مجله مخاطرات محیط طبیعی
پیاپی 9 (پاییز 1395)

It has been known that weak structural foundation of rural area of Iran has been the most important element of obstacle on Rural development. In these human settlement meanwhile, natural hazards such as floods and earthquakes impose serious damages on its socio – economic organization as well as physical structures. In such state, renewal of damaged villages rising from of natural hazards, with rational approach to planning, and the government intervention in use location – spatial arrangement is the end senario and resettlment of damaged villages is such an approach.That among these neglected and are located in rural people and what matters will be the result of spatial and physical reconstruction programs. This validation study with emphasis on implications of social, economic and spatial strategies for rural resettlement after disasters natural (earthquakes) to measure an outcome of this abgarm county of Ardebil in district villages during the earthquake were destroyed in 1375 deals. This research provided the following reviews outcome indicators for rural resettlement after natural disasters (earthquake) is. Looking at three aspects of social (social cohesion, social cohesion and sense of place), the economic consequences (job changes, income) and physical consequences (the destruction of pastures, changing pattern of housing, agricultural land use change and the rate of access to infrastructure services ) were performed. Research - descriptive and analytical methods, including documents and field data collection (observation, interview and questionnaire) is

Research on major natural disasters and related technologies has become an important subject in geography and its application. The complexity analysis of the issue is possible in a system approach to theoretical and applied geography also in the integrity of physical and human geography. Due to the Caspian Sea water-level fluctuation in the coastal zone of Mahmoudabad which happens very quickly in decade scale, the observance of safety element will be possible in light of the integrated coastal zone management with determining of sea frontage. In this context, geography and especially geomorphology are a main basic in this kind of coastal management. Detection of sea level fluctuations causing morphological changes in the earth surface and damage to facilities clarifies the necessary of the present research to study the role of geomorphological indices in Mahmoudabad coast zone constructions. The Coastal Vulnerability Index (CVI) is one of the most commonly used and simple methods to assess coastal vulnerability to sea level rise, in particular, due to erosion and/or inundation. The CVI provides a simple numerical basis for ranking sections of coastline in terms of their potential for change that can be used by managers to identify regions where risks may be relatively high. The CVI results can be displayed on maps to highlight regions where the factors that contribute to shoreline changes may have the greatest potential to contribute to changes to shoreline retreat.

Desertification is the ecological and biological reduction of land that maybe occur naturally or unnaturally. The desertification process influences the arid and semiarid regions essentially and decrease the lands efficiency with increment speeds. Therefore, recognizing this phenomenon is very important. In this research, the Landsat satellite images 5 and 8 used as studies base for studying region desertification. Moreover, the topography maps 250000 and 50000 and geology maps used as complement too. After completing the information data base, first, the soil salinity and vegetation NDVI indices exerted on the satellite images. According to artificial neural network MLP method, the usage recognized in the studied region, according to controlled categorize method Fuzzy ARTMAP. According to studied satellite images Isfahan have been grown about 260 km2. During this 29 years’ periods, the eastern and southeast regions of Isfahan indicate the most decline in vegetation that have been encountered to decline about 60% relative to the first year of study. This decline amount is considerable in the north region of Isfahan too. With decreasing the vegetation in these regions, onset of saline and desert lands is visible that displaced to regions with vegetation. This increasing amount in saline and desert regions is about 580 km2 that represent decreasing the ecologic and biologic potential of region.

Changes bed rivers features a main river geomorphology are the most discussion. A river system is highly sensitive to changes in response to movement of the Earth's land, build geomorphologic features of structural changes with substrate and substrate changes be self. In this study, using digital elevation model (DEM) and satellite image and GIS (GIS to assess the potential of making a new field of application geomorphic changes of the river bed and geomorphological features will Osku chay. Using Digital Elevation Model DEM application environment Arcgis9.3 maps of slope, topography, and drainage sub-basins with different degrees estraler method will provide, for mapping faults from maps 1/100000 Geological Survey will use. After determining the direction of the flow channel and the number of them in any way, the parameters of the anomaly index will be used for Osku chay River. River sinuosity S, River defines the extent of the balance. Stream length gradient index river SL, tool for the study of tectonic geomorphology, Drainage basin asymmetry index channel AF, evaluation drainage in terms of tilting of tectonic, Ratio of valley floor width to valley height VF, indication of the valley floor of the V or U shape and the resulting impact tectonic activity in the formation of the valley V-shaped, shape index Basin BS show that represents a circular or elongate the basin, the influence of tectonic activity. data analysis of topographic, river systems region and geomorphologic evidence of field observations and by parameters on three major river osku chay basin and evaluate them using LAT indicators that the situation in the morphology sub basin geomorphology, a channels and the indicators in the study have an effective role in the end, according to surveys found that back as recently as 1990 of the study active tectonic zones

Urbanization modifies river systems more than other human activity. Urban streams adjust channel morphology as a consequence of urbanization. In this paper, effects of urbanization on Babol River, survey using with Rapid Geomorphic Assessment (RGA) in Babol city. This protocol designed by Stormwater management (SWM) of New York State. These qualitative techniques have various indicators are grouped into four categories indicating a specific geomorphic process. Babolrood channel was divided into 8 reaches. Field surveys were achieved reaches with four factors including: Aggradation, Degradation, Channel Widening and Planimetric Form. Then, satellite images of Google Earth were used to document of modification of river channel width. Based on the findings of Rapid Geomorphic Assessment, All sites achieved a score of less than 0.25, and were in stable class. Aggradation and channel widening have earned more scores than the other factors. During the period of 8 years, the channel width had modified between -7 m and 5 m. Also, there is a significant relationship between land use and changes of channel width. In this case, landuse of residential and agriculture have decreased or increased changes respectively. The result of T paired Test at the 0.05 significance level represents the channel width has experienced a Significant changes in the six reaches. Also, there is a significant relationship between land use and changes of channel width.

Identification of active geological structures can make a lot of help to identify seismic zones. There are several ways to study and identify structures. Accordingly, the horizontal and vertical movements can be detected in the area. In order to identify the intensity of vertical movement on the part of the Markazi province, morphometry indices in Qara-chai watershed have been studied. Qara-Chai basin, following of Zagros and Central Iran Tectonics. In this study, topographic data, geological maps and geological information were scrutinized qualitative and quantitative. These data along with the streams data in the basin of choice, utilizes various specialized software’s are analyzed. There are many faults, some of which quaternary, and are young, it is a sign of high seismic potential range. Young Quaternary sediments, fractures and faults compliance and various geomorphometry indices surveys to indicate Indes and Koshk-e-Nosrat fault zone in west, south Saleh abad and Yal abad faults, Tafresh fault in north, North West and west of Tafresh city and Talkhab fault in North West of Arak from the perspective of uplift, are active and relatively high seismic potential. According to the relative tectonic activity indices of East and North Markazi province around Ashtian, Tafresh, Farahan and Saveh cities have high tectonic activity. These cities require special planning in the Markazi province. Undoubtedly, geomorphometry is not everything in mobility of Qara-Chai basin. Some fault zone has a strike-slip motion, which requires the use of methods other than geomorphometry indices.

Study area (Aleshtar plain) is located about 52 Km far from Khorramabad city (Lorestan Province centre) in the northwest direction. Excessive groundwater withdrawal in recent years, caused some hazards such as the high decline in groundwater level. In this research, the amount of aquifer drawdown is estimated to be about 4m using plain unit hydrograph according respective data of the study period (2002-09). Also, for determining the areas with critically low water levels as well as for simulating the groundwater responses to further withdrawal under various conditions in future, the mathematical model of the aquifer was developed. Then, by combination of mathematical model of the aquifer and geographical information system (GIS), simulation model of the aquifer was constructed via using the GMS software. According prediction outcomes of simulation model, the groundwater level would have about 3.5m further depression at the end of the consecutive five years'' period. Finally, some management approaches offered for appropriate withdrawal aimed at compensation of drawdown as well as hydraulics and economic considerations, and were evaluated by the aim of GWM software. Amounts of required water which lost due to withdrawal reduction, would be compensate through pumping from new proposed wells which are located outside of high depression area.