فصلنامه جغرافیای طبیعی
پیاپی 7 (بهار 1389)

Alluvial fans is one of piedmont landforms in arid and semiarid region. This features are sensitive to occurrence of earthquake as a geomorphic hazards. Study area is situated between 38° 09′ to 38° 15′ parallels and 45° 34′ to 45° 50′ meridians. The necessity of planning in alluvial fans areas, is clear with due regard to importance of settlements(13) and agriculture activities. For several reason, especially nearby to faults, soft layers, alluvial fans of this region exposed to earthquake hazards. Shaking activity was studied with historical and installation data. In attention to occurrence of several earthquakes in the past and probability happening the shaking power of area faults is calculated with different methods include Zareh, Ashjaei and Norozie. Results of research shows study area and around region faults has shaking power more than 6 Rishter and also shaking power is related to length of fault.

There are about 200 salt doms in the south of Zagros mountain and Persian Gulf. In some areas of these salty doms, there are karsty sinkholes which cause special features in natural structures and morphology and influence the quality of surface water and ground water .The aim of this research is to study the morphology of Jahani salt mountain with he use of lab methods and field observation, aerial pictures, safelights images topography and making go logical map with the scale 1:50000. The sinkholes are the main karst Phenomena's in the salty domes. The distribution of the sinkholes are studied via Arial pictures 1:20000, 1:40000 and field studies. (field researches). The sinkholes have different forms most of which have forms like funnel shaped and bowl shaped or circular with single or several holes They change according to slope, eight, size and number and they are in most areas dispersed. It seems that tectonically forces haven`t had in fluency or have had little influence on their existence. (Faults have caused the existence of tectonically sinkholes. The sinkholes exist around the faults).The mineral and salt water springs inside and around these salt domes are ther karst phenomenas. Main karst forms in the area are rillen Karen, slide, salty openings which exist as the result of tectonically forces and solution, caves, salty thin vallies, solution galleries and solution columns called genie chimney.

Identification of regions having potential for landslide occurrence is one of the basic measures in natural resources management. Different landslide hazard zonation models re proposed based on the environmental condition and goals. In this research landslide azard zonation map using multiple regression model was provided and applicability of this model is investigated in Bagh Dasht watershed. Dependent variable is landslide inventory map and independent variables consist of information layers as Geology, slope, aspect, istance from river, distance from road, distance from fault and land use. For doing this, existing landslides have been identified and an inventory map made. The landslide hazard zonation map is based on the multiple regression provided. The level of similarity potential hazard classes and figures of this model were compared with the landslide inventory map in the SPSS environments. Results of research showed that there is a significant correlation between the potential hazard classes and figures with the area of landslides.The multiple regression model is suitable for application in the Bagh Dasht Watershed.

There is divesting relationship between physical development of cities and geomorphologies consequences. Because of geomorphologies limitations and instability of slope, physical development of cities in mountainous areas is highly Fragile. The scope of these study deaths with Roodbar that is located in Sefidroud edge in Guilan province. This research intends to investigate the limitations of physical development of Roodbar from natural point of view with the emphasis of geomorphology phenomenon. The data using in this research include: Topography maps, geology, land application, sustainable soil, Roodbar map and satellite images with space supervisions. The analysis of this method is based on the existing data and it is descriptive. To analyze data, the researcher transfer the needed maps to software and after providing opography maps, geology, slope, solid, land application, rock resistance, liturgy, and the distance of fault, he tries to provide geomorphology map of this area. The result shows that physical development of Roodbar is under influence of several factors. However, slope, repulsive movement and earthquakes respectively have the major effect on physical development of this city. So the sustainable areas for development are limited. The development of these areas need high cost with the morphological danger.

Drought is a natural hazard temporarily affecting almost every region in the world. The temporary shortage of water poses a great threat on nature, quality of life and economy. This have at sec sectors and mealy more stringency. Wastage unlike usage normal rainfall motive hack accession drought. Medication drought is Impressive in water poses, agronomy and locale economy If the drought author become, decrease sister-in-law's water downfall surface under ground water and reduction quantity water poses, then will down hydrological drought. Soften thither perennial stream have not of this extent, water resources is dependent to under ground water for example Qantas, shafts and in springs who trace vengeful of rainfall commutation. The object this research is scrutiny drought in the central region who (is soften under extents Dasht-e-Loot) and efficacy for this basin water resources. At this research conspicuous grow outbreak drought and that proportion with two indexes: percent of normal and Standardized Precipitation Index) SPI). Then receipt proof with two indexes: downfall surface water tablecloth subterranean, reduction water measure, plurality shattering bottom in shafts extent and reduction plurality fountains water who n fountains water and author became hydrological drought in the study instances precinct. Therefore analyses threshold 48 times rainfall in statistic term and influence division rainfall at sensation drought. Then receipt proof with fore indexes: downfall surface water tablecloth subterranean, reduction water measure, plurality shattering bottom in shafts extent and reduction plurality fountains water who affected drought of year 1986 than 2006 result leaved upon fountains water and author became hydrological drought in the study instances precinct. This droughts author reduction quantity water resource precinct on affect drought result leaved upon measure %48 in Qantas, %30 in shafts and %31 in spry.

Geomorphologic characteristics of the basis of the natural resources of watershed basins Because of the these characteristics is influence by many factors such as climate and Soil, Hydrology, ecology, geology, etc, are the erosion which can create problems. Undoubtedly, the erosion forms to suit the characteristics and features found in the development of geomorphology. In this study, using topographic maps, geology, satellite imagery, aerial photographs and GIS to identify existing drainage problems in the environment in relation to other natural parameters (soil and water resources, physical features and geology and basin) and the effect of these factors on soil erodability in the region is studied. Geomorphology subsequent studies showed that the study area based on profile height, slope and shape protests geological terrain mountain units, respectively (1) foothills (2) a range of plain and alluvial fan (3) are separable from 12 fancies due to different geomorphologic processes were identified among them fancies rock mass covering erosion and soil deposits with detached suitable rangeland vegetation to rocky outcrops about 20 percent of the earth covered mountains in the unit to a regular type domain (5/38 percent of the total watershed area) the highest level to the accounts is among the forms of erosion (erosion surface) significantly in the area there as spots on the soil surface without vegetation or with poor vegetation cover is almost basin at all levels is visible. In addition to natural factors, human factors as well as with poverty and lack of principles Activity Range, vegetation can be effective in spreading such Mind.

Climate is the significant factor in development of tourism section activities. Therefore, the main objective of this study is investigation of climatic condition impacts during the year on tourism and recreational activities in Marvdasht. Hence, the total monthly precipitation and average of temperature, hours of sunshine, wind speed, relative humidity, minimum relative humidity and maximum temperature data of Dorodzan Dam synoptic station for 18 years statistical period (1987-2006) were used as well as the number of tourists who visited Achaemenian historical complex during 10 years statistical period (1997-2007). For analyzing the effect of these parameters on tourism activities, Tourism Climatic Index (TCI) was used. The results revealed that winter months (Jan, Feb, March and December) are not suitable for tourism activities because of the precipitation and low temperatures but spring and fall months (April, May, October and September) have the best conditions for tourism activities in Marvdasht. Also, June, July and August are not desirable for tourists because of high temperatures. According to the results, there is a significant positive correlation between the number of the tourists and average air temperature, hours of sunshine and wind blow parameters, while there is a negative correlation between number of tourists and humidity and precipitation.

The advancement and industrialization of the human societies increased the concentration of greenhouse gases and caused some change in the climate of the globe throughout the last century. The sign of these climate trends exists in the parameters of meteorology in long changes. Thus, the purpose of this research is determination of time trend and scattering the parameters temperature, wind speed, sunshine and vapotranspiration in the whole country. After collecting the statistic and information of 36 synoptic station in record lengths 45 years, the process of time trend of these parameters was calculated by slope line trend meaningful test. The result is that the minimum temperature have positive trend in more than 75 percent of stations in autumn and summer and more than 65 percent in winter and spring, and also the time trend of maximum temperature was climbing in 75% of stations in autumn and falling in 60% of them in the winter. The parameter of dew point temperature have negative trend in 80 percent of stations in the spring, autumn and winter seasons and 60% in summer season. Wind speed has the positive trend in 60% of station in summer, autumn and winter seasons. The parameter of sunshine has the climbing process in nearly whole country, too and reference evapo-transpiration is increasing in 65% of stations in annual and seasonal scale.

Drought is the one of the important problem for the mostly semi-arid countries that Iran as of those. Purpose of this article is studying about locations and temporal drought event patterns in Kashan desert. Height average of case study region from sea level is 1987 meters. Common lands of region include sandy hills and salty lands Meteorological data stations in Abyane, Ardestan, Qum, Kashan, and Natanz and basic information environmental consist of Hypsometry, geology and land ability. Meteorological drought temporal and location patterns are determined by research internal method with precipitation Z score in GIS. The climatic studying of region is based on metrology data of synoptic station during 1964-2004 and with focus on Qum and Kashan stations. Bose of heavy rain ranges atmosphere elements in Kashan region and because of influence of environmental condition, we used Z score. By attention to seasonally precipitation of Z score show that in some years not only climatic situation is knowable, (2002-2000 April) but region environmental condition combines a region between desert to mountain that can be explained by a climatic differences condition in the same temporal situation. Z normal indicator shows spring precipitation with positive indicator and generally in 3 years (1999- 2001) had shown negative condition and unsuitable precipitation that the heavier precipitation situation recorded in spring 2001. However, as we said in 2002, precipitation amount explains wet condition and rest of years showed normal condition till low positive.