فصلنامه مطالعات جغرافیایی مناطق خشک
پیاپی 19 (بهار 1394)

Iran is located in the desert and sandy location because the large sections of this country is on arid and semi arid belt of the world. Due to the dust and Haze in these areas is a major problem that has plagued the residents and bystanders and so lives of them is disrupted every so often. Airflow of the monsoon winds, which caused a mass of clay and silt as so as spread dust and smoke in the atmosphere, it does limit sometime visibility between 1 and 2 km in the horizontal. In addition to the environmental problems of this phenomenon, it has many hazards for heart disease - cardiovascular and respiratory and so be detrimental to the children. In this regard, the subject soil stabilization using polymer as a way to reduce the production of dust is defined for prone area. In this paper, the effect of polymer acrylic on a mass of fine-grained soil has been studied. The soil has been simulated for different sizes of fine grains. Samples in this study were uncompacted particles of soil with different amount of water-solvated polymer (0, 5, 10, 15,20,25,30 grams per meter squared) poured over them. These samples are kept in experimental environment for 7 days. After ensuring complete dryness, their stabilities are tested against wind flow with 72 km/h speed. Results show that adding more polymers to soil would considerably increase its particles’ stabilities. This stability is due to positive reaction of polymer with soil particles. The effect of this stability is maintained during sample drying time in the lab and the soil maintains its characteristics during testing. The best results are obtained for 4% polymer, where caused increase in stability to about 15 times that of the soil without polymer

Because the geographical space is the fundamental content of the geography science, the discussion of nature of it and this question that what is the “geographical” meaning of “space”? Are always essential issues in the geography science? This article tries to prepare a context to debate of the nature of "geographical space" and it tries to answer to this question that what is the "geographical space"? This article does these via the debating of the philosophical kind of spatial thoughts and via a critical view to them. Research The method of this article is a philosophical - logical method tries to make a systematic set of reasons by making logical relations between philosophical concepts and geographical concepts. In final, it shows geographical space is same Heideggerian “being-in-the-world”. Discussion and The philosophical view to geographical space tell us geographical space is made from two parts: objects (un- Dasein) like trees, mountains, rivers, building, streets, land use, … and subjects (Dasien) like citizens, managers, planners, …. So geographical space is a complex network it is made from complex network of objects (un- Dasein layer) and from complex network of subjects (Dasein layer). “bing – in- the- “world” means being-in-the-“world”. The meaning of the Heideggerian “world” is “compelx network of understandings” (malayeri, 2011, 220), what kind of understandings? The understanding of two layers of geographical space (Dasein(s) and unDasien(s) layer). So the meaning of “bing - in- the - world” is “bing - Dasien(s)-in-the compelx network of understandings of other Dasien(s) and un-Dasien(s). Geographical space is also the understandings of Dasiens (humans) of things exist around them (un-Dasien(s) like mountain, treet,... and Dasien(s)- like all of humans). So the geographical space is“bing – in- the- “world”. only the geographical spaces is kind of space that involves the complex network of understandings subjects and objects together because only the geographical spaces is kind of space that involves subjects and objects together. Each other space do not involve all of them. for example: social space do not involve mountains, trees, physical space do not involve social relations and … but geographical space involves all of things that Dasien(s) live with them and understand them. So only the geographical spaces is “being-in-the-world”. With looking to ‘space’ from Heideggerian perspective of “being-in-the-world”, we can name another spatial thought that is called “world-life” spatial thought, this is most geographical of the kind of spatial thought. so the answer this question: “what is the geographical space?” is ‘being – in-the-world’ or the ‘geographical space’ as ‘being – in-the-world’.the concept of “being-inthe-world” is the concept of “geographical space” because “geographical space” involves subjects (Dasiens that understands things(other Dasiens and un-Dasiens))and objects(un-Dasien that is understood by Dasien) together.

Understanding the environmental factors is considered as an applied study aiming to shed light on edaphic and ecological factors influencing the very labor ever and their management. In the hills and sandy desert land with soil conditions grow special plants. In the current research the relationship between the physicochemical properties of the soils and growth characteristics of the S. pennant. In the current research the relationship between the physicochemical properties of the soils and growth characteristics of the S. pennanta including density, canopy cover, height and cordage protean have been studied in the lands of the Sabzevar plain about 75 km southwest of the Sabzevar city.The climate of the study area is cold dry. Research A random systematic design has been applied in 4 sites called A, B, C, and D within a distincthabitat of S. pennanta. Soil samples have been taken from 2 depths (0 - 30 cm) and 30-60 and prop Hon of clay, silt and sand content, amount of N, P, K, C, Na, Ca, Mg,; in addition and PH have been determined in a soil lab. The soil physico–chemical and plant growth data have been analyzed through statistical methods using the SPSS software and Excel worksheet. Discussion and Vegetation consists type Salsola - Astragalus - Stipagrostis.The most important ecological factor for the growth and distribution of Sand plain desert region as a dominant species and communities of habitat, species Soil compatibility with sandy hair root sheath and the development of the root system in wide area network. The results indicated that the soil texture of the study area is predominantly sandy (more them 91%); it is concluded that for establishment of Spinet the soil of area should have at least 90% sand. However the sand amount of more than 90% dose of sand does not have signifying inflounce on the S. pennanta growth characteristics. Further finding of this study show that the growth characteristics of S. pennanta such as density, canopy cover, height and forage production rarely depend on soil chemical properties while they are mainly influenced by ecological factors. However, it should be mentioned that there is a statistically significant positive correlation between the canopy cover and amount of Ca. This has been shown by higher canopy cover in site B which has higher Ca. The results show that there is a direct relationship between the amount of nitrogen and Calsiom and canopy. This has been shown by higher canopy cover in site B which has higher Ca. The result showed that the S. pennanta height in all sites is nearly similar. The lower density of S. pennanta in sites C and D in comparison with sites A and B is mainly due to ecological factors such as existence of more accompanying species, hence more competition among species in sites C and D. In the presence of nitrogen and plant litter and nutrients that nitrogen source, the impact on plant growth and production. Research has shown that the macro elements and especially the nitrogen of the soil on plant growth is desert. Tangway (2004: 111) with degraded pastures Australian study using analysis of variance were the factors of soil organic carbon and nitrogen has the greatest impact on plant communities. According to the survey results, the comparison of habitat cow tail and a control area without cow's tail by Azarnivand and colleagues.This desirable species should be used to stabilize sand dunes and arid flowing from the pastures in the wilderness and desert, with some nitrogen and pH-neutral to slightly alkaline calcium are introduced.

Various plannings in agriculture, hydrology, architecture and energy largely depend on the correct estimation of the amount of solar radiation. To estimate the solar radiation, most of the previous studies have used Angstrom model, having the values of sunshine hours as it's input, or regression equations through considering the climatic factors and elements affecting the radiation. In this study, optimized "Bird and Hulstrom" model is used to estimate incoming solar radiation in Kermanshah Province by using the daily data from synoptic weather stations of the province between the years 1990- 2009. For this purpose, all parameters involved in radiation, including length of day, humidity, air mass, air pressure, precipitable water, sky albedo, atmospheric absorption and absorption by ozone were used and the resulting spatial-temporal variations of radiation were analyzed. The results showed that there is little difference between the radiation values measured by pyranometer and values estimated by the model. This indicates the ability of the model to estimate radiation. The least amount of incoming solar radiation in the region occurs in January and December, which varies from 9 to 13 MJ/m2/day in different locations of the province. The amount of radiation absorbed by ozone is reduced in the summer due to the reduction of air mass, especially in the highlands; while the amount of direct radiation and thereby total radiation is increased in this season. The highest amount of incoming solar radiation in the region occurs in June, which varies from 32 to 42 MJ/m2/day in different locations. In autumn and winter, radiation differences in the region are reduced because of the role of diffuse radiation.