Davood Nikkami; Samad Shadfar
Abstract
Soil, as one of the components of any ecosystem and an important source of food production, has a very serious role in the continuation of human life. Therefore, the need to support and protect the soil and prevent its erosion is essential. Regarding the amount of soil erosion and sediment yield in the ...
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Soil, as one of the components of any ecosystem and an important source of food production, has a very serious role in the continuation of human life. Therefore, the need to support and protect the soil and prevent its erosion is essential. Regarding the amount of soil erosion and sediment yield in the country, different figures have been mentioned and in some studies, the difference is with several times. These figures vary from less than one to more than five billion tons per year. Therefore, calculating and plotting erosion and sedimet yield maps provides important information that is used in the design of dams, reservoirs, canals, soil protection operations, onsite and offsite erosion damage assessment, and land use planning and land capability assessment projects. Soil erosion map is one of the basic, scientific and applied maps in various executive, research and educational sectors. Due to the need of determining the amount of soil erosion and sediment yield for the entire country and determining the executive priorities in areas with high soil erosion potential, this project was defined and carried out by the Soil Conservation and Watershed Management Research Institute. Accordingly, the watersheds of the seventh category were divided into seven regions or districts, including 1) Eastern Alborz 2) Middle Alborz 3) Western Alborz 4) Central Iran 5) North Zagros 6) Middle Zagros and 7) South Zagros. Long-term sedimen data of 118 hydrometric stations in these areas were analyzed and the amount of sediment in each station was determined by the logged mean load within discharge classes method. According to the amount of river bedload rates and using EPM model, the amount of sediment yield and cosidering sediment delivery ratio of watersheds, the amount of soil erosion were etermined and the soil erosion map of watersheds overlooking hydrometric stations was prepared. Results showed that the average sediment yield and soil erosion in the watersheds overlooking hydrometric stations are 3.3 and 16 tons per hectare per year, respectively. The lowest and highest soil erosion rates of 9 and 32.4 tons per hectare, belong to the Middle Zagros and South Zagros regions, respectively.
Jamal Mosaffaie; Davood Nikkami; Amin Salehpour Jam
Abstract
In order to achieve sustainable development, planning an appropriate management program is essential. Watersheds are the main units of land management and the main objective of this paper is to review the history, current status and future management needs of these units in Iran. For this purpose, the ...
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In order to achieve sustainable development, planning an appropriate management program is essential. Watersheds are the main units of land management and the main objective of this paper is to review the history, current status and future management needs of these units in Iran. For this purpose, the concepts of watershed and watershed management were explained and organizational structure, activities and current approach to watershed management have been investigated. Four case studies of the approach and practices of watershed management in Iran and abroad were also mentioned (two internal samples and two external). The historic course of watershed management in Iran indicates that signs of changing approach are ongoing from a traditional mechanical to the systemic management approach. As a general conclusion for improving integrated management of watersheds in Iran, some suggestions were offered as follow: improving the current organizational structure of watershed management and establishing committees called watershed council, considering the scale of the watershed, applying a united and appropriate watershed management model, shifting the attitudes from technical engineering to managerial approaches toward the nature of watershed management, watershed participatory governance and establishing an unitary and coherent organizational structure.
Jamshid Yarahmadi; Davood Nikkami; Ali Shahnavazi; Mohammad Ebrahim Sadeghzadeh
Abstract
Watershed residents' benefit increasing and soil erosion controlling are the main goals of agricultural sustainable development. Landuse optimization operation is an effective solution in order to maximizing the benefits, as well as minimizing soil erosion damages. Current research was executed in southern ...
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Watershed residents' benefit increasing and soil erosion controlling are the main goals of agricultural sustainable development. Landuse optimization operation is an effective solution in order to maximizing the benefits, as well as minimizing soil erosion damages. Current research was executed in southern parts of Ahar Chaey Watershed in East Azerbijan Province. In this research, Multi-Objective linear programing based on Simplex method applied for optimizing landuse in form of three different scenarios: current landuses, implementation of management into current landuses and performance of the standard landuses by WinQSB software. Results showed that due to landuse optimization, irrigated orchards could be increased from 1.736 to 6.629 km2. In addition, based on suitable soils and adequate rainfalls, it is expected to expand the rainfed orchards up to 9.72 km2. Also, the weighted average of soil erosion reduces from 16.3 to 14.8 and from 10.11 to 9.5 tha-1year-1 within the first and second scenarios, respectively. This rate will reduce up to 6.8 tha-1year-1 in the standard landuse situation. On the other hand, maximizing results showed that the annual net benefits increases from 6.6 to 12.9 and 8.46 to 14 million Rails per unit area in the first and second scenarios, respectively. This rate increases up to 15.67 million Rails per unit area for standard landuse situation. Sensitivity analysis results showed that irrigated and rainfed orchards are of high sensitivity in maximizing profit functions due to high profitability of these landuse in unit area. In contrast, the rangelands, forests and drylands are of high sensitivity in soil erosion minimization, so that with increasing their area, soil erosion will increase significantly in the region.
Abolghasem Dadrasi Sabzevar; Davood Nikkami
Abstract
One of the most important factors of soil erosion is the improper use of lands according to their potencial. According to sosio-economic factors of watershed, it is impossible to reduce the amount of soil erosion in the rate of natural erosion, but, it can be reduced, through integrated watershed ...
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One of the most important factors of soil erosion is the improper use of lands according to their potencial. According to sosio-economic factors of watershed, it is impossible to reduce the amount of soil erosion in the rate of natural erosion, but, it can be reduced, through integrated watershed management. Soil loss mitigation while having high productivity is possible by appropriate land use and land capability. In this research, Sheshtamad catchment of Khorasn Razavi Province was selected for determining the optimal level of land use and the effect of correct methods of management on maximizing net income of residents and minimizing the effect of soil erosion. Multi-objective linear programming model and simplex method were used in three different scenarios of 1) current land use conditions with current land management, 2) current land use conditions with improved land management, and 3) Standardized land use condition. The amount of net income and soil erosion were computed in rangelands, orchards, wooded ranglands, dry-lands and irrigated lands in all three scenarios and then the area of each land use was optimized, using optimization software. Results showed that land use optimization in Sheshtamad Watershed, decreases soil erosion, and increases total net income, although the amount is small, because of the conditions studied. The amount of annual soil erosion was reduced by 0.08%, 0.36%, 0.75% and the amount of annual net income was increased by 3.12, 20.88 and 313.75 thousand Rials, respectively, in the above three different scenarios,. The results also showed that in the case of some propoer management practices, the soil erosion reduces by 3.25 times and net income increses by 6.7 times.
Reza Sokouti; Hamidreza Peyrowan; Davood Nikkami; Mohammadhossein Mahdian
Abstract
Considering to high distribution of the marly lands in west Azarbaijan province and high sediment yield of such lands, in this research, the relation among the form and the rate of erosion on marls with their erodibility properties were studied. So marly regions of province with the special properties ...
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Considering to high distribution of the marly lands in west Azarbaijan province and high sediment yield of such lands, in this research, the relation among the form and the rate of erosion on marls with their erodibility properties were studied. So marly regions of province with the special properties were recognized and soils were sampled. Soil erodibility indices were determined and analyzed by statistical methods considering the form and the rate of erosion. Also portable rain simulator were used to study of the runoff and sediment yield potential of such soils. Finally the factors affected the soil erodibility were determined by variance analysis. Results showed erosion rate could be classified as moderate. Gully erosion had highest number in Gara-agaj and Gara-tape areas whereas rill erosion had high number in all area of marlly lands. Surface runoff volume ranged between 255 to 577 cm3 in Shabanlu and surface runoff coefficient 0.23 to 0.53 in Gara-tapeh. Maximum yielded turbidity was 180 gr/lit in Gara-Agaj area. Clay ratio was the effective factor to gully form and Surface runoff volume also was the factor to form surface and rill erosion.
Jalal Barkhordari; Davood Nikkami; Mohammadbagher Samadi; Monirosadat Tabatabaeizadeh
Abstract
Rainfall erosivity is one of the most important factors in determining soil erosion. This factor is usually expressed as erosion indices that are based on rainfall characteristics. In this study, after construction of 12 runoff-sediment plots in Nir Research Station in Yazd province, the amount of runoff ...
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Rainfall erosivity is one of the most important factors in determining soil erosion. This factor is usually expressed as erosion indices that are based on rainfall characteristics. In this study, after construction of 12 runoff-sediment plots in Nir Research Station in Yazd province, the amount of runoff and sediment from each plot were monitored and measured for 12 rainfall events. Then, based on a world wide literature review, 61 rainfall erosivity indices were identified. The rainfall erosivity indices were determined for each of the storms with extracting the required parameters. In order to determining suitable rainfall erosivity indices, the correlation between the rainfall erosivity indices and soil loss values were determined. The results showed that PI602, PI302, RPI602, RPI302, RI60 with 0.730, 0.713, 0.703, 0.694 and 0.664 percent had highest correlation with soil loss amount. Generally, in the climatic condition of study area, the indices based on rainfall intensity with total amount of rainfall multiply in the square of 60 and 30 minutes rainfall are better than other indices.
Davood Nikkami; Mohammad Hossein Mahdian
Abstract
Rainfall erosivity as one of the major factors of soil erosion is expressed as indexes. The objective of this study is determining the appropriate rainfall erosivity index in Iran and generalizes it by its estimation from more readily available indexes to stations without rainfall intensity data and ...
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Rainfall erosivity as one of the major factors of soil erosion is expressed as indexes. The objective of this study is determining the appropriate rainfall erosivity index in Iran and generalizes it by its estimation from more readily available indexes to stations without rainfall intensity data and to determine the most accurate interpolation method for preparation of its map. For this reason, necessary data were collected from seven soil erosion research plots in Western Azerbyjan, Khorasan Razavi, Zanjan, Semnan, Mazandaran, Markazi, and Yazd provinces, respectively. The rainfall intensities were recorded, as was the sediment yield associated with storm events, and 64 different erosivity indices based on rainfall intensity were computed for these soil erosion research stations. Our founding shows that were the best correlated with sediment than other erosivity index. Further, rainfall erosivity indices, based on the amount of rainfall, were also computed for all soil erosion research plots and synoptic and climatic stations. The results showed that the modified Fournier index had a significant correlation with After normalizing the primary data, semi-variograms were determined and the best model was obtained. Then, different interpolation methods were compared and spline was chosen for drawing the rainfall erosivity map. The output map showed a decreasing trend from west and north to east and south of the country and this trend was correlated with climatic change from humid to semiarid regions.
Hossein Eteraf; Mohammadali Dorri; Davood Nikkami
Abstract
Abstract Soil erosion is one of the most obvious factors of soil degradation. Vegetation can affect on maintaining soil fertility and the amount of soil loss by reducing runoff and sediment. This study was conducted in Maraveh-Tapeh in the north-eastern part of Kalaleh watershed, located in 55◦ 56' ...
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Abstract Soil erosion is one of the most obvious factors of soil degradation. Vegetation can affect on maintaining soil fertility and the amount of soil loss by reducing runoff and sediment. This study was conducted in Maraveh-Tapeh in the north-eastern part of Kalaleh watershed, located in 55◦ 56' 35" and 37◦ 49' 01" to investigate the role of plant species on soil stability with in a randomized complete block design with five treatments and three replications. Crop and pasture plants as herbal treatments were included Medicago sativa, Agropyron elongatum, Cyminum cuminum, Hordeum vulgare and a mixture of alfalfa and Agropyron. Plots were considered to have a 22 m long on slope direction (10%) by a wide of 5 meters. Runoff and sediment collecting tanks were installed at the bottom end of each plot to measure runoff and sediment. In this study the effect of cultivated plant species on the amount of soil erosion and fertility was investigated. The average volume of runoff during four years of executing the project was 6.93 and 22.9 m³ha-1in treatments of Hordeum vulgare and Cuminum cyminum, respectively. The average amount of sediment yield was 48.42 and 124.72 kgha-1 in treatments of mixed Medicago sativa and Agropyron elongatum and Cyminum cuminum, respectively. Results also demonstrated that Cyminum cuminum is not an appropriate species for cultivation on steep terrains with the aim of soil conservation due to its reverse effects on increasing runoff and reducing soil fertility in Maraveh-Tapeh.
Davood Nikkami; Reza Sokouti Oskuee; Ebrahim Brooshkeh; Faniz Heshmati
Abstract
Eroded soil particles within watershed areas are transported in three shape of dissolved, suspended and bed loads by river water discharge. Knowing the amount of suspended and bed loads are necessary in estimating sediment yield of watersheds. Usually, suspended load is measured daily in hydrometric ...
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Eroded soil particles within watershed areas are transported in three shape of dissolved, suspended and bed loads by river water discharge. Knowing the amount of suspended and bed loads are necessary in estimating sediment yield of watersheds. Usually, suspended load is measured daily in hydrometric stations, while this does not happen for bed load. Although, there are many differences between geology formations, rainfall intensities and water discharges of watersheds, the amount of bed loads are considered as a constant unique coefficient of suspended load. So, there would be highly errors in watersheds’ sediment load estimates. In this research, after collecting bed and suspended load data of three hydrometric stations of Badlan on Alandchay, Pol Yazdakan on Ghotourchay and Mazraeh on Baroonchay Rivers in Western Azerbaijan, the data were analyzed and best relations were fitted between bed load and suspended loads. According to statistical analysis all data had high coefficient of correlation at the level of 99 percent and the best equations were chosen accordingly. The ratio of bed to suspended load in Yazdakan, Badlan and Mazraeh stations were 79, 49 and 13 percent, respectively. This ratio was 47 percent for all three stations.
Ali Jafari; Davood Nikkami; Esmail Abbasi; Fateme Tavakoli Rad
Abstract
Improper land use management has inverse impacts on available resources. To reduce these environmental and economic effects of soil erosion, there is a need for proper watershed plans. Land use optimization is of the solutions for achieving sustainable development and reducing the loose of resources. ...
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Improper land use management has inverse impacts on available resources. To reduce these environmental and economic effects of soil erosion, there is a need for proper watershed plans. Land use optimization is of the solutions for achieving sustainable development and reducing the loose of resources. The main objective of this research was determining the optimal level of land use to increase the income of residents and reducing the effect of erosion in the Sana Dam Watershed. To apply an optimal pattern of land used for minimizing soil erosion and maximizing land income by a multi-objective programming model, optimal scenarios were chosen proportion to the shape of objective functions and constraints. For this purpose a linear programming model was used for three different scenarios of a) present land use conditions b) present land use condition with some applied land use management and c) standard land use conditions according to principles and scientific criteria. The results showed that present land use is not in optimal level and should be changed. Also, results demonstrated that the amount of soil erosion could be decreased by 5.3, 31.7 and 43.4 percent and the amount of net income could be increased by 47.73, 242.57 and 242.57 percent by land use optimization in present land use conditions, present land use condition with some applied land use management and standard land use conditions, respectively.
Ali Akbar Davoodirad; Davood Nikkami; Mehdi Mardian
Abstract
Increasing in production and welfare of rural household along with soil erosion mitigation are the most important objects of a watershed management program. Land use optimization is an efficient approach that leads to a sustainable development plan. In this research, the land use optimization was applied ...
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Increasing in production and welfare of rural household along with soil erosion mitigation are the most important objects of a watershed management program. Land use optimization is an efficient approach that leads to a sustainable development plan. In this research, the land use optimization was applied using a two-objective linear programing model and geographic information systems by Lingo 11.0 software in Adineh-Masjed Shahzand watershed of Markazi province, Iran. The model was defined with three scenarios of current conditions, applying management conditions, and standard conditions for two objectives of maximizing net benefits and minimizing soil erosion. Results showed that the annual soil erosion decreased by 1.27, 18.69 and 26.93% in current land use, land use management, and standard land use conditions, respectively. Also annual net income decreased by 18.56% in current land use; but increased by 48.01 and 220.07% in land use management and standard land use conditions, respectively. Considering weighting value of decreased soil erosion of 1.27% that is less than weighting value of decreased net income in current conditions, land use optimization with no management practices or land standardization is not justifiable.
Davood Nikkami; Hadi Chamheydar; Mohammad Hossein Mahdian; Ebrahim Pazira
Abstract
Environmental and economic impacts of soil erosion are due to improper land management in a watershed. Although it is impossible to stop soil erosion completely under natural conditions, there is a great need to control erosion for proper land use planning. According to the scarcity of literature in ...
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Environmental and economic impacts of soil erosion are due to improper land management in a watershed. Although it is impossible to stop soil erosion completely under natural conditions, there is a great need to control erosion for proper land use planning. According to the scarcity of literature in the area of soil nutrient evaluation with optimization models, the main objective of this research is determining the optimum level of land uses to minimize soil erosion and nutrients losses and maximize people incomes that live in a watershed. For this purpose, Abolabbas Watershed in the north-eastern part of Khouzestan Province was chosen for this research. A linear programming model was used in three different scenarios including current land use condition without land management, current land use condition with land management and standardized land use condition. Results demonstrated that the current land uses are not optimized for the least soil erosion and nutrient losses and high income. At optimized conditions, the area of forests and orchards increased by 1.81 and 55.7% respectively, rangelands with no changes, and irrigated and drylands decreased by 67.5 and 31.4% respectively. Also, results showed that land use optimization, in current land uses with no land management, decreases total soil erosion by 3.2% and total nutrient soil losses by 2.5 and increases total income by 29.7%, in current land uses with land management, decreases total soil erosion by 35.3% and total nutrient soil losses by 70.2 and increases total income by 37.2%, and in standardized land uses, total soil erosion by 47.2% and total nutrient soil losses by 70.4 and increases total income by 41.8%. Sensitivity analysis, also, showed that the change in the area of orchards and Irrigated lands has the most effects on increasing income and decreasing soil erosion and nutrients losses in Abolabbas watershed.
Farzad Bayat Movahhed; Davood Nikkami; Mohammad Tokasi; Parviz Moradi; Hamideh Daghigh
Abstract
In arid and semi-arid regions the precipitation occurs erratically, and often, with high intensity which causes sediment production and soil loss especially in the areas ploughed parallel to the hill slope direction. In such areas, we can reduce those undesirable effects through employing proper management ...
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In arid and semi-arid regions the precipitation occurs erratically, and often, with high intensity which causes sediment production and soil loss especially in the areas ploughed parallel to the hill slope direction. In such areas, we can reduce those undesirable effects through employing proper management method. In this survey the effect of two treatments of applying straw mulch in standard plots and over three slope classes of 0-12, 12-20, and 20-40 % with three replicates in the split plot format on the base of RCB design were compared. In all plots, the parallel plough to slope direction was done. After wheat cultivation, on the half of plots, straw mulch was applied uniformly by hand on the soil surface. After any rainfall events, the amount of sediment was measured. Results showed that application of straw mulch caused a reduction of about 36.9, 10.8, and 55.4 % soil loss in three slope classes compared to the plots without mulch application respectively. These amounts for organic carbon loss were 33.2, 7.1, and 29.43 %. Statistical analysis by SAS software showed that difference between two treatments for sediment and Organic Carbon was significant at 5% probability. These results show that straw mulch application can highly increase the infiltration and water absorption and reduce soil and O.C. loss. Also, it can prevent the reduction of soil fertility through reducing organic material loss.
Ali Mohammadi Torkashvand; Davood Nikkami; Mehrdad Esfandiari; Seyed Kazem Alavipanah
Volume 2, Issue 3 , October 2010, , Pages 150-160
Abstract
Rill erosion map is one of the basic maps in erosion and sediment studies and also watershed management programs. Some methodologies for preparing rill erosion map (1:250000) by using RS and GIS were compared in a research carried out in Kan-Sologhan and Jajrood sub-basins in North-west and North-east ...
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Rill erosion map is one of the basic maps in erosion and sediment studies and also watershed management programs. Some methodologies for preparing rill erosion map (1:250000) by using RS and GIS were compared in a research carried out in Kan-Sologhan and Jajrood sub-basins in North-west and North-east Tehran, Iran. At the first phase, four working units' maps were prepared by integration of a) plant cover, geology and slope b) land use, geology and slope c) land use, rocks sensitivity to erosion and slope and d) land use, rocks sensitivity to erosion and land units’ layers in Kan-Sologhan basin. For comparing the efficiency of four working units’ maps, 53 ground control points were investigated. Results showed that map "d" was better than "a", "b" and "c" in providing rill erosion regarding economic and executive considerations. At the second stage, map "d" was compared with three maps of e) land units f) rocks sensitivity to erosion and g) satellite image photomorphic units (ETM+ images) in a broader basin of Jajroud. Rill erosion intensities in 314 ground control points were controlled and ground truth rill erosion map was prepared. Rill erosion map was crossed with different working unit maps where results showed that the highest accuracy is related to the images interpretation (81.0% accuracy). Accuracy was 78.4, 66.8 and 59.9 percent for methods of "d", "e" and "f", respectively. Root Mean Squared Error was the highest for map "f" and the least for integrated layers method (map "d"). The greatest precision is related to image interpretation and the images interpretation method is better than other methods in preparation of rill erosion map.
Davood Nikkami; Peyman Razmjoo; Farzad Bayat Movahed
Volume 2, Issue 2 , July 2010, , Pages 65-72
Abstract
The amount of water erosion is basically related to rainfall erosivity and its consequent runoff. In soil erosion and sediment yield models, intensity and energy of rainfall are mostly considered. In this research, some parameters such as the amount of rainfall, maximum intensity and energy in different ...
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The amount of water erosion is basically related to rainfall erosivity and its consequent runoff. In soil erosion and sediment yield models, intensity and energy of rainfall are mostly considered. In this research, some parameters such as the amount of rainfall, maximum intensity and energy in different basic times are correlated to the amount of runoff and sediment outflow from erosion plots to investigate rainfall erosivity index. For this purpose two years of precipitations of Sohrain-Gharacharian flood spreading research station were monitored by recording raingauge. During 2003-2004 period, two plough treatments of parallel and perpendicular to slope direction on three slope classes of 0-12, 12-20, and 20-40 percent with three replicates and randomized complete block design were studied under regional wheat planting and fallow conditions in 1.8x22 sq. meter erosion plots. The correlation between the amounts of runoff and sediment, as dependent variables, resulted from 12 rainfall events and the amounts of rainfall, maximum 1, 5, 15, 30, 60 and 120 minutes of rainfall intensity, rainfall energy and rainfall erosion index, as independent variables, computed by different methods were analyzed with the SPSS V11. Two variables of the amount of rainfall and the maximum rainfall intensity in different base times had the maximum correlation with the amount of runoff and sediment at the levels of 99 to 95 percent.
Farzad Bayat Movahed; Davood Nikkami; Hassan Shami
Volume 1, Issue 4 , February 2010, , Pages 275-279
Abstract
In arid and semi-arid regions, operating the plough on slope direction, specially, in rain falling with more intensity, results in soil loss and erosion. In such areas, undesirable effects can reduce with operating suitable management. For this purpose, the effect of perpendicular plough to slope direction ...
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In arid and semi-arid regions, operating the plough on slope direction, specially, in rain falling with more intensity, results in soil loss and erosion. In such areas, undesirable effects can reduce with operating suitable management. For this purpose, the effect of perpendicular plough to slope direction and application of straw mulch in 1.8 * 22.1 meter erosion plots on three slope classes of 0-12, 12-20, and 20-40 percent with 3 replicates and RCB design in two different years were tested in Sohrain floodwater spreading research station. In the half of plots in 2003, the perpendicular plough to slope direction and in the others, plough on slope direction were operated. In 2005 at first, the plough on slope direction was done in all of the plots and then, straw mulch were used after wheat cultivation in half of plots. During the study period, the amount of soil loss was monitored after any rain fall by the tanks that located at the end of each plot. The results showed that operating of perpendicular plough to slope direction reduced soil loss about 10.1, 11.5, and 10.4 time relate to parallel plough to slope direction. Also, application of straw mulch reduced 36.9, 10.8, and 55.4 time relate to mulch application in three slope classes respectively. These results show that both perpendicular plough to slope direction and straw mulch application can reduce soil loss and thus, increase the infiltration rate and soil fertility.
Mohammad Hemmati; Davood Nikkami; Hassan Ahmadi; Gholamreza Zehtabian; Mohammad Jafari
Volume 1, Issue 1 , May 2009, , Pages 21-31
Abstract
Soil is one of the four elements of life and one of the most important agricultural and rangeland production factors. Soil erosion has impact on fertility of upstream lands and indirectly causes downstream damages. On a global scale, more than 50% of rangelands and about 80% of farmlands are significantly ...
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Soil is one of the four elements of life and one of the most important agricultural and rangeland production factors. Soil erosion has impact on fertility of upstream lands and indirectly causes downstream damages. On a global scale, more than 50% of rangelands and about 80% of farmlands are significantly suffering from soil erosion and sedimentation phenomenon. Despite of agricultural benefits of rainwater, its erosive energy in the primary stages, detaches soil particles and creates surface runoff which has the most severe impacts on soil erosion. The effective energy in this shape of erosion is called rainfall erosivity, which is rainfall erosion potential and depends on rainfall physical characteristics. Some different indices are developed for quantification of rainfall erosivity. Some indices emphasise on the amount of rainfall or rain intensity. Worldwide investigations show that applying a certain index, like EI60 in USLE equation has not sufficient credit and according to climatic condition the best rainfall erosivity index should be determined. In this research, after establishing 21 erosion plots in Kaboudeh Oliya village, Kermanshah city, on two land use types of dry farming of 6, 12, 16 and 17 percent slopes and rangelands on 25, 35 and 45 percent slopes with three repetitions, 15 rainfall events which produced surface runoff were monitored by a recording rain gauge and the amount of surface runoff and sediment were measured. According to the literature, 45 rainfall erosivity indices were chosen to be compared. For facilitating and increasing accuracy of calculations on rainfall erosivity indices, a computer program was developed to analyze and extract necessary factors from each storm. The result showed that in the study area, EI60 is the best rainfall erosivity index and has maximum correlation coefficient of 0.721 with soil loss.
