This study was conducted to evaluate the current management of furrow and border irrigation systems in the Dez irrigation network. Of the eight farms studied, three grew wheat and one each grew com, sugar beets, lettuce, sesame and mung beans. The study found water application efficiency in the five farms with furrow irrigation systems to be 25.8% and for the three farms with border irrigation systems to be 32.7%.The main reason for water loss was found to be runoff and deep percolation. SCS infiltration equation parameters were calculated using the obtained data. For each farm, conditions were simulated using the SCS equation. Methods for optimum irrigation were developed based on variables such as discharge inflow, furrow/ border length and cut-off time and cut-back methods.

SIRMOD model is more suitable tools for evaluation of irrigation systems that must be tested and evaluated before use in practice. Sensitivity of SIRMOD to input parameters in three solution methods of Saint- Venant equation was evaluated with ±25% of input parameters variation. Sensitivity analysis results was shown, model is more sensitive to input parameters in advance phase and runoff volume than other parameters (Slope, roughness coefficient and furrow geometry). Model in infiltrated water volume is more sensitive to infiltration equation coefficient and inflow respectively, than other input parameters. SIRMOD isn't sensitive to solution methods of Saint-Venant equation. Sensitivity of model is variable with soil type. The percent of input parameters variation isn't effective in sensitivity order. Therefore, the parameters must be measured with maximum accuracy consist on inflow and soil infiltration coefficients.

By using the temperature of the canopy cover of the plant, a practical parameter called the crop water stress index (CWSI), it was determined that this index is one of the methods of checking the water requirement of the plant and it can be considered as a suitable tool for irrigation management in the field. Therefore, this research was carried out with the aim of determining the water stress index of sugarcane in two methods of surface irrigation (CI) and subsurface drip irrigation (SDI) at research station number one of Khuzestan Research and Training Institute for Development of Sugarcane and Related Industries, in June 2022. The fields included the third field culture (Ratoon 3), of the CP69-1062 variety, and were selected with four repetitions in both methods. First, the equation of upper and lower base lines for the surface irrigation method was determined as (Tc-Ta)ul=1.7 and (Tc-Ta)=-0.09VPD+1.27, respectively. Then, using the equations of the lines based on the surface irrigation method, the average of crop water stress index for subsurface drip irrigation method and surface irrigation was calculated as 0.28 and 0.66, respectively, and the equation was presented according to the irrigation scheduling of the Sugarcane in June.

Given the scarcity of water resources using modern methods of irrigation in agriculture will be inevitable. Today, process improvement, development and use of drip irrigation practices as one of the most advanced methods of irrigation in agriculture is increasing. So this study was conducted to determine the impacts of irrigation interval and drip irrigation method and their interactions on yield, water use efficiency and quality characteristic of cotton in Kashmar Agricultural Research Station, Khorasan Razavi Province. The study was carried out during 2006-2008. Experimental design was a completely randomized design with four replications. Treatments were included irrigation intervals (2, 4 and 6 day) and drip irrigation methods (surface and subsurface drip irrigation). The results showed that the irrigation methods had significant effect on Yield and Water Use efficiency (P£0.01). There was significant difference between yield in surface and subsurface drip irrigation that was 3074 and 3988 kg/ha, respectively. Water use efficiency was 0.349 kg/m3 in subsurface drip irrigation that was greater than surface drip irrigation. The highest yield and water use efficiency in drip irrigation and subsurface irrigation 4 days, 4315 kg/ha and 0.375 kg/m3 respectively and the lowest with 2 days 3107 kg/ha and 0.265 kg/m3, respectively. Yields in irrigation intervals of 2, 4 and 6 days were 3491, 3725 and 3364 kg/ha, respectively, with no significance difference. The highest water use efficiency and yield were obtained in subsurface irrigation method with 4 days interval as 4315 kg/ha and 0.375 kg/m3 respectively, while the least water use efficiency and yield was obtained in surface irrigation method with 2 days interval as 3107 kg/ha and 0.265 kg/m3, respectively. Finally, using subsurface drip irrigation with irrigation every 4 days was chosen as the best treatment.

SIRMOD is a simulation model used in design and management of surface irrigation system. In this model, Saint-venant equation is solved by Full Hydrodynamic (HD), Zero-Inertia (ZI) and Kinematic Wave (KW) methods. Performance of this model was evaluated in the field. This study was conducted on a clay soil located in research fields of University of Tehran. Flows of 0.8-1.2 l/s was deliverd to 200 m-long furrows with 0.75 width. Field tests for determining of advance rate, runoff, infiltration, flow geometry and inflow rate were conducted and the results were compared with SIRMOD model. The results show HD, ZI and KW models estimate advance and infiltration rates to be less than field observations. This study shows that advance rate of HD model is closer to field observations than ZI and KW models. In runoff comparison, model eoverstimated the observed data. Therefore overestimation of runoff inevitably result in lower estimation of infiltration volume.

Water restriction is one of the most important factors inhibiting the crop production. Accordingly, application of pressurized irrigation systems to optimize utilization of water resources is inevitable. This study was conducted in Behbahan Agricultural Research Station during three cropping seasons (2013-2016) and based on a randomized complete block design with a split plot and three replications. The main plots were consisted of Subsurface Drip Irrigation (SDI) system that applied irrigation water at three levels of 75, 100 and 125% of water requirement and a surface Drip Irrigation (DI) system with application of 100% water requirement. The sub-plots were consisted of two varieties of date palm; Khasi and Zahedi. The crop water requirement was estimated based on Penman-Montheith method and using a daily weather information data collected from Behbahan weather station. Analysis of variance showed a significant difference (5%) between water use efficiency of different levels of irrigation water. As, the SDI system with 75% irrigation level showed the highest water use efficiency to be 0. 698 kg/m3. The comparison of interaction effects showed that the water use efficiency of Zahedi dates in 75% SDI system with 0. 744 kg/m3 is higher than that of Khasi dates. In the other hand, the 75% SDI system saved 2509. 6, 5019. 2 and 2630. 3 m3/ha irrigation water as compared with 100% and 125% SDI and 100% DI systems, respectively. According to the results, the interaction impact of irrigation levels and varieties on water use efficiency was significant but the interaction of irrigation systems and varieties were not significant. The stiffness of fruits was measured to be 11. 3 lb per square meter in 75% SDI system which was the highest as compared to those for other treatments. The results of this study showed that the SDI system could be used for palms trees without restriction while use less water without significant impact on yield.

In order to evaluate the effect of different irrigation management, a split-split plot design was carried out in a randomized complete block design in Shahrekord Agricultural and Natural Resources Research Center in the growing season of 2018. This experiment consists of two methods of irrigation (surface and subsurface drip irrigation) in the main plots and four irrigation levels (Full irrigation, FI; deficit irrigation, RDI-80; Regulated deficit irrigation, RDI-65; and Partial Root-zone Drying (PRD-75) in subplots, in three replications for potato (Bourren cultivar). The results showed that the effect of different irrigation management on tuber yield, number of tubers per plant, percentage of tubers size, dry matter percentage, normal harvest index, percentage of starch, percentage of soluble sugars, percentage of nitrate and water productivity were significant (P≤ 0. 01). Surface drip irrigation, as compared to irrigation of subsurface drip, increased the yield and water productivity by 7%. For surface irrigation, by increasing the amount of irrigation water from 65% to 100%, the average of starch and nitrate increased 18. 8% and 33. 6%, respectively and the soluble sugars decreased by 13. 8%. With Compared to different irrigation treatments in two irrigation systems, average of maximum yield and normal harvest index for complete irrigation were obtained 50. 3 𝑡 ℎ 𝑎 and 0. 48, respectively. In surface irrigation and 𝑅 𝐷 𝐼 80 treatment the highest water productivity was achived 12 𝑘 𝑔 𝑚 2 which is recommended as a water saving solution.