مجله مهندسی و مدیریت آبخیز
سال دوازدهم شماره 4 (زمستان 1399)

One of the resources that have been severely affected by drought is groundwater, however it has been considered less than other water resources. Due to the recent droughts especially in the central regions of Iran, investigating the impact of droughts on water resources is very important. The main aims of this study are characterization of meteorological and hydrogeological droughts, assessment the effects of drought on groundwater level fluctuations and determining the critical regions of Shahrekord Plain Aquifer. For this purpose, modified Standardized Precipitation Index (SPImod) and Groundwater Resource Index (GRI) were used to assess meteorological and groundwater droughts, respectively. Also, the cross-correlation test was used to investigate the relationship between the meteorological drought and the groundwater drought. In this research, the monthly precipitation data of Shahrekord synoptic station and monthly groundwater level data of 35 piezometers in this plain in the period of 1984-2015 were used. Based on the result of GRI index, Shahrekord Aquifer was divided into three regions which cover the north and northwest, central and south-east and southwest. The results of correlation between modified SPI in various time scales of 1, 3, 6, 9, 12, 18, 24 and 48 months and GRI index indicates the highest correlation between 18-month modified SPI and GRI. The results also showed that the effect of meteorological drought on GRI index appears with 6 and 18-month delay on northern and central areas, respectively, and without delay on the South West of the Shahrekord Aquifer.

High soil phosphorus (P) can increase the amount of runoff P and cause pollution of P in water bodies. In this paper, to select the best method between laboratory extracting and rainfall simulator method for determining environmental threshold level of P concentration was compared. For this purpose, surface soil was sampledfrom 30 points of Talkherood Watershed inEastern Azerbayjan with widely available P contents. After determining some of general properties, four soil P tests comprising Olsen, Mehlich-3, Iron oxide, and Soltanpour were used. Water soluble P in lab was measured and runoff soluble P of soils was determined with using rainfall simulator by applying 75 mm h-1 rainfallfor 30 minutes. Relationship between P concentrations determined by four methods with  a) water soluble soil P, as P loss index, and b) runoff soluble P, showed that environmental soil P concentration can be estimated by both lab extracts and rainfall simulation methods for lime soils of this region. As the lab extracts method are easier and less time-consuming, this method is recommended for threshold concentration estimation. Since in iron oxide method, slope difference between the two split-lines was greater than other methods and high correlation coefficients were obtained for all of the methods, as a result iron oxide method is better than others for threshold concentration estimation of available P concentration. Since changing point for dissolved reactive P was seen in 0.36 mg l-1 concentration, as a result this concentration is lower than environmental P concentration for eutrophication phenomenon.

Since the most consumed water is in the agricultural sector, available water resources, especially in arid and semi-arid regions, are the main limiting factor for agricultural production. Therefore, by rain water harvesting systems and its proper management, it is possible to compensate part of water shortage in the mentioned region. The purpose of this study was to select the most suitable rain water harvesting techniques based on multi-criteria decision-making system using Analytic Hierarchy Process (AHP) and investigation of its effectiveness in supplying the water demand of pistachio gardens. The results of the AHP analysis indicated that the environmental impact criterion with a weight of 0.342 and permanency criterion with a weight of 0.284 were the most effective criteria for selecting of the best rain water harvesting system. Finally, the rain water harvesting system with geomembrane insulator with a weight of 0.371 was selected as the most suitable insulator cover, and two other rain water harvesting systems with plastic and isogam insulator were weighted with the weight of 0.350 and 0.279, respectively in the following priorities. Also, the results showed that from the insulated surface with an area of 800 m2 and an average annual rainfall of 300 mm, it is possible to harvest at least 200 m3 rainwater per year. With this volume of harvested water and the choice of drip irrigation with gravel filter, the annual irrigation water demand of 200 fruitful pistachio trees will be supplied during a crop season. Therefore, due to rainwater harvesting techniques, some parts of irrigation water demands of gardens will be provided in arid and semi-arid regions, as well as maintaining sustainability of production and increasing gardeners' revenues, the double pressure on surface water and underground water will also be reduced.

In this research, the effect of climate change on the groundwater level of Chamchamal Plain in the two 20-year periods was investigated. The GMS groundwater model was used to simulate the aquifer and was calibrated and verified for evaluation and validation of the model for two periods of 18 months, respectively. In order to investigate the effect of climate change on the fluctuations of groundwater level in the region, six AOGCM models were used under three emission scenarios A2, A1B, and B1 in the upcoming period. Then, two methods of weighting and extraction of probabilistic levels were used to consider the uncertainty prediction of climate change models for temperature and precipitation parameters. The predicted climatic variables for scenarios A2, A1B and B1, and two Probability levels 90% and 50%, respectively, show the average temperature changes of +0.57, +0.57, +0.57, -0.04 and +0.6 °C and average precipitation variation of +0.12, -1.8, +2.49, -31.78 and -2.33 during the period 2011-2030. Similarly, for the period 2046-2065, the average temperature changes were +1.92, +2.12, +1.46, +0.98 and +2.3°C, and the average precipitation variation was -20.59, -26.07, -19.55, -47.15 and -15.74 percent. Finally, the effect of climate change on the aquifer level was determined under scenarios. The results showed the groundwater level, under scenarios A2, A1B and B1 and two probabilistic levels of 90 and 50 percent for the periods 2011-2030 and 2046-2065 will drawdown between -9.6 to -17.92 meters, which is Compared to the period 1996-2015, it showed a change in level between -1.06 to -9.38 meters.

Marl formations due to their unsuitable physico-chemical properties have low vegetation cover and so are highly erodible. These formations make up about 2000 km2 of lands in Sabzevar and Davarzan areas. In this research, geology, pedology and vegetation cover of marl formations were studied. Geologically, there are two kinds of marl formations consisting salty and red gypsiferous marls. Marly lands in southern aspects usually have no vegetation but in northern aspects the vegetation varies between 0 to 27 percent. Three vegetation communities consisting of Salsola aucheri, Artemisia seiberi and Ephedra intermedia are stablished on marly soils. For recognizing soil factors of each vegetation community, studies localized in establishment area of Salsola, Ephedra and Artemisia vegetation types. Many soil profils were dug. Soil samples were taken from depth between zero and 40 cm of marly soils and were analyzed. Results showed that in all plant types with increasing of percent of plant cover from 0-10 to 10-24 percent, the main soil factors such as EC, pH, gypsum, silt an clay, Na+, K+, Mg2+, Cl-, So42-, total Cations and Anions and SAR were decreased and factors such as Organic carbon, N, P. T.N.V, Co3-1 and sand percent were increased. The statistical analysis of data was conducted with the SPSS software. This study showed that Artemisia and Ephedra had the highest and lowest vegetation percentages, respectively. Analyzing of data acording to Duncan Test showed that the differences between plant cover percent in three vegetation communities are very obvious (P<0.05). Meanwhile, the amount of EC and gypsum of  marly soils were important soil factors that had the most roles in establishment of  vegetation.

Adaptation to drought is considered as one of the most important approaches in agricultural and watershed management. The purpose of this study is to assess the social acceptance of drought adaptation policies at a regional scale using the reasoned action theory. Information was collected through a questionnaire in Chaharmahal and Bakhtiari Province. The population size was 66019 and the sample size was 382. Samples were distributed according to the proportion to size of regions’ population. In each region, four settlements were selected randomly and the questionnaires were distributed randomly to the farmers. The response rate was 96%. Content validity has been approved by nine experts. Reliability of the questionnaire was confirmed by test retest method. The correlation coefficients of the study constructs were confirmed; knowledge (r=0.84), attitude (r=0.91), subjective norm (r=0.87), and behavioral intention (r=0.86). The findings showed that knowledge, attitude, subjective norm and behavioral intention of farmers were at a moderate level, although the level of subjective norm was higher than other components. There were significant correlations between the knowledge and attitude (r=0.72), knowledge and subjective norms (r=-0.62), behavioral intention and subjective norms (r=0.67), income and knowledge (r=0.59), income and subjective norms (r=-0.63), literacy level and behavioral intentions (r=0.74). There were a significant difference between the attitude and subjective norms of farmers who engaged in dry farming and other farmers. Analysis of the findings showed that despite the increasing droughts, adaptation policies have not been seriously accepted by farmers. The level of knowledge and attitude of farmers about drought adaptation were not high and farmers' behavior was influenced by the behavior of other farmers rather than influenced by the policies of the institutions.

Soil degradation and erosion caused by human factors is the main threat to the functions of soil resources. The consequences of this phenomenon are reducing the sustainability and quality of production as well as environmental problems. Also, moisture stress, especially in rainfed lands, is a major limitation to improve productivity in these lands. The use of subsurface water harvesting is one of the options that is prevalent in Zagros provinces, due to topographic and geological conditions. This research was designed to evaluate the effectiveness of the operation of the traditional system of land use change of dryland to grape, almond and alfalfa cultivation with supplementary irrigation using subsurface water harvesting system in improving soil permeability and inhibition of soil degradation and erosion in the Razin Watershed of Kermanshah Province. To do this, after selecting the study area, some of the diagnostic features of selected area including the soil permeability with the disk permeameter and the soil degradation and erosion condition with GLADIS method were measured by field measurements in the study area as well as the control area. In the laboratory, soil texture, bulk density, saturation percentage, lime, acidity, salinity, nutrient concentration and organic carbon storage were measured the soil samples collected in the operation and control area. The results showed that the hidden form of erosion, the gradual washing of fine particles and the coarse grains of gravel and pebbles remaining known as Armor, is the most important form of erosion in the region. In the long term, the construction of this system was able to remove this form of erosion and loss of soil from the region. Also, exploitation of the underground dam system and extraction of subsurface water harvesting within its scope, in addition to enhancing all soil quality indicators (including its organic carbon accumulation), resulted in a 23% increase in soil permeability capacity and soil erosion has inhibited 5.56 tons per hectare.

Snow cover has a significant role in management and supply of water resources in mountainous basins. In this order, this study aimed at estimating of contribution the snowmelt runoff in Chehelgazi Sub-basin at Kurdistan Province in supplying water requirements of its farmlands during 2012 and 2014. To do so, SRM model and MODIS satellite images were applied to estimate runoff from the snowmelt and CROPWAT model was implemented to determine water requirements of farmlands. Through the findings, it was found that SRM model with coefficient of determination (R2) of 0.97 and volume difference percentage of 0.14 for the calibration year (2012-2013) and coefficient of determination of 0.96 and volume difference percentage of 0.66 for validation year (2013-2014) was able to estimate snowmelt runoff. Moreover, the result from CROPWAT model showed that water requirement for farmlands in Chehelgazi Sub-basin was 1939371 m3yr-1. Ultimately, it was shown through the model that runoff from the snowmelt has 100 % potential in supplying water requirements in the basin. The result from this study can be used to provide a model for water planning in Chehelgazi Sub-basin.

Climate change is an effective phenomenon on many natural processes, including hydrologic cycle. The evapotranspiration as one of the parts of the hydrologic cycle will be at the forefront of these changes. Due to the importance of evapotranspiration in water resources management and agricultural planning, the present study was conducted to investigate the effect of climate change on this parameter in Moghan Plain. For this purpose, the HadGEM2 atmospheric and oceanic circulation model was used under RCPS and Lars-WG6 downscaling in 2011-2030 and 2030-2060 periods. Also, Penman-Monteith and Hargreaves-Samani methods were used to calculate evapotranspiration. This study showed an increase of 6 to 8.4% of calculated evapotranspiration with Penman-Monteith method in each of the scenarios in 2030-2011 and 2030-2060 periods compared to the observed years. Also, calculated evapotranspiration of the Hargreaves-Samani method will increase from 4.5 to 7.7% in each scenario in 2030-2011 and 2030-2030 periods compared to the observation years. These increases affects on water demands of Moghan and Khodafarin irrigation and drainage networks in the maximum months, which requires appropriate solutions to adapt to climate change conditions.

Soil erosion is an important chalenge in arid and semi-arid regions which has a negative impact on soil productivity and lose soil. Improper management of natural resources causes soil erosion. This reaearch was implemented in the north of Sistan and its aim was to idintyfy the effect of sand on increased moisture in the plant root zone. For this pupose, three soil samples were collected from 0-50 cm depth and their pH, EC, C, Ca, Mg, K, Na, ESP, available phosphor, cations and texture were tested. This research had eight treatments including plant, soil and irrigation which have been done in split split-plot in four  replication durig tow years. After plating a 20 cm layer of sand was applied on the soil surface in each pit. In this experiment, soil moisture was measured monthly and plant growth was measured in growing season. Statistical analysis of the data was performed using MSTAT software. Result showed that the amount of moisture was 28% higher in sand compared to other treatments at the level of 99%. According to the findings of statistical analysis on the impotance of methods used for soil moisture, the sand along with subsurface irrigation of toot had better groth at the level of 99% and were in class A and the other treatments were in class B. The conclusion was that sand causes decreasing in capillary, reducing soil evaporation, increasing moisture around root zone of the plants and water and soil conservation.

Regional flood frequency analysis is a powerful tool for estimating and analyzing flood flow in watersheds. In this research, different methods of regional flood analysis and hydrological homogeneity of catchments that has been done in the country has been investigated. Among the many methods for determining the homogeneity of sub-catchments, cluster analysis due to the ability of factor analysis to select the most important factors, simplicity of considering various factors, independence of effective factors, accuracy of separation of homogeneous groups, and advantage of using proper diagnostic functions, was the most appropriate method. Multivariate regression method, especially when the homogeneity of catchments have been accurately determined, has shown good performance in regional flood analysis. L-moment method, due to uniqueness and existence has good performance in estimating parameters and selecting appropriate statistical distributions. So that in the regional flood frequency analysis, the L-moment method performs better than other methods, particularly in the case of shortage and skewed data. The analysis of the intelligent models such as artificial neural networks (ANNs) and fuzzy logic, showed the high ability to establish nonlinear relationships between multiple input variables. The results of the Investigation of different factors used in regional analysis methods showed that Physiographic factors were highest (72.11%) followed by climatic factors (17.69%) and land cover parameters (7.48%). Also, the lowest contribution was related to hydrological factor with 2.72%. Among the physiographic parameters, the area factor with 30.19% of the contribution had the most influence on the regional flood analysis. Among the climatic factors, the highest application was related to the average annual rainfall factor with 73.08% contribution.

Evapotranspiration has a key role on spatial and temporal distribution of available water, as vital component of water balance. ET ground measurements at large scale has limitation, so, different methods have been developed to estimate actual ET based on remote sensing data. The purpose of this study was to evaluate accuracy of actual ET estimation for MOD16, MYD16 and SSEBOP global database models in monthly and seasonal time scales for different land use and wet, dry and normal climate conditions at Karkheh Dam Basin. First, SWAT model was calibrated and verified based on data of hydrometric stations included: river discharge, base flow and aquifer storage. After ensuring the accuracy of SWAT model performance in estimating water balance components at the studied basin, simulated actual evapotranspiration values were used to evaluate the temporal-spatial accuracy of actual evapotranspiration data of global database models. Results showed that all three models underestimate actual evapotranspiration values with a significant difference from the SWAT model results. The RMSE and MBE values varied from 15 to 21.74 and -15.93 to -8.19 mm on a monthly scale and from 40.17 to 59.32 and -47.74 to -19.36 mm on a seasonal scale, respectively. The concordance between the actual evapotranspiration results of the global database models and the simulated SWAT model values ​​in the dry year is lower than wet and normal years. Although the results of the SSEBOP model had less error than SWAT model, the actual evapotranspiration time variations of the MOD16 and MYD16 models were more consistent with the time series data of the SWAT model. The results also showed that in the dominant agricultural basins, the SSEBOP model and in the forest and pasture basins, the MYD16 and MOD16 models have less error.

Karstic springs, as the main resources of rivers such as Karkheh, have encountered scarcity in the western of Iran during past years. It is necessary to consider the effects of climatic and human co-factors to prepar a rehabilitation plan in watershed scale. The present study was carried out to evaluate this phenomenon in the case of Sarab-e Niloufar, in Kermanshah Province. Two methods including Standard Precipitation Index (SPI) and Moving Average (MA) are used in this study. Four wet and dry periods were occured, including wet periods from 1980-1981 to 1997-1998 and from 2003-2004 to 2005-2006, dry periods from 1998-1999 to 2002-2003, and from 2006-2007 to 2014-2015 water years. The SPI results showed two main periods from 1989 to 2015, include 1989 to 1999 and 2000 to 2015. The first period is wet or normal, but the second period is very dry to normal and is characterized by persistence and severity of dryness. Also, the results showed that spring discharge has been stable in a-29 years period from 1969 to 1988 with fluctuations by seasonal rainfall, but a sharp decrease over the second period. The average spring discharge was 1100 ls-1 during the first period, but 337 ls-1 in the next 19 years. Other results showed a harmony period between decreasing of the spring discharge with drought cycles resulted from MA and SPI, except for the wet period of 2003-2004 to 2005-2006. Nevertheless, the spring discharge had decreasing rate in the wet period of 2003-2004 to 2005-2006. In addition, spring decreasing discharge rate was greater than rainfall. Therefore, despite the fact that the effects of drought are recognized as a major factor of spring deficit, other factors such as decreasing in water table of adjacent aquifers are also important to consider for rehabilitation of the spring.

Urban watersheds due to their development, have more complex hydrological behavior than natural watersheds, and understanding their hydrological response will help to design appropriate flood control facilities. In this study, SWMM model was used to investigate the potential of urban runoff production in a part of Babolsar urban area. The purpose of this study was to analyze the water availability of rainwater collected during different return periods for urban use. For this purpose, the SWMM model defined 65.65 ha of study area in the form of six hydrological units (from 5.94 to 16.82 ha), six output nodes and four channels were defined, and the height of runoff from 24-hour rainfall was obtained with different return periods. According to these results, the 24-hour rainfall with a 25-year return period is 70.37 mm, of which 33.73 mm for infiltration and 35.60 mm for runoff. Results showed that about 52.1% of rainfall of Babolsar City plan could have the ability to become runoff. The highest runoff coefficient is in the hydrological unit S3, which has a value of 0.637 at the 100 year return period. However, the lowest runoff coefficient is in hydrological unit S1 which has a value of 0.352 at 2-year return period. The results also showed that the runoff coefficient is directly related to the return period and the larger rainfall has a higher runoff coefficient. Through the collection systems, in addition to reducing the flood hazards of Babolsar City, a water supplement that offsets part of household consumption in the non-urban sector, also water resources management can be done.

Like most of the wetlands in the country, Bisheh Delan Wetland is in poor condition and its ecological balance is fragile and unstable. The purpose of this study was to develop and implement a training program on the importance of Bisheh Delan Wetland and how to use it responsibly by governmental and non-governmental stakeholders with the aim of repairing and supporting its restoration. In this regard, 10 workshops were conducted in a non-randomized purposeful manner in order to gain insight into the economic, social, technological, political, and cultural issues of the study area. Then, using elite ideas, strengths, weaknesses, opportunities and threats of the wetland were identified. After, in accordance with the CEPA Action Plan, four strategies, including: A) public participation-information and socio-economic issues, B) promotion of national conservation and cooperation wetland management, C) achieving optimal environmental status and D) achieving optimum soil and water status were determined and then ranked. Based on the results of the strategy rankings as well as the results from the QSPM matrix, the conservative WO strategy was identified as the main strategy for the study area. In this strategy, handicrafts and indirect sales of its products to tourists are opportunities in the region that can, while directly and indirectly employing local communities, reduce the region's weaknesses (such as lower household income levels, poor infrastructure facilities and etc). Based on the results of this study, empowering local communities in achieving participatory wetland management is one of the best strategies for sustainable utilization of Bisheh Delan Wetland.

In recent years, a considerable part of the western oak forests of the country has been faced with drought and decline. Initial studies have identified one of the factors affecting oak forest dryness as increasing frequency and severity of dust phenomenon. In this study, the MODIS sensors with a resolution of 1 km and 250 m and meteorological data of Kermanshah Province synoptic stations over a 15-years period (2014-2000) was used to investigate the dust phenomenon and the process of forest vegetation changes in the region. Dust intensity was investigated using visibility data and unsupervised image classification method. Also, in this study, the relationship between the occurrence of dust and vegetation changes in oak forests was investigated. Survey of dust events showed that Kermanshah Province had the highest number of dust events in 2008 and 2009, respectively. The highest incidence of severe dust was in 2012. In addition, satellite imagery and spectral indices also showed that the highest reduction of vegetation in dense forests (>50% canopy cover) by 67% and with an overall accuracy of 62% in the south and southeast of Kermanshah Province and at the border of Lorestan and Ilam provinces has happened. Results also showed that the frequency of dust phenomenon is highly correlated (70%) with the phenomenon of oak forest degradation; and dust has the effect of reducing the greenness of oak forests in Kermanshah province.

Relationships between river water quality parameters and physical, geochemical and biological processes carried between basin resources (soil, vegetation, geology, land use, etc.), meteorological variables (temperature, precipitation, snowmelt, etc.), River hydrological variables (flow discharge), as well as human interventions are often very complex, nonlinear and non–deterministic in a way that makes their complete understanding impossible. In this situation, the use of computational intelligence (such as artificial neural networks) is a useful tool in simulating and estimating river water quality variables such as suspended sediment load. In the present study, by combining open source GIS libraries and neural network models (with and without supervisor), an intelligent GIS system has been designed and coded that can estimate daily suspended sediment load under univariate or multivariate conditions. The results of applying this system to Mazaljan River Watershed at Razin hydrometric station showed that this system is able to simulate suspended sediment load with proper performance and validation  (with root mean square error of 1033 tonday-1, mean absolute error of 455 tonday-1 and Nash-Sutcliffe efficiency of 0.89 for the test data set). In general, this system can be used as a national infrastructure in the simulation and management of suspended sediment in all hydrometric stations in the country by relevant organizations.

Today, with the increase in population, land use has been changed to meet the needs, which has made it more important to know the future status of land use. Investigating land use changes plays a fundamental role in environmental studies, modeling and simulation of land use changes and water resources management and helps managers in better land use planning. So, in this research, first, the land use map of Rahim-Abad Basin was extracted for 1999 and 2016, using ETM+ and Landsat 8 sensors in ENVI5.3 software environment, with a kappa coefficient of 95% and overall accuracy of 97% that indicates the high accuracy of the 2016 map.Then, the maps of affecting factors on land use change including maps of distance from the road, distance from the river, distance from the city, distance from the village, distance from the fault, geology, soil texture, rainfall, evaporation, elevation digital model, gradient, groundwater level and the amount of solar radiation were prepared in Arc-GIS 10.6.After, using logistic regression, the role of effective factors on land use was determined and the Relative Operating Characteristics curve (ROC) was used to evaluate the logistic regression. Finally, the land use map of the study basin was simulated for 2026 using the CLUE-s model.Results showed that the area under the ROC curve was 0.9, 0.88, 0.9, 0.92 and 0.91 for grasslands, rain-fed lands, irrigated lands, water and, residential zones, respectively, which expresses the acceptable accuracy of the regression method in investigation of affecting factors on land use.Also, the most changes of land use in 2026 would be related to conversion of rangelands to rainfed lands, and 6.47% rangelands would decrease and 18% rainfed lands would increase.

The success of the artificial recharge projects of aquifers need to recognition the appropriate points. The aim of this investigation is finding appropriate points for artificial recharge in “Kavir Meighan” basin in Markazi province. Because of that the Geographical Information System (GIS) is used. In this investigation. the method“Analytic Hierarchy Process (AHP)” is used to find suitable points. By using the opinion of the experts, the necessary criterion to choose suitable points are: Water Quality, Water Depth, Slope, Land use, Geology, Soil texture and the position of wells, springs and Qanats. In AHP methods the raster layer of used criterion was prepared. Then by using double comparison and Expert choice software, the weight of the any layers was made. In this method the maps were put together by overlap methods. After that, inappropriate points those are too close to wells, springs and qanats, were showed. Finally, the potential map of artificial recharge zone was prepared. In AHP method the potential map contents 29 zones, the total area of them is 14,770,183 square meters.

Erosion and sediment resulting from it, is one of the most important factors in watershed management. The estimation of sediment yield and prioritization of watersheds in terms of water erosion is the main objectives of watershed management. One of the ways to estimate soil erosion and sediment yield is to use empirical models. The aim of this research is to evaluate the efficiency of the EPM Model in Fars Province. To examine this, five small watersheds were selected in Fars Province. Five basins in which the earth dams and check dams were built were selected. There is no overflow from these dams in rainfall events and the most of them was made near to 10 years. The amount of sediment deposited in upstream of the reservoirs was calculated by means of precision mapping. Deposit bulk density was determined in the field to convert the volume into the weight. In parallel, the sediment yield of the basins was determined by EPM Model. Results showed that the minimum and maximum sediment yield measurements varied from 0.89 to 2.62 tonh-1y-1, but the estimated sediment was between 3.3 to 6 tonh-1y-1. The results of the relative error of estimation of EPM Model in each of the studied basins showed an over estimation in all basins (minimum 121.5 and maximum 447.2 percent). The Relative Root Mean Square Error (RRMSE) of the model was calculated as 2.39, which indicates a too much error of the model. Statistical analysis results comparison of actual sediment yields of watersheds with estimated values by model, using paired t-test, shows that there is a significant difference between these values (t=8.728 and sig.=0.001). According to the presented findings, the results of this model estimation for the investigated areas are not accepted.