Physical Geography Research
Year:2010 | Volume:- | Issue:73|Papers Count:11

Extreme temperature events can impose serious impacts on environments and societies. Frost is one of the most severe weather conditions that affect human activities in many parts of Iran. The first fall and the last spring frosts usually cause damages to plants. Occurrence of the first fall frost, at the beginning of freezing period, damages crops that are still in the field. The last spring frost at the end of freezing period, which occurs at the beginning of growing season, causes damages to seedlings and young plants and to those that are already in the flowering stage. In addition to these characteristics, one of the other most important characteristics of frost is its persistence in a region…

Active faults are the ones that at the post-Quaterner and especially the Holocen epoch have had movements and it expects that in the future they alsq exposure to a relative movement because of their renewed activity and generate a shear on any structures locality on them To identify these faults, seismogram and historical record information, direct and indirect paleosismology studies are utilized. The indirect paleosismology has been based on geomorphologyic studies. Its advantage is that it studies a wide scope with a high speed and the attained to interpret the changes of thousands years ago. Geomorphologyic indices used to study drainage system condition are influenced by the earth material and region climate as well as tectonic….

Road accidents are among the major causes of death, injuries and financial problems of Iran. The important climatic causes of road accidents in Iran are such as slippery of road surfaces due to frost, snow, rainfall, occurrence of fog, avalanches, etc. The object of this study is to analysis the effect of weather conditions on road accidents and rating of the studied areas based on road accidents in relation to weather conditions. This study analyzed the influence of hazardous climate factors on road accidents on the road between Karaj and Chalus axis, one of important relational roads in Iran….

A natural disaster is the effect of a natural hazard (e.g. flood, earthquake, or landslide) that affects the environment, and leads to financial, environmental and/or human losses. The resulting loss depends on the capacity of population to support or resist the disaster, and their resilience. These understandings concentrated in the formulation: "disasters occur when hazards meet vulnerability". A natural hazard will hence never result in a natural disaster in areas without vulnerability, e.g. strong earthquakes in uninhabited areas. Evidence indicates are continuously increased all types of natural crises, from frequency and severity. Natural factors always impose dangers throughout history and around the world to natural environments and built ones….

Climate change is expected to affect agriculture very differently in various parts of the world. The resulting effects depend on current climatic and soil conditions, the direction of change and the availability of resources and infrastructure to cope with change. Biological systems are based primarily upon photosynthesis and are thus dependent on incoming radiation. However, the potential for production set by the radiation is greatly modified by temperature and rainfall….

The base of analysis of applicative geomorphology is according to systemic standpoint. Systemic geomorphology is based on recognition of geomorphic forms and processes and relationships between them. Efficiency of this stand point, when there are linear and nonlinear reciprocal re-1fitionshipsbetween parts and elements of system, is very important. The studied feature in this research is Barchan dunes in the south of playa Chah Jam. In studied field, hundreds of barchans can be found; generally all of them have same size and shape. These landscapes are mobile dunes, which constitute a considerable threat to infrastructure in study field with their mobile sands….

Most of Iran areas have been located in arid and semi arid climates. Water resource scarcity is one of the wobbles that has been attended by experts, decision makers and managers of the country. With respect to occurring droughts in recent years, proper management of existing water resources and also achieving to the better solution for their usage are essential. One of the ways that a large volume of water can be losses through the land surface is evapotranspiration (ET) as it has an important role in water resource management. ET of each region is generally affected by different climatic parameters as well as its geographical attributes. To have a proper management of the ET, as a great water losing way, it seems to be necessary to know and study the ET and its effective parameters in each region. Sensitivity analysis is always known as one of these approaches. This approach seeks to attribute uncertain output to specific input parameters. The input parameters are varied in turn and their effects on the model output are quantified….

Generally there are two ways for frost protection: active methods and passive ones. Passive methods should be carried out much earlier than the frost occurrence, for these methods are not the direct ways of frost protection but are the ways of avoiding and escaping from the frost. Active methods are the ways of frost protection that are carried out right before the frost or at the time of its occurrence. These methods include garden heaters, spray irrigation, wind machines, etc. In the present study, 3 ways of frost protection namely fogger, heater and fogger heater were compared with the control treatment….