مجله آبیاری و زهکشی ایران
سال دهم شماره 2 (خرداد و تیر 1395)

Because of decreasing the value and availability of water resources¡ we have to use water resources in a best way. The new irrigation systems like subsurface drip irrigation can improve irrigation efficiency and water use efficiency. To properly manage SDI systems¡ the precise distribution of water around the emitter must be known. Several models have been developed to simulate soil moisture pattern and wetting front by using soil hydraulicparameters¡ the emitter’s discharge and the volume of discharged water. In this paper¡ HYDRUS-2D model was used so simulation results were compared with two sets of experiments involving SDI with emitters installed at two different depth (40 &50 cm) while the emitters space was 75 cm with 3.5 l/h emitter discharge. The RMSE at different locations around emitter varied between 0.014 and 0.033 for volumetric water content in 40 cm installation depth and 0.009 and 0.025 for 50 cm installation depth. The continuous horizontal wetting profile was achieved so the space of emitter was suitable. With due attention to our results¡ 75 cm distance between emitters and 50 cm installation depth with 3.5 l/hr emitter discharge is proposed to be applied in loamy soil.

For over three decades, hydrologists were recommended multivariate models to describe and modeling complex hydrological processes. While recently the multivariate models in hydrology is discussed. In multivariate models, the modeling and predicting various parameters can be improved by involving other factors. In this study, univariate and contemporaneous multivariate ARMA models (CARMA) were evaluated for modeling of Urmia lake water level. The time series of Urmia Lake water level in annual scale in the period of 1982-2011 were used for ARMA models and the time series of Shahrchai, Nazloochai and Barandoozchai flow rates and Urmia Lake water level in mentioned data period were used for CARMA models. The results of evaluation and verification of models showed that by adding river flow data, the accuracy of modeling and verification of models will increase. Also the results showed that according to R-square coefficient equal to 0.75 between validation data of models and the root mean square error criterion equal to 0. , the CARMA models can provide better results than ARMA models. Using multivariate models in the modeling and forecasting of Urmia lake water level increased the accuracy of modeling about 20 percent.

Mechanisms of crop root water uptake play an important role in agricultural water management. The aim of this study was to investigate soil water dynamics and root water uptake for an apple tree. Surface irrigation was performed around of tree. Tube-time domain reflectometry (TDR) –Profile Probe type- was used to measure soil volumetric water content. Therefore Specific tubes of 1 meter length and distance of 30 cm from each other were installed in both side of tree trunk. Moisture simulations were carried out with HYDRUS- D model. Results showed that most changes in soil water occurred until the depth of 40 cm. These changes in surface layers are greater than above layers. Also root water uptake mostly is limited in the depth of 0-40 cm and radial distance of 0-60 cm from tree trunk. Root water uptake rate was reduced with increasing distance from the tree. HYDRUS- 2D model successfully simulated the variability of soil water dynamics in until depth of 40 cm¡ but predict of soil water dynamics from depth of 60 to 100 cm is not good. This Difference is due to soil of this layer is very compact. So with attention to these results¡ a more detailed schedule will be designed in relation to irrigation water management.

Population growth and decreases water availability led to decreases water resources and consequently decreasing in the water portion of agricultural sector .So researchers in this condition have to find new solutions for utilization of low quality water in agriculture .This research was performed in order to assess the possibility of saline water use in Hashemi rice production¡ Rice yield estimation using production function and Find the best time to use these waters in Rice Research Institute during 2010 crop season .Plan was in pot cultivation under shelter with factorial arrangement in a randomized complete block design in 4 levels of water salinity i.e. 2¡ 4¡ 6¡ and 8 dsm 1-that were applied at 4 different growth stages i.e .tillering ¡panicle forming¡ heading and ripening . Saline water was made by using NaCl CaSO4 (2:1). Results showed that the effect of different levels of salinity and different growth stages on yield was significant. Applied salinity levels¡ respectively represented 21¡25¡ 37 and 47 percent yield losses .The panicle formation and tillering stages with 1.92 and 2.41 T5on per Hectare of yield were the most sensitive stages to salinity. There was positive correlation between Grain yield and Panicle weight¡ 1000-grain weight and panicle length but negatively correlated with the Percentage of emptiness per panicle .According to results it is possible to predict rice production function under conditions of salinity at different growth stages using Panicle weight¡ Percentage of emptiness and number of tillers¡ can predicted.

Tomato is one of the major agricultural products in Fars Province. Previous studies show that the tomato farms under traditional surface irrigation systems lose a large volume of water with low water productivity. In the present research¡ the influence of different irrigation regimes on tomato yield quality and quantity was studied. The farm under study located in Marvdasht plain and has a heavy soil texture. The irrigation water was applied base on 60¡ 80¡ 100¡ and 120 percent of Penman Montieth water requitement method. Another treatment was considered and irrigated by the farmer management. Results show that the obtained yield increase with irrigation water while the water productivity decrease. The maximum water productivity was observed in the treatment irrigated about 80% of water requirement¡ about 11.66 to 14.21 Kg/m3. Increase in irrigation water¡ decreses the fruit brix and increases the percent of fruit juice. These variations were not statistically significant in some of the conditions. The maximum and minimum of yield were due to Super Urbana and Kingston varieties¡ respectively.

The Toyserkan plain in Hamedan province has faced a significant drop in groundwater levels. The aim of this study is simulation of the groundwater demand and supply for basic year (2011)¡ predicting them to 2025 and defining tree scenarios: 1-Efficiency of irrigation increasing¡ 2- change of land use¡ 3- urban water management¡ and evaluating them effects on groundwater demand and supply by WEAP’s Model. Based on results¡ if continue demand current trend¡ the aquifer encounter drought and will occurred intensive critic for all demand sites in 2019. Result of change of land use scenario indicated that will be delayed becoming dry of aquifer to 2022. Urban water management scenario results indicated that groundwater storage in comparison to reference scenario increase annual from 2012 to 2020 and this increase arrive to 10.95 Mm3 in 2 . Based on results of Efficiency of irrigation increasing scenario¡ if Efficiency of irrigation arrive to 59.13 percent in agricultural sites¡ not only met all of demand sites water requirement¡ but also groundwater storage provide annual and gap between of groundwater demand and supply will arrive to minimum of self amount.

Prediction of lake level fluctuations is one of the most important issues in water resources planning and management. In recent years¡ the significant decline in water level of Urmia Lake had detrimental environmental impacts on this region. In this study¡ the performance of genetic expression programming and support vector regression models for predicting Urmia Lake water level was evaluated based on six different patterns during 1976-2009 to determine the best input pattern. The historical data of water level were used in four patterns¡ and precipitation¡ evaporation¡ seepage and water level were used in two other patterns. The results showed that the genetic expression programming had better performance than SVR model and the model performance improves with increasing input for model training. Also¡ at the best pattern the mean square error and coefficient of determination were calculated 0.08 m and 0.99 for GEP model and 0.60 m and 0.92 for SVM¡ respectively.

Reusing of treated waste water (TWW) for agricultural irrigation is one of the common management strategies for dealing with water deficit in arid and semi-arid regions. The aim of this study was to investigate the effects of irrigation with TWW for ten years on some chemical and biological properties of irrigated soils in surrounding land of Kashafrud River located in Mashhad (Iran). The soil samples were collected from 8 points and 3 replications at intervals of 1 Km from surrounding lands of river. Also the soil sample that irrigated with underground water and had the same agricultural management practices was selected as control. The results showed that irrigation with TWW increased the soil pH and electrical conductivity (EC) in comparison to the control. Also¡ the TWW increased the concentration of zinc (Zn)¡ iron (Fe)¡ and lead (Pb)¡ so that they were less than toxicity limits and the concentration changes of cadmium (Cd) and nickel (Ni) in soil due to TWW was negligible. Application of TWW significantly increased the ratio of Cmic/Corg¡ respiratory activity and microbial biomass in comparison to the control. The metabolic coefficient (qCO2) values of irrigated soil samples with TWW were significantly less than that of control. The results of this research demonstrated that the irrigation with TWW did not only have adverse effects on soil properties and it also improved them. Furthermore¡ due to the different entrances of waste water into river¡ the soil chemical and biological properties were various in different points.

Deficiency of irrigation water in irrigated agriculture as the most deterrent factor and nitrogen Deficiency of as one of the main limiting factors of plant growth¡ is Presented. So management of water and nitrogen fertilizer for agricultural production because of Deficiency of resources and environmental problems and prevent loss of capital¡ should be considered. The purpose of this study was to optimize the water use efficiency and nitrogen fertilizer using marginal analysis theory for silage maize in Pakdasht located in the southeastern region of Tehran. The tests in the summer of 1393 in the form of split plot randomized complete blocks design with four treatments for water and four treatments for nitrogen fertilizer in three replications was used. The results showed that the maximum water use efficiency at ET = 839 mm and fertilizer consumption 384 kg per hectare happens while the global maximum yield at ET = 1020 mm and fertilizer consumption 365 kg per hectare is achieved and by 17.74% of water saving only 9.73 percent of the product is reduced. So when we face with restriction of water sources¡ water use efficiency must be goal and if there are no restrictions for water supply¡ with the goal of maximizing yield the values optimal irrigation and fertilization be specified. As well as the water supply should not exceed from 1020 mm.

The most important of design and exploitation of water supply systems for agricultural needs¡ is the Estimation of crop water requirement. This aim of is studing the impact of climate change on evapotranspiration phenomena at five stations in the dry¡ semi-dry¡ Mediterranean¡ humid and very humidclimates¡ using HadCM3 general circulation model under two scenarios A2¡ B1 for Near future (2039-2010)¡ the intermediate future (2069-2040) and the Far future (2099-2070) and the period 2000-1971 as the base period and downscaling process is asssessed by Proportional downscaling and change factor methods. The potential evapotranspiration for five stations was calculated using Monteith¡ Makkin¡ torque wet and dry areas¡ Priestley- Taylor ¡ Hargreaves - Samani and Blany Keridel methods was calculated The results showed that in the ET will increase by 12% and decrease by 35% in winter and summer¡ respectively. Stations the climates with more humidity greater impact of climate change is accepted. The changes in evapotranspiration stations A2 scenario will occur in the distant future. For future periods¡ the Priestley-Taylor method has more proximity with FAO- Penman-Monteith Than the other methods model and stations having high humidity climates will be affected more by climate change.

The assessment of groundwater vulnerability to pollution has become an important element for proper water resource management and land use planning. The available methods do not evaluate the regional risk within the perspective of the well capture zone and hence fail to predict the implications that high vulnerability areas have on the water quality of abstraction wells. This study presents a methodology to search for areas within the well capture zones with the highest risk indices. This includes the use of DRASTIC methodology for vulnerability mapping and numerical modeling¡ using MODFLOW and MODPATH¡ for capture zone delineation. The integration of these elements¡ performed in a GIS environment¡ provided the mechanism to assess risk mapping and identify areas within the capture zone in Firouze county in Razavi Khorasan Province in Iran that must be prioritized in terms of groundwater monitoring and use restriction.

Application the modifiers is one of the ways to control and reduce evaporation from the soil. The aim of this study was to evaluate the impact of the amendments on amount of evaporation from the soil. This research was carried out as a randomized complete block design with three replications and factorial arrangement in faculty of agriculture in Ferdowsi University of Mashhad. The treatment including amendments (water crystal super absorbent¡ Vermi Compost and barely residues) at four levels (0¡ 0.01¡ 0.03 and 0.05 wt %)¡ were mixed with a loamy soil and filled into pots of 5 Kg. By addition the water during 4 months¡ soil moisture was retained at constant content of field capacity. Then he evaporation rate was measured in April and August 2015 through the daily weight of the pots. The results showed that there was no significant differences between treatments in the rate of evaporation¡ but at the end of evaporation measurement and its cessation both in April and August¡ super absorbent had the least amount of evaporation and water loss and maximum amount of moisture in the soil. Also¡ organic modifiers increased soil aggregation and MWD. Due to non significant difference between amendments in the rate of evaporation from soil and high cost of super absorbent¡ application of barely residue and vermincompost is recommended for controlling the evaporation rate.

This study was conducted with the purpose of investigation the effect of different amount of water on vegetative characteristics¡ yield and water use efficiency (WUE) of peach (Prunus persica L. cv. «Spring time» and Sabze Mashhad) trees at Khorasan Razavi Agricultural and Natural Resources and Research Center. A split plot experiment was laid out in a completely randomized block design including 3 different levels of water treatments with three replication. Treatments were including different amount of water 60¡ 80 and 100% water requirement) in main plot and drip irrigation method (surface and subsurface) in sub plot. In cultivars¡ interaction water percent and irrigation method had significant effect on vegetative characteristics. Subsurface drip irrigation with 80% water requirement had highest vegetative characteristics (height of tree¡ crown width¡ trunk diameter). In «spring time» ¡ the highest (31. 4 ton/ha) and lowest (19. 8 ton/ ha) yield were obtained with 100% and 60% water requirement respectively. There were not significant differences on yield in surface (24. 5 ton/ha.) and subsurface (26. 2 ton/ha) irrigation method. In « Sabze Mashhad”¡ the highest (32. 5 ton/ha) yiled were obtained with 100% water requirement. With reducing amount of water¡ there were significant differences on yield. Subsurface drip irrigation method with 31. 4 ton/ha was the better of Surface drip irrigation method. Finally our results showed that subsurface drip irrigation with 80% water requirementwasthe best water use efficiency treatment in both peach cultivars.