علی عصاره

In the past, various methods have been proposed to control beach heel scouring.  For shallow rivers (such as mountain rivers), various types of overflows are used.  Therefore, the development of scour in cross-vane and w-weir structures for coastal protection was investigated in this study.  The results showed that by installing a w-weir structure in a 90-degree position compared to a 30 and 60-degree position, a 37.9% and 19.7% reduction of scouring was observed, respectively.  Also, by installing the cross vane structure in the 90-degree position compared to the 30 and 60-degree position, a 35.4% and 21.2% reduction of scouring was observed, respectively. With increasing width (L / B) (ratio of the width of structure to the width of flume), the w-weir structure decreased from 1.5 to 2, scour rate of 7.9%.  Also, with increasing width (L / B) (ratio of the width of structure to the width of flume), the cross-vane structure has decreased from 1.3 to 1.7, and the scour rate has decreased by 4.7%. The w-weir structure had an average of 7.3% less scouring than the cross-vane structure.

To monitor and compare the changes of salts in the soil profile around the roots of the corn plant, the plant yield, and the productivity of corn water, an Experimental was conducted in a completely randomized block of three repetitions in two crop years 2017-2018 and 2018-2019 at Ahvaz Agricultural Research Station. Experimental treatments included two subsurface drip irrigation systems with a working depth of 30 cm from the soil surface and tape irrigation and two irrigation intervals of 2 and 4 days. The results of monitoring soil solutes obtained from sampling depths (0-25, 25-50, and 75-50 cm) showed that soil salinity in the second year in both systems as a result of improving the quality of irrigation water from 3.61 dS/m to 2.01 dS/m, it was reduced by two times. The results of soil salinity monitoring showed the highest ratio of salinity reduction with a 2-day irrigation interval in both irrigation systems. The most leaching was done at the irrigation depth of 25-50 cm in the subsurface drip irrigation system and at the depth of 0-25 cm in the tape system. The highest yield of corn dry fodder was 9.13 and 7.13 tons per hectare, respectively, and the best water efficiency based on dry corn fodder at the rate of 13.74 kg/m was obtained in the strip drip irrigation system (tape) with a two-day irrigation interval and in the second crop year. Also, the results of the soil salinity measurement showed that the implementation and exploitation of the drip irrigation system can be the basis for improving the quality of the soil as the most important non-renewable resource of agriculture.

This study is focused on the treatment and reuse of agricultural drainage water using permeable reactive barriers (PRBs). To construct the physical model, a cubic iron tank with dimensions of 1×1×1 is used. Drainage pipes with a standard diameter of 16 mm are installed at a depth of 20 cm. To determine the depth of the static level, piezometer tubes are used in the model. After permeability tests and evaluating the obtained results as well as considering the availability of materials, the mixture weight ratios of the materials in PRB are selected as follows: 25% sand, 25% anthracite, 20% zeolite, 20% iron borings, and 10% poplar wood sawdust. The permeability coefficient of the PRB with this mixture after complete saturation over 24 hours is equal to 0.0322 cm/s. An initial nitrate concentration of 100 mg/liter is considered for the column to obtain the break through curve of the synthetic wastewater. It takes 15 minutes to detect the nitrate breakthrough. The breakthrough curve is considered a normal curve, and the only unknown of the problem, i.e., the longitudinal diffusion coefficient (D_L), is obtained by trial and error as 1.5×〖10〗^(-7) m^2⁄s, which is an acceptable value. The Peclet number for the proposed PRB is 14.344, which indicates the identical effects of the dispersion and diffusion processes. In this study, the drainage filter, which includes PRB and sandy loam soil, is able to eliminate nitrate by 99.44% after 24 days.

The limitation of the country's water resources and the aggravation of this limitation, which is caused by the continuous increase in the demand, has caused the maximum use of the available water resources and the increase in productivity and, as a result, the increase in production per unit area. The present research was conducted with the aim of evaluating the water quality of Dez River in terms of efficiency in pressurized irrigation systems.

For quality assessment of Dez River water in terms of efficiency in pressurized irrigation systems, 7 hydrometric stations were selected including Sepid dashte Sezar, Sepid dashte zaz, Tange pange sezar, Tange pange bakhtiari, Dezful, Harmaleh, and Bamdezh. Qualitative data of Dez River water along a decade (2005-2014) were taken from Khuzestan water and power authority.

The Qualitative analysis using piper diagram showed that water quality in Sepid dashte Sezar, Sepid dashte zaz and Tange pange sezar stations was calcium bicarbonate. Although, in Harmaleh and Bamdezh stations the most of samples were neutral. The results showed that salinity amount was increased from the upstream to the downstream of the river. Whereas, Bamdezh station had low to medium limitation at 95 percent of times for drip irrigation usage. Dez River had no limitation for infiltration due to suitable averages of SAR and EC. Besides, cations and anions coefficient of correlation was variable between 0.67 to 0.78 and -0.249 to 0.6 respectively. Chlorine in the river water from Harmaleh station toward the downstream of the river, had low to medium limitation for sprinkler irrigation usage. The most limitation of bicarbonate was observed at 97.5 percent of times in Sepid dashte Sezar station for using sprinkler irrigation. In addition, sodium amount in Harmaleh and Bamdezh stations compared to Dezful station increased 134 and 233 percent respectively. Langelier Saturation Index (LSI) was negative in the entire stations and calcium carbonate sediment won’t be created.

It is necessary to use mathematical models to determine the river's response to pollutants. These models are able to simulate the effect of existing and future pollutants and facilitate related decisions. In this study, the water quality of Dez River and its main feeding drains were extracted and analyzed through sampling and laboratory analysis from Dez diversion dam downstream of Loreh drainage during seven months from March to September 2018. The results of the measured samples were compared with those of the simulated values through the HEC-RAS model. The river path was investigated in the study period and seven sampling stations were determined along the river and six stations at the point of drainage into the river to determine the sampling stations, as well as the sources of pollution of Dez River. The results indicated the lack of self-purification of DO, BOD, NO3, NO2 parameters in Dez River during seven months of 2018 due to the inflow of drains and lower river discharge in this period. Also, the base on NSFWQI index, in drought seasons the first half of the river quality index is less than 68, that indicates average quality, and in the second half of the river, the quality index is less than 50 (poor quality). This decreasing trend of NSFWQI quality index is consistent with the trend of qualitative variables of HEC-RAS simulation and indicates the lack of relative self-purification of the river during the study period.

The use of natural processes, including the physiological potential of plants, is a suitable solution. In this study in order to assess the effect of waste leachate and industrial wastewater on the absorption of heavy metals by the Vetiver plant, two separate factorial experiments were performed in the crop year 2020-2021 as a completely randomized design. Experiment treatments factors included waste leachate and industrial wastewater use separately on 5 levels (0, 25, 50, 75, and 100%) in three replications (B1, B2, B3) and two irrigation periods of 5 and 10 days (A5, A10). The amount of iron, zinc, copper, manganese, potassium, and sodium measured in vetiver showed waste leachate had a significant effect at the level of 5% (P <0.05). Meanwhile, the use of industrial wastewater had a significant effect on the amount of iron, zinc, copper, manganese, and sodium absorbed by the vetiver at the level of 5% (P <0.05) but it had no significant effect on the potassium amount (P> 0.05). R4A1 and W5A1 treatments showed a relatively good response with a decrease in biomass production below 10% compared to the control treatment. According to the results, the Vetiver species has relatively high compatibility in the absorption of heavy metals with unconventional waters and can have a special application for soil and water protection.

An accurate and reliable prediction of groundwater level in a region is very important for sustainable use and management of water resources. In this study, the generalized feedforward (GFF) and radial basis function (RBF) of artificial neural networks (ANNs) have been evaluated for monthly predicting groundwater levels in the Dezful-Andimeshk plain in southwestern Iran. The partial mutual information (PMI) algorithm was used to determine efficient input variables in ANNs. The results of using the PMI algorithm showed that efficient input variables for monthly predicting groundwater level for piezometers affected by water discharge and recharge include only water level in the current month. Also, efficient input variables for predicting the water level for piezometers affected only by water discharge include the water level in the current month, the water level in the previous month, the water level in the previous two months, transverse coordinates of piezometers to UTM, the water level in the previous three months, the water level in the previous four months, the water level in the previous five months and longitudinal coordinates of piezometers to UTM. In addition, efficient input variables of monthly predicting groundwater level for piezometers neither affected by water discharge nor water recharge, respectively, include the water level in the current month, the water level in the previous month, the water level in the previous two months, the water level in the previous three months, the water level in the previous four months, the water level in the previous five months, the water level in the previous six months, transverse coordinates of piezometer to UTM and longitudinal coordinates of piezometer to UTM. The results indicated that the GFF network is more accurate than the RBF network for monthly predicting groundwater level for piezometers including water discharge and recharge and piezometers including only water discharge. Also, the RBF network is more accurate for monthly predicting groundwater levels for piezometers that include neither water discharge nor recharge than the GFF network.

Due to the simplicity of operation, Stepped Chutes are among the most common water buildings to reduce water flow energy in irrigation systems. So this research has studied the impact of structure slope, the number of stairs and structure height on energy dissipation rate in stepped chutes. Experimental models used in 2, 20 and 30 cm height, 26.5-degree slope channels (1: 2) and 33.3 degrees (1: 1.5) and in 3, 5, and 7 stairs were built. All tests were done in 4 different rate discharges 10, 13, 15 and 20 liters per second in the laboratory flume, Islamic Azad University of Ahvaz. The results showed that by increasing the amount of  the energy dissipation rate will be reduced. It can be also seen that for a certain value of  Yc/Δz, the increase in the number of stairs reduces the amount of relative energy dissipation. Also Results showed that increasing the slope, the relative energy dissipation rate increases. In this study, the maximum amount of relative energy dissipation for a model with a slope of z = 2 and a height of 30 cm obtained and the minimum amount of energy dissipation for a model with a slope of z = 1.5 and a height of 20 cm obtained. Results showed that increasing the Froude number, the energy dissipation rate will be reduced.

Water demands will increase in the next 50 years due to 40 to 50 percent population growth and the expansion of industries and cities, According to the World Water Association report. This demand will be significant for countries with a water deficits. Water demand for Iran by 2025 will increase by 110% of extractable water resources. With the current climate of the country, access to this volume of water seems impossible. One way to reduce reliance on water resources is to collect rainwater. Rainwater harvesting systems have been adopted in many parts of the world, especially in arid and semi-arid regions, as a practical way to minimize the risk of drought. Because rainwater can be easily collected without special tools and can be used for non-drinking demands. In this study rainfalls that cause to creation of runoff from autumn to late spring in Ahvaz city were investigated.

Two sites were considered for this research. The first was located in the department of parks and green space organization in the south of Ahvaz with the roof area of 115.6 m2, and the second was in the north of Ahvaz town, with the roof area of 35 m2. The roof of both sites had Waterproof insulation levels. The roof runoff of these sites was transferred by gravity from the outlet point to the water storage tanks through a pipe.The tank volume was designed for the first point with a capacity of 2100 liters of polyethylene and the second point with a capacity of 220 liters of plastic (polypropylene). Reservoir volume design was calculated based on 3 components: the average maximum rainfall of the region (December), roof level and runoff coefficient of 0.7. Tanks were installed and calibrated under the outlet pipes of the respective roofs. The volume of water collected at midnight of every day during the test period (in case of rain) was read and the tank was emptied for sampling the next day. On days when the rainfall was more than the volume of the tank design; To prevent the tank from overflowing, the tank water was drained and recorded during the rain. Sampling was started from October 2018 to June 2019. Rainfall data was received from Ahvaz Synoptic Station. The calculation of the roof area of the residential units was based on the urban area houses calculated and was compared with the area of the roofs obtained from Google Earth.

The rainfall statistics reported in Ahvaz by the Meteorological Organization of Khuzestan Province showed that from October 2017 to June 2018, there were 61 rainy days. There were 18 rain events in autumn, 28 events in the winter, and 15 ones in spring. The average runoff coefficient in Ahvaz city was obtained respectively 0.759, 0.711, and 0.797, for autumn, winter, and spring seasons. The runoff coefficient for autumn, winter, and spring seasons were reported 0.66, 0.69, and 0.62 in Mashhad, and 0.75, 0.76, and 0.69, in Noor city, respectively. This difference can be due to the difference in rainfall regime, the type of roof insulation, the slope of the roof, and so on. Also, the results showed that with the extraction of rainwater from the roof surfaces of Ahvaz in the months of October to May, respectively, 2.24, 8.4, 21.2, 14.85, 13.65, 9.17, 7.44, and 4.03% of the domestic needs (except for drinking and cooking), 16.85, 63, 100, 100, 100, 68.84, 55.77 and 30.2% of the public needs, 8.43, 31.5, 79.61, 54.68, 51.19, 34.42, 27.88 and 15.10% of the commercial and industrial needs and 1.06, 4.48, 13.17, 8.88, 7.66, 5.05, 4.3 and 1.88% of the greenhouse needs can be supplied.

The results showed that in the city of Ahvaz, 75% of the rainfall has led to runoff production. The runoffs that can be extracted from the roofs were the most share in December and winter months and the last one in June, July August, and September in Ahvaz. The highest amount of rainfall in Ahvaz, which did not lead to runoff, was 0.2 mm. In other words, rainfall that is less than this amount does not lead to runoff. Also, the lowest amount of rainfall in Ahvaz, which has led to runoff, is 0.3 mm. Therefore, the probability of the threshold of runoff in Ahvaz is 0.3 mm. In other words, rainfall that is more than this leads to runoff production. Also, the results obtained from this study showed that in December, January, and February, water that can be extracted from the roof surface, in addition to providing 100% of the city's general consumption needs in these 3 months, can save 416.14 million liters, Which will be usable in other months. Due to the lack of measurement of quality parameters, the collected water is not recommended for drinking.

The present research was conducted to determine water stress tolerance and water productivity (WP) of 5 alfalfa cultivars as a split-plot design in a randomized complete block with 3 replications in the Safiabad Agriculture and Natural Resources Research Center (SARRC) with Silty clay loam soil texture during 2018-2019. The main plot was 4 levels of water irrigation depth (including 25, 50, 75, and 100% water requirement supply) with a constant irrigation cycle and the sub-plot was the five alfalfa cultivars (Baghdadi, Yazdi, Nikshahree, Omid, and Mesasirsa). Two-year data on forage yield and WP for six harvests (from June to November) were analyzed by SAS software. The results showed that the wet and dry forage yield decreased by applying water stress and the percentage of dry forage increased. The highest yield of dry matter (12.4 tons ha-1) and WP of dry forage (0.94 kg m-3) were obtained from 75% water requirement supply treatment. Baghdadi genotype with wet and dry forage yield 39.1 and 10.7 tons ha-1, respectively, and the WP of dry forage 0.9 kg m-3 was higher than other genotypes. However, the Yazdi genotype had the lowest yield of wet and dry forage (30.3 and 8.5 tons ha-1, respectively) and dry forage WP (0.75 kg m-3). Therefore, the Baghdadi genotype with a 75% water requirement supply is recommended for similar conditions to the climate of Northern Khuzestan to increase water productivity.

Water resources limitation and plant stress due to water shortage is one of the important and common environmental stresses in agricultural production, including forage production in hot and dry areas. Therefore, the selection and development of drought-tolerant cultivars are very important. In irrigated lands of Iran, the average of irrigation efficiency is 37% and water productivity is 0.8 kg per cubic meters, which is lower than the world average. For increasing water efficiency, maintaining the production capacity and creating sustainable agriculture, it is necessary to identify the effective factors on the reduction of irrigation water productivity and provide an appropriate solution. In arid regions such as Khuzestan province, by using both a proper irrigation program and irrigation levels below the water requirement, obtaining the acceptable yield of alfalfa could be expected. In order to achieve these objectives, determination of the irrigation water productivity of tropical alfalfa cultivars and their drought tolerance under different irrigation regimes were the main aims of this study.

For evaluating tropical alfalfa genotypes under different drought stresses, an experiment was carried out based on split plots design with three replications in Safiabad Agricultural Research Center, Dezful, Iran, in 2019-2020. The main factor was four levels of irrigation (25, 50, 75 and 100% of water requirement) and the second factor was five alfalfa cultivars (Baghdadi, Nikshahri, Yazdi, Mesasirsa, and Omid). In this experiments, plant characteristics including dry and wet forage yield, percentage of dry forage, leaf to stem weight ratio, chlorophyll index (SPAD), electrolyte leakage from the leaf cell membrane (EL), relative leaf water content (RWC), and Maximum quantum yield in the dark-adapted conditions (ΦPSɪɪ) were determined.

The results showed that by applying drought stress, wet and dry forage yields, RWC, and ΦPSɪɪ were decreased but the percentage of dry forage, leaf to stem weight ratio, EL, and SPAD were increased. Among the studied genotypes, the Baghdadi genotype had the highest dry forage yield in all situations; non-stress conditions (16.9 t/ha), mild drought stress (15.094 t/ha), moderate drought stress (9.58 t/ha) and severe drought stress (4.664 t/ha). The Yazdi genotype had the lowest dry forage yield; 9.9, 9.7, 5.7 and 3.6 t/ha for non-stress, mild, moderate, and severe drought stresses conditions, respectively.

In our experiment, the Baghdadi genotype showed a high-stress tolerance index (STI) and we highly recommend planting it in the north of Khuzestan province, but the Yazdi alfalfa genotype despite low dry forage yield under both non-stress and drought stress conditions is not recommended due to low production. We suggest using Yazdi genotype in eugenic plans due to high yield stability index (YSI) under drought stress conditions and having some favorable physiological and photosynthetic parameters associated with drought stress tolerance.

Due to the fact that many variables are effective in the amount of sediment trapping and the amount of water loss in the eddy tube, this study was conducted to investigate the performance of the eddy tube in laboratory conditions. 4 ratio of pipe gap width to pipe diameter (t / d), 0.15, 0.20, 0.25 and 0.3, 3 granulation D1 (particles passing through sieve 8 and remaining on sieve 10), D2 (particles passing through sieve 16 and remaining on sieve 20) and D3 (particles passing through sieve 20 and remaining on sieve 30) were selected at a 45 degree angle with different flow rates. The results showed that if the area is not facing water shortage and water supply problems and preventing sediment from entering the system is preferable to water supply, t / d = 0.3 is a more desirable option; But if it is very important in water supply areas and there is basically water shortage; The better option is t / d = 0.25.

In this research, the simulation and optimization models are integrated to apply the reservoir hedging policy. The simulation of the studied basin is executed using the WEAP model to conduct the system optimization and the multi-objective MOPSO model is utilized so that the first purpose is to maximize the percentage of supplying demands, while the second one is to minimize the violation of allowable capacities of the reservoir during the operation period. In this regard, the operation modeling from the reservoir was carried out based on the current condition for a 360-month period. Finally, by defining the optimized scenario and applying the reservoir hedging policy, the optimization of the operation from the reservoir is conducted and the results were compared with the outcomes of the reference scenario. In this study, by considering 24 decision variables including 12 hedging level variables and 12 hedging coefficient variables, the optimal answers were achieved after 1000 iterations. The results showed that the violation of the allowable capacities has not occurred in any periods, while in the reference scenario the reservoir level has reached the dead level in sequent months with more water shortage which might lead to the lack of water supply in such months and serious damages to the system. Due to the application of hedging policy in the optimized scenario, the percentage of supply in the critical months has increased between 20-35% compared to the reference scenario, which indicates a significant reduction in the failure rate in such months compared to the reference scenario.

Rivers and water resources polloution caused by uncontrolled industrial wastewater discharge. Precence of high concentration of phosphate ' sulfate and nitrate anions in sugarcane indusrial wastewater ' required treatment of the waste water for nutrients and corrosive substances deletion. This study is an attempt to investigate the effect of electrical current' initial wastewater PH and retention time on phosphate ' sulfate and nitrate pollutants removal of sugarcane industrial wastewater. In this study ' the electro coagulation method with aluminum electodes were applied for wastewater treatment in sugar cane of Hakim Farabi. 6 electrodes – aluminium in vertical position were connected to power supply by monopolar method. Septic tank was selected for sampling. Initial wastewater concentration and PH were measured for phosphate' sulfate and nitrate. Then the effect of three operation parameters: PH(5' 7' 9' 11) electrical potential (10 and 30 volts) and retention time (15' 30' 45' 60 minutes) for phosphate ' sulfate and nitrate removal efficiency have been investigated. The results showed that in equal retention time and different initial PH the removal of phosphate' sulfate and nitrate could be promoted by increasing the electrical potential from 10 volt to 30 volt.. The results indicated that the highest removal efficiency of phosphate was observed in neutral condition and increasing PH decreases phosphate removal. whereas the highest removal efficiency for sulfate and nitrate was observed in alkaline PH .also the results proved that in all condition of PH and voltage' increasing retention time cause increasing in removal percent for phosphate' sulfate and nitrate.

Water deficit is known as the most important limiting factor in agricultural products, especially in the arid and semi-arid regions. Agriculture has been negatively influenced by low obtainable water and because of climate change, making water stress conditions for economic crucial plants. As Iran's major region is consisting of the arid and semi-arid areas with limited water resources, in case of the minimum plant water use is not maintained, the plant would experience drought stress and the products would suffer irreparable losses. One way for optimal use of the water resources and their preservation is the use of superabsorbent polymers which not only provide conditions for improved products quality but also results in increased water consumption efficiency in the arid and semi-arid areas. Superabsorbent polymers could absorb and retain water up to several times of their weight. Due to the drying up of the environment, the water retained in the superabsorbent will gradually discharge, and thus the soil would remain moist for a long time, without needing further irrigation. This property is the great importance to confront water shortage and reduce the harmful effects of drought stress in plantations. Superabsorbent polymers cause water retention in the soil and reduce the number of irrigation frequency up to 50%.

In this study, the effect of water stress and different levels of superabsorbent on cucumber crop (variety of super dominus hybrid) in a farm with sandy soil, in Seymareh region, Ilam province, Iran was evaluated. This experimental farm was conducted at 33° 09′ N and 47° 24′ E, and with an elevation of 982 m. Seymareh region has a Mediterranean summer and winter. The average annual precipitation is about 350 mm and the average temperature is about -2° C in the winter and about 45° Celsius degrees in the summer. The hydrophilic polymer: Super-AB-A-300 used in this study. This polymer is a granular type and produced by Rahab Resin Co. with product license holding of Iran Polymer and Petrochemical Institute. This hydrophilic polymer is a terpolymer of acrylamide, acrylic acid, and acrylate potassium. The experimental design was according to a split-plot method in a randomized complete block design that was done with 12 treatments and 3 replications. In this study, 3 different depths of irrigation were considered as the main treatment including I1, I2, I3 as 100, 80 and 60 percent of water requirement of plant respectively and different levels of superabsorbent were used as secondary treatment including S0, S1, S2 and S3, equal to 0 (control), 15, 30 and 45 g m-2 respectively. The size of each plot was 4 * 1.2 m2 including 6 lines. The Superabsorbent for each line in each plot was distributed in a depth of 30 cm from the soil surface. The cucumber variety of this plan was planted manually in April as spring planting and in August as summer planting. The space between planting rows was 20 cm, and between each plant in each line was 40 cm, so a total density of planting was 60 plants per each plot. Three grains were planted at each point which after germination, they were thinned out to one plant. From the 3 to 4 leaf stage (after the complete establishment of the seedling) the deficit irrigation treatment was applied. For planning and determining the irrigation interval, by adopting the no water stress treatment as the criterion, the soil moisture index and the soil matric potential were incorporated. The percentage of soil moisture content was measured through sampling to the depth of plant root in the days before irrigation and when the weighted mean of the volumetric soil moisture reached the allowable depletion for the cucumber plant, the next irrigation was performed; therefore, the irrigation interval was determined; concerning the treatment with no water stress (control) and simultaneously all the treatment plans with equal irrigation intervals and with different water depths were irrigated.

According to the results, the independent effect of irrigation and superabsorbent treatments at 1 percent level on cucumber crop yield was significant. The maximum and the minimum of cucumber fruit weight and crop yields were 72.86 and 56.90 g, and 3.7 and 1.97 kg m-2 related to the complete irrigation (I1) and severe drought stress (I3) respectively. Results showed that in the drought conditions, superabsorbent application increased cucumber fruit weight and crop yield compared to control treatment. Also, the independent effect of irrigation and superabsorbent treatments at 1 percent level on water use efficiency of cucumber crop was significant. The maximum and the minimum of water use efficiency were 8.11 and 6.15 kg m-3 related to the complete irrigation (I1) and severe drought stress (I3) respectively. In addition, a quadratic function was introduced as the optimum water-yield production function of cucumber crop (variety of super dominus hybrid) in the presence of superabsorbent, in sandy soil. Finally, the results showed that superabsorbent could prevent the significant reduction of cucumber crop yield in sandy soil and under drought stress conditions.

In this study, the effect of water stress and different levels of superabsorbent on cucumber yield (variety of super dominus hybrid) in a farm with sandy soil was evaluated in Seimare region, Elam province, Iran. Experimental design was performed according to split plot method in a randomized complete block design. Three different levels of irrigation were considered as the main treatment including 100 (I1), 80 (I2) and 60 (I3) percent of crop water requirement and four levels of superabsorbent were used as secondary treatment including zero (S0), 15 (S1), 30 (S2) and 45 gm-2 (S3). According to the results, the effect of irrigation and superabsorbent treatments was significant on cucumber yield at 1 percent level. The average maximum and minimum crop yield were 3.7 and 1.97 kgm-2 which were corresponded to the full irrigation (I1) and severe drought stress (I3) treatments. In addition, the effect of irrigation and superabsorbent treatments was significant on water productivity of cucumber crop at 1 percent level. The maximum and minimum water productivity were 8.11 and 6.15 kgm-3 which were corresponded to the full irrigation (I1) and severe drought stress (I3) treatments. Also, a quadratic function was introduced as the optimum water-yield production function for cucumber crop (variety of super dominus hybrid) in the sandy soil amended with superabsorbent. Finally, it was concluded that the superabsorbent could prevent from the significant reduction of cucumber yield in sandy soil and under drought stress conditions.

Introduction Water stress is the most important cause of reduced wheat yield in semi-arid areas. In most regions under wheat cultivation, especially in regions with Mediterranean climates, wheat plants are exposed to various stresses during the seed filling. Seed filling often occurs when temperature rises and less water is available. Irrigated wheat in Khuzestan Province mainly faces end-season drought caused by limited water supply on the one hand and the reduced precipitation and competition by other crops for water on the other hand. Therefore, introducing wheat genotypes tolerant to end-season drought is of great importance for this Province. Materials and methodsThis research was conducted at the Agricultural and Natural Resources Research Center of Safiabad- Dezful in the crop years 2014-2015 and 2015-2016. Eight promising durum wheat lines in warm regions in Iran together with the Behrang cultivar were studied. The following two separate experiments were conducted using the randomized complete block design with two replications: (1) full irrigation until maturity and (2) application of end-season water deficit stress through irrigation cessation from the spike emergence stage to physiological maturity.Results and discussion Results indicated that the effect of year was significant under drought conditions but not significant in the absence of drought conditions. Moreover, the mutual effect of genotype and year were significant in the absence of drought but not significant under drought conditions. The mean two-year yield under conditions without water deficit stress was 4844 kg/ha, with the highest average seed yield (5101 kg/ha) belonging to line 1 and the lowest (4669 kg/la) to line 2. Although yield of line 3 under conditions without water deficit stress (5039 kg/ha) was a little lower than that of line 1, it enjoyed higher yield stability compared to the other lines because it had the average ranking of 2.5 and the standard deviation of 0.5. Furthermore, the mean two-year seed yield under end-season drought conditions was 3991 kg/ha, with the highest mean seed yield of 4332.5 kg/ha belonging to line 4 and the lowest (3710 kg/ha) to line 9. Under end-season drought conditions, line 4 had the largest seed yield and the highest yield stability in the two years of experiments with the average ranking of 2.5 and the standard deviation of 0.5.Principal component analysis (PCA) and the shape of the by plot were employed for the simultaneous study of the relationships between the genotypes and the quantitative drought tolerance indices. Results of the PCA showed that most of the variance in the data could be explained by the two components of PCA1 (the first component) and PCA2 (the second component) with 63% and 30%, respectively. In addition, among all of the calculated components, only PCA1 and PCA2 had eigenvalues higher than 1 (5.67 and 2.66, respectively). ConclusionThe strong positive correlation between seed yield in the two environments with and without water stress and the STI, MP, and GMP indices indicated that these indices had a high efficiency in selecting drought tolerant genotypes. Based on the results of PCA, genotypes 1 and 3 were selected as water deficit stress tolerant genotypes because of their high PCA1 and suitable PCA2 values and also due to their closeness to the important drought tolerance indices MP, GMP, K1STI, K2STI, and STI; whereas lines 6, 9, and 10 were introduced as water deficit stress sensitive genotypes because of their low PCA1 and PCA2 values and also due to their closeness to the SSI vector. Line 7 was between important drought tolerance indices and drought sensitivity indices and enjoyed relatively desirable drought tolerance, but the high estimated values of SSI and TOL for this cultivar indicated that it lacks suitable yield stability. Moreover, this cultivar is close to the Yp vector, which shows that drought tolerance in this genotype is due to its high yield in stress free environments.

Increasing water productivity in agriculture is one of the effective strategies for sustainability of water resources. In this research, irrigation management and water productivity in North Karkheh irrigation and drainage network were evaluated by examining the cropping pattern and the use of land use productivity indices, CPD, BPD and NBPD. The results of the study showed that the mean wheat cultivation in the 5 years period of study (2009-2013) increased by 132% compared to the designer's proposed cultivar, while the average barley yield decreased by 470% compared to the design pattern of the designer. Also, the cultivation of fodder plants such as alfalfa and clover has not been welcomed by farmers in the region. The average 5 years of cultivation at the network level was 5924 hectares and the average water consumption per year was 55.5 million cubic meters; if the water required for the designer crop pattern was an average of 86 million cubic meters per year For 6500 hectares. The five-year average CPD index for wheat, as the product with the highest cropping area, was 818 gm-cubic meters, and for spring crop watermelon, as the product that had the highest water intake among cropping patterns It was 2301 grams per cubic meter. The five-year average of BPD and NBPD for wheat was 5870 and 3018 Rials per cubic meter.

The aim of this study was the evaluation of drought effects through SPI index assessment on the water quality of the Dez River. For the determining the drought, ten-year meteorological data (2005-2014) were achieved through the weather stations of Hussainiya, Dezful, and Shush and for impact evaluation of drought on the water quality of the Dez River, discharge statistics and qualitative parameters related to seven hydrometric stations along the Dez River achieved through Khuzestan Water And Power Authority. The mean frequency of dissolved anions and cations in the hydrometric stations of the Dez River achieved like HCO3>SO4>Cl and Ca>Na>Mg. The variance analysis of the water qualitative parameters showed that the effect of station and year on the amounts of discharge, EC, TDS, SARIW, pH, Cl, HCO3, Ca, Mg, Na, and SO4 had a significant difference (P

Khouzestan province with about 1000 hectares of seed clover is the most important region for seed production of berseem clover (Trifolium alexandrinum) in Iran. Extending the cultivation area of berseem clover (BC) is important due to the favorable effects of BC on soil fertility and the necessity of this region to a desirable crop rotation. The harvest date of summer crops such as corn leads to delay in optimum sowing date of BC. Several investigators in other areas have demonstrated that early sowing dates improved yield of BC. On the other hand, the most important factor in crop yields is water irrigation; it plays an important role in sustainable agriculture. Based on the existing literature, early sowing date reduces the number of irrigation events and increases water irrigation use efficiency (IWUE). Therefore, this experiment was conducted to evaluate the response of spring BC sowing date and last irrigation cutoff time on seed yield and IWUE. This study was carried out in Safiabad Agricultural Research Center in two years (2014-15). Soil texture of the experimental field was silty clay loam, well drained without salinity (ECe=1.2ds m-1), with 0.75 percent organic carbon. The statistical design of the experiment was split plot based on a randomized complete block design with four replications. The main plots were allocated to sowing date including 10th Feb, 20th Feb, 2st Mar and 12th Mar, and the sub plots were assigned to irrigation cutoff dates including 5th Jun, 15th Jun and 25th Jun. Daily evaporation from class A evaporation pan of the Safiabad weather station (nearby the experimental field) was measured to calculate water irrigation depth, and BC evapotranspiration was calculated by applying a pan coefficient of 0.8. Irrigation interval was managed based on 80 mm accumulated evaporation from the pan evaporation. The measured traits included seed yield, IWUE, number of seeds per inflorescence (NSI), number of inflorescences per square meter (NI), days to flowering, straw production, total dry matter (TDM), harvest index (HI) and weighed a thousand seeds. There was a significant difference between the irrigation cutoff date for all traits except the number of days to flowering and HI. The results of the mean comparison showed that the, sowing date of 20th Feb and irrigation cutoff in 15th Jun, with seed yield (631 kg.ha-1) and IWUE (0.72 kg.m-3) was better than the other treatments. In this treatment, the plant growth period in the first sowing date (88.6 days), and the NI (623 numbers), and the NSI (37.1 numbers) was higher than the other treatments. The correlation between seed yield and other traits was positive and the stepwise regression analysis showed a positive and high effect of NI on seed yield in BC. The results of this trial confirm previous findings that BC early sowing dates, will had higher seed yield. Also, the results showed that delaying in irrigation cutoff is effective in decreasing IWUE, so that irrigation until 25 th  June in comparison with 15 th June, In spite of significant increasing in yield, decreased IWUE significantly.

In order to investigate the effect of drought tension after flowering on dry matter remobilization in 56 wheat genotype, the present experiment was conducted as rectangular lattice 8x7 with two replications during 2010-11 cropping year at research farm of the Campus of Agriculture and Natural Resources of Kermanshah Razi University. Results showed that there was a significant difference at one percent level among genotypes in terms of grain yield and about 27.2 percent reduction in grain yield was observed in response to drought tension after flowering. Mean comparison of yield in different wheat genotypes showed that under humidity control conditions, Darab 2, Navid and UN-11 genotypes (760, 690 and 662 gram per meter square, respectively) had the highest and Rasad cultivar (419 gram per meter square) had the lowest grain yield and also under drought tension conditions after flowering, 330 and Moghan1 genotypes by 542 and 510 gram per meter square, respectively, had the highest and Shiroudi cultivar by 187 gram per meter square had the lowest grain yield. In terms of dry matter remobilization and remobilization efficiency, lower stem internodes compared to peduncle and penultimate internode, showed superiority. Under studied genotypes had a significant difference in remobilization and dry matter remobilization efficacy. According to the obtained results, it appears that remobilization efficiency has been affected under genetic and environment and probably higher production of dry matter at flowering stage would be resulted to higher dry matter remobilization to the grain.

Iran is an arid country with water crisis. Regarding the role of surface water in the region's ecosystems and the impact of drought on water quantity and quality, the present study was conducted to investigate the frequency of droughts in Khuzestan province. For this purpose, the annual rain fall of statistics synoptic stations were used for Dezful, Shoushtar, Behbahan, Abadan, Masjed Soleiman, Ahvaz and Izeh for a period of 20 years. Data correctness and uniformity test were done on the method of test runs and doubly mass. Then, the occurrence frequency and droughts severity was studied based on five indexes namely, analysis of rainfall data (SPI), normal threshold climate Index (RI), reliable rainfall index (DR) and the methods of Niche and PNPI. Results for SPI index showed that in the stations of Ahvaz, Dezful, Abadan, Masjed Soleiman, Behbahan, Izeh and Shoushtar were 7, 6, 6, 6, 7, 9 and 8 cases of droughts, respectively. On the basis of RI index at selected stations were 10, 3, 4, no drought, 4, 5 and 4 cases of droughts.On basis of DR index at the stations of Ahvaz, Dezful, Masjed Soleiman, Behbahan and Izeh 6 cases and at the stations of Abadan and Shoushtar 5 cases of droughts, based on Niche at the stations of Ahvaz and Dezful 5 cases, at the stations of Abadan and Behbahan 4 cases, at the stations of Masjed Soleiman 3 cases, at the stations of Shoushtar 2 cases and at the station of Izeh one case of drought were observed. However, the results of research based on PNPI index showed that at the stations of Bahaman and Izeh 9 cases of droughts, at thestationsof Ahvaz,Masjed Soleiman and Shoushtar 7 cases and at the stations of Dezful and Abadan 6 cases of droughts were occurred. The results showed that in all the studied stations during each year at least 30% drought has occurred.

To achieve the goal of high yield, deep understanding of physiological, agronomic and environmental factors is necessary to improve the performance and sustainability of agricultural systems. This may not be practical unless the plant complex systems and the type of response to inputs and environmental conditions are known as important factors. In modern agricultural methods the uses of different models are important for management, optimize productivity, accurate understanding of the system and obtaining a precise formulation of the standard. In order to simulation of soil moisture under different water conditions on wheat(Chamran cultivar) a field experiment was conducted at the Agricultural Research Center- Ahwaz. In this experiment, three irrigation levels include I1 ( no water stress ), I2 (stop irrigation at the heading stage and I3(stop irrigation at the milky grain stage) and five levels of nitrogen fertilizer namely N1(no nitrogen fertilizer), N2=40, N3=80, N4=120 and N5=160 kg/ha were used as treatments. In this research, HYDRUS-1D was used as simulation model. Analysis of results for sensitivity of model showed that soil moisture coefficient of model under saturation condition θs is more than other coefficients and a slight change in coefficient caused a large change in output variation of model. The minimum effect was observed in α, I and θr coefficients. Meanwhile, results indicated that model was estimated moisture content less than reality condition. Also, the amount of moisture on the basis of simulated model was estimated less than the real moisture. The model efficiency that reflects to quality and observed data was estimated between 0.67 and 0.90. This was due to high efficiency of simulated model for soil moisture.