مجله مهندسی آبیاری و آب ایران
پیاپی 10 (زمستان 1391)

May، designer consulting engineers access to all the basic information for selecting the best plan is not provided. Therefore، in construction stage that problems of designation appear، it is suitable supervisor consulting engineers arrange again a set of technical specialists to analyze and evaluate details of project using value engineering in order to construct project by minimum of costs and time consuming. Among the projects that are faced with such problems farm development and land renovation that aims to develop paddy fields and the increasing mechanization of agricultural production through improved land use systems. Farm development and land renovation subject of this research، involving four villages bordering Chngmyan، Tamesk، Sorkhkola and Golmazar from Dashtsar rural district in Dabudasht division of Amol city، Mazandaran province، Iran. In Supervision system، value engineering team was formed with the required combination of expertise include: site supervisor، land of village representatives، contractors and employer representatives. After value management processes، these results has been estimated: 9720m2 increasing in the net surface (being cultivated) land and 19. 4% saving in costs compared to the original design. The present study proposed that the value management techniques، if necessary in any project and is a serious recommendation، in paddy field farm development and land renovation project is an issue injunction.

Water as a production input, like other inputs has demand and thereby price. The applicants of this important source buy water with considering the kind of its consumption and the values of its output. The aim of this paper is to determine the value of groundwater irrigation water in Mybodcounty, Iran. To find the market price of irrigation water in agricultural sector the production function was used. This method is used when the unit price of water is not distinguishable in market place. Therefore, the cluster sampling method is used, some 183 questionnaires were completed for determining the values of water and land in 2010.The findings indicated than the marginal production per unit of water was higher than corresponding cost of pumping.

Statistics were not required in the absence of erosion and sediment delivery (SDR) and deposition in the watershed basin of Iran is considered the most important problems، Actually hinder the proper planning، especially for the preparation and implementation of watershed management plans are. Determine any areas of erosion and deposition as one of the first steps is for watershed management. Erosion and sediment materials from different directions are considered. It is important that the loss of fertile land into agricultural fields to barren deserts، filling reservoirs and dams، irrigation canals and filling the land is cultivated with new sediment. The purpose of this study to determine the most appropriate experimental method to estimate the SDR using the EPM and the physical properties basin. In this study، many experimental methods to determine that the SDR was assessed according to three criteria، the mean، standard deviation and coefficient of variation Renfro (1983) method was chosen as the experimental method.

The fracturing bridge due to scour of foundation (includes bed and abutment)، reveals the necessity of study for scour predict and the protected methods. Generally،the methods of scour reduction include: placing foundation at the lower level of erosion pit depth، rasing bed resistance and decressing erosion power factors (decreasing downflow and horseshoe vortex). Utilizing a spreadsheat around abutment called collar is one of the methods of power decrease. The collar decreases the power of downflow and horseshoes vortex around the abutment further it decreases the depth of scour decrease. In this research a collar of two times than the abutment width exposed to a discharge of 20 and 25 lit/s. The operation of collar in 3 different depths (on the bed، at 2cm above bed and at 4cm above bed) was studied in the scour conditions of clear water and was compared with abutment without collar. the research indicate that collar decreases scour and it showed better operation above the bed. as a maximum percentage decrease of scour with a discharge of 20 and 25 lit/s is 94% and 93% respectively.

Investigation of soil hydraulic properties like permanent wilting point (PWP) and field capacity (F. C) are very important for studding and modeling the soil water and solute transport in soil in which their spatial and temporal variability led to development of indirect methods in prediction of these soil characteristics. Therefore; in the present study in order to evaluate the amount of water at F. C and P. W. P، 63 samples have been taken from 15 pedons in Fashand region. The particle size distribution have been determined by hydrometric method، bulk density by volumetric method (using undisturbed clods)، saturation percentage by weight and percentage of water at F. C and P. W. P by using pressure plate apparatus. We applied the artificial neural network (ANN)، multivariate regression (MR) methods and used several pedotransfer functions (PTFs) to predict the F. C and P. W. P parameters، using the easily measurable characteristics of clay، silt and sand percentage، bulk density and water at saturation percentage. The results showed that the ANN method give the best results followed by MR method and finally the PTFs. Regarding the PTFs، the classic are showed better results relative to parametric and point PTFs. In conclusion، the results of this study showed that، training is very important in increasing the model accuracy of one region.

Suspended sediment caused so many problems in recent years. Because of this matter two common formulae used for calculation of suspended sediment discharge were investigated in Armand River. The best formula was then chosen through this study. These equations are Lane-Kalinske and Bagnold. Data used in this paper has been accumulated from 30 year measurement in the area. After application of both equations it was found that Bagnold has better estimation in comparison to Lane-Kalinske and also Lane-Kalinske has more fluctuations in its computation. On the other hand all the input data and also the measured suspended sediment discharges were entered to Spss-16 environment. In this way all the measured data were investigated under path analysis method to show that which one has the most important role in the amount of measured suspended sediment discharge. This method is one of statistical analyzing methods which are done most likely by application of multiple variable regressions. At last applying path analyzing method in Armand River on both considered formulae، it was proved that velocity and depth have significant impression on measured suspended sediment discharge.

Mapping the temporal and spatial soil variations addresses to the optimal site specific management in agricultural lands. In this paper، the impact of water management and soil texture on the distribution pattern of the electrical conductivity of pistachio orchards in Hormozabad، Rafsanjan was investigated. For this purpose، a regular 11 by 7 grid with a distance of approximately 500 m between sampling locations was designed and 77 sampling sites determined. Afterwards، three samples were collected from the depths of 0 to 40، 40 to 80 and 80 to 120 cm at any point and the necessary physical and chemical analyses were performed on them. The ordinary kriging maps of the selected soil characteristics were prepared in ILWIS software after variography and estimation stages were carried. The obtained results illustrated the significant effects of soil texture and water management on the increase of soil salinity. So that، the increased irrigation intervals (average of 28 to 52 days) on the one hand and the finer soil texture on the other hand، have caused soil salinity to be increased in all depths from the southern to the northern parts of the studied area.

One of the simplest methods of regional frequency analysis is Flood Index method. In recent years، L-moments as alternatives for moments have been used and some approaches were made and described for this purpose. In this study we have attempted to investigate efficiencies of these methods on Aras watershed and then compared their accuracies by assessment of confidence intervals of them. The results of this case study showed that discharge estimates using L-moments on a homogenous region in 90 percent confidence level has smaller uncertainty in comparison with flood index method. In addition it sounds using of Wakeby distribution as regional distribution and also L-moments on a heterogeneous region is an appropriate approach for cases that other distributions have not an good fit.

Using vertical intakes is a common method of water withdrawal from rivers or storages to supply potable or agriculture water. Formation of vortex at vertical intakes is one of serious problems encountered in vertical intakes. Vortex formation reduces the efficiency of structure and causes loss of life. In this study، according to hydraulic conditions and geometry of vertical intakes، vortex formation was predicted by the K-nearest neighbor modeling for different ratios of channel length to width (L/W). The efficiency and precision of the model was evaluated by some statistical coefficients. Appropriate values of the correlation coefficient 0. 912، the efficiency of model 0. 827 and the root mean square error 0. 105 shows this model is suitable and efficient.

Subsurface drip irrigation is now considered as one of the most advanced methods of irrigation in agriculture. In subsurface drip irrigation will be given water to plant in low volume and pressure and will be moved by the force of the soil matric. These factors reduce losses and increase water use efficiency as a result. It should be noted that lack of proper and improper management of these irrigation systems، which reduces their efficiency in water use. To investigate the distribution of moisture content and depth of subsurface drip irrigation system installed and optimized flow design with 2 ls-1 emitter discharge، the depth of installation tubes (30 and 45 cm) and four layers deep moisture readings (0-30، 30-60، 60-90 and 90-120 cm) in a farming soil at the agriculture researches center of Kerman. The results of the simulation of moisture by the HYDRUS-2D model were compared with results from field experiments. Average of Root Mean Square Error (RMSE) and correlation coefficient (r) values were obtained respectively 0. 0065 and 0. 992 for Installation depth of 30 cm. Average of RMSE and r values were obtained respectively 0. 0085 and 0. 977 for Installation depth of 45 cm، which showed the model capable in simulating the distribution of moisture in the subsurface drip irrigation system. Comparison of correlation coefficient in both of depths in the linear model fitted in both cases were indicated higher accurately of estimates of 30 cm to 45 cm Installation depth. Also the installation depth of 30 cm was selected as the optimal installation depth.