سیدعلی اصغر هاشمی

Soil is one of the most important natural resources of any country, which plays a key role in food security, self-sufficiency in food production, national economy, and sustainable agriculture. Soil erosion is one of the most obvious factors of soil loss, and rain erosion is one of the most important forms of erosion. Therefore, the knowledge of the processes governing soil erosion and sediment transport is very important in water and soil resources management, as well as, the development of soil erosion models to achieve sustainable development is of great importance. Previous research has shown that rainfall patterns are one of the factors influencing rain erosion. Vegetation also reduces soil erosion by protecting the soil against the effects of raindrops and runoff. Rain erosion is especially important in arid and semi-arid areas due to the lack of vegetation and low initial soil moisture. This research was conducted, regarding the effect of rainfall patterns on rain erosion, by investigating the rainfall pattern and vegetation changes over 25 years in Ebrahim Abad and Royan watersheds situated in Semnan City. 

First, the physical characteristics of the watersheds were obtained; using ArcGIS software, and the precipitation information was extracted from the rain gauge sheets with an accuracy of 10 minutes. To compare the rainfall for different amounts of precipitation, the dimensionless cumulative rainfall curve of each event was obtained. The time of each rainfall was divided into 10 parts and the percentage of rainfall was determined for each part. The rainfall curve was divided into 4 quartiles (1st, 2nd, 3rd, and 4th quartiles) depending on the occurrence of the maximum precipitation. According to the information on the sediment layers in check dams located at the outlet of each watershed and the precipitation data, the storm-related to each sediment layer was determined and the effect of the storm pattern on the sediment pattern was investigated. To check the similarity of precipitation and sedimentation patterns in check dams, the average difference in precipitation and sedimentation in each time step and standard deviation changes were used. Considering the dynamic changes of vegetation compared to other characteristics of the watershed, remote sensing data were used to investigate the changes in vegetation and its area. Due to the effective performance and high accuracy of NDVI index and landsat satellite images in dry areas, Google Earth Engine system was used to estimate vegetation cover, manage and recall the satellite images. Then, the influence of watershed characteristics such as slope, area, soil type, shape factor, and vegetation cover on watershed sedimentation was investigated. 

The average similarities in precipitation and sediment pattern in Ebrahim Abad and Royan watersheds were 48.2 and 46.1%, respectively. Also, the percentage of coarse-grained sediments augments by increasing the precipitation quarter number, during each storm event, which shows the important role of the rainfall pattern on the sedimentation pattern in each watershed. The average monthly vegetation cover (obtained from Landsat images) in Ebrahim Abad and Royan watersheds during the mentioned period was 5.15 and 4.99%, respectively, which is less estimated than reported by previous research. In this research, a threshold limit of 0.1 has been used for the NDVI index, in which very weak vegetation has been omitted.

In both watersheds, in more than 51% of cases, by increasing vegetation cover in each storm event, the thickness of the corresponding sediment layer augments, which shows the effect of vegetation cover on the erosion and sedimentation of the watersheds.

Splash (raindrop) erosion plays an significant role in soil loss, especially in arid and semi-arid regions with poor vegetation. In this paper, by analyzing the pattern of rainfalls that occurred during 26 years in four basins located in Semnan County, their effect on the pattern of eroded sediments from the basin was investigated. Sedimentary layers from the sampling of retarding reservoir sediments in 2017 were related to the corresponding precipitations. Due to the occurrence of the highest amount of rainfall in each quarter of rainfall, rainfall hyetographs were divided into four categories. Cumulative precipitation curves with similar quartiles were drawn in one shape and compared with sediment curves and vice versa taking into account the physical characteristics of the basin. The results showed that the Aliabad basin (with less slope and more elongation) with an effective quarter of type 3 had the highest similarity in precipitation and sediment patterns. Also, the Western Soldereh basin (with the highest slope and the least elongation) with an effective quarter of type 2 had the least similarity in precipitation and sediment patterns. The results indicate the vital role of rainfall patterns on the resulting sediment patterns, which show up to 85% similarity.

Phytophthora species are a serious threat to plant products worldwide. Therefore, identifying them is the first step in finding a way to treat the disease. The aim of this study was to identify Phytophthora species causing root and crown rot of persimmon trees in Fars province.

Samples were taken from the crowns and roots of diseased persimmon trees, in the summer of 2018-2019. Infected root and crown tissues were cultured in CMA-PARPH medium. Isolates of Phytophthora species were purified by single spore method and morphological and molecular characteristics were used to identify them.

Six isolates were obtained from the roots of diseased persimmon trees and identified as Phytophthora citricola based on their morphological characteristics. Phylogenetic studies based on beta-tubulin (βtub) and 28S rDNA genes showed that all isolates (Iran-Pc1 to Iran-Pc6) were grouped into clade 2 with a validation scale of 100 and confirmed the identification of P .citricola.

This is a new report of persimmon root and crown rot caused by Phytophthora citricola in Fars Province.

Estimation of sediment bed load is one of the most important issues in river engineering. Accordingly, several methods and relations have been proposed to estimate the bed load in streams for the past decades. The present research aimed to select the most accurate method to estimate bed load through the testing of various relations to estimate the bed load of the Hablehroud River. The hydraulic and geometric specifications of the Hablehroud River at Bankouh hydrometry station were measured on specific dates by the expert team. The bed load rate was calculated by four different relations in Bankouh hydrometry station from 2011 to 2017. Resultant data showed that the Toffaletti method with RMSE, MAE, and R2 of 20.07, 10.86, and 83 estimates more accurate in comparison with other methods. The sensitivity analysis of the Toffaletti equation revealed that the bed load depends greatly on the velocity of the river flow. Such a method is firmly recommended to use in the mountainous region.

With passing the time and progress of civilization, access to sufficient and high quality water resources in order to provide the needs of human societies, is very important. With increasing impenetrable surfaces in urban areas and its resulting flood hazards, the new prespective of management methods of LID- BMPS has been considered in order to use surface runoff, decreasing peak discharge and preventing flood in urban areas on developed or developing parts. In this research, the effect of correction of channel dimensions, reservoir design for flood control and provision of required water for the green area and the use of LID facilities including implementation 100% of Permeable pavement for Sidewalks area and rain barrels in two conditions (using 100% of the surface of the roof) and (using 50% of the surface of the roof) on decreasing peak discharge and the volume of flooding 12 subbasing in the study area of Golestan settlement in Semnan city was evaluated using SWMM model. Finally, by using AHP- TOPSIS methods, rain barrels (using 50% of the surface of the roof) with about 81% reduction of peak discharge flood for the return period of deasining 5 year and 78% reduction of peak discharge flood for the return period of deasining 10 year have been allocated themselves the first and the last rank of correction of channel dimensions.

Kohrange sub-catchment is one of the main sources of North Karoun River. Climate variables, such as precipitation and temperature might have considerable impact on discharge of North Karoun River. To evaluate the impact of these variables, 27 years climate data were used. For this purpose, the mean of last ten years of 8 variables including, annual mean, max and min temperatures, number of snowy and rainy days, amount of annual rainfall, max daily rainfall intensity at Kohrang station and discharge of Dezak hydrometric station over mean previous years were evaluated and analyzed using Mann-Candall and Sen’s estimator methods. The above statistical methods showed that the mean annual temperature has increased by 1.5 degrees Celsius compared to mean of previous years at the level of 95 percent confidence interval, but the max and min annual temperatures did not show a statistically significant trend. Although, the max daily rainfall intensity and the number of snowy and rainy days have reduced annually, but these tests did not show a statistically significant trend either. The above mentioned statistical tests confirmed decreasing trends in annual precipitation by 11 percent (155.4 mm/year) and 19.7 percent in discharge at Dezak hydrometric station.

One of the methods used for calculating flood peak discharge in non-statistical watersheds is experimental methods. One of the empirical methods used in this study is the Fuller method which has advantages over other empirical methods for different flood periods. In this research, we have compared the linear programming optimization techniques and genetic algorithm in optimizing the fuller experimental formula coefficients in Excel and MATLAB respectively for selected watersheds of the region. For this purpose, the statistics of maximum 24-hour discharge of 9 stations in West Azarbaijan province with a statistical period of 21 years were studied. Comparison of the results showed the superiority of the genetic algorithm method and then linear programming. The results also show that the use of smart search methods improves the performance of conventional methods significantly. For this purpose, the statistics of maximum 24-hour discharge of 9 stations in West Azarbaijan province with a statistical period of 21 years were studied. Comparison of the results showed the superiority of the genetic algorithm method and then linear programming. The results also show that the use of smart search methods improves the performance of conventional methods significantly. For this purpose, the statistics of maximum 24-hour discharge of 9 stations in West Azarbaijan province with a statistical period of 21 years were studied. Comparison of the results showed the superiority of the genetic algorithm method and then linear programming. The results also show that the use of smart search methods improves the performance of conventional methods significantly.

Measuring deposited sediments behind small dams, large dams, and other reservoirs is essential in many research and development projects. Unfortunately, there is no guide for sediment surveying in reservoirs that are dry for some times every year. In this paper, these reservoirs are divided into three classes and methods for surveying sediment volume and weight was explained based on author's experiments countrywide by providing examples, figures and photos. Some important points on measuring siltation depth and determination the boundary of coarse-grained (delta) and fine-grained deposits (lacustrine sediments) and their contribution in total sedimentation were described in this section. Determining the bulk density is required to calculate the sediment load, which is subsequently described in more detail. This section first explains sediment stratification method in the control profiles and then describes two methods for measuring bulk density. In the following section, technical considerations on measuring sediment cracks to correct bulk density and finally calculating sediment weight are given.

Estimation of scour depth and understanding the flow field around pier would help to design with safer factor. In this study, we used the numerical model SSIIM as a CFD model to simulate flow and scour pattern simultaneously around single pier. The model was verified using laboratory data including the results reported for single pier. In this model, we considered the as a turbulence model to solve the 3D Navier-Stokes flow equations and used their outputs as inputs of sediment transition equations. Comparison between scour calculations of SSIIM model and experimental terms showed that the model has appropriate deviation value for estimating the maximum scour depth around single pier. Numerical and graphics discussions of scour pattern and flow field have been done in various simulation time for pier. Graphical results showed that the down flow at front of pier and upward flow at the rear of pier. In addition, the maximum down flow was simulated with high accuracy in compare with experimental results.

Land use optimization is one of the appropriate methods for soil conservation which helps decision makers and watershed planners in order to make the optimum decision among different land uses. The main objective of this research was to find the optimum area of each land use to reduce soil erosion rate as well as to increase the income of stakeholders in Golroudbar watershed located in Semnan province of Iran. The linear programming model was used in three different scenarios including current land use condition without any land management plan, current land use condition with land management plan and the standard land use level. The results showed that in the optimized condition, the orchard land 28.85 percent, rangelands 74.12 percent and irrigated lands 283.78 percent were increased. Additionally, by optimization of the land in standard condition, soil erosion decreased 16.28 percent and the profitability increased 94.58 percent.

Severe lack of data on soil erosion and sedimentation in many national watersheds requires the application of appropriate empirical methods for their estimation. This study is aimed to evaluate the efficiencies of Universal Soil Loss Equation (USLE) and some of its variations including MUSLT, MUSLE-E, MUSLE-S and AUSLE in semi-arid climates. This study was undertaken on standard plots in the ranges of Margsar, range and livestock management research station, Jashlobar, Mahdishahr, Semnan province. For this, all of required variables and input data for the respective models have been calculated for the respective plots. Finally, the estimations from both models and measured sediments have been compared during 15 showers. The results of t student’s t-test showed that there is no significant difference between MUSLE-E, MUSLT and MUSLE-S models and the measured sediment. Also, the results from efficiencies of the models by Nash-Sutcliffe method as well as relative root mean square error (RRMSE) showed that MUSLE-E, MUSLT and MUSLE-S models have higher efficiencies than other variations.

Non-linear Muskingum model is an efficient method for flood routing. However, the efficiency of this method is influenced by three applied parameters. Therefore, efficiency assessment of Imperialist Competition Algorithm (ICA) to evaluate optimum parameters of non-linear Muskingum model was addressed in this study. In addition to ICA, Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) were also used to find an available criterion to verify ICA. In this regard, ICA was applied for Wilson flood routing; then, routing of two flood events of DoAab Samsami River was investigated. In case of Wilson flood, the target function was considered as the sum of squared deviation (SSQ) of observed and calculated dischargem. Routing two other floods, in addition to SSQ, another target function was also considered as the sum of absolute deviations of observed and calculated discharge. For the first floodwater based on SSQ, GA indicated the best performance; however, ICA was in the first place, based on SAD. For the second floodwater, based on both target functions, ICA indicated a better operation. According to the obtained results, it can be said that ICA could be recommended as an appropriate method to evaluate the parameters of Muskingum non-linear model.

Implementation of management policies and sediment control is considered requirements. And requires of these programs, identifying and obtaining information about the relative importance of sediment sources and there by identifies critical areas within the watershed. In this study, Sediment deposited in the behind of sediment control structures were studied that constructed on the main channel watershed Nokandeh in Golestan Province. The purpose of this studyis separation of sediment sources with using the tracing method. The first, accordingto available information and maps of the lithology was determined land use, erosion and slope map units and in every work unit were taken the number of three sediment samples.Then samples being analysis in laboratory with X-ray diffraction and 9 clay minerals recognized based on statistical methods Kruskal Walis and were evaluated of discriminate function. The results indicate the proper separation of sediment sources, so that 2 clay minerals the Muscovite and Quartz could have %100 separation sediment sources. Average of low relativeerror, the high performance coefficient above model and also good consistent results with field observations show that tracers method was utilized in this study, a method is valuable for the separation of sediment sources in the watershed. The reesults also showed that using a combination of tracers characteristics, sediment sources separation rates are significantly higher than any of the individual properties.

Accidents and traffic events are the most influential factors in health. Given the importance of this matter, we designed this study to investigate accidents and analyze the data. This is a cross-sectional study. Data were collected via recorded inputs in the accident registries in Health Network in 2012 and analyzed using descriptive statistics. In 2012, a total of 913 events were registered which 614 cases (67.3%) were male and the rest of them (32.7 %)were female. Most of events were related to accidents and traffic events (41%), poisoning (18%) and fall (10.1%) respectively, and a total of 55.2% of the accidents had been occurred among persons with the age of 15 to 35.Conclusion Since, half of the events occurred in the age groups of young and productive population, it should be considered to train them accurately.

Soil erosion and sediment production are among most important problems in developing countries including Iran. In this study it has been endeavored that applicability of four (AOF, MUSLE-S, MUSLT and USLE-M) models is investigated in Srfiddasht Research Site, Semnan province, at event scale to estimate the sediment. For this, all required variables and inputs of the model have been calculated in the watershed and the estimations from considering statistical models with measured sediments of 15 cloudbursts have been compared. The results for t-student correlation test showed that there is no significant difference (at 1%) between MUSLT, MUSLE-S models and measured sediment. Based on these, it can be said that in this study, the results from these two models have higher accuracies to estimate the sediment from cloudbursts than other methods. Also, the results of evaluation and efficiency of the model using Nash-Suttcliffe criterion and root relative mean squared error (RRMSE) statistic showed that MUSLE-S and MUSLT models have higher efficiencies than other models and inefficiencies of USLE-M and AOF models to estimate sediments from cloudburst have been confirmed in the studied research station in this study.

In this research, two small sub-basins were selected in Darjazin Watershed of Semnan to evaluate the effect of ruck check dams on peak and volume of flood in small watersheds. Two watersheds were chosen as study area in a part of southern Alborz Mountain with arid and semi-arid climate. These watersheds are located in upland of Mahdishahr city and many check dams are constructed for flood control in past few years. All check dams were examined during field operation and their sedimentation were assessed. Results showed that all check dam reservoirs were filled by sediment. In this research, the peak and volume of floods were assessed in three scenarios of 1) watersheds with no check dams 2) watersheds with empty of sediment check dam reservoirs and 3) watersheds with full of sediment check dam reservoirs. HEC-HMS model was used for rainfall-runoff simulation.. Mean comparison test by paired method for all three scenarios showed that flood peak and volume have significant difference at α=1% level. But, flood peak and volume in scenario 2 are computed less than that of scenario 1 and in scenario 3 are computed more than that of scenario 2. On the other hand, flood peak and volume in the scenario 3 slightly decreased by 4.8 and 5.7 percent respectively compared to scenario 1 where is not significant based on the objectives of project.

Change in land use and tillage practices has great influence on soil physical and chemical properties. The present study has focused on the effects of converting undisturbed soil to agricultural lands. Chemical and physical soil properties, infiltration, cation exchange capacity (CEC), electrical conductivity, pH, bulk density, porosity, sodium, potassium, total Ca + Mg, organic matter percentage, sodium adsorption ratio (SAR) and lime percentage were measured using standard frequently used methods. Fifty soil samples from agriculture land and other 50 soil samples from undisturbed land were collected from 0 – 30 cm depth and different statistical analysis were performed. Agriculture land is Cultivated for more than 20 years. The results showed that change in land use from undisturbed to disturbed soil did not significantly changed soil organic matter content. Also, soil electrical conductivity showed a huge increase whereas pH showed non-significant changes due to land use change. Unlike pH, SAR, organic matter percentage and lime percentage, some other soil parameters showed significant decrease in quality through land use change. Correlation coefficients of the effective factors were calculated to explain the main reason for lowering soil quality. The results showed that sodium in EC; bulk density in porosity and CEC; sodium and Ca+Mg in SAR; EC in soil infiltration and Ca+Mg in organic matter showed the most correlation.

Check dams are considered as main measures for flood and sediment control in watersheds، and their uses have been rapidly increased from 1990 onward in Iran. This research is done in Darjazin watershed in north of semnan city. The check dams have been constructed from 15 years ago in two sub basins of the watershed for flood control in Mahdishar. More than 650 check dams were evaluated for effects on flood. The collected data in the field was fed to ArcGIS software. The effects of these structures on flood reduction were evaluated by HEC-GeoHMS extension and HEC-HMS model. Because of homogeneity of watershed management projects in the basin due to building more check-dams in different watercourses، any flood discharge is related to check dams. Evaluating the effects of check dams on flood by t-test showed significant differences between flood discharge before and after construction of check dams at 5 percent level. So، check dams have been able to reduce flood discharge by 16. 7 percent on average.

With respect to the problem of direct measurement of soil parameters in recent year using indirect method such as artificial neural networks has been considered. In the present study, 200 soil samples were collected from Ghoshe location in Semnan province. Half of samples were collected from disturbed agricultural lands and the other half were collected from undisturbed nearby lands. Some soil chemical as well as physical properties such as electrical conductivity (EC), soil texture, lime percentage, sodium adsorption ration (SAR) and bulk density were considered as easy and fast obtainable features and soil cation exchange capacity as difficult and time consuming feature. The collected data randomly divided in two categories of training (70%) and testing (30%) and they used for train and test of two artificial neural networks, multi-layer perception using back-propagation algorithm (MLP/BP) and Radial basis functions (RBF) and nonlinear regression model. Results of this research show high efficiency of artificial neural network compared with nonlinear regression and also MLP network was better than RBF network. Sensitivity analysis was also performed for all parameters to find out the relationship between soil mentioned parameters and soil cation exchange capacity for both disturbed and undisturbed soils. At last, the correlation between soil parameters and soil cation exchange capacity was determined and most important parameters which could influence the soil cation exchange capacity were described.

Due to diversity، high frequency and transportation as suspended materials، clay minerals can be used as sediment source indicators in drainage basins. In this study، clay minerals were used in Amrovan and Atary catchments، Semnan Province، Iran. To identify clay minerals، X-ray diffraction analyses were used. By performing four different treatments on the samples (K، KT، MG، MGG)، the respective graphs were obtained. To determine the percentage of each clay mineral، the area-under-a-curve method was used. Finally، the potential of each clay mineral in differentiation of sediment sources was determined using Kruskal-Wallis and Discrimination Function Analysis (DFA) statistical tests. The results of the Kruskal-Wallis test showed that all characteristics were below critical probable amounts، and، therefore، are suitable for differentiating sediment sources. Smectite is a clay mineral with the highest differentiation ability. It correctly classified 57. 5 % and 62 % of samples in the Amrovan and Atary Catchments، respectively. The results also showed that the combination of source indicator characteristics increases the differentiation ability of the characteristics up to 72. 5 % in the Amrovan catchment and 76 % in the Atary catchment.

Erosion and sedimentation are main challenges in Iran, which cause the reduction of soil quality and quantity. Soil conservation and watershed management activities should be implemented to reduce the impact of these phenomena. Therefore, the knowledge of critical area is necessary through the learning the amount of sedimentation and erosion. Because of lack of sediment measurement stations in more watershed outlets in Iran and insufficient data, empirical models are proper tools for data layers generation. Factorial Scoring Model (FSM) is one of the experimental models which has been recently developed out of the country. The main objective of this research is to compare sediment yield estimated by FSM model and observed values. So, in order to evaluate the model, nine small dams of 10 years old with no overflows were selected from in Semnan province. For modeling sediment yield, topography, lithology, gully, catchment shape and vegetation cover of related catchments were studied and required data layers were prepared and scoring indexes were given and finally, the calibrated model was presented. Estimated model values were then compared with measured values. Results showed that main model equation does not have sufficient efficiency. Also, results demonstrated that calibrated FSM model has conformity with observed sediment values at 84 percent.

Common methods to determine the soil infiltration would need lots of time as well as costs. On the other hand، the existence of non linear behaviors in soil infiltration would make it difficult to be modeled. Regard to the difficulties of direct measurement of soil infiltration، using indirect methods for estimation of this parameter، has received attention in recent years. In spite of the existence of various theoretic as well as experimental equations، some other indirect methods such as artificial neural networks are used to estimate this soil phenomenon. Now a day، artificial neural networks are shown high efficiency in modeling non linear equations. In the present study، 200 soil samples were collected from Ghoshe location in Semnan Province. Half of samples were collected from agricultural lands and the other half were collected from pastures nearby lands. Some soil chemical as well as physical properties such as electrical conductivity (EC)، soil texture، lime percentage، sodium adsorption ration (SAR) and bulk density were considered as easy and fast obtainable features and soil permeability as difficult and time consuming feature. The collected data randomly divided in two categories of training and testing and they used for train and test of two artificial neural networks، multi-layer perception using back-propagation algorithm (MLP/BP) and Radial basis functions (RBF) and nonlinear regression model. Results of this research show high efficiency of artificial neural network compare with multiple regression and also MLP network was better than RBF network. Sensitive analysis was used to determine correlation between independed parameters and permeability.

For implementation of soil conservation and sediment control plans in drainage basins، the recognition of the main sediment sources and erodible area is necessary. In this research the relationship between sediments of small dams which are constructed on drainages of Ebrahim-Abad and Royan Catchments in Semnan Province، with the upland sources was determined using composite and quantitative Tracing Method. The aim of research has been the differentiation of sediment sources and determination the contribution and the relative importance of each source in sediment production. By field investigation، the combination of both surface areas under different lithology and sub surface sources (gully walls) were selected as sediment sources and source differentiation was evaluated using 15 fingerprinting properties and by Kruskal Walis and Diffraction Function Analyses. Finaly the contribution of each sediment source was determined by calculating multivariate mixing models. The results have shown good differentiation of sediment sources، so that in Ebrahim-Abad Catchment، an optimal composition of illite، Mg and Organic Carbon with 95. 8% and in Royan Catchment، Cholorit، XFD، N and Organic Carbon with 92. 9% differentiation power could differentiate sediment sources. The results of calculation using composite multi-variate statistical methods have show that Quaternary units and Shemshak، Dalichay، Hezar-Dareh، Karaj and Lar Formations in Ebrahim-Abad Catchment and Quaternary units، gully erosion and Karaj، Shemshak، Upper Red and Lar formations in Royan Catchment are the most important sources of sediments، respectively.

Evaluation of empirical models for sediment yield in watersheds is a necessity. One of the conventional models in Iran is MPSIAC that has been used extensively. Sediment measurement of small dam's reservoirs is one of the methods for evaluation of these models. In this research, 9 small watersheds were selected in Semnan Province. There is an earth small dam at the outlet of each watershed built in the past 10 years. These dams have not spilled since they were built. Therefore total sediment volume discharged from each watershed was entrapped behind the dams. The amount of deposited sediments in these reservoirs was measured by surveying and estimation of apparent Specific Weight which then compared with estimating values of MPSIAC model by paired t-test. The results showed that the difference between the means for estimated volumes of sediment yield by use of MPSIAC model at the level of 5% had no significant difference while the difference between mean weights of sediments at the level of 5% was significant. Also determination of performance and relative root mean square error showed that MPSIAC model has no appropriate efficiency for application in the region.

In order to quantitatively evaluate the sediment yield in ungauged basins, it is necessary to use empirical models. The EPM model, as a model which is using in Iran, has sometimes been evaluated. Most evaluations have often been conducted by using river's sediment information and direct measurements of dam reservoir sedimentation have been less used, while the sediment measurement method on reservoir is more carefully. 9 small watersheds from Semnan province (Iran) were selected in this research. There is a small earth dam which have been built on the outlet of each watershed in the past years that them age is 10 years. These dams have not been weirs since they have been building to now. Therefore total of sediment yield volumes of each watershed are entrapped in the dam reservoirs. The volume of sediments deposited in reservoir were calculated by surveying. Sediment's apparent specific weights were measured in each reservoir and the volume of sediments transformed into sediments weight. By EPM model the volume and weight of sediment yield were estimated. Values of sediment yield measured in reservoirs were compared with estimated values by t-test. The results showed that at level 5%, there was not any significant difference between sediment yield values estimated in reservoirs by EPM model in comparison with values of volume and weight which were measured. But determination of performance and relative root mean square error showed that EPM model has low efficiency for estimation of sediment yield in the case study of watersheds.