the area. In the removed topography simulation, the precipitation of the eastern and central-western smoothed heights is reduced from 177 to 157 and from 244 to 144 mm respectively. However, in the Loot area, the precipitation shows an increase of more than 100% (i.e. 67 to 148 mm). It is to be noted that, in the absence of the mountainous mass, the spatial distribution of precipitation becomes more uniform and the precipitation significantly increases in the Loot region. Therefore, it can be concluded that the Loot region is inherently a desert resulting from the general circulation of the atmosphere, and the Kerman province mountains have intensified the arid conditions into hyper arid conditions.

The potential of soils for wind erosion is related to such agents as the particle size distribution of the surface texture, surface moisture, and wind velocity. The relationship of dust concentration with surface moisture and particle size distribution of soil is investigated in this research using a portable wind erosion simulator. The measurements were done in 10 moisture-apt and 11 wind-erosion-apt regions. Field studies have shown an increase in the threshold friction velocity and a decrease in the produced dust concentration as well as an increase in the moisture of surface soil (0-3 cm) from zero to 3%. Also, the dust concentration falls to almost zero at the moisture of 2.8%. The soil of region 6 had the minimum and the soil of region 2 had the most increase in the threshold velocity. Also, the soil of region 3 in dry conditions had the most dust produced for 161.26 mg m-3 and the soil of region 2 in the same conditions had the lowest dust emission for 101.23 mg m-3. So, the variation in the decrease rate of dust concentration is different for different soil regions, but dust concentration drastically decreases toward zero in all the regions at the moisture of 2.2%. Threshold friction velocity as well as surface moisture increases when the surface soil contains more particles with sizes of less than 100 microns. Also, soil potential for erosion increases in dry conditions when more particles with sizes of less than 75 microns are available in the soil surface texture.

Desertification is one of the major threats to the lives of all humans. So far, many efforts and inventions have been taken into consideration to deal with the issue, but its negative effects are still increasing. The effects of desertification are now beyond regions which are considered as deserts in terms of climate; rural areas are affected too. Ferdows is one of those cities which, because of being on the verge of the desert, suffers from the completely negative effects of this phenomenon. These effects are to such an extent especially in economic and social dimensions that they have changed the political structure and population of the city incredibly. On this basis, this study aims to deal with the situation by descriptive and analytical methods. The required data are obtained through empirical evidence and surveys of experts in this field. The number of samples is selective and determined by using the available sampling method (census) consisting of 50 experts. The collected data are analyzed by SPSS software, regression models, etc. The results indicate that the desertification phenomenon has a significant impact on the economic and socio-cultural development and this, in turn, affects other related aspects.

This study was done in Abarkuh plain where the disasters of land subsidence and land slide have been reported in some sites. The current study is limited to the land slide on a farm near Abarkuh. After taking an inventory of morphological properties, soil sampling from land subsidence locations was done. Routine physical and chemical analyses of the soils and depositions were also done. Advanced analyses such as spectrometry, x-ray fluorescence and x-ray diffraction were conducted on the clay fractions and the soil. One of the new concepts of this research was the dolomitic bed rock that has been confirmed after chemical and x-ray diffraction analyses to rarely form karst in arid climates. Therefore, karst cannot be a serious agent for land slide in these areas. The second new concept in this research was that interlayer random mixed minerals of illite and smectite can be intensifier agents for land depression and slide. Also, ground water table fluctuation together with downward level of groundwater can be the third factor for land sliding. As a suggestion, adding calcium compounds to soil can decrease the activity of clay to increase soil stability against soil divergence. More detailed stratigraphy in this area for surveying hazard maps of land subsidence leads to more logical land management and ground water utility.