Physical Geography Research
Year:2015 | Volume:46 | Issue:4|Papers Count:8

Thunderstorm rainfall is one of the most important climatic phenomena in the northwest Iran. It has specific variability in spatial distribution. These rains play an important role in climatic conditions of the study area of this research. The purpose of this study is investigation of spatial distribution of thunderstorm rainfalls in mountainous areas of the Northwest Iran to make a modeling of these events in the study area. Because of that precipitation data of TRMM images from 2009 to 2012 have been selected and processed in the applications of ArcGis, ENVI and EDRISI.

IntroductionThe most important indicator of climate in a region is vegetation communities. Climate may be different over large areas due to changes in vegetation communities. Vegetation influences weather and climate in its surrounding areas mostly by way of evapotranspiration and albedo so they play a role in the earth’s energy balance. These effects on the earth’s energy balance are taken through air temperature, relative humidity, rainfall, solar radiation and cloud cover on their own micro-weather (Neilson, 1986; Small and Kurc, 2003; Weiss et al., 2004). Disasters such as drought, flood, forest fire and so on can occur whenever the global energy balance goes out of the normal range.

IntroductionPerceptible water is the main part of water cycle in the atmosphere and an important variable for climate studies and also an important element of atmospheric humidity, in particular atmospheric raining. Perceptible water, therefore, has been considered as an appropriate index on short and long term changes in climate. Recognizing the changes within a decade of perceptible water is essential for knowing the region and local climate change. Identification of changes, within a decade, (decade to decade) of perceptible water can lead to the identification of climate oscillations as a decisive factor in raining. Thus, it plays a significant role in macro planning based on precipitation.

IntroductionRainfall, as the main representative factor of every region's natural and hydro-climatic specifications, has a high degree of importance in water resources planning and management. Rainfall events have noticeable spatial and temporal variations. Rain gauges of various types are used for the measurement of spatial variations of precipitation. Due to the limitation of the possibility for expanding these rain-gauge stations to all locations, the precise estimation of a regional rainfall is not possible. Therefore, sufficient consideration is required to be taken into for choosing the location and number of stations for achieving sufficient precision in regional rainfall estimation. Because of numerous factors involved in determining the optimal location of these stations, development of an optimal structure seems necessary for placement of the stations or expansion of an existing rain-gauge network.

IntroductionThe use of climatic and natural variables in regulation of agricultural activities has a particular importance. One of the important characteristics of climate is the onset and retreat dates of rainy seasons which have a deterministic role in the agricultural activities such as seeding time, cultivation period, irrigation and other agricultural programs and strategies. Iran located in the arid and semiarid region has a variety of climates and consequently experiences high irregularities in spatial and temporal distribution of precipitation and other climatic elements. Southern coasts of Caspian Sea in Iran as a region with the highest precipitation in the country, has good potentials for agricultural activities. Among the most important crops for the development of cultivation in this plain is colza (canola). Since colza can be cultivated under rainfed conditions in high precipitation areas. Therefore, the analysis of precipitation characteristics in the region in one hand, and onset and retreat dates of major rainy season in that plain on the other hand, can play an important role in the development of cultivation area.

IntroductionTo avoid the adverse consequences of tourism, some appropriate decisions must be made about its development. To achieve this purpose, one of the first steps is to identify suitable areas for tourism development and optimum land use planning. This will eventually lead to a model for development of tourism destination. Due to having unique natural attractions such as mountains, dense forests, rivers, up-country - historical villages, waterfalls and natural springs as well as beautiful beaches of the Caspian Sea, Talesh County has a very good potential for ecotourism. However, unfortunately, lack of proper tourism management and the unsustainable tourism development have led to destruction of these unique resources in a growing trend. As the largest county of Gilan province, Talesh is located in the west part of this province.

IntroductionNatural disasters management requires local information to make human societies ready against dangers and reduce the disaster procedure. Hence, evaluation of landslide occurrence in the areas prone to landslide due to geographical condition and human constructions is highly crucial. Ghale Chai Dam located at Ajabshir Watershed is one case of such areas. Thus, the aim of present investigation is to identify hillside instabilities and movements and their influencing factors to prevent their harmful effects on natural resources and other parts of economical and engineering development and recognize points with high vulnerability. Hence, the aim of the present investigation is to assess Analytical Network Process (ANP) and Heuristic method to determine the landslide prone areas in range axis and reservoir of Ghale Chai Dam of Ajabshir.

IntroductionThe recognition of the behaviors of atmospheric circulation patterns and effective climatic elements is very important in occurrence of floods. Abnormal climate changes such as global warming in the recent years tend to make changes in atmospheric circulation patterns and outbreak climatic inelegances in many areas of the world. Intensive and torrential precipitations in anomalous time and space are very important for a country like Iran with specific climatic characteristics. It is always among the factors that may have some irrecoverable effects on human life and finance in different geographical regions. The event has widely affected human beings and nature. The south-west region of Iran is located in the windward slopes of Zagros Mountains and in the path of westerlies and rain bearing air masses. It is among the regions exposed to destructive floods due to different atmospheric circulation patterns and receives heavy precipitations. The flood event of November 20, 2011, which has occurred in Khuzestan and Kohkilou-e-va-Buyer-Ahmad Provinces, is an obvious example of such flood events. This flood imposed many death tolls and caused a big mass of financial damages in those regions. Precautious measures before happening of accidents and hazards is key factor in crisis management. Therefore, identification of the patterns causing flood and their punctual prediction can facilitate better management of the crises and hazards and also minimize death tolls and financial damages caused by these natural disasters.