GEOGRAPHY AND ENVIRONMENTAL HAZARDS
Year:2012 | Volume:1 | Issue:3|Papers Count:8

Introduction: Drought is a climatic hazard that occurs in the vast areas throughout the world. It causes physical suffering, economic losses, and Environmental instability. Drought is a slowly developing very which is phenomenon, and it is very difficult to determine when a dry spell becomes a drought or when a severe drought becomes an exceptional drought. It is usually starting with less dramatic effects than other natural disasters, but its effects are long lasting and widespread (Mavi and Tupper 2004).Meteorological droughts are characterized by a lack of precipitation, often combined with higher than normal potential evapotranspiration, for a long period of time and over a large areas. Meteorological drought indicators use precipitation data to determine meteorological droughts.This paper is focused on drought hazard distribution and its Environmental impacts in the Gilan province. We used the precipitation data as Meteorological drought indicators to determine Meteorological droughts...

Introduction: Because of the vital role of water in human life, examining the phenomenon of climate change effects on drought severity and frequency is important for any area of interest. Nowadays, climate Researchers considers the effects of climate change and climate simulations by using the atmospheric-ocean general circulation models. To achieve the prediction of climatologically parameters, various statistical and dynamical models have been developed to simulate and downscaling of GCM output models. The statistical model of LARS-WG is such a model, which is very powerful for this aspect...

Introduction: Active Mending Rivers are the most dynamic and sensitive parts of the fluvial landscapes. Meandering rivers suffer a large Geomorphic changes during the annual flood events. Based on large flood evidences, reconstruction of the channel bed migration will be possible, which is use for Evaluation of future Evaluation and flood risk assessment in the flood plain areas. The morphological evolution of river meanders has been analysed by many authors and various pattern and models has been suggested (eg.Alfredo 2010, chen 2006, Hook 2008, Borisova 2006). Many researchers have examined the morphological impacts of floods and some studies of channel instability have combined time scales, examined the combined effects of flood phases and demonstrated temporal and spatial variability of stream stability.There are many meandering rivers passing from flood Palin areas in Iran which are studied by Iranian researchers (eg. Bayati Khatibi 2012, Rezaei moghadam and khoshdel 2009, Yamani 2008, Jahadi Toroghi and Hosseinzadeh 2012).The purpose of this paper is to demonstrate of active channel changes of Aji-Chay River over the time and assessment of flood occurrence potential based on displacement of bending river course...

Introduction: Soil losses and erosion is one of the main causes of fertility decreasing, sedimentation in River cannels and irrigation canals, decreasing of storage capacity in dams, increasing of floods frequency, environmental pollution and it prevents from stable development. More than 70% of Iran land is covered with arid and semi-arid areas. Soil erosion as one of the main causes of soil degradation, annually loss large volume of fertile soils in the Fars province. CORINE methodology is a standard method used by the countries of the European Union to determine erosion risk and qualities of the lands. Using the methodology, countries of the European Union sharing the coasts of the Mediterranean Sea have completed their erosion risk maps and classification of their lands. The main goal of this research is preparing actual soil erosion and potential soil erosion map. In this research, the CORINE method has been modified according to the Jahrom watershed basin as study area of the research. CORINE model applied for assessing and estimating soil erosion risk in the Jahrom basin. To calculate of actual soil erosion, estimating erodibility, erosivity, slope, land use and vegetation is needed...

Introduction: Worldwide salinization and degradation of soil is a widespread and important environmental challenge. Soil salinization is one of the most common land degradation processes in arid and semi-arid regions, where evaporation exceeds over precipitation. Under arid climatic conditions, soluble salts are accumulated in the soil, influencing soil properties and environment with ultimate decline in soil productivity.Soil salinity monitoring in irrigated and drained fields is necessary to follow the control of soil salinity provided by a drainage system. A subsurface drainage system can prevent or decrease the salinization hazard Trend, a common phenomenon wherever irrigation is practiced under arid and semi-arid climatic conditions. About 77 million hectares of the world's land have been saline as a consequence of human activities (secondary salinization), with 58% in irrigated areas.20% of the world’s irrigated lands are affected by salt, but this condition increases to more than 30% in countries which are located in arid lands such as Egypt, Iran and many similar areas.Implementation of this assessment, before doing any action, needs to use adequate techniques and to record the changes and disclose of soil salinity ratio and domain. Remote sensing data providing namely satellite image and Arial photos along with processed thematic maps from this images over GIS platform is most effective in both coast-speed and accurate to control and assessment of this phenomena.Data providing is one of the main challenges in case of soil salinity studies based on remote sensing techniques.In this case, data resolution in form of spectral, spatial and temporal is an important task for data selection and collected from source. In order to provide data for such studies many sensors can be nominated while the TM and ETM sensors carry by Land sat satellites as well as ASTER sensor are more popular which is many researches has been done so far...

Introduction: Environmental protection is one of the most priorities in Land use planning. In this regard, place and location have the greatest role and its importance is increasing when the adverse effects of environmental neglect, can cause irreversible situation.Selection a suitable location for the burial of solid waste can prevent the unfavorable ecological and socio – economic effects. Landfill site selection requires spatial data analysis, acceptable rules and standards.Choosing the various factors and therefore the number of Map layers, decision-makers to lead them unconsciously into a system that in addition to high accuracy also has high speed and simple of operation.Nowadays, these processes are using spatial models and GIS in the desired method is provided.A selected landfill is an important process in urban planning that effect on economic and environmental sectors and environment hygiene.Multi-criteria evaluation methods and GIS can use as an efficient tool for managing and applying layers seeking information in the place. In developed countries and also in Iran, a great deal research has been done in this field.This study with utilize past experiences and applying GIS technology want to provide a method for landfill site selection...

Introduction: Climate change is an important environmental hazard that has been discussed in recent years. Increasing the number or frequency of extreme climatic events such as severe droughts, floods, storms, heat and cold waves and heavy rains are the evidences of climate change. Any of these events, due to the severity and persistence and their spread are a natural hazard that adverse effects on living life to enter. Among the environmental hazards, the occurrence of severe colds cause adverse effects on various aspects of development planning and regional economic recession and social crisis each year in different parts of Iran. As part of the interaction between temperature and atmospheric circulation characteristics of the local space is uneven and the altitude (Masoudian, 2012), explaining the relationship between climate change and the patterns of abnormality surface can reduce the effects of climate planners and Forecasting atmospheric climatic disasters and help. Preliminary studies showed that all of the spring frosts is the type of transmission (synoptic) and in nearly all cases the displacement of the trough at 500 hPa and surface migratory high movement in the West Mediterranean, towards Iran, and integration with Siberian High pressure is going on spring frost leads (Barati 1986)…

Introduction: Landslide is a geologic process that occurs over a wide variety of spatial and temporal scales in many mountainous landscapes. Landslides have a correspondingly wide range of effects that depends strongly on their spatial pattern of occurrence and frequency and magnitude of movement. Mass movements can be the dominant source of erosion responsible for the long-term geomorphic evolution of hillslope morphology. A number of different models have been developed for landslide susceptibility mapping, such as heuristic, conditional probabilistic, logistic regression (LR), artificial neural network (ANN), support vector machine (SVM), and deterministic models. These approaches have been reviewed in detail in recent publications (Carrara et al., 1995, 1999; Aleotti and Chowdhury, 1999; Guzzetti et al., 1999; Dai et al., 2002; Guzzetti, 2003; van Westen, 2004; Brenning, 2005; Wang et al., 2005; Chacon et al., 2006; Alexander, 2008; Corominas and Moya, 2008; van Westen et al., 2008). Among these approaches, SVM modeling is becoming increasingly popular. The procedure is based on statistical learning theory, and involves a training phase with associated input and target output values. The trained model is then used to evaluate a separate set of test data (Yao et al., 2008). SVM modeling has been undertaken less frequently than other approaches to landslide susceptibility mapping. Yao et al. (2008) showed that two-class SVM modeling produced more accurate susceptibility maps than one-class SVM and LR modeling on the natural slopes of Hong Kong, China. Brenning (2005) showed the predictive power of LR, SVMs and bootstrap-aggregated classification trees in a case study of the Ecuadorian Andes. In that study, LR with stepwise backward-selection of variables yields the lowest error rates and demonstrates the best generalization capabilities. Landslide is among slope process dominant on South Alborz and especially in Darakeh basin. Identify area that are prone to landslide is very important, because near of basin to Tehran city, tourism aspect and human settlement in the basin. In this research we tried using SVM algorithm is determined and zonation landslide hazard and Areas susceptible to landslides in the basin. Seems that output of research has a role in sustainable environmental management and a document used in future planning for development of infrastructure…