مجله آبیاری و زهکشی ایران
سال هشتم شماره 4 (زمستان 1393)

In order to determine the Correct optimal Management of Agricultural water، optimum use of water in irrigation networks is necessary. One factor in the complexity of irrigation networks and water management is unsteady flow. Sources of unsteady flow in irrigation networks are different but the most important source is irrigation canal operation. Optimum set of control structures for the management of unsteady flow can improve the performance of irrigation networks. For this purpose The ICSS hydrodynamic model linked to Ant Colony optimization method and the ICSS-Ant model was developed. In this research at first some alternatives of unsteady flow in E1R1 canal of Dez irrigation network simulated and using assessment indexes the rate of canal performance decrease calculated. Then using ant colony algorithm all options in optimal conditions were simulated. The output of the simulation- optimization model is optimal tuning of canal structures involes turnouts opening and and the height of check structures. After optimization result we can see totally the canal performance improved and for other results the reason is ideal condition for initial canal condition.

The impact of climate change on precipitation and temperature changes by climate predicted models analyzed. General circulation models of the atmosphere and subsequent use of subscale models such as LARSWG5 make it possible، but these predictions are encountered with uncertainty. In this study، the investigation of uncertainty output of LARS-WG5 model after the forecasting of two parameters of precipitation and temperature over thirty years also studied، from 2041 to 2012 in synoptic station of Mashhad. The results showed that the output of this subscale model does not have certainty، as the amounts of subscale precipitation in the first and fourth quartiles are different in Mashhad station. Through using A2 Scenario and three models of HadCM3، GFCM21 and INCM3 in the first quartile، 75% of the predicted rainfall respectively، over 53. 95، 57. 17 and 44. 93 mm in March، and in the third quartile، 25 percent of the data respectively are greater than 59. 86، 63. 53 and 50. 23 mm.

A field experiment including of six rotations، six cultivars of wheat and two irrigation regimes (rain-fed and supplementary irrigation) treatments with three replications was carried out over four years (2007-2012). This article is part of the mentioned project result that focuses on soil moisture distribution in some winter crops. Results show that bean and canola have a higher comparative advantage than the continuous cultivation of wheat because they are planted earlier and also harvested earlier than the wheat. The most of the moisture were depleted in the soil at the end of the wheat season، both in supplementary and in rainfed conditions، as a result soil moisture conditions would be in appropriate in the next planting. For example، the results shown in the second، third and fourth year sat the end growth stage of the bean cultivation was remained about 73،30 and18 mm of soil moisture higher than the land under wheat cultivation which is available for the next summer crop.

One of the principal methods to improve water productivity in irrigation network is to use the suitable distribution of water. In this research، the distribution of water in Doroodzan dam irrigation network was evaluated using 14 years of data (1996-2010). This irrigation network is located in northwest of Fars province and distributes stored water in Droodzan dam. Distribution of water between Hamoon، Ordibehesht، Left side Principal and Abarj canals was studied. Monthly distribution of water showed that in April and May، inflow in canals are high، in November they are low and in February there is no water in canals. The index of delivered water per unit area of land must be equal between canals. The lowest amount of this index was 0. 19 (l. s-1. ha-1) for Hamoon canal and the highest amount was 0. 37 (l. s-1. ha-1) for Abraj canal. The results showed that Hamon canal compared to others received less water per unit area and Abarj canal، received the highest amount of water per unit area. It was recommended that the water must be distributed between canals by equal amounts per unit area on volumetric basis based on crop water requirements.

Climate change is effective on the amount of precipitation in all areas and consequently it is effective on IDF curves. The aim of this study is the evaluation of effects of climate change on IDF curves in Babolsar station in future period since 2011 to 2030 using atmospheric general circulation model and under emission scenarios. In this respect، two appropriate statistical distributions، the Gumbel and Log - Pearson Type III، were fitted with hourly rainfall values between 1998-1966. Then IDF curves have extracted For intervals of 10، 20، 30 min and 1، 2، 6، 12 and 24 hours and return periods of 2، 5، 10، 25، 50 and 100 years. Next، data in daily time scale were estimated for intervals of 2013-2030 using atmospheric general circulation model of HadCm3 under emission scenarios A1B، A2، B1 and down scaling model of LARS-WG. The derivative curves of assumption scenarios have extracted by modified relationships of Bell. The results indicate that the values of correlation coefficient in Gumbel distribution were in the range of 0. 996-0. 998 and for Log - Pearson Type III، they were in the range of 0. 969-0. 974 that shows more significant correlation for Gumbel distribution. Comparison between rainfall predicted by the scenario mentioned and rainfall calculated by Gumbel distribution for data from 1966-1998 is showed an increase in precipitation intensity for BABOLSAR station in future periods (2 - 2011). For example، according to three scenarios A1B، A2، B1 the rainfall value for interval of one hour and return period of 2 year، respectively، 28%، 17% and 25% have increased than the values of basic rainfall.

Super absorbent polymers because of Water absorption and hold water can increase the water-holding capacity of the soil and decreases tension caused by dehydration effect. This study evaluated the effects of different levels of superabsorbent polymer and water stress on yield components in maize In Agriculture Research Center of Varamin city in July 2012 Was carried out as a pot factorial complete block randomized design with 3 iteration. Treatments consisted of four levels of water stress، w1، w2، w3 and w4 (50، 75، 100 and 125% of crop water requirement) and 4 superabsorbent Hybrozom s1، s2، s3 and s4 (control، 3، 5، 7 grams per kilogram potting soil). Traits Review was Included: Length of Bush، Fresh weight of leaves and Dry weight of leaves. The Results indicated that، with increase rate of superabsorbent polymer was increased leaf dry weight، total dry weight and plant height so that this parameters in the treatment s4 (7 grams per kilogram of soil) than controls، respectively 63. 72، 90. 14، 36. 42 percent has increased.

Application of efficient policies to operate dam reservoirs is of great importance due to water shortages and frequent droughts in the country. For this، different approaches can be implemented، which are based on different modeling systems. The present paper aims to compare some of these approaches for optimal water allocation in Zayandeh Rud agriculthral system during 1998-2000 droughts using some evaluation criterion. The mentioned approaches include: 1) dynamic programming (DP) considering constant agricultural water demand and no uncertainty in inflows، 2) stochastic DP (SDP) with constant agricultural demand and uncertainty in inflows and 3) Sampling SDP (SSDP) considering constant demand and inflow uncertainties and 4) variable agricultural water demand with respect to crop types، growing stages، irrigation systems using linear and non-linear programming (LP and NLP) modeling and no uncertainty in inflows. Results showed the first and fourth approaches had the simplest and most complicated modeling process، respectively. However، with respect to some efficiency indices like temporal and volumetric reliability، maximum as well as total shortages، the stochastic approaches i. e. the second and third ones outperformed respectively equal to 38%، 68%، 157 and 330 MCM. This superiority was considerable especially for the third modeling approach. The comparison of net benefit values from optimization approaches as well as real obtained one for Zayande Rud system showed the optimization approach could increase the benefit from 68% to 73%.

The recommended strategies in intensifying water shortage condition is changing the surface irrigation system to drip irrigation، in which case notification of the root system of mature trees for drip irrigation management is essential. The goal of this study was to investigate the effects of surface irrigation، automatic drip irrigation and traditional drip irrigation on olive tree root growth. The soil texture was sandy loam with 50% gravel. The fresh weight، dry weight and fresh volume of root were measured within 30 cm of tree under tree shadow area for 80 cm soil depth. The results showed that percent of fresh weigh was reduced 40% to 5% and 5 to 4 gr with increasing of depth and tree trunk distance to 240 cm، respectively. Also existence of gravel in soil was effective in root development، and fresh weigh and fresh volume density were decreased with increased of gravel. The olive root development was affected by irrigation system and dripper layout. The results showed that، changing of surface irrigation system to drip irrigation system for mature olive trees is possible; however، need to consider root growth system under previous irrigation system.

South Khorasan province، with an average annual rainfall of 180 to 200 mm، Average annual production of over 490 thousand tons of agricultural products، overdraft more than 138 million cubic from groundwater، takes place so of 24 Prairie Independent State، 13 Plains Forbidden، 2 Plains critical prohibited، 3 Plains proposed ban. In this study، the average virtual water crops in South Khorasan Province was about 1312 cubic meters per ton of product and agricultural water use efficiency is 0. 62 kgm3. As a result، rice imported about 7. 76 million cubic meters of water in virtual form due to agricultural product trade in 2008 to 2012. During this period، the largest volume of virtual water export was tomato sauce، potato and apple which declined from 24. 5 to 17. 2 million cubic meters. In 2012، the net water requirement in potential condition for food security of 662،534 populations was about 723 million cubic meters. To achieve food security، requires about 448 thousand tons of food supplies، taking into account the actual conditions and efficiencies of 35%; we need about 2065 million cubic meters of water to form a virtual. The water footprint of province was 1142 million cubic meters or 1723. 7 cubic meters per capita per year.

In order to study the effects of irrigation water (50، 75 and 100%) and potassium fertilizer (50 and 100% Potassium fertilizer required) on the growth of roots and shoots of sorghum varieties (Pegah، Karaj and Speedfeed)، a pot experiment was conducted in Agricultural Research Center of Semnan province (shahrood). The experimental treatments were arranged as split plots based on a randomized complete block design with three replications. Factors in this study were including irrigation water، potassium fertilizers and varieties of forage sorghum. To measure the characteristics of shoot plant، at first they were removed and leaf area، leaf dry weight، stem dry weight and shoot weight were measured. Then the roots were completely removed and washed. The root volume was determined by immersion in water and weighed. Root length and root volume was calculated by the method of Atkinson. The results showed that the effects of irrigation water and potassium fertilizer on the root morphological characteristics (length، volume، area and dry weight) and plant shoot (leaf dry weight، leaf area، shoot dry weight and shoot to root ratio) were significant. The maximum length، volume، area and root dry weight، dry weight of leaf، stem dry weight and leaf area were obtained from the water level of 100 percent. The maximum length، volume، area and root dry weight، leaf dry weight، stem dry weight were obtained from the fertilizer level of 100 percent. Speedfeed variety had maximum length، volume، leaf area and root dry weight. Speedfeed variety was the most sensitive to the amount of irrigation water. The amount of irrigation water affected on the growth characteristics both shoots and roots severely.

Water is an important factor in crop production، and is of a high value in agricultural Engineering. Water shortage is the most restricting factor in irrigated areas. Because of quality and quality limitation، deficit irrigation research has a special value in water use optimization and determination of water depths indexes inirrigation strategy. Thus، a determination of the water-yield relationship is essential. This study was carried out in Gorgan region to evaluate the effects of water stress on yield and water use efficieny of soybean in six levels of irrigation (is1-is6) for Sepideh variety in six replications using line source sprinkler irrigation method. Yield function for was derived as (Y=-0. 0528x2+54. 907x-3073. 5، R2=0. 93). Under full iriigation، the sepide cultivar need 354. 9 mm of water to produce maximum yield of 10190 kg/ha. Maximum and minimum of water use efficiency were obtaibed 16. 0 and 35. 3 kg/ha. mm at IS1 and IS4، respectively. Average grain yield and number of pods per plant were increased by increasind water depth. Minimum of grain yield، number of pods per plant and thousand grain weight were obtained in Is1. FAO water stress index (Ky) was obtained 0. 94. Ky was derived 0. 92. The comparison between the ky of cultivated soybean cultivars at Golestan province showed that katool cultvar has the more suitable response to water deficit than sahar and G3 cultivars to increase yield and optimal use of limited water resources.

Quantity lack of required water resources for agriculture and quality decreasing caused by entrance of poor quality drain water resulted environmental threatens in the resources. Inappropriate application of nitrogen fertilizers that are one of the most important required nutrients for plants causes entrance of nitrogen components more than allowed limits to the water resources. Modified natural zeolite usage for nitratereduction from aqueous solutions in batch and dynamic experiments investigated in this research. Equilibrium time and the amount of nitrate adsorption resulted from physical model were compared to the results of batch tests. Equilibrium time resulted from both conditions was about 60 minutes but the portions of nitrate adsorption andremoval percent were different. While the different observed results caused by physical drain channel model، effects of two flow rates including 0. 05 and 0. 08 (lit/s) and three sorption box widths including 2، 3 and 5 cm on nitrate removal were surveyed. Results showed 8 to 16 percent better zeolite efficiency in more flow rate. About 19 percent removal increase observed by reduction of adsorption box widths from 0. 33 to 0. 13 of adsorption box length.

Wheat is one of the most important product in Fars province and accurate irrigationscheduling causes to increase irrigation efficiency and optimal use of water resources. Because، most of rain events occurs during wheat growing period in Fars province، irrigation of winter wheat is important. Therefore، in this study، a simple daily rainfall generator model with two components was used. Stochastic output of this model coupled to a water balance model that used average deterministic ETp values. Irrigation dates and amountsat 32 climatologically stations in Fars province were determined. The model was based on daily water balance approach and used crop and soil data as input. In the next step، a predictive irrigation schedule at selected probability level for irrigation dates developed with Arc GIS. Finally، spatial maps of simulated values under same probability level was drawn. Because wheat is most sensitive to water stress during critical stages of booting and two weeks before pollination، predictive scheduling does not lead to water stress. The results showed that number of irrigation in southern، west southern and east southern stations in Fars province is higher. Under 75 probability also the highest irrigation requirement was predicted in southern and east southern station. Analyzing the result of model according to certain risk level، is helpful in determining irrigation requirement ofwinter wheat and water resources strategies in Fars province.

Pistachio is a strategic product with high economic value in Iran، which is cultivated in arid regions withlimited water resources and poor water quality. Therefore، it is essential to use irrigation systems capable of yielding high irrigation efficiency along with effective management of soil water and salinity. In recent years، application of Subsurface Drip Irrigation (SDI) system has been widely accepted by manypistachio growers. Since، irrigation water is of poor quality in major pistachio plantations، utilization of this irrigation method will result in accumulation of salt in the vicinity of soil surface، hence a reduction in pistachio yield. In addition، appropriate irrigation interval for Pistachio orchards irrigated by SDI systems is unknown. A field experiment was conducted on 15-year old pistachio trees grown on loam silt soil and irrigated by subsurface drip irrigation with saline water (EC= 4. 2 dS/m) in a region under desert climate to investigate the effects of different irrigation regimes on the soil moisture and salinity distributions as well as pistachio yield. Two irrigation frequency treatments، namely I3 (Once every 3 days) and I14 (Once every 14 days)، replicated three times were applied to one hectare block of a farm in Sirjan. The results revealed that irrigation frequency had significant effects on the spatial distribution of soil water content within 0-100 cm depths with a higher soil water contentforI3. In contrast to I14، salt accumulation in the root zone for I3 was significantly (p<0. 05) low due to more water application. Pistachio yield for I3 and I14 was 3. 3 and 3. 7 kg/tree، respectively، indicating non significant difference. However، I3 showed marked enhancement in quality traits such as osteoporosis and smiling.

The Float method is a quick approximation technique for measuring velocity and thus flow rate. Surface velocity obtained by the Float method of correction factor is multiplied by the average velocity in the cross section obtained. This coefficient by the The United States Bureau of Reclamation (USBR) to measure the Float method is presented. Surface velocity coefficients published by USBR are based solely on average water depth. But other hydraulic factors such as longitudinal bed slope، the wall roughness height، the shape of the channel cross section، the location of the float object and… may also affect the value of the coefficient. In this study the effect of these parameters on the surface velocity coefficient in a rectangular and compound open channel studied and the results are compared with the coefficients published by USBR. The results indicate that these parameters are the effective surface velocity coefficient and considering effect of other parameters in addition to the average water depth، be accuracy of the float method could significantly increase.

In order to evaluate the effects of intermittent deficit irrigation on corn SC-704. An experiment was conducted in randomized complete block design with four irrigation treatments and three replications research farm of college of Aburaihan at Pakdasht in 2013. Treatments included irrigation method A (control treatment، complete irrigation)، B (irrigation alternating with an irrigation full and round، with 85 percent of full irrigation to the plant) treatments C and treatments D with 65 and 50 percent similar of treatments B، was performed. The results of variance analysis showed that intermittent deficit irrigation had significant effect on characteristics of dry weight of plant، ear weight، grain yield and water productivity. For reaching more water productivity، plant height، biomass yield، ear weight and grain yield، there is no need of full irrigation (100 percent)، and through irrigation Form of treatment B، maximum yield could be reached. According to Correlation of characteristics Determined that ear weight maximum positive correlation and significant one percent with grain yield. So far the most convenient method of applying deficit irrigation for corn in the area، intermittent irrigation with a complete irrigation and the next round with 85 percent complete irrigation.

In recent years، there is much more attentions to the extreme climatic events، which have many economic، social and financial damages. Lots of studies had been done on climate change using average climatic parameters، so there are not enough works on extreme events، which have more severe damages on variouscountries’ sections such as agriculture. Objective of this study is to assess temperature and rain extreme events at3 stations of Mashhad، Sabzevar and Torbat-e-Heidarieh، in khorasan Razavi province in 1961-2010 with the Mann-Kendall method. Results showed in this region there is generally decreasing trend of frost days، icy days and cool periods and increasing trend of summer days، tropical nights and warm periods. This indicates there is increasing trend of temperature. Rain extreme events had more fluctuations thantemperature and generally show very slow decreasing trend. The year of change in every parameter had been determined with Mann-Kendall method. These results could help to decrease crop production risks and to choose more proper regions for planting with attention to the extreme events.

Major share of water resources are used for agricultural purposes. Irrigation networks، have important role in optimal use of water resources. Due to several factors many of the irrigation networks in Iran، are performing below expectations. Therefore performance improvement of irrigation networks and their rehabilitation is necessary. Due to the complexity of the problems of irrigation networks and the interactions between components، irrigation performance improvement، requires a comprehensive and prospective approach. One of the management tools for this purpose is dynamics system. In this research، Causal loop diagrams for Foomanat irrigation network are determined and conceptual model is developed. Afterward the quantitative model is developed and several rehabilitation policies are analyzed. The results suggest that if current processes are continue، the utility of irrigation network will decrease. It is shown that various policies can improve the network utility in different ratios. Among the individual policies the policies of investment for physical improvements and limiting the expansion of cultivated area have greater impact on network utility improvement in short-term and long-term respectively.

The hydraulic and physical properties of soil have important role in design irrigation and drainage projects. Variability of hydraulic parameters of soil is very high depending on time and space. Inorder to study these variations، a field experiment was carried out in a randomized complete block design with three treatments andthree replications in a corn field in North of Khuzestan (Dezful) in 2013. The treatments were including No tillage (NT)، Minimum tillage (MT) and conventional tillage (CT) practices. The measurements using a disc Permeameter in different suctions (zero، 3، 5، 10 and 15) in four times include as: before irrigation and in second، eighth and tenth irrigations was performed. The data was measured from depth of soil 10 and 20 cm) and in different times was analyzed by split plot design in time. The results showed that the tillage practices and depth of measuring and their interactions had a significant effect at 1% level on apparent density of soil. The saturate and nearly hydraulic conductivity in CT was significantly more than the other tillage practices (NT and MT) and in the MT and NT hydraulic conductivity is nearly equal. There was significant difference between different times in all suctions، except of the suction 15 and Gardner. The initial soil moisture had an important role on variability hydraulic conductivity in time. The interaction effect between tillage and time was significant only in saturated hydraulic conductivity.

Drought is one of the most important climate phenomena which occur in all climate conditions and regions of the world. For monitoring and evaluation of various index used. Variable in this study were employed to examine the phenomenon of drought and wet years consist of SPI، PNPI and NITZCHE. therefore، In this research، annual precipitation data of 6 weather station in the province of North، Razavi and South khorasan for a period of 30 years (1981-2010) analyzed the rainfall and the dry and wet years were studied. Using different methods and comparing the results showed most of the years were normal or dry and very dry or wet conditions were rarely observed according to the reluts. The Standardized precipitation Index (SPI) was recognized better and more accurate comparing to the other indexes because of Stronger capabilities in seprating dry and wet classes and higher sensivitivity to precipitation variation in Khorasan Province.

Snow is one of the main elements of hydrological cycle of the mountainous basins. In the basins، snow runoff plays the main role of the river flows. Although there are snowfalls in the eastern highlands of the country، the effect of this kind of hydrological element is different from the western areas. The goal of the study is to investigate on the effect of simulated runoff on the flowing water balance parameters in the BAAR NEYSHABOUR basin. To reach the goal، the counted discharge of ARIYE hydrometric station located onBAAR River is used and to count the rainfall، BAAR-ARIYE evaporation center is utilized. Counting term is about 30 years. Water years of 1975 to 1989 for simulating and calibration and the verification are happened from the years of 1995 to 2009. The consequences show that، despite the simplicity، WASMOD model is able to simulate the runoff even by low receiving data. So the mentioned model can be used in the basins with the low available data. The capability of the model was studied in two ways، and the results suggested that the model with the effect of snow is more related to the reality. Modeling is possible even with no regard to the snowfall. Basic runoff conduction under the effect of the snow is nonlinear as well.