Gholm Reaza Rahi; A Kaviyan; K Soleimani; H Pourghasemi
Abstract
Creating a gully is a reaction to the geomorphologic conditions, this type of erosion extends over a wide range of environments, and the threshold of topography is related to the slope and drainage level and Controls the position and expansion of gullies in different uses. The slop-area equation as a ...
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Creating a gully is a reaction to the geomorphologic conditions, this type of erosion extends over a wide range of environments, and the threshold of topography is related to the slope and drainage level and Controls the position and expansion of gullies in different uses. The slop-area equation as a relationship between the slope and the upstream area of the watershed in any area will in part help predict gully erosion. The above relationship has been influenced by several factors including environmental conditions (climate, lithology, soil type), the type of land use, and the type of effective mechanisms for the creation and expansion of the gully (surface flow, sub-surface flow, dissolation, and piping), and the type of method used for extraction of slope - area is located. And this is the simplest formula used by two parameters to predict gully erosion. The results show that the value of the relationship between -0.233 and -0.205 was obtained. The equation for agricultural use was equal to Y = 5.7426X-0.205and for the pasture use equal to Y = 10.653X-0.233. In this equation, the power can be close but the coefficient of the equation is different. Gully erosion of the whole hinterland (farmland, agriculture) is expanding. The threshold of topography indicates a negative relationship between land area and slop in different kind of agricultural and rangeland. By reducing the slope, more area is needed for the development and expansion of the gully, and most of the gully is due to surface runoff.
Seyed Masoud Soleimanpour; Bahram Hedayati; Majid Soufi; Mohammad Javad Rousta; Samad Shadfar
Abstract
One of the important relations in the erosion of gullies is to study the threshold of erosion creation and expansion. In recent decade, creation of new knowledge in determination of relation between variables was led to develop prediction methods in different science and therefore, investigating the ...
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One of the important relations in the erosion of gullies is to study the threshold of erosion creation and expansion. In recent decade, creation of new knowledge in determination of relation between variables was led to develop prediction methods in different science and therefore, investigating the ability to use these methods in erosion and soil conservation is essential. Also, in order to control the erosion of the gully, the mechanism of gullies growth and its dimension expansion, especially increasing in gullies length, has to be carefully determine; for this purpose, the present study aimed to determine the threshold of the most effective factors on increasing the length of the gully, using the K-Means data mining algorithms and the CART decision tree in the Ghazian watershed in the north of Fars province. The results of this study, which include measuring various variables of gullies under field condition and in laboratory, and using data mining techniques, showed that increasing the length of gully in this area depended on the factors of the area above headcut, saturated extract electrical conductivity, forehead slope, canopy cover percentage, and sodium adsorption ratio. It is recommended control of erosion in the foreheads is highly important in reducing the increase in gullies length and sediment production. Also, improving the soils of this area with soil amendments and the restoration of compatible vegetation and the increase in soil organic matter should be considered as the priority of effective actions to control the increasing length of gullies.
ALIREZA Arabameri; khalil rezaei; mojtaba yamani
Abstract
Gully erosion is one of the erosive processes that mostly change the shape of the earth surface and has severe environmental and economic damages. The aim of this research is modeling between geo-environmental parameters effective in gully erosion and gully occurrence in the study area and gully erosion ...
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Gully erosion is one of the erosive processes that mostly change the shape of the earth surface and has severe environmental and economic damages. The aim of this research is modeling between geo-environmental parameters effective in gully erosion and gully occurrence in the study area and gully erosion susceptibility mapping using evidential belief function (EBF) data driven model in toroud watershed that has high susceptibility to gully erosion. At first, a gully erosion inventory map is prepared, using extensive field surveys and 80 gullies which have been identified, 70 percentage (56 gully location) randomly selected to modeling, while the remaining 30 percentage (24 gully location) are used to validation. In modeling, if there was high correlation among parameters, reduce accuracy of model, thus has done multi-collinearity test among independent variables. Tolerance and the variance inflation factor (VIF) are two important indexes for multi-collinearity diagnosis. Finally 15 parameters including geomorphological, geological, environmental and hydrological are selected for modeling. In evidential belief function model four relationships were calculated: belief (Bel), disbelief (Dis), uncertainty (Unc), and plausibility (Pls) and belief function are used for gully erosion susceptibility mapping. Area under the curve are used for model validation. According to results, EBF model with prediction rate (1) and success rate (0.959) had excellent accuracy and capability in identification of prone areas to gully erosion in study area. The results indicates that 21.79 percentage (90.84 km2) in study area located in high and very high susceptibility class.
sajad neisi; bizhan khalili moghadam; amin zorati pour
Abstract
Gully erosion is one of the aprogressive forms of soil degradation in ranges and agricultural lands which is a warning sign of land degradation and progressive erosion. Monitoring effective factors of gully length development over time is a necessity for sustainable development in watersheds. In this ...
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Gully erosion is one of the aprogressive forms of soil degradation in ranges and agricultural lands which is a warning sign of land degradation and progressive erosion. Monitoring effective factors of gully length development over time is a necessity for sustainable development in watersheds. In this research, the advancement of 30 headcuts were assessed through digital interpretation of multi-temporal aerial photos, photometric methods, field observations and GIS data analysis over two periods of 1964-1993 and 1993-2013, and its contribution to sediment suspended and bed load, using sediment balance model which was carried out on DarbKhazine basin. Moreover, the stepwise regression analysis procedure was applied to extract the effective factors on gully head advancement (such as topography, physio-chemical soil attributes and morphology of gully). The results indicated that the mean of gully head advancement over the periods of 1964-1993, 1993-2013 were measured 0.37, 0.65, respectively which implies on average, 77percent have increased. Further, regression analysis revealed by 9 main factors and R 95%, as themodel indicated among main factors, the Na, EC and organic matter factors with R2 , 0.83 and R , 0.91 leave the most effect on gully head advancement. The gully sediment balance showed that two-thirds and one-third of sediment discharge are formally suspended load and bed load, respectively. This topic is useful as a suitable criterion to distinguish active gullies in order to prioritize conservation activities.
Aliakbar Nazari Samani; Fatemeh Avazadeh Tavakoli; Hassan Ahmadi; Gholamreza Rahi
Abstract
Gully erosion is one of the most destructive types of channeled water erosion that removes aconsiderable volume of soil as it develops. This type of erosion consists of complex a geomorphicprocess that has been known as an indicator of accelerated soil erosion. In this research theadvancement of 25 headcuts ...
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Gully erosion is one of the most destructive types of channeled water erosion that removes aconsiderable volume of soil as it develops. This type of erosion consists of complex a geomorphicprocess that has been known as an indicator of accelerated soil erosion. In this research theadvancement of 25 headcuts were assessed through digital interpretation of multi-temporal aerialphotos, field observations and GIS data analysis over the two periods of 1967-1995 and 1995-2008.Moreover, the stepwise regression analysis procedure was applied to extract the effective factors ongully head advancement (such as topography, physico-chemical soil attributes and morphology ofgully). The results indicated that the mean of gully head advancement over the periods of 1967-1995,1995-2008 and the mean of two periods were measured 1.36, 1.23 and 1.3 m/y, respectively. Further,regression analysis revealed that headcut's contribution area, distance of gully-head to ridge, height ofgully head cut and SAR are the main factors on gully head advancement. Therefore, distance to ridge,headcut high and presence of plunge pool could use as suitable criteria to distinguish the active gulliesin order to prioritizing the conservation activities.
