Physical Geography Research
Year:2014 | Volume:45 | Issue:4|Papers Count:9

Introduction: Scientific concepts, language and terminology go through changes over time. One of the most basic and important concepts in environmental and geologic science, which has gone through this change, is the term subsidence. The depth and breadth of change in the concepts related to this term is noticeable, although it has applications in other fields, even dentistry. Known as a geomorphological phenomenon, subsidence has turned into a theory on its own in geology and with its emergence it also outlined some other concepts and schools of thought in the field of geology. It also caused evolutions in common beliefs in this field.

Introduction: Temperature and its changes are considered as an important factor in the physical weathering of rocks. The maximum influence of temperature is frost action and thermal expansion. The effect of temperature on the degradation of rocks, moreover temperature range, depends on the strength of rocks. During freezing, water in cracks and fissures of rocks is increased 8 to 11 percent in volume and this has a force of about 2000 pounds per square inch. The continued practice of freeze and thaw can cause small fissures, cracks and separation. The result of this process is formation of the Talus and debris cones (Blyth and Freitas 2005). Evidence of glacial geomorphology is one of the most visible legacies of the Quaternary period Climate change (Mahmoudi 1988). One of the most important legacies of Pleistocene climate in the highlands of the Iran, especially in the Alborz Mountains, West and North West of Iran is the dominance of the glaciers and related landforms (Yamani 2002).

Introduction: Dust storms are atmospheric phenomena in arid and semi-arid areas such as Middle East. Iran in west of Asia regularly experiences dust storms (Modarres and Silva, 2007) due to its location in arid and semi-arid belts of the world (Jalali et al., 2008). For example, intense dust storm occurred over Middle East in 18 Mars 2012. This dust storm affected many countries such as Iran, Iraq, Kuwait, Bahrain, Qatar, and Saudi Arabia.

Introduction The word “Loess” has been derived from the German word “Los”, meaning loess, which was used for the first time by Leonard in 1824. Regarding the definition of loess presented by many authors, aeolian origin and silt fraction dominance have been accepted as the two main attributes of loess deposits. Wind- blown deposits of loess are characterized by a lack of stratification and uniform sorting and occur as blanket deposits (Bell, 2000). The common mineralogical composition of loess deposits is as follows: quartz, feldspars, carbonates, mica and heavy minerals in the silt fraction. According to Pye (1995), four fundamental requirements are necessary for its formation; a dust source, adequate wind energy to transport the dust, a suitable accumulation area, and a sufficient amount of time.

Introduction Energy is one of the necessary factors for industrial activities and a requirement for today life.Hence, demand and supply of energy in human society is increasing continuously. Population growth and its distribution, along with the increasing need of human being to newer and more efficient energy resources have changed the human approaches to natural renewable energy forms. Since the fossil fuels as the primary fuels of are going to exhaust rapidly and cannot be a reliable energy source as well as due to the global warming issue, the use of fossil fuels should be limited as soon as possible. Henceforth, renewable energy resources were proposed to solve these challenges.

Introduction Wind is considered as one the most important causes for erosion and land degradation in arid and semi arid regions. Thus, it is necessary to study temporal pattern of wind properties to prevent the huge damages. (Refahi, 1999: 22).There are a variety of different methods, parameters, indicators and diagrams for analysis of windy status and wind dynamic conditions. These are wind rose, storm rose and sand rose diagrams, drift potential, dustiness indices and wind threshold velocity maps.

Introduction: Due to capabilities of imaging radar, there has been an enormous surge of interest in microwave imaging technology. Unlike optical imaging, understanding the theoretical underpinnings of imaging radar can be challenging, particularly when new to the field. The technology is relatively complicated, and understanding the interaction of the incident microwave energy with the landscape to form an image has a degree of complexity well beyond that normally encountered in optical imaging.

Introduction: Cities with their physical development are the major causes of land use and land cover changes which lead to many problems such as loss of agricultural land, loss of green space, water pollution, soil erosion and declining of environment quality. The main reason for physical development of cities is population growth in urban areas which enables the physical expansion of the cities in geographical space. Tabriz, as the center of East Azerbaijan Province, has experienced considerable changes in recent decades due to increasing population in the surrounding lands and rural communities located in regions of influence sphere.