Journal of Spatial Analysis

Wind erosion is important in areas with less than 150 mm of rainfall Measuring the extent and severity of wind erosion in many countries, including Iran, there is no station to measure wind erosion sediments and so the deposition estimation methods rely on empirical models so that in many cases there are measurement errors. With estimates wind and water erosion and deposition potential compared using IRIFR EA and MPSIAC models in semi-arid Nematabad Bijar watershed concluded that the IRIFR model quantitatively and qualitatively accuracy and, due to a 22.6% wind erosion and 77.4 percent water erosion effective in reducing the fertility of soil (Ahmadi et al, 2006). This study estimates deposition and wind erosion potential using IRIFR method in esfarayen Miandasht region.

In this study, the data collection and basic research in the area uses of maps such as topography, geology, geomorphology, land capability, vegetation, and include information and meteorological studies, field visits, and the prevailing wind direction in the form of desert and question naires were completed and work units to people in another way - specific preparation, IRIFR experimental model of wind erosion in each of the work units were defined the land to wind erosion susceptibility map was prepared using IRIFR and deposition potential temperature using the relationship between precipitation and sediment yield were obtained. After scoring each of the factors affecting wind erosion facies geomorphology (erosion) and the sum of given annual sediment production rates, the rate of erosion severity maps were produced in ArcGIS environment. Soil erosion severity and sedimentation of the area, were obtained nine factors affecting wind erosion scores are considered in five classes.

The results showed erosion class I (very little) with an area of ​​about 11287.21 acres more land erosion. This erosion class is includes geomorphological facies 1-1-2 (water erosion on the erosion piedmont) and 1-2-2 (water erosion on the apandajz piedmont). and class IV (erosion) with an area of ​​6682.45 acres, is the second largest in the area. This erosional class also includes geomorphological facies detachement region - farm lands – fine desert pavement and the stream. Among stream geomorphologic facies (5-3-2) and arable land (2.3.2) have the most the highest amounts of precipitation.

Wind erosion in the miandasht region,  include 8 erosional form and severity of erosion stream facies, etachement region, farm lands and fine desert pavement have high erosion rates. Topography is flat and low-slope land in the north eastern parts of the area where directly affected by the prevailing winds, led to the destructive power of wind improve. One of the best ways to combat wind erosion in the area around the farm and out carminative Miandasht construction area of agricultural land around the study area and the direction of the prevailing winds in parts of the east, the north east is. The study area of wind erosion control perspective is a set of constraints and capabilities. Fine tissue silt abundant salts in the soil and reduces adhesion of soil particle aggregate structure fragmentation and reduce the threshold velocity of wind erosion in the region and the area are prone to erosion. Existence drought resistant species such as Haloxylon prsicum Artimisia sp. in the region can be developed that will help to control wind erosion.

We can identify the flood not only considering circulation pattern in occurring day but also by studying circulation pattern a few days before fresh event. This subject has mutual approach. In one hand, it indicates  that circulation patterns which were before flood event have important role in determining the conditions and moisture content of studied area and playing the fundamental role in few coefficient of region because it determines the previous moisture. On the other hand, it indicates that we should tracking the rain-genesis synoptic systems from source to end place of their activity for studying floods and their meteorology factors which have created them. By this way, we can acquire more comprehensive recognition about the relationship between circulation pattern and floods. In the other words, the identification of synoptic patterns that have created the flood reveals not only the mechanism of their emergence but also is useful for prognosis and encountering with them. The extensive researches have been accomplished about Inundation in the world and Iran, but Iran haven’t much antiquity about synoptic researches. For foreign researches, we can name researchers such as Hireschboeck (1987), Kutiel et al(1996), Komusce and et al (1998), Krichak  and et al (2000), Rohli and et al (2001), Kahana (2002), Teruyuki Kato(2004), Ziv and et al (2005), Carlalima and et al (2009). The numerous researchers have studied the Inundation climatology in internal of country such as Bagheri (1373), Ghayour (1373), Kaviani and Hojatizadeh (1380), Moradi (1380), moradi (1383), Mofidy (1383), Masoodian (1384), Masoodian (1384), Hejazizadeh et al(1386), Parandeh Khozani and Lashkari (1389). In this research, we considered the heavy precipitation of Azar 1391 in southwestern of Iran that resulted in flood phenomenon in the cause and effect manner so that can do necessary prevention actions before occurring the flood for preventing the probable damages and optimal use of precipitations by forecasting the patterns that have created the flood.

In this synoptic study, we need to two database: one group is variables and atmospheric data consisting of geopotential height of 500 hpa level (in meter geopotential), zonal wind and meridional wind (in m/s) and special humidity (in gr/kg) during this times 00:00, 06:00, 12:00 and 18:00 Greenwich in 0-80° northern and 0-120° eastern with local resolution of 2.5*2.5 Arc that have been borrowed from database of (NCEP/NCAR) dependent to National Atmosphere and Oceanography Institute of USA, and other group is daily precipitation data of region rain gauge stations during 4-8^th Azar of 1391 (24^th November – 28^th November 2012). In continuation. By applying the environment- circulation approach, we took action to drawing circulation pattern maps of 500 hpa level, thickness of atmosphere patterns of 500-1000 hpa and moisture flux convergence function from 4-8^th Azar of 1391 (that for calendar, conform with 48 hours before beginning the showery precipitation until ending the storm activity) by using data which obtained from database of NCEP/NCAR and the synoptic conditions of above flood have been studied and interpreted in the region.

Flood is one of the most destructive natural hazards that have imposed and impose many damages to people during the history. Hence, the final aim of this research is to explain the key interactions between atmosphere and surface environment and in other words exploration of the relationship between circulation patterns leading to the flood generating precipitation in the southwestern of Iran for forecasting the time and intensity of showers occurrence that lead to flood. For this purpose, by applying environmental-circulation approach, the circulation patterns identified and studied which resulted in flood generating precipitation. The result of this research indicated that torrential precipitations in the region have formed the deep trough in days 4-8 of Azar on the east of Mediterranean and the studied region placed in the east half of this trough that is the location of atmosphere instability. At same time, thickness patterns, indicate the flux of cold air from northern Europe to lower latitudes and spreading the warm air of north of Africa to latitude 50° northern. As a result we expected the frontal discontinuity in the encountering place of these two air mass. Analysis of the moisture flux convergence patterns also indicated that torrential precipitations were the result of moisture flux from Mediterranean and Persian Gulf; and Red Sea and Arab Sea taken into account as reinforced sources.