List of Articles Aerial photos

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  1 - Identification of Erosion Severity Area with Study of Fargas Model (Case Study: Sangab Drainage Basin- Iran)
  H. Ahmadi A. A Mohammadi
  In order to identify critical sediment sources in large catchments, using easilyavailable terrain information at regional scale, a methodology has developed to obtaina qualitative assessment necessary for environmental management. So it has been triedto study and used F More

  In order to identify critical sediment sources in large catchments, using easilyavailable terrain information at regional scale, a methodology has developed to obtaina qualitative assessment necessary for environmental management. So it has been triedto study and used Fargas and etal, method in this research. This has been done in oneof the sub-basins of Hable Rood basin called Sangab with an area of 7684.71 hac inNE Iran, arid and semiarid climate of Iran. The main objective of this model is to usebasic terrain data related to the erosive processes that contribute to the production,transportation and accumulation of sediments through the main water paths in thewatershed. This model is based on the selection of homogeneous zones regardingdrainage density and lithology, achieved by joining the basic units by a rating system.The values of drainage density are rated according to an erosion class. The lithology israted by erosion indexes, adapted from FAO (1977). The combination andreclassification of the results brings about five qualitative classes of sediment riskaccording to Fargas and etal (1997). The privileges of this method is, it used only twomain factors of the erosion, that are lithology and drainage density, and this factors arein our geologic and topographic maps in Iran. The mapping scale was 1:50000 and themodel were implemented through a vector GIS (Arc GIS9.2). The tested methodologyhas been proved useful as an initial approach for erosion assessment and soilconservation planning at regional level and also to select priority areas where furtheranalyses can be developed and finally for environmental management. Manuscript profile
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  2 - Investigation of effective factors and proposed model for define potential gully head advancement (study area: Hableh Roud drainage basin)
  . H Ahmadi . A. A Mohammadi جمال Ghodousi. علی Salajegheh.
  Gully erosion is one of the most complicated and destructive kinds of watererosion. In order to prevent this erosion, the important factors of gully headadvancement must be recognized. For this case, this research has been done in one ofthe sub basins of Hable Rood drai More

  Gully erosion is one of the most complicated and destructive kinds of watererosion. In order to prevent this erosion, the important factors of gully headadvancement must be recognized. For this case, this research has been done in one ofthe sub basins of Hable Rood drainage basin with name’s of Dehnamak in arid andsemiarid weather. Then, effective factors of gully head advancement of four models:Thompson, SCS(І), SCS(ІІ) and FAO, that are: gully head cut watershed area, claypercentage amounts, gully bottom slope percentage and other factors such as solublesalts percentage, silt percentage amounts and sand percentage amounts have beenminded. Meaning amount of each effective factor with gully head advancementamounts in stage of 95% in period of time 1956 to 2005 studied.Result of statistical studies shows, factors such as gully head cut watershed areawith correlation coefficient of 0.98, soluble salts percentage with correlationcoefficient of 0.97 and clay percentage amounts with correlation coefficient of 0.96,intermittently have a most meaning in stage of 0.95. After this, model with usingeffective factors, above mentioned, and SPSS software and two methods, Enter andBackward formed. Then, potential of gully head advancement in following years in theway of comparison estimated amounts by models and measure amounts by aerialphotos studied. Finally with regards to minute difference of 0.001% between twomethods Enter and Backward, Backward method proposed. Manuscript profile
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  3 - Investigation of the variations of middle zagros forests area between using aerial photo interpretation and use of GIS (case study: Kaka Reza region of Lorestan province)
  آرش Derikvandi مهری Khosravi مجتبی Taseh امین Heidarpour Monfared
  Abstract: This study cognitional changes area and accumulation in various gradients and altitudes of these forests is studied via aerial photos in 1955 (1:55000) and in 1997 (1:40000). For this purpose, geometric corrections are done as the movement correction issued More

  Abstract: This study cognitional changes area and accumulation in various gradients and altitudes of these forests is studied via aerial photos in 1955 (1:55000) and in 1997 (1:40000). For this purpose, geometric corrections are done as the movement correction issued from ups and downs on the pictures taken in the air is performed, then the forest frontier localities are fixed through sight inter pretation and thickness layers of canopy was appointed in a dotted network with the width of 2 millimeters. The frontier line of separated layers is drawn in Arcview software in the form of closed polygons and the area of these polygons are measured separately. Then any changes in area of these polygons in every stage of photographs are compared through software and the layer changes of the thickness of canopy are provided. Then, the prepared gradient and altitude maps in the three classes in ArcView software and from combining each of these maps with density map in the years 1955 and 1997, the forest changes were found in different classes of gradient and altitude. Results shows that the bulk density of the forest in classes of dense (F1) and semi-dense (F2) is with most of the area in gradient class (30-60 %) and the lowest is in the area of gradient class (more than 60 % ). But the class of sparse density (F3) is with most of the area in gradient class (30-60 %) and the lowest is in the area of gradient class (0-30 %). In addition, results shows that the surface dense density classes (F1) and semi-dense (F2) and sparse (F3) possess is with most of the area in altitude (1700-2000 m) and the lowest is in the area of altitude class (more than 2000 meters). Manuscript profile