h.ebrahimian

In this research, to evaluate the Zero inertia model in SIRMOD and WinSRFR software, data from the advance time, recession time and runoff volume were obtained from conventional furrow irrigation (CFI), fixed alternative furrow irrigation (FFI) and alternate furrow irrigation (AFI). The simulation results were used with the help of the relative error index (RE) for the infiltrated water volume and the root means square error (RMSE) index for prediction of advance and recession time. To determine soil permeability coefficients were used of the model SIPAR-ID, Multi-level optimization, Two-point method of Elliott-Walker and IPARM. The results of the CFI method in SIRMOD software, the Elliott-Walker two-point method with RMSE equal to 1.81 and in the WinSRFR software, the multi-level optimization model with RMSE equal to 1.66 The results had the highest accuracy in predicting advance times. The simulation of the advance and recession time of the FFI method indicated that the best value of the RMSE index for using the SIPAR-ID model in SIRMOD and WinSRFR software was 2.42 and 2.41 minutes, respectively. The results showed that in the AFI method, using the IPARM model in SIRMOD software and the multi-level optimization model with WinSRFR software, the best accuracy was achieved with RMSE 1.61 and 1.24 min, respectively, at advance times, respectively. As a general result, it can be stated that according to the similar prediction of two SIRMOD and WinSRFR software, it is recommended to simulate, design and evaluate irrigation systems in the case of accurate estimation of influence coefficients.

The scarcities of fresh water resources for agriculture production on the one hand and low cost establishment and energy supply and easy maintenance on the other hand, has led researchers to conduct many studies about increasing surface irrigation efficiency. In this study, effect of deficit irrigation at the furrow end on furrow irrigation performance indicators and effect of soil moisture profile on silage corn yield (biomass) were investigated in Karaj, Iran, in 2014. Four treatments (100% irrigation: full irrigation, 75% irrigation: 25% deficit irrigation, 50% irrigation: 50% deficit irrigation and 25% irrigation: 75% deficit irrigation at the furrow end) were considered. Deficit irrigation increased application efficiency. Runoff was as a main irrigation water loss due to short furrow and high slope. Deficit irrigation increased non-uniformity of moisture profile and crop production along the furrow. The most non-uniformity of crop yield along the furrow was observed in the 75% deficit irrigation treatment. Crop yield was greater at the upstream than at the downstream of experimental furrows. There was a direct relationship between crop yield and storage efficiency. The treatment with 25% deficit irrigation at the furrow end was identified as the best treatment regarding water saving and low reduction of crop yield.

Water and energy resources are limited; however, water and energy consumption for production of agricultural crops is increasing to meet the food demands of a growing population. The present study compared the energy and economic productivity of sprinkler irrigation with surface irrigation when groundwater is used as an irrigation source. The study used data on irrigation systems and yield of crops cultivated on the Qazvin plain in 2011. The data was obtained by survey from regional farms, design plans for the irrigation systems, and the Qazvin Agricultural Organization. Results showed that maximum and minimum energy productivity of sprinkler irrigation were 9 and 1.3 kg/kWh for wheat, 7.79 and 2.09 kg/kWh for barley, 8.64 and 1.09 kg/kWh for corn, and 3.74 and 3.37 kg/kWh for alfalfa, respectively. The values for surface irrigation were 13.7 and 2.5 kg/kWh for wheat, 20.28 and 2.93 kg/kWh for barley, 15.2 and 1.5 kg/kWh for corn, and 6.3 and 0.3 kg/kWh for alfalfa, respectively. The energy economic productivity for surface and sprinkler irrigation systems for wheat was greater than for the other three crops. The results also showed that energy productivity for the conjunctive use of surface and groundwater for irrigation was greater than for the sole use of groundwater.

The low irrigation application efficiency is the major problem of surface irrigation systems due to weak management and poor design. In this research، in order to analyze the performance of furrow irrigation system، a field experiment was conducted during maize growing season. Three furrow irrigation methods; conventional furrow irrigation، fixed alternate furrow irrigation and variable alternate furrow irrigation were considered to collect field data and، then، to evaluate the performance of WinSRFR (surface irrigation model). This model was calibrated and evaluated based on the experimental data with Zero-Inertia (ZI) and Kinematic Wave (KW) solutions. The sensitivity analysis of WinSRFR showed that the most sensitive parameters were inflow rate، cutoff time and parameters of the infiltration equation، respectively. There was a small difference between ZI and KW to estimate advance time، runoff and infiltration due to high field slope. The minimum absolute error for estimation of advance times was obtained about 1. 5% (0. 8 minute). The minimum absolute error in estimating runoff and infiltration were 5. 7 and 5. 0%، respectively. Using operations analysis of WinSRFR، the iso-performance contour plots of furrow irrigation system was obtained to optimize cutoff time and inflow rate under maximizing of application efficiency and distribution uniformity and minimizing of runoff and deep percolation. Application efficiency iso-performance contour plot of fixed alternate furrow irrigation، indicated by managing of cutoff time and inflow rate، application efficiency could be increasing from 54. 5% in current evaluation to 74%، provided water supply of Dreq. Also based on this contour plot، increasing of application efficiency more than 74% was impossible provided water supply of Dreq، under current furrow geometry parameters and it was possible with changing furrow geometry parameters.

Evaluating drainage systems, exploring their strengths and weaknesses, provides a comprehensive perspective to designers and organizers for optimum design and implementation of guidelines for the future. This study was conducted at an experimental site consisting of three plots on a subsurface drainage network under operation in Behshahr, a coastal region in northern Iran. To evaluate system performance,discharge rates from laterals and the depth of water table between laterals were monitored for a period of three months during the autumn. A second degree equation similar to the Hooghoudt formula was developed to show the relation between the hydraulic head and discharge rate. This equation was used to estimate the hydraulic conductivity (K) and equivalent depth (d) of the impermeable layer. The obtained K for the three plots ranged from 1.4 to 2.4 md-1, which was greater than the design value. This analysis also showed that the laterals were placed on the permeable layer. The Glover-Dumm equation was used to show the rate of water table fall and to calculate the specific yield () S y and reaction factor (α). Based on these results, the actual α was 8%, which is greater than the design value of 4%, and the average S y obtained was 5.7%, compared to the design value of 7.7%. From these results, it can be concluded that the lateral spacing was overestimated.

By evaluating the performance of the current drainage systems and exploration of their strengths and weaknesses a comprehensive perspective can be given to designers and organizers for optimum design and implementation of drainage systems for future plans. This study was conducted to evaluate the performance of subsurface drainage systems using rice husk as envelope in Behshahr, a coastal region in the northern part of Iran. For this purpose, eleven piezometers were installed between two subsurface drains designated as S3PD14 and S3PD15. Subsurface drainage system was monitored during rainfall seasons in 1383 and 1385. Parameters such as daily water table fluctuations and drain discharge rate were recorded. The overall conclusion was that subsurface drainage system performance was not satisfactory due to poor control of water table depth and low water discharge, which was mainly because of the drain envelope clogging. Therefore, the Hooghoudt’s equation should not be used for evaluation of design parameters, due to the fact that this equation is only valid for normal conditions (envelope without clogging).