جستجوی مقالات مرتبط با کلیدواژه « drainage » در نشریات گروه « آب و خاک »

Flooding and drainage cycles affect the biological and chemical characteristics of the soil in paddy fields and play an important role in cadmium (Cd) availability. In this study, the effect of biochar (B), hematite (H), and their simultaneous application (HB) on pH, Eh, and calcium chloride extractable Cd was investigated in a Cd-contaminated soil during a flooding and drainage period. Also, the Cd fractionation at the end of the incubation period was studied. The pH value increased during the flooding period and decreased with the beginning of the drainage period. The Eh value decreased from the beginning of the flooding and showed an increasing trend during the drainage period. Calcium chloride extractable Cd decreased during the flooding period, while at the beginning of the drainage increased with a slight slope and followed a decreasing trend up to the end of the drainage period. Cd concentration reduced at the end of the flooding period in the B, H and HB treatments compared to the control by 16.8%, 20.5%, and 25.7%, respectively. Also, the reduction in Cd concentration compared to the control treatment at the end of the drainage period was 18.2, 23.1 and 28.2% respectively. HB treatment reduced the Cd availability by reducing the soluble and exchangeable fractions and increasing organic, iron, and manganese oxides fractions. The results indicated that the application of amendments can reduce Cd availability in paddy fields and its uptake by the rice plant.

Magnetic susceptibility (χ) is a fast, non-destructive and simple method for determining soil properties and describing soil formation processes, which has been studied at different geomorphic levels, in order to investigate the effects of soil formation factors (elevation, elevation, and parent materials). This research aims to evaluate the changes of different forms of iron, drainage, land use and human activities (agriculture) on changes in soil magnetic receptivity and investigate CIW, CIA and CPA aeration indices in different geomorphic units in the year 2021 in Chaldaran study area in the northwest Iran and West Azarbaijan province. For this purpose, 9 test soils were excavated and evaluated in five dominant geomorphic units in the region, such as slope plain, covered pediment, alluvial cone, plain and flood plain. After dissection and sampling from the genetic horizons of the excavated rocks and transporting them to the laboratory, the physicochemical properties of the samples were measured along with their magnetic properties and aeration indices of CIW, CIA and CPA. The results showed that the range of magnetic receptivity of the soils of the region varied from 42.90 x 10-8 to 1053.20 m3 kg-1. Also, the average value of χlf of the studied soils in different geoforms was observed as flood plain > alluvial cone > covered pediment > plain > slope plain. Although the values of magnetic receptivity depending on the frequency of the examined soil samples were variable between 0.07% and 3.50%; But in most horizons, the value of χfd was less than 2%. This result indicates the presence of multi-domain coarse particles in the region that were added through parent material. Also, the results of CIA, CIW and CPA aeration indices indicate the stage of weak to moderate aeration in the region. Further, it was observed that the leaching of diamagnetic materials to the lower soil layers, ferrimagnetic minerals transferred by water and agricultural activities, has led to changes in the χlf trend with depth. Also, according to the A-CN-K curve and the chemical composition of the oxides of the studied elements, a moderate aeration process was observed in the region. On the other hand, the studied region is affected by water sediments and agricultural activities; It seems that carrying out the processes of sedimentation, soil formation, aeration and cultivation in this area has changed the chemical composition of the soils. Finally, it can be concluded that the equitic conditions caused a decrease in the acceptability and amount of Fed due to poor drainage in the studied soils.

This research was carried out to investigate the physical and chemical properties of the soils obtained from dredging of the drainage drains in Abbas Irrigation channels in Ilam province. The area encompasses 16 thousand hectares. In this study sampling was carried out from two major branches. The drainage No. 1 with 21 km length, is flooded to the Rafahyeh river and drainage No. 2 with 5 km length is flooded to the Chikhab River. Sampling was done from drainage soil, dredged soil and the arable land around drainage. A comparison was performed between the three regions of drainage floor area, drainage agricultural land and dredged soil. Soil physico-chemical properties such as particle and bulk density, potassium, magnesium, sodium, calcium and phosphorus, carbonate and bicarbonate, sodium absorption ratio, exchangeable sodium percentage, organic matter, organic carbon, cation exchange capacity, sulfate, base saturation percentage and nitrogen. The results showed that the amount of potassium in dredged soil is more than recommended for soil. Phosphorus concentration was also higher than recommended for soil. Sodium, magnesium and calcium was lower than soil recommended levels. Due to the presence of calcareousmaterial,the amount of limein soils washigh and the amount of gypsum was high as well, due to the warm and dry climate and low rainfall. Soil pH of the region was mostly higher than 7 so they are categorized as alkaline and semi-alkaline soil. The studied soil is classified as saline soil due to high electrical conductivity.Soil texture was sandy clay loam.

In today's agriculture, the use of different chemical and organic fertilizers is inevitable via to adding the amount of production. However, in some cases, application of fertilizers could result to introduce of some pollutants such as nitrates into the environment and water and soil resources. In such a condition, the application of urea coated fertilizers or slow released may cause less pollution. In this research, the amount of nitrate transport in soil profile was investigated due to the application of some common chemical and organic fertilizers in comparison with slow release urea (sulfur coated) fertilizer (SCU). For this purpose, 15 cylindrical columns of soil and water, with a height of 150 cm and a diameter of 10 cm were designed, constructed and used. The columns were filled up to a height of 120 cm with a sandy loam soil. Drainages were installed at different depths of the columns. The amount of applied fertilizers was calculated and applied based on the amount of nitrogen required for the tomato plant. In this research, a statistical factorial with completely randomized design was used to study the factors including: type of fertilizer (no fertilizer as control treatment, urea, ammonium nitrate, coated urea and poultry manure); sampling depth of drainage water (30, 60 , 90 and 120 cm from the soil surface); irrigation rotation (5 times) and sampling intervals in each irrigation (5 times based on specific volumes of drainage water discharge of a complete purvolum of soil) with three replications. The results of the analysis of variance indicated that the effects of the type of applied fertilizer, irrigation rotation and sampling time on the amount of nitrate measured in the effluent samples (nitrate leaching) were statistically significant at the 1% level. But nitrate concentration in the samples prepared from the different depths did not show significant changes. Investigating the mean values of nitrates in drainage water showed that nitrate transfer to soil depth was the highest in ammonium nitrate application (with a mean of 51.67 mg/l) and was the lowest in control treatment (with a mean of 38.39 mg/l). Also, urea fertilizers (with a mean of 48.16 mg/l), poultry (with a mean of 40.70 mg/l) and coated urea (with a mean of 39.88 mg/l) were placed in between them, respectively, and the differences were statistically significant at one percent level. In general, application of coated urea (SCU) fertilizer could have a clear effect on reducing nitrate leaching to soil depth, especially in the condition of this research and in comparison with other types of common fertilizers.In today's agriculture, the use of different chemical and organic fertilizers is inevitable via to adding the amount of production. However, in some cases, application of fertilizers could result to introduce of some pollutants such as nitrates into the environment and water and soil resources. In such a condition, the application of urea coated fertilizers or slow released may cause less pollution. In this research, the amount of nitrate transport in soil profile was investigated due to the application of some common chemical and organic fertilizers in comparison with slow release urea (sulfur coated) fertilizer (SCU). For this purpose, 15 cylindrical columns of soil and water, with a height of 150 cm and a diameter of 10 cm were designed, constructed and used. The columns were filled up to a height of 120 cm with a sandy loam soil. Drainages were installed at different depths of the columns. The amount of applied fertilizers was calculated and applied based on the amount of nitrogen required for the tomato plant. In this research, a statistical factorial with completely randomized design was used to study the factors including: type of fertilizer (no fertilizer as control treatment, urea, ammonium nitrate, coated urea and poultry manure); sampling depth of drainage water (30, 60 , 90 and 120 cm from the soil surface); irrigation rotation (5 times) and sampling intervals in each irrigation (5 times based on specific volumes of drainage water discharge of a complete purvolum of soil) with three replications. The results of the analysis of variance indicated that the effects of the type of applied fertilizer, irrigation rotation and sampling time on the amount of nitrate measured in the effluent samples (nitrate leaching) were statistically significant at the 1% level. But nitrate concentration in the samples prepared from the different depths did not show significant changes. Investigating the mean values of nitrates in drainage water showed that nitrate transfer to soil depth was the highest in ammonium nitrate application (with a mean of 51.67 mg/l) and was the lowest in control treatment (with a mean of 38.39 mg/l). Also, urea fertilizers (with a mean of 48.16 mg/l),

To study the soil-landscape change in the Chaldoran region, 9 representative soil profiles were studied in 5 dominant geomorphic units of the study area including piedmont plain, mantled pediment, alluvial fan, plain, and flood plain. The results showed that the accumulation of pedogenic carbonate in some soils was concretion and light in color. In control soils in the piedmont plain (profile 5 and 7), mantled pediment (profile 6), and flood plain (profile 8) clay transferred from the surface horizons and accumulated in the lower horizon, due to relatively good rainfall in the region and distinct dry and wet seasons has led to the formation of argillic horizons along with the formation of crust on the surfaces of aggregates and building units and has formed the Alfisoils order. Mineralogical results showed the presence of chlorite, illite, kaolinite, and smectite minerals. According to the evidence, illite, chlorite, and kaolinite minerals were inherited and smectite minerals were formed due to weathering and evolution of illite, chlorite, or palygorskite minerals. Also, the results of the CIA index in the region indicated that the soils of the region are in the stage of weak to moderate weathering. In general, the results indicated the critical role of drainage, land use, and parent materials in the soils of the study area.

Identifying the amount of water used to produce agricultural products is of great importance, and it can be very effective in recognizing and providing appropriate solutions to reduce water consumption in agriculture. In this study, in order to investigate the water consumption of sugarcane in Khuzestan province for sugarcane production, the water footprint index in two 25-hectare farms (free drainage and controlled drainage) from Salman Farsi agro-industry unit was used. Using the collected and available information, the AquaCrop model was calibrated. Then four irrigation scenarios (100, 110, 85, and 70% of water requirement) were implemented. Based on the results, the water footprint index was recalculated. The results showed that the amount of water required for sugarcane production in the field with free drainage was 258 cubic meters per ton. Of this amount, 12% was green water, 72% blue water, and 16% gray water. Using controlled drainage, this amount was reduced to 222 cubic meters per ton, of which green, blue, and gray water were 16, 69, and 15 percent, respectively. The results of the model showed that in scenarios I1 and I2, the water footprint index in controlled drainage is 18% lower than the free drainage.  This value is 18% and 19% for I3 and I4, respectively. Comparison of the results showed that in the controlled drainage condition and supply of 85% of the plant water requirement, the water footprint index decreases by 23% compared to the normal (which is running) condition, which is the best option among the studied scenarios.

In recent years, floods and waterlogging conditions in the northern and southern provinces of Iran have become important challenges, which directly and indirectly affect the solubility and availability of most of the soil nutrients. To investigate the effects of waterlogging, seven soils were selected from the orchards of different regions of East Mazandaran (Ghaemshahr, Sari, and Neka). In a pot experiment, the soils were placed under continuous waterlogging conditions for 70 consecutive days, and the trend of changes in oxidation-reduction potential (Eh), electrical conductivity (EC), pH, concentrations of Ca2+, K+, Na+ and iron (Fe2+ and Fe3+) of these soils were studied. The results showed that the mean Eh values of soils dropped within 2 days of waterlogging, then increased slightly in the third day, and then began to drop again, and this drop trend continued until the end of the period, from 552 mV at the beginning of waterlogging and reached -99 mV at the end of the period. The average soil pH decreased from 7.8 to 6.88 after 10 days of waterlogging, and then increased and reached a relatively stable equilibrium (about 7.05). The average EC values of soils, increased after the first day of waterlogging, then, declined to 2.13 dS/m, and again increased to the maximum value (about 3.09 dS/m) after 10 days. The concentration of Ca2+, K+, and Na+ in the soil solution increased after waterlogging and reached the maximum within 2 days, then gradually decreased and reached a relatively constant amount. The concentration of Fe within the first days after waterlogging was 1.95 mg/L, increased to 6.67 mg/L after 10 days, then decreased to 4.27 mg/L after 20 days, and eventually increased to 9.98 mg/L at the end of the period (70 days). Based on the results of this study and considering the trend of EC changes and concentrations of nutrients in soil solution, application of chemical fertilizers to soils should be avoided after waterlogging occurrence. Also, due to the changes in soil Eh, the continuation of waterlogging for more than 5 days can lead to relatively anaerobic conditions in the soil and damage to fruit trees, therefore, drainage of excess water is recommended.

Leaching modeling in the conditions of non-uniformity leaching in soil profile is desalination challenges. The final salinity in the soil profile has different values in two dimensions of soil depth and distance from the drainage pipe. Therefore, estimation the salinity values in the soil profile requires two-dimensional modeling of leaching. In this research, the data required for modeling were prepared by soil profile leaching in a physical model with dimensions (height × width × length) of 1×0.5×2 m. In this model, soil drainage conditions were created for half the distance between the two drains. The target of this study was to compare the relationships of one-dimensional (in soil depth) and two-dimensional (in soil depth and distance from drain) in leaching modeling. Regression models included linear, exponential, logarithmic, polynomial and power functions. The results showed that in one-dimensional modeling, the coefficientR^2 for linear, exponential, logarithmic, polynomial and power functions were equal to 0.392, 0.557, 0.404, 0.406 and 0.562, respectively. But in two-dimensional modeling, it was equal to 0.796, 0.94, 0.55, 0.614 and 0.587, respectively. Therefore, increasing the coefficient R^2 in two-dimensional modeling, showed an increase in validity in leaching modeling. In evaluating two-dimensional models by terms of ME, RMSE,R^2,R_adj^2and EF, were selected exponential and linear models as the optimal model, respectively. For leaching modeling in the soil profile between two drains, using the two-dimensional model had better performance than the one-dimensional model.

In an experiment, the effect of soil surface plotting on leachinguniformity of soil profile was investigated. The experiment was performed in a physical model with dimensions (height×width×length) of 1×0.5×2 meters. The leaching of the soil profile was simulated in presence of subsurface drainage pipe. The plots were made by separating the soil surface into four equal parts (with dimensions of 0.5×0.5 m), in order to prevent water mixing on the soil surface. An equal water depth was applied for soil leaching, before and after soil surface plotting. After leaching, the ECe of soil samples taken from different depths (20, 40 and 60 cm) and different distances from the drain pipe (25, 75, 125 and 175 cm) were measured. The amount of standard deviation of soil salinity data were 2(dS/m) and 0.63(dS/m) before and after soil surface plotting, respectively. The uniformity coefficient of salinity distribution in the soil profile before and after soil surface plotting was estimated to be 45% and 76%, respectively. The results showed that the presence of drain pipe was effective on infiltration rate at different parts of the soil surface. So that the infiltration rate was estimated to be 1.9, 1.7, 1.56 and 1.47 (mm/h) at 25, 75, 125 and 175 cm far from the drain pipe, respectively. Through soil plotting, the unbalanced water infiltration to the soil surface was prevented, in order to have a uniform soil washing at different places. The results showed that the soil leaching uniformity can be achieved by adopting a management strategy. Therefore, more drainage water production, depletion of soil nutrients and environmental pollution are prevented.

At the same time with development of agricultural and industrial activities and reduction of quantity and quality of water resources, assessment of surface water resources quality has been paid more attention. Due to limitations of conventional methods for surface water quality assessment, development of alternative methods has been considered for monitoring water quality. For example, biomonitoring using alga is a proper indicator for surface water quality assessment. In this study, the relationship between epilithic alga population and concentration of common nutrient residuals including nitrate, nitrite, phosphate, sulfate and water-soluble iron in Bozhan and Kharw Rivers in Neishabour was determined in two consecutive years; 2017 and 2018. IRWQISC quality index for Bozhan and Kharw River was calculated as 50.03, 66.65% and 47.66, 55.69% during 2017-2018 respectively, which ranged between moderate to relatively good. Significant differences were observed in the concentrations of phosphate and iron in Bozhan River. The source of iron could be due to effluent from Bozhan village gardens. This gardens use Sequesteren iron fertilizer with no management. Due to the direct role of these nutrients in stimulating growth of alga communities, distribution rate of epilithic alga in Bozhan River was shown to be more than the ones in Kharw River. Therefore, investigation of changes in alga communities as a proper bioindicator could be useful for assessment and prediction of residuals such as phosphate and iron ions in water resources. These findings could be used in better recommendations for gardening and more accurate management of drainage water entering the riverside by studying the distribution of algal communities.

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.

The Fe forms diversity is related to parent materials, climate, soil process, biocycles, water table fluctuation, redox, organic matter and etc. in soil. The main Fe forms are Fed (extracted by dithionite citrate bicarbonate), Feo (extracted by oxalate ammonium) and Fe crystals. Feo/ Fed ratio also shows active Fe forms. Magnetic susceptibility (MS) increases when ferri-magnetite is formed due to soil processes. This characteristic (MS) changes with parent material, climate, relief, and organism. Therefore, this study was undertaken to evaluate different Fe forms and MS with soil forming factors in some gypsic soils of Khuzestan province. The study area was located in Ramhormoz and Haft-Kel regions in Khuzestan province. Soil moisture and temperature regimes were ustic and hypertermic, respectively. Soil parent material consisted of the eluvial deposit of Gachsaran and Aghajari geological formations. The soil profiles location was selected according to topography map, ETM+ Landsat satellite images, and then 14 soil pedons were dug and described according to the standard methods. All horizons or layers were sampled and 5 pedons were selected for the analysis of different Fe forms. Fed and Feowere, respectively, extracted by citrate-bicarbonate-dithionite (CBD) and oxalate ammonium, and Fe cocentration was then determined by atomic absorption spectrometry. Furthermore, MS was determined by MS2 meter Barlington Dual frequency in low (0.46 kHz) and high (4.6 kHz) frequencies. All MS were calculated for carbonates, gypsum, and OM free. These calculations were also done for Fe forms in these samples. The statistical analysis was carried out with SPSS and Pierson methods between Fe forms and MS. The Duncan’s test was used to compare the mean values. Pedons were classified as Entisols, Inceptisols, and Aridisols soil orders. The range of clay content, pHe, ECe, CEC, OM, CCE and gypsum was 15-59%, 7.1-8.5, 0.6-58.1 dS/m, 4.2-22.4 cmol(c)/kg, 0.3-2.4%, 21.2-39.7%, and 0-78.7%, respectively. All epipedons were classified to be ochric and developed soils had cambic diagnostic horizon (Bw) in subsurface. Feo content was maximum in young soil under poor drainage, and minimum Feo content was observed for developed pedons with good drainage class. The sepedons have not been cultivated yet. Feo was maximum at surface soils in all pedons, and decreased with increasing depth. A decreasing trend was observed from surface to subsurface for Fe content in cultivated soils. This negative trend was not, however, detected in poor drainage class or pedons with lithologic discontinuity. This trend can be ascribedto more organic matter content in surface soil in comparison with subsurface soil. Organic matters increase soil acidity and therefore, Feo can not be converted to other Fe forms under this circumstance. Maximum Feo was determined under poor drainage class in low lands. In addition, Fed displayed no trend from the surface to depth at most pedons. Maximum Fed was foundin old plain and the hill slope summit. This Fed was positively strongly correlated with soil development trend. Fed had a positive association with clay content (r=0.463), and negative correlation with sand content (r= -0.411), salinity (r= -0.533), and total carbonate, gypsum and OM (r= - 0.389). Feom (Feo menerogic) was maximum in Byz (4.04 gr/kg soil) and minimum content for Feomwas found in Byb (0.29 gr/kg soil). Maximum andminimum Fedmwas measured in Cy (9.21 g/kg) and Bg2 (1.54 g/kg), respectively. The Feo/ Fed ratio was largerin young soil and decreased with time. These values decreased from the surface to depth with the range from 0.07 to 0.8. The greatest and lowest Feo/ Fedwere, respectively, observed inthe hills and the low lands. There was no significant difference in Feo/ Fed between hill and plain. MS changed from 5 to 25.5. Maximum and minimum MS was detected in the hills and the low lands. MS decreased with depth in almost all horizons. The highest and lowestMS were, respectively, found in pedon 3 (Byb horizon) and pedon 12 in the Bw3 horizon. The MS minerogenicwas statistically significantly associated to sand content (r=0.56**) and significantly negatively correlated with total carbonates, gypsum, OM (r=-0.667**), silt content (r= -0.506) and clay content (r= -0.456). The positive relationship between sand content and MS can be explained by the effect of magnetic materials inherited from the parent materials. Fed and Feo- Fed showed a close correlation with soil development. Feo/Fed ratio increased with decreasing soil age. Feo content had a positive correlation with total carbonate, OM, salinity. MS was more in older soils such as hill physiographic unit but it was low in younger soils or soils with weak drainage. MS was greatly affected by sand material size which seems to be linked to parent materials. MS showed no trend with soil development but land use, drainage and parent material largely impacted MS and different Fe forms in these gypsiferous soils.

The goal of innovation of modern irrigation networks was to increase efficiency. Negligence in operating and maintaining of irrigation network infrastructure is the main source of inefficiency. In order to achieve the optimum efficiency, effective factors should be classified and ranked, and all criteria be considered for making decision. Analytical hierarchy process (AHP) is one of the generalist systems in cases of decision making. The method was developed by Saaty in 1994. In this study, AHP was used to evaluate operating situation of command units of Fumanat irrigation network as a part of the Sefidrud river irrigation and drainage network, Guilan, Iran. The network is located on left side of the Sefid-rud River, between Pasikhan and Shafarud rivers, and limited to Anzali wetland and the Caspian Sea from the north and Fumanat main channel from the south. In the current study, hierarchy structure was made in three levels by criteria and alternatives (command units) of the network and was developed based on the axis of irrigation network operation program include of "control and water resource allocation" and "control and water distribution". Collecting the requirement data, an application has designed based on hierarchy structure and pairwise comprise. Pairwise comparison and number of elements (number of criteria and alternatives) and their required judgments are the factors that the test questions designed based on them. Four effective criteria involved in operation of irrigation network included: type of water regulation and distribution structure, water allocation, method of water distribution and adherence to cultivation pattern. Weighing the criteria, the opinion of experts of Guilan irrigation network operation company (GINOC) via questionnaire and farmers via interview, with difference policies were considered. By the application of criteria and based on Saaty's numeric weight table (1994), the pairwise comparison tables were created with individual involved components. Then, according to Aczel and Saaty (1983), individual pairwise comparison matrix converted to grouping judgment matrix, by computing geometric mean of components. Collected data points which computed and analyzed were introduced to Expert Choice (EC) software to compute the weight of criteria and commend area. Hierarchy structure was made in EC software and the elements were compared in pairwise. The hierarchy model was solved from the lowest level to the highest. Results of pairwise comparison were displayed on the diagram of weights that showed the inconsistency ratio, as well. Considering the pluses in AHP, for example existence of the consistency between decision maker’s opinion and existence of the pairwise comparison in the giving criteria, the suitable method would be obtained. This model evaluated scale of the effect of criteria in the irrigation network operation problems with simplifying the unintelligibility and complexity in the hierarchy analysis, by high accuracy. This research validated the command unit's priority and showed conformity between results and reality. Based on the results, F1 command unit with the most weight of 0.422 had the best situation in term of operation. This command unit was the first one that was operated by modern irrigation network and being on the upstream could lead it to have the better situation. Also, F1 achieved the first ranking in term of evaluating opinions, while F2, F3 and F4 were in the next ranking. According to final weight results, "type of water regulation and distribution structure" with the weight equal to 0.512 was the most effective criteria in term of operation. So, finding the most effective method for improving the operation of these units would need especial consideration and focus on the case of water regulation and distribution structure. Regulation and fixing are two factors involved in ranking in order to prevent illegal withdrawal by farmers. Final weight of alternatives ratio for difference criteria in F1, F2 and F3 command units showed that the most effective factors in ranking were water allocation, type of water regulation and distribution structure and adherence to cultivation pattern, respectively. Also in term of water allocation, F1 command unit had the first rank ratio and the other criteria (F2, F3 and F4) set in the next ranking. The same ranking of the command units was also observed in term of "type of water regulation and distribution structure". Also, the inconsistency ratio of the model was 0.07 that confirmed grouping judgment.

In order to evaluate using effluent (as sequential irrigation), a study was conducted at research farm at Shahid Chamran University of Ahvaz (located at latitude 31˚ 18’, longitude 48˚ 39’ and elevation 18m) during 2014-2015. Regarding to this purpose, a farm (with long 30m and width 24m) was selected and divided into 3 parts (A, B and C). Corn, soybean and sunflower were cultivated in parts A, B and C, respectively and effluent was used for irrigation of next parts. In part B, a split-plot design as randomized complete blocks with two treatments: irrigation type (Karun River and effluent) and urea fertilizer (100%, 75% and 50% application) was applied. Experiment design in part C was similar to part B except at 75% urea fertilizer. ANOVA results for soybean revealed that interaction between irrigation type and urea levels had significant effects on growth yield and biological water productivity (P

In this study the analytical and numerical solutions are used in the steady-state drainage problem in the three rectangular, semicircular, and triangular cross-section trenches. Equations that are derived by conformal mappings and complex potential theory were used for the analytical solution and SEEP/W software was used for the numerical simulation. Furthermore, physical sandbox models are designed for all the three sections in laboratory conditions and the outflows from the drainpipe are measured at 10, 20, 30, 4 and 50 cm depths. According to the three methods, in this study optimum installation depth of drainpipe that has maximum drainage outflow in the both rectangular and semicircular cross-sections is obtained at 40 cm and for the triangular cross-section is 32.5 cm using the analytical solution and 30 cm using the numerical solution and the experimental results. The results are assessed by the differences between the dimensionless discharges obtained from the analytical and numerical solutions and from the experimental conditions using relative root mean square error (RMSE) and coefficient of determination (R2). RMSE in the analytical solution for the triangular section 0.048, the semicircular section 0.061, and the rectangular section 0.071 and the R2 are 0.99, 0.98, and 0.98 and in the numerical solution 0.045, 0.056, and 0.041 for RMSE and 0.87, 0.97, and 0.97 for R2 are obtained, respectively. Comparison of the analytical and numerical solutions results with the experimental results showed that the both methods can simulate seepage flow in the trench with high accuracy. However, the accuracy of numerical solution was more than analytical solution, that it comes from some simplifications and assumptions considered in the analytical solution. In the analytical solution the ponded depth of water is considered small and negligible and the circular perimeter of the drainpipe is taken intoaccount as a line that these are the reasons for the less accurate results of analytical solution. Additionally, the hydraulic of the flow in entrance to the drain pipe is not considered in the analytical solution.

In a 2-year field study, soil moisture and EC of soil extract (ECe) during growing season as well as grain and biological yield and water productivity of barley plant cv. Nosrat were monitored as affected by two salinity levels of irrigation water. Salinity levels of irrigation water were 2 and 12 dS.m-1. The results showed that salinity stress reduced grain, biological yield, and water productivity by, respectively, 36.0%, 52.1%, and 23.0% in the first year, and 48.4%, 69.1% and 31.7% in the second year. Higher losses in the second year were due to lower precipitation. Two-year averages of water productivity in terms of grain yields were 0.87 and 0.64 kg/m3, for 2 and 12 dS.m-1 water, respectively. In all days after imposing salinity treatment, soil moisture in control plots was significantly lower than saline plots. This difference was more distinct in the first depth and continued until the end of the growing season. On average, soil moisture levels in saline plots were higher than the control plots by 16.8% and 22.4% in the first and second years, respectively. In both years, ECe was also affected by salinity treatment, and this effect became more over time. The 2 and 12 dS m-1 salinity treatments decreased and increased ECe, respectively. The highest ECe values were observed at 160 days after planting in all three soil depths. Overall, in this condition, irrigation with saline water increased ECe about twice at the end of season compared to early growth, and increased ECe by 20% over EC of irrigation water. Greater soil moisture in saline conditions is not useful for crops because it is not easily available and has low quality, however, halophytes such as Panicum antidotale, Kochia spp., Salicornia spp. in rotation with barley might use this higher soil moisture and produce acceptable yield with less water.

While providing conditions for crop diversification and improving productivity of northern Iran’s paddy fields¡ subsurface drainage can be a threat to downstream water resources. This research was done to quantify the effects of two types of conventional water management in rice cultivation systems including midseason drainage and alternate irrigation and drainage as well as free drainage in canola growing season on salinity of subsurface drainage effluents. Required experiments were conducted on subsurface drained paddy fields during 4 rice growing seasons and two canola growing seasons (2011- 2015). Each type of management strategy was repeated twice during the study period. Measurements of water table depth and drain discharge were done during drainage periods of different growing seasons. Moreover¡ drainage water salinity was measured in due times. Alternate drainage and increase in water table depth raised drainage water salinity in rice and canola seasons¡ respectively. Compared with midseason drainage¡ alternate irrigation and drainage resulted in 121- 420 kg ha-1 increase in salt loss in different drainage systems. Salt discharge was considerably higher in canola season than rice season due to free drainage condition in canola seasons. Total salt load under midseason drainage¡ alternate irrigation and drainage and canola cropping through different drainage systems ranged¡ respectively¡ 78.4-365¡ 240- 695 and 3056- 5656 kg ha-1. Based on the results¡ water table management through installation of shallow- suitable spaced drains can be effective to decrease salt load from subsurface drained paddy fields.

The type of rivers are dry or seasonal in arid or semiarid zone and current flowing through them is short or if there is no flow. One of the best methods to divert the flow in the river basin system is implementation with subsurface drainage network in the river bed A laboratory model for study the effects of hydraulic and geometric characteristics of the intake flow rate diversion was designed ¡ Which the possibility measuring the inflow and outflow of diversion was considered.in this study were evaluated the effect of bed slope intake and diameter size of particle on diversion flow in two condition¡ water level constant and without control input discharge . The results showed that the slope of the porous medium tangible impact on current of deviation is in a state of constant water level. But the steep increase in input mode increases the deviation is negligible in Dubai. The 20% increase in diameter drains¡ in case the input of 9% and 20% in fixed alignment surface water drainage flow improves.The SPSS were using to obtain an equations that by them can estimate the diversion flow base of head flow hydraulic conductivity in porous media.

In this research, the hydraulic behavior of two kinds of envelopes including synthetic envelope, PP450 and gravel envelope with USBR standard in two soil tank models with silty loam texture was investigated. Three water heads including 55, 75 and 105 cm (water logging) from drain level were used. The discharge of pipe drain in the steady state condition for gravel envelope and at 55, 75 and 105 cm water heads was 188.9, 172.0 and 897.0% more than those in PP450, respectively. Envelope hydraulic conductivity rates at gravel envelope for 55, 75 and 105 cm water heads were 24.6, 14.0 and 21.2 times higher than those in PP450, respectively, and gradient ratios in these water heads for gravel envelope were 14.5%, 2.8% and 14.2% lower than those for synthetic envelope. There were also different behaviors in the two kinds of envelopes for hydraulic conductivity and entrance resistance of pipe and envelope in 55 and 75 cm water heads relative to 105 cm. In general, according to the measured parameters in this research, gravel envelope showed a better performance.

Water shortage is one of the society''s problems regarding to population increase and industries development nowadays. In addition to quantity، water quality is of special importance. The quality of groundwater and prevent further contamination، especially in areas where have highly vulnerable aquifers is particularly important. Most of the canals in the Kuchesfehan-Astane plain are no lining and this factor leads to more water waste. High water leakage has the main role of underground water pollution in this region because ground water level is high and the salient farming is the water farming in this region. This article attempts to determine the rate of water leakage from traditional irrigation canals by the Seep w software and regarding this the network parameter was made and added to drastic parameters as the 8th parameter. A new plan was drawn that presented better results regarding to the standard drastic plan. It is realized that the vulnerability rate of NW drastic plan is about 7. 9 percent but in the standard drastic plan is about 1. 67 percent by the comparison of standard drastic plan and NW drastic plan. Correlation coefficient was used for the appropriateness assessment and comparison of two plans (between vulnerability and nitrate density factors) and it was about 40 percent for the standard drastic and 60 percent for the NW drastic that shows the high accuracy of NW drastic plan.