Samad Shadfar
Abstract
One of the types of environmental hazards that causes the destruction of agricultural lands, rangelands and Infrastructure in many parts of the country is gully erosion. In this research, fuzzy logic operators were used with the aim of determining the different hazard zones,obtaining the area of each ...
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One of the types of environmental hazards that causes the destruction of agricultural lands, rangelands and Infrastructure in many parts of the country is gully erosion. In this research, fuzzy logic operators were used with the aim of determining the different hazard zones,obtaining the area of each one of them, and presenting the map of the gully erosion hazard in Troud watershed. In order to achieve this goal, satellite imagery, interpretation of 1:20000 scale aerial photos, 1:50000 scale topographic maps, 1:100000 scale geological maps, field studies and ArcGIS software have been used as the main research tools. To do this, at first, some of the effective variables which had more important roles in the formation and development of gully erosion, as well as the areas with gully erosion, were identified. In the next stage, the effective factor classes were weighted and the gully erosion map was prepared using fuzzy operators including fuzzy algebraic sum, fuzzy multiplication, fuzzy gamma 0.5 and fuzzy gamma 0.8 in the GIS environment.The results indicate that in the fuzzy algebraic summation method, 100% of the gully areas are located in very highclass, in the fuzzy algebraic multiplication, 83.29% of the gully areas are located in low class, in 0.8 fuzzy gamma method,60.93% of the gullies are located in low class and about 17 %are located in high and very high classesbut, in 0.5 fuzzy gamma method, around 1.5% of the gully areas are located in low class and about 62% are located in high and very high classes.
Saied Olfati; Khadijeh Moradi
Volume 23, Issue 89 , May 2014, , Pages 43-45
Abstract
Gully formation is always accompanied by erosion and land transformation which produce a significant amount of sediment, cause land degradation, destruction of roads and irrigation networks and dam overflow. Climatic situation of the area is one of the most influential elements in formation of gullies. ...
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Gully formation is always accompanied by erosion and land transformation which produce a significant amount of sediment, cause land degradation, destruction of roads and irrigation networks and dam overflow. Climatic situation of the area is one of the most influential elements in formation of gullies. The present article seeks to investigate gully erosion and formation of gullies in Dire basin in Gilan-e gharb which is one of the main agricultural centers of Kermanshah province. In this regard, 5 climatic indicators are applied. These indicators include hydrothermal coefficient, Ws coefficient or the amount of humidity in formations, Sepaskhah model, Arnoldos model, and second model of Fournier. Hydrothermal and Ws coefficients indicate high sensitivity and very high potential in gully formation. Moreover, the other third models which apply climatic factors to estimate the amount of produced sediments indicate that 27.24818 ton erosion has happened across the area. This volume of erosion plays a significant role in gully formation.
Mohammad Hossein Ramesht; Leila Gorjii; Mojgan Entezari
Volume 18, Issue 70 , August 2009, , Pages 16-19
Abstract
For more than half a century, soil erosion prediction and modeling technology has been used as a valuable tool in protective design, engineering plans and research development. This technology includes mathematical equations that calculate estimates of the dependent variables of erosion (soil losses, ...
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For more than half a century, soil erosion prediction and modeling technology has been used as a valuable tool in protective design, engineering plans and research development. This technology includes mathematical equations that calculate estimates of the dependent variables of erosion (soil losses, production and sediment) as a function of independent variables (four main factors: climate, soil, topography, and type of use). The parameters in these equations include exponential powers and coefficients that determine or modify the values of the independent variables as part of mathematical calculations, some of which are empirical values prepared according to basic data, while others have physical definitions associated with erosion processes. Mathematical symbols and logical sequence are among other features of mathematical models. In general, erosion mathematical models include regression-derived models, characteristic models, and process models. In addition to empirical methods, several mathematical models are presented concerning erosion, in all of which mass conservation law or the continuity equation are used as the controlling equation. These models include the dynamic and static models, the weep model, GULTEM and EGEM model, each of which is related to a particular type of gully and is applicable in certain conditions. Undoubtedly, the models introduced in this paper can not be considered as comprehensive models without any probable defects. Therefore, it is suggested that according to the climatic, geological, geomorphological, and ... characteristics, a suitable model be determined for assessing the rate of gully erosion in each region.
