GEOGRAPHY AND ENVIRONMENTAL HAZARDS
Year:2013 | Volume:2 | Issue:7|Papers Count:8

Introduction: Piping is a subsurface form of erosion which involves the removal of subsurface soils in pipe-like erosional channels to a free or escape exit. Although it is one of the coolest and rarest Erosion phenomena that can be formed in any weather conditions, but generally it develops in geological formation with low infiltration capacity and high soluble minerals. Piping materials are commonly highly erodible. However the situation is not fully understood, especially in terms of geomorphology. Compared with surface soil erosion by water, subsurface erosion (piping) is generally less studied and harder to quantify. However, wherever piping occurs, it is often a significant or even the main sediment source (Verachtert et. al., 2011). This erosion process might occur at any crack that exists in the earth structure, due to differential settlements, seismic movements, tension stresses, or holes caused by dry roots or gnawing animals (rabbits, rats, and etcetera). The erosion starts at any point where the seepage water discharges and works toward the reservoir, gradually enlarging the seepage channel. Field scientists studying badland processes in Mediterranean and Semi-arid climates require assurances that the material in which gullies are presented is not dispersive (Faulkner, 2010).

Introduction: Malaria is a global public health challenge, with about one million deaths each year and a further 250 million new cases of malaria diagnosed annually. Interestingly, malaria have been distributed disproportionately such that the poorest countries in sub-Saharan Africa bearing about 85% of the burden of malaria morbidity and mortality in the world .However, more than half of the populations of the Eastern Mediterranean Region are at potential risk of contracting malaria. The Islamic Republic of Iran is one of the countries located in the Eastern Mediterranean Region with low malaria endemicity, with some regions having a reported API ranged from 0.14 to 8.74 per 1, 000. The south-eastern areas of Iran, including Sistan & Baluchestan (S&B), Hormozgan and the tropical part of Kerman provinces accounting for around 95% of all malaria cases in the country (Raiesi, 2011).

Introduction: Hot days are considered as one of the manifestations of extreme temperature. Hot days are very important atmospheric events in terms of losing water resources, large demand for water and energy, and its effect on human comfort. Accordingly, these events could have physical, economic and social consequences. As Bonsal et al (2001) has stated this atmospheric event and the related atmospheric systems might emerge and occur during every month. These kinds of temperature anomalies especially in large scales are in relation with given synoptic systems.

Introduction: Probabilistic risk analysis is a systematic approach capable of bringing multiple expertizes and fields of sciences together for a comprehensive analysis of performance of engineering systems. Moreover, risk analysis is a managerial tool in hands of the disaster managers for decision making considering different methods to examine reactions to probable risks and vulnerabilities. At international policies level, the term “multi-hazards risk analysis” was first introduced in UN permanent development plan (UNEP) in 1992. The document calls for “complete multi-hazard research” as a part of man settlement programming and management in hazards prone regions (UNEP 1992).

Introduction: Pollution can be defined as an undesirablechange in the physical, chemical or biologicalcharacteristics of the air, water or land that canaffect health, survival or activities of humans orother organisms. Air pollution is the biggest environmental problem in whole of the world that industrialization and increasing in number of city cause to increasing of its intensity. Tehran, one of the heavily-populated capitals and air pollution is known one of the environment problems for Tehran citizens during past recent century so this city today''s is known one the pollutant city in the world. Some factors such as Tehran topography and climatology, population growth (more than 10 million person), increase in the number of motor vehicles (more than two million vehicles) as well as industrial expansion, cause to intensify of air pollution in this city. Also this city is a greatest industrial city in Iran andthere are some Power plant, Refinery and chemical plants in it. In fact the important reason for Tehran air pollution is irregular consumption fuel fossil particular gasoline.

Introduction: Air pollution caused by changes in the quantity and quality of atmospheric gases. This phenomenon is due to the increased use of fossil fuels in urban areas. Status of natural environment of the city and the characteristics of the weather elements and phenomena cause congestion, transport and displacement of pollutants, particularly in the central areas of a city. Tehran have Known as a one of the largest city in the world by population. It usually meets critical air quality condition special in central part of the city. In this context, for careful analysis of the physical and natural factors in mitigation or aggravation of air pollution, the micro-scale numerical modeling methods based on a laboratory model of airflow (CFDs) are used. The usefulness of this method is being the quantitative effect of each of the urban fabric and climatic factors in small-scale on spatial and temporal resolution. However, this method can be largely resolves this problem.To evaluate the effects of urban spaces on air pollution in micro-scale, the components such as street width and orientation, mass-produced building model, land use, and green space patterns and classes against atmospheric elements including local prevailing wind direction and intensity, temperature and humidity fluctuations have been discussed. In spite of the fact that numerical modeling can offset most part of micro-scale data deficiencies.

Introduction: United Nations statistics show that floods and storms have a greater number of casualties and cause more damage to communities compared to other natural disasters. Flood occurs due to the specific climate and topography conditions and especially after rainfalls with high intensity and duration. In Iran, investigation on direct flood damage at recent 50 years showed that its rate increased over than 250 percent. Flood predictions are made by processing hydrometric data, and the most commonly used parameters applied to such processes are those of peak flow and flood volume. However, the necessary statistics are often incomplete due to a lack of meteorological stations so it is important to develop a process for making predictions using indirect techniques for flood discharge estimates.

Introduction: Salinity is a highly important problem in arid and semi- arid region. In Iran, about 235,000 km 2 (or 14.2% of the total area of the country) area is salt-affected, which is equivalent to about 50% of irrigated lands in Iran (Pazira 1999). Irrigating of these lands causes to transfer salts to the area of root growth and thus increases the osmotic pressure and reduces the absorption of the nutrient elements and product. Some of researchers believe that this process is one of the disasters that threats development of human societies. Esfahan province is exposed to the danger of salinity.