Iranian Journal of Soil and Water Research
Year:2019 | Volume:50 | Issue:1 |Papers Count:20

The intensive and inappropriate use of pesticides caused environment to be contaminated. Quantifying the fate of applied herbicides in the soil is essential for minimizing their mobility in the soil and environmental pollution. The leaching and degradation of the metribuzin herbicide in three soils were investigated under laboratory conditions. Metribuzin was mobile in the soils when tested using non-aged and aged soil columns. The mobility of herbicide in the soil is related to the adsorption phenomenon in the same soil. It was found that the mobility of metribuzin in the soils 7 and 5 (with less organic carbon) was more than the one in the soil 1. The difference in the adsorption affinity of metribuzin in different soils appears to be due to differences in soil properties, such as clay content, organic matter content and pH value. The calculated half-life values in sterile and non-sterile conditions ranged from 37. 92 to 105. 74 days. Metribuzin persistent in the soil was corresponded to columns 1, 5 and 7 respectively.

The complexity of drainage process in paddy fields and time consumption of field tests make simulation models to be used inevitably for assessing subsurface drainage systems performance. The objective of this study was to evaluate DRAINMOD model and the effects of drainage management of paddy fields on the salinity of drainage water. In this regard, a physical model with 3m in length, o. 6m width and 1m height was constructed and equipped with controlled drainage. The corrugated drainage pipe, covered with geotextile was laid at a depth of 70 cm in the box. The tank was filled with silty loam soil with the same density and layering as in the paddy fields. After rice cultivation and during the experiment, the soil solutions were collected from the depths of 40, 50 and 70 cm and their TDS were measured in the laboratory. In order to evaluate the accuracy of DRIANMOD model for simulation of qualitative and quatitive subsurface drainage water, the solute transport parameters including dispersivity, tortousity factor, molecular diffusion coefficient, precipitation limit and the hydraulic conductivity were obtained through minimizing differences between the observed and the estimated salt solusion and drainage volume using genetic algorithm optimization method. The results showed that the model could simulate the performace of drainage system very well at before and after the midseason (NRMSE < 20%) and excellent at the mid and end season (NRMSE < 10 %). The TDS and drainage volume were estimated by average RMSE of 63. 27 mg/l and 0. 0145 cm3 respectively. The comparison of estimated and observed values showed a better performance for the model at the nonsubmerged conditions. The results of calibration and validation of model showed that the DRAINMOD-S model is capable to simulate the performance of subsurface drainage in paddy fields.

Multi-variate statistical methods such as principal component analysis (PCA) and regressions could be used to facilitate the interpretation of complex relationships. The objective of this study was to determine the most important soil fertility properties affecting rice yield in the paddy fields. For this purpose, soil samples were taken from the plow layers of 119 points with suitable distribution in the paddy fileds located in Shaft and Fouman cities of Guilan province. Then after, physical and chemical properties of the soil fertility were measured and analysed using descriptive statistics, principal component analysis and regression methods. Results showed that three PCs with eigen values greater than one named as “ k and it’ s preservation factors” , ” Total N and it’ s provider factors” and ” P and Thickness of plow layer” are respectively explained more than 67. 4% of the variability in the soil physical and chemical properties and 55% of the yield variability. In addition, the corresponded properties to the PCs explained 80% of the yield variability. Consequently, in order to increase the yield, management practices such as proper fertilizer applications of nitrogen, potassium and phosphorous and proper tillage for creating suitable plow layer are recommended.

Groundwater is of valuable resources that its conservation needs quality and quantity monitoring. Different indices such as WQI (water quality index) are used in order to monitor the groundwater quality. The objective of this study is to assess spatial-temporal changes in WQI in groundwater aquifer of Golestan province including Ghare-Sou, Grgan-Roud and Gorgan gulf basins. The Golestan province was selected as the study area. WQI was calculated based on the quality parameters data of 114 deep wells in the study area, collected during a 21-years period. After zoning WQI in GIS, the spatial-temporal changes of this index were investigated considering the range of changes, the observed minimum and maximum values during the study period. The empirical Bayesian kriging method presented better results in comparison to other methods for WQI zoning in GIS environment. The quality zoning of WQI in the studied area showed that the aquifer is in a good and very good condition and it is only bad in a small part of aquifer located in the eastern shores of the Caspian Sea and the northern part of the study area. In addition, no considerable differences were found between the WQI averages of the two events data sampling during the year. Also, the investigations show a decrease in water quality as closing to the sea shore and to the northern part of the study area. According to the fact that WQI follow the general slope of the region, there was a good spatial structure in the region which caused a better result for empirical Bayesian kriging interpolation method.

Rill erosion is one of the most important reasons of the soil lost in the plowed rainfed fields alongside the slope. Increasing infiltration rate in the soil and decreasing the erosivity of flow is essential for controlling rill erosion as well as increasing crop yield. This research was carried out to find out the effect of wheat straw on hydraulic characteristics of the flow and rill erosion in the wheat rainfed field in semi-arid region in Zanjan. The experiment was performed at seven straw mulch levels (0, 25, 50, 75, 100, 125 and 150 %) using the randomized complete block design with three replicates under the field conditions with plowing alongside the slope. At 100% level, 0. 5 kgm-2 equivalent to five tons per hectare of straw mulch was applied into the soil. The results indicated that the effects of wheat straw on flow velocity, flow power and rill erosion was significant (p< 0. 05), while its effect on the hydraulic radius and shear stress wasn’ t statistically significant. These results were associated with a low depth of flow as affected by straw mulch in the furrow rills (p> 0. 05). By increasing the wheat straw mulch level, the flow velocity, flow power and rill erosion decreased about 19, 23 and 55% respectively, as compared to the control treatment. There was a high correlation between the rill erosion and the flow velocity (r=0. 71). The 100%-level of wheat straw mulch which decreased the flow power (34%) and the rill erosion (71%), was the most appropriate amount for decreasing rill erosion in rainfed wheat field. Generally, it can be concluded that the application of wheat straw mulch is a biological and proper practice for reducing erosivity of flow and controlling rill erosion in rainfed fields.

This research was conducted to test how to exchange mass between the main channel and the stagnant areas of the stream. The transient storage differential equations were selected as the governing equations for simulation of advection-diffusion of pollution in river flow. The experiments were conducted in a gravel bed flume, with length, width and depth of 12, 1. 2 and 0. 8m, respectively. Three longitudinal slopes of 0. 001, 0. 004 and 0. 007 and three discharges of 7. 5, 11. 5 and 15. 5 (l/s) were selected for the experiments. The numerical model of OTIS-P was used to estimate the four parameters of the transient storage model. Then the observed breakthrough curves were regenerated at the same locations of measured points. Goodness of fit was estimated with the root mean square error (RMSE), Nash and Sutcliffe model efficiency coefficient (NS) and the mean absolute error (MAE). The comparisons revealed that the OTIS-P model (with RMSE between 0. 031-0. 118 and Nash-Sutcliffe between 0. 48-0. 9) could be employed successfully for estimation transient storage parameters. Finally, the reliability of the estimated parameters of the transient storage model was confirmed by the non-dimensional Dam-kohler number.

In this study, the trend of agricultural water consumption was investigated for 22 years (1989-2011) in Iran, considering crop and livestock requirements per capita. Crop and livestock products were categorized into nine groups so that, each group has its particular subgroups. The results of this study showed that the trend of water consumption per capita was ascending over the proposed period with regard to the diet variations. Wheat in cereal crops and meat in livestock products had the largest water consumption values. The average capita water consumption was estimated about 1420 m3 during 1989-2011 which the maximum and minimum amount of water consumption corresponded to the year of 1389 and 2007, respectively. The volume of virtual water consumed by crops and livestock has been increased from 61 billion m3 in 1368 up to 120 billion m3 in 1390. The portion of imported virtual water through agricultural and livestocks products has been 11-27 billion m3 with an average of 17. 6 billion m3 in the proposed period. Rainfed productions with average consumption of 17. 3 billion m3 of water by rainfall provide a part of annual water consumption. Therefore, the portion of renewable water resources in agriculture was estimated to be varied from 63 (2008) to 81 (2011) billion m3. According to the water resources assessment indices, Iran was faced to water crisis during the proposed period in which population growth and diet changes may be effective. Regulation of Proper diet such as reducing creal and meat consumption, establishing a dynamic market for selling agricultural products, recycling waste products, importing particular food products and increasing water productive could be effective in prevention of water management crises.

Daily increasing salinity is one of the main problems of agricultural lands, especially in arid and semi-arid regions, with high evapotranspiration rates. The purpose of this research was to investigate the simultaneous effect of salinity at five levels 2, 4, 8, 16 and 20 dSm-1 for wheat and 0. 7, 2, 4, 6 and 8 dSm-1 for bean and matric suction at four levels 2, 6, 10 and 33 kPa, on evaporation rate and redistribution of moisture and salinity in the soil profiles of sandy loam and clay loam. This study was conducted in greenhouse conditions in pots by compeletly randomized factorial desigh with 3 replicates. It was found that evaporation rate decreased by time in the saline and water stress treatments, especially in the clay loam soils, and this reduction was more in the high suction and salinity levels. The lowest evaporation reduction was observed in treatments with the highest soil moisture content. Because, water availability reduced the salinity effect on evaporation. As, at the 2kPa matric suction, the evaporation rate was approximately the same at all levels of salinity and the highest throughout the day after treatment. In the 15th day after treatment and at the 33kPa suction, different salinity levels (from 0. 7 to 20 dSm-1) reduced the evaporation rate by 19% in both soils. Also, the results showed that the ECe of the drained soils with 10kPa constant suction increased exponentially with moisture reduction. This trend was more in the clay loam soils. Because the evaporation/drainage ratio of the clay loam soil is more than the one in the sandy loam soil. The salinity redistribution in the both soil profiles and for the two plants were almost constant over time. Also, moisture reduction over the time was higher in the clay loam soil than the one in the sandy loam soil, especially under low salinities.

Soil mesofauna have important role in different ecosystems by organic matter breakdown and improvement nutrient cycling. Different types of land uses through variations in inputs of organic matter contents affect soil mesofauna communities and their habitation. The aim of this project was to study the effect of three kinds of land uses including forest (oak trees), agriculture (wheat) and pasture (different pasture species) on population and diversity of the soil mesofauna and on physical and chemical properties of the soil in Cheharmaleh and Tolomeh region in Ilam province. According to the results, the kind of land uses have a significant effect (α = 0. 01) on all soil chemical and physical properties, indicating the importance of different land uses on soil characteristics in the study area. The soil depth for the top (0-10 cm) and sub (10-30 cm) layers also showed a significant effect (α = 0. 01 and 0. 05) on most of the soil properties. For example, the soil depth had no significant effect on lime content (TNV) from chemical properties and SP or silt percentage from physical properties. Interaction of the soil depth and the land use had significant effect on pH and EC at 1% level and on P and K at 5% level. In contrast, this interaction had significant effect on some physical characteristics such as porosity and clay percentage at 1% level and on SP, FC, BD and the sand percentage at 5% level. With respect to arthropods in the soil mesofauna, 24 species and 15 different families from insects, mites and pseudo scorpions were identified and collected. There was a significant effect on the insects and mites of the soil mesofauna affected by the land use and soil depth factors. In addition, there was a significant effect on all arthropods orders by different land use and soil depth, with the exception of beetles order. Based on the soil mesofauna communities, the most density of the insects found in the top layer of the forest soil and the least one in the sublayer of the range soil. The most density of mites was found in the top layer of the forest soil and the least one in the sublayer of the agricultural soil. The most density of mites and collembolan communities were found in the top and sub layers of the forest soil.

The presence of heavy metals in water and soil are major concern for the environment due to their toxicity to many life forms. Stabilization of heavy metals in remediation of contaminated soils is one of the costeffectiveness and rapid implementation method. In order to study the effect of diatomite on chemical forms of Lead in calcareous soils, a factorial experiment was conducted in a completely randomized design (CRD) with three levels of diatomite application in soil (0, 2 and 5 % by weight), four levels of incubation time (1, 2, 4 and 8 weeks) and in two contaminated soils with three replications. Chemical distribution of Lead in soils were determined using Tessier sequential extraction method during the mentioned incubation times and reduced partition index (IR) and mobility factor (MF) of the metals were calculated as a Lead mobility indices in the soils. The obtained results showed that the application of diatomite significantly (p ≤ 0. 01) decreases the lead in the exchangeable and carbonate fractions and increases it in the iron and manganese oxide, organic and residual bond fractions significantly in comparison to the control treatment. The IR and pH values increased but MF and DTPA-extractable Lead values decreased with increasing diatomite level and incubation time which demonstrates a decrease in the mobility of lead in the soils. Lead mobility reduction in the clay loam soil compared to the one in the sandy loam soil was probably due to higher content of clay and lower content of Calcium Carbonate Equilibrium. Generally, itcan be concluded that the addition of diatomite into the soil especially with high levels (5%) reduces the bioavailability and mobility of the Lead in the soil.

The fraction of clay that disperses in water, water-dispersible clay (WDC), is recognized as an important property with respect to predicting soil erosion, colloid leaching and soil development. The WDC is measured by different methods producing different results. In this study, three methods (Rasmussen, Mechanical stirrer and Ultrasound) were compared in terms of measuring the amount of WDC in soils. For this purpose soil samples with different physio-chemical properties were collected from different region of Khuzestan province and the WDC were determined by the proposed methods. The correlation between WDC and the soil properties were analyzed using regression model and equations were fitted for the three methods. The results showed that the WDC measured by Rasmussen, Shaker and Ultrasound methods were 72. 6 (%), 33. 4 (%) and 14. 1 (%) from total clay, respectively. The results showed that the most important soil properties affecting the WDC for Rasmussen method were gypsum and clay, for Mechanical stirrer were linear extensibility coefficient (COLE), organic matter (OM), clay, gypsum and total sand, and for Ultrasound method were gypsum content, linear extensibility coefficient and silt. These varieties could be related to the nature of each method. Also, statistical analysis showed that the gypsum, COLE, and silt content had maximum effect on the WDC in Rasmussen, Mechanical stirrer, and Ultrasound methods, respectively. Organic matter, gypsum, sodium adsorption ratio (SAR), soluble sodium, and electrical conductivity had negative correlations with WDC, and the total clay content, lime, COLE, cation exchange capacity and pH had a positive correlation. Therefore, it is suggested that the selected method for measuring WDC should be according to the research emphasizes and soil characteristics. Also, the effect of aggregates size, type and organic matter composition on the WDC should be investigated in future study.

Intake structures which are used as water diverting structures in open channels, rivers, and reservoirs are of the oldest issues of hydraulic engineering. In this study, a lateral pipe intake was proposed as a flow diversion structure provided in side walls of a channel, and its discharge characteristics and flow pattern was studied numerically using 3D CFD package, Flow-3D. The simulations have been performed for various parameters. The results showed that the lateral pipe intake with 90o angle has the highest efficiency among all of our simulation scenarios. The vortex and the separation zone in the lateral pipe intake were formed behind the pipe. Also, formation of the recirculation zone behind the lateral pipe intake can be affected by other parameters like inlet Froude number and transversal position of the pipe intake mouth. Furthermore, an equation was developed for the discharge coefficient in the lateral pipe intake. The computed discharges were within ± 15% of the observed ones.

Environmental pollution consist of heavy metals is the most important environmental problems and leads to serious damage for human health. In order to reduce the harmful effects of heavy metals, their treatment methods should be developed, of which the use of biological absorbers are particularly important. The objective of this study was to isolate the 𝑍 𝑛 +2-resistant bacteria from Ravanj lead-and zinc-Mine in Markazi Province and to find the most efficient strains for zinc adsorption. For this purpose, samples were collected from the mine sediments and the 𝑍 𝑛 +2 resistant bacteria were enriched in the medium and isolated. After determining the resistance of isolated bacteria to 𝑍 𝑛 +2, the most effective strain (MS3, Delftia lacustris) were detected by 16S rDNA sequencing. Then after the dried strains biomass was prepared and the effect of main operational variables such as 𝑝 𝐻 , Zinc to Bacteria Biomass concentration ratio (𝑍 𝐵 ), and the retention time of bacteria biomass in the Zinc medium on Zinc removal has been evaluated and analyzed using the response surface method and Box-Behnken model. A numerical optimization model was performed to obtain the maximum amount of Zinc removal from aqueous solution. Among the isolated strains, the MS3 (Delftia lacustris) was the most tolerance strain to the Zinc (1200 mg/l). The maximum percentage of Zinc removal based on the quadratic model was obtained at 𝑋 𝑝 𝐻 = 0. 8990 (means 𝑝 𝐻 = 5. 84), 𝑋 𝑍 𝐵 = − 0. 8627 (means Zinc to Bacteria Biomass concentration ratio of, 1: 327. 83 and 𝑋 𝑡 = − 0. 9394 (means 𝑡 = 9. 34 𝑚 𝑖 𝑛 ). The maximum amount of Zinc removal percentages based on the experimental design and the simulated model were 9. 86% and 9. 49% respectively, indicating the high accuracy of the model. Therefore, the MS3 strains can be used as a bio-absorbent for Zinc removal.

Sarcheshmeh copper mine is the second largest open-pit copper mine in the world which its mining activities, dewatering operations, and dam construction could cause pollution to the surface and groundwater of the region. In this study, the heavy metal pollution index (HPI), heavy metal evaluation index (HEI), and degree of contamination (Cd) were used to evaluate heavy metal concentration in the 82 samples of surface water. Also, the main effective parameters on the heavy metal pollution indices were investigated using principal component analysis (PCA). The hybrid multiple linear regression (MLR) and PCA model was used to develop new equations for HPI, HEI, and Cd indices using minimum number of heavy metal variables. The study area was divided into three sub-sections with different mining activities. The concentrations of elements in water samples were compared with the maximum admissible concentration values of WHO standard for drinking purposes. Based on the spatial distribution maps in GIS, the highest concentrations of heavy metals were found in mining sites and sedimentary dam, and the lowest ones found in the Shour River. Based on the HPI values, 70% of the samples were in the critical range of 100-482245. 3 and only 30% of samples were classified as having low pollution levels. The HEI and Cd results revealed that the 79 (96%) and 69 (84. 2%) samples were polluted with heavy metals, respectively. The PCA extracted four components, of which the first component with 63. 3% of the total variance contains high loadings for Al, Cd, Co, Fe, Zn, Mn, and Ni elements. Despite of very wide ranges of indices variation, the accuracy of proposed MLR-PCA model was confirmed for less number variables in the study area. Findings of this study can be used for investigating preventive measures and to control pollution in the study area and similar regions for drinking purposes in the future.

The prediction of wind components including wind speed is one of the important factors, especially in the case of evaporation in a watershed. In this paper, in order to increase the efficiency of support vector machines (SVM) for predicting wind speed, the SVM model was combined with the firefly optimization algorithm called hybrid model (HM). In this regard, the wind speed data from synoptic stations of Isfahan province were used to estimate the monthly wind speed values of the unknown neighboring stations. Then, the efficiency of the SVM and HM models was compared. Finally, the RMSE, MAE, WI, and NS indices were used to evaluate the both models performance efficiency. The results in the evaluation step showed that the hybrid model (HM) with high correlation and lower error values has higher performance efficiency as compared to the SVM model. as Also, the method of using neighboring stations data as inputs for the predictive models of unknown station is a proper method for estimation of wind speed.

In order to investigate the effect of irrigation interval on water use efficiency, yield, yield components and also determining the most suitable maize cultivar, a split plot experiment in a randomized completely block design was implemented with four replicates for two years (2014-2016) in Behbahan Agricultural Research Station. The main factor of drought stress was irrigation after 100 and 200 mm evaporation from class A pan and the sub factor was cultivars in four levels including Karoon 701, S. C. Mobin, S. C 704 and PH1. After the complete emergence of the field when the total evaporation from the class A reaches to 100 and 200 millimeters, the amount of irrigation water is calculated based on the deficit moisture content to field capacity and is applied to each sub-plot by a flowmeter. The comparison of mean irrigation treatments showed 100 mm evaporation from class A pan had a significant superiority in all properties than 200 mm evaporation from class A pan. The yield of corn in stress treatment (200 mm) showed a decrease of 16. 7% as compared to the non-stress (100 mm) treatment. For each cm reduction in water consumption per hectare, the yield of corn decreased 164 kg per hectare. The earlier appearance of corn in PH1 variety of maize caused a premature cultivar and a reduction in the growth period which cause a less water consumption and a more opportunity for land preparation for the next cultivation. The comparison of traits mean in irrigation and cultivar interaction showed that the PH1 cultivar with 100 mm evaporation from class A pan was superior in terms of grain yield and water use efficiency which were equal to 7143. 5 kg/ha and 1. 353 kg/m3, respectively. The results of Pearson correlation coefficient showed by increasing the yield components of corn, the grain yield and water use efficiency increases and vice versa.

Determination of infiltration equations coefficients with proper accuracy is one of the important issues in irrigation planning. For determination of these coefficients, double-ring test method is usually used which only involves the point and hydrostatic dimension of infiltration. In this research, a parabolic shape furrow was used for simulation of an irrigation furrow with 50 m length, 12 cm depth, and 0. 20 m/m bed slope. Three experiments were performed with lengths of 4. 7, 20 and 40 m, and inflow of 0. 6± 0. 02 lit/s with three replicates. For each length, a test with the minimum measurement error was selected. To determine the infiltration equations coefficients, input and output hydrographs were measured using flow measurement flume and the output hydrographs were routed by Muskingum-Cunje, Zero-inertia and kinematic wave methods. Finally, the infiltration discharge values were obtained by considering the SCS and Horton infiltration equations and the average flow area in the proposed furrows. Computational hydrographs were obtained from the difference between routed output hydrographs and infiltration discharges. Finally, the objective function was derived using the least square method (LSM) for observational and computational output hydrographs. The results indicated that the mean value of the relative error between the observed and optimized output hydrographs of the proposed method is less than 5 percent. By increasing the length interval, the amounts of infiltration discharges decrease due to the reduction of static head water. The efficiency of the model for all lengths was more than 90 percent based on the Nash-Sutcliff criterion which indicates that the simultaneous use of the Horton equation and the zero-inertia method provides the best results.

Accurate and precise characterization of the natural rough bed has great importance. Without any doubt, there is not any example of natural flow or flow near hydraulic structures with no roughness on their surrounding walls Although the traditional bed roughness characterization approach is based on the grain size distribution curve, in the recent approach, roughness determination is based on the point-to-point height measurement of the bed, which cannot be easily determined. Therefore, despite of many studies and various methods and tools which have been developed for determining the digital model elevation and statistical properties of such substrates, there is a lack of simple and low-cost method with high accuracy. In the present study, the capabilities of a close-range photogrammetric method called the Structure from Motion (SFM) have been investigated for determining the bed surface particles sizes. For verification, the digital elevation of various objects with regular geometric shapes, such as spheres and cubes, was determined using SFM method and compared with the theoretical values derived from their mathematical equation. The results of the model derived by the structure from motion method for irregular geometric shapes was performed using a laser scanner and a caliper which indicated the high precision of the simple and low-cost SFM method. The results showed that the SFM method could accurately developed a digital model of an artificial gravel and sand bed (absolute error of 0. 19 to 1 mm). Furthermore, this method was applied in the real environment; Kordan River bed and the size distribution of the point to point bed particles were calculated based on the cloud points of the developed digital model, indicating the capability of the method for determining the natural roughness of the river bed based on the concepts of statistical methods.

In this research, the short-term beneficial effect of using different pistachio wastes biochars on improving some fertility properties of a loam soil was investigated. Therefore, the effects of two factors 1) types of amendments added to the soil, including biochars of pistachio mildew (PM), pistachio hard skin (PHS) and wood of 20-year pistachio trees (W) papered at 600o C (with amount of %5 by wt), and 2) time of incubation (1, 2, 3, 4, 5 months), were investigated on pH, electrical conductivity, soluble potassium, nitrate and availability of iron, copper, manganese and zinc. This experiment was performed as factorial based on the completely randomized design with three replicates. The results of this study showed that the application of biochars and different incubation times does not have a significant effect on soil pH. But, the threated soils at all incubation times showed a significant increase in electrical conductivity and organic carbon as compared to the control treatment. Addition of biochars and incubation time increased significantly potassium content of the soil solution, so that the treated soils had an increase of approximately two times solution potassium as compared to the control. Application of biochars to the soil caused an increase in nitrate retention and a decrease in nitrate solution as compared to the control sample. Biochars application led to a significant increase in iron content and irregular increase in zinc, copper and manganese. The availability of these elements in the soil decreased by time due to reduction of biochar decomposition and transformation of those elements from available into less available forms.

Accurate hydrological forecasting is a main tool for the water resources planning. In this paper, the inflow rates to Bakhtiari and Rudbar Dams in Lorestan province – IRAN, were forecasted using support vector regression (SVR), Multiple Linear Regression (MLR) and Autoregressive Moving Average (ARMA) models. In order to pre-process the input data for the above mentioned models, the moving average approach was used. Furthermore, Nash-Sutcliffe Efficiency (NSE), Root Mean Square Error (RMSE), correlation coefficient (R) and Taylor diagram were used to evaluate the efficiency of the models. The results showed that the moving average pre-processing approach improved the performance of the above mentioned models dramatically. For instance, the values of Nash-Sutcliff correspond to SVR hybrid model in forecasting inflow rate to Bakhtiari and Rudbar-Lorestan dams with moving average pre-processing were improved by 13. 4% and 6. 6%, respectively, as compared to those in the SVR model without pre-processing.