Physical Geography Research
Year:2009 | Volume:- | Issue:67|Papers Count:10

The highest temperatures of the world are recorded in dry and warm climates. This can especially be observed in deserts, where vegetations and soil moisture are very low. As a result, the soil surface receives high thermal energy and its temperature rises up. The Lut desert has the above characteristics, making it a suitable environment to prepare land surface temperature (LST) models. Objective of this study was preparing of LST model in the Lut desert. It has been used 12 satellite images of NOAA-AVHRR in 2001 as well as meteorological data to model the LST of Lut desert Yardangs for the study. To test the model accuracy, 8 ground control points were applied. Results have shown that useful information of surface (mention them) can be attainable. Due to several problems present in measuring the surface temperature of features using thermal remote sensing data, it is necessary to apply precise radiation potential for features or soils to measure temperature precisely.

Topography and natural phenomenon are among effective elements in site- selection, dissemination, physical development and morphology of cities. Essential objective of this research is identifying natural restrictions of physical development in Sanandaj city, and obtain the best site for future developments. For achieving this goal we use topographic, geology and land use maps. Meteorological data, library sources and field studies have also been used. First of all we defined limitation of study area on the topographic and geological maps and then we used Auto Cad Map 2004 and ArcInfo 8.0 software for digitizing, repairing of errors and creating topology layer of maps. We created database for maps by using GIS. We used spatial analyst extension to provide output. Then field studies started. Results showed that some factors such as Abidar elevation, hills inside the city and Gheshlagh river have made restrictions for urban development, so that less than 4.81 percent of district are suitable for urban development.

The presence of glacial deposits is among the most important evidences of quaternary climatic changes. The Aalamkooh and Thakht-E-Solieman Glaciers are the samples of those glaciers in the Alborz Mountains. All Iranian and foreign researchers who have worked on the Alamkooh glaciers believe the glaciers of northern Alborz are parts of active ones in Iran. The objective of this research is investigation of the previous performed works about the dynamics of glaciers through strict and quantitative measuring of Glacier motions. For reaching to this objective we considered the sections on glacier tongues and marked them during a four-year period which their changes were measured per year. The results show that the Alamkooh glaciers due to global warming are gradually melting. However It seems that in glacier time their aotivates served much more than this time. At present, they move in deep direction of valley with the maximum rate of 2.30 m. in each year. The existence of glacier landform, ice cores by the end of glacier tongue, change of volume of surface moraine, the presence of rimaye fissure at the end of glacier cirques, and destruction of climber's housing made on the glacier tongue are counted as the most evidences of moving and activities of the glaciers.

The subjects related to Geomorphologic studies of Tehran metropolis from assessment aspect that developed during last half a century are numerous. One of the related issues is the analysis of vulnerability caused by landslide in mountainous areas during urban development. (Apart from strengthening the vulnerable area) avoiding these areas is an important solution to decrease damages caused by landslide. At this article, using Landslide Index Method (LIM) we have prepared the map of landslide zonation hazard in mountainous areas of the city, to determine risky strips. Considering the research has been done by the use of field visits and the experiences of the expert. The factors which are effective in landslide incidence in the region include: lithlogy, elevation, slope of mountainsides, direction of mountainsides, annual precipitation, 24-hours maximum precipitation (high), distance from faults and distance from drainage system. Then we matched the final map of landslide zoning obtained from the above-mentioned method, to the map of urban region in mountainous areas. In this way constructed region have been distinguished from very high to very low zonation. These limits were compared to the present situation of Tehran Metropolis. The research procedure is based on analytical method. The key elements of this research are compiling of Geographic Information System (GIS). The finalized results indicate that some mountainous regions of Tehran Metropolis are apt to landslide with middle to high risk. At present 875 hectares (17.3 percent) of residential regions in mountainous parts of the city have developed in middle to highly risky strips. As a result, some residential units have damaged. The comparison of the present border of Tehran (especially in middle parts) to the borders of low and high risky zones (more than average) also indicates that these lines do not match well.

Storm is one of the most destructive climatically parameters which cause different damages. Among the local winds of Iran, 120day wind of Sistan is specially well-Known. This wind the velocity of which reaches to 148 km. per hour flows in the eastern part of Iran from June 5th. To Aug. 6 tho The studied region has always borne many damages from these winds. The movement of running sands in studying area caused a lot of destruction on the roads, farms, villages, quintals, settlements, irrigational cannals and some other industrial installations. Satellite images and field investigations have shown that the length of irrigational cannals filled because of draught and the movement of running sands decreased from 44.2 to 51.1 km., first class roads from 11.6 to 18.8 km., second class roads from 13.2 to 41.4 km., the number of destroyed villages form 9 to 28, and the area of sand hills or dunes from 9421 to 14353 hectares It seems that water reservoirs of Chahnime which is the only resource of drinking waters in Zahedan and Zabol has been seriously threatened by the running sands. In the present paper, we are going to study - by Utilizing of Satellite Images - the effective factors of wind erosion and sand drifting towards the agricultural lands, Communicative roads, villages and installations which are subject to running sand, so that incurred damages are reminded to the authorities for taking the necessary measures in this regard.

In recent years there has been studies concerning the investigation of macro-scale geomorphic proxies of Quaternary climatic changes in the study area. Without detail analysis of slope geomorphic features, there can be little progress on expanding the knowledge of past slope development in the northwestern Iran high mountain environments. Consequently, the information pertaining to these Quaternary environments has remained rather rudimentary. Block streams are among landforms that relate to past climatic changes on Northern slope of Keyamaky Mount. The paper describes the Ghal- é blockstream as the most important and completes blockstream in study area with dimensions in 630m. longitude and meanly 80m. width. In this study, Holocene climatic changes evaluation is based on data gained from field studies and interpretation of Ghal-é blockstream characteristics. Botanical development and rehabilitation of small trees around blockstream, blockstream structure and existence of three distinct layers are reliable proxies for Holocene climatic changes. The results showed that the characteristics described for Ghalee blockstream closely resemble those of other areas in the world. This blockstream is among low altitude and steep slope blockstreams that settled on superficial slope deposits containing blocks. In spite of insignificant climatic changes in Holocene, the existence of factors such as fit conditions for bedrock weathering, activity of rock avalanches and frost-coated clast flows as transportation mechanisms, and activity of frost and melt process have been result severe blockstream activity in study area. However, four periods including present warm period, little ice age synchronous period, upper Holocene warm period, and iron epoch synchronous cold period are recognizable based on blockstream characteristics.

Decreasing changes of climatic elements such as: daily precipitation, weekly precipitation, seasonal precipitation and annual precipitation can be toward to drought phenomena. The recognition it and planning for passing it, could be decreasing of disasters, because create of drought is slow but it effects is very damages. The aim of this paper is descriptive analyze and it type of research is applied research with uses of field work and obtains of tree ring desk and comparison precipitation in statistical at study time (1995-2003) in Soome-e-Sara of Gilan province by a research project. Result of this paper has shown that drought or deficit of rain has been direct relationship with growth tree ring index (TRI). Diameter increment in (Populus Deltoids) Poplar-trees and relationship between annual precipitation and annual tree ring index has been with correlation r=0.662 (a=5%), but without view of year happen this correlation is r=0.88. Changing of decreasing precipitation from 1200 millimeter to 800 millimeter (Drought) accompanying has been with 2.3 millimeter decreasing of Tree ring indexed in the time of study period. This factor has been accompanying with high destroy in area. Increasing of studying and look at to suggestion ways of this paper could be benefits.

Sub-coastal zone sections and determining environmental sensitivity level of the coastal regions in the country is an activity that has been considered in recent years due to sensitivity and vulnerability assessment of coastal area in front of socio-economic development process and selection of environmental managed regions. Coastal landforms, network method (base line) and coastal townships boundaries are three styles that have been used for unit separation due to assessment. Guilan Province shorelines were assessed sensitivity and vulnerability by three methods as well as assess by criteria of coastal-marine protected areas. Results showed according to the valuation in 17 grids (each grid is 15 km length) and 30 coastal townships, and 13 landform Sub-coastal sections, Guilan Province shorelines were divided into high, medium and low sensitivity areas. Then the three sub-coastal zone sections methods were compared using IFE & EFE matrix in order to determine the best one. For this reason, the experts ideas and opinions about the strengths, weaknesses, opportunities and threats of each method were collected and concluded since the Caspian sea shorelines are approximately uniform, so the best assessment sub-coastal zone sections method for environmental purpose is coastal landform, because it is matched on the natural borders of ecosystems and has undeniable preferences on two other methods.