فهرست مطالب مجید نوری محمدیه

The process of spatially allocate the water demand is a potential source of errors that should be considered when building the hydraulic simulation model. There are several methods for this purpose and each has limitations and advantages. In the case of existing accurate recording of coordinates for water meters in GIS, there are several base demand automated allocation strategies for modeling the spatial distribution of water consumption in water networks. Where the spatial data for water meters are not available, conventional methods such as Thiessen and LDM (Length Dependent Method) can be used. And if this data is incomplete mixed practices can be used. This study proposed a mixed method named SAWDSL (Spatial Allocation of the Water Demand based on Data of Consumers) that divides the total consumption in subgroups related with corresponding water meters’ recorded. This method assigning the demand of each subgroup into the nearest pipe. The simulation results of WaterGEMS software using SAWDSL, Thiessen and LDM methods, after calibration, were compared to field measurements in zone I1 of Mashhad city. RMSE between observed and simulated pressure with the SAWDSL, Thiessen and LDM methods were determined to be 0.9, 2.3 and 1.4 respectively. That shows if the incomplete data of water meters would have existed and have enough time to use them, SAWDSL method is more accurate than others. Otherwise LDM method is more accurate than Thiessen method.

Nitrogen (N) is the most usually used crop nutrient which represent importance of the efficient use of nitrogen fertilizers. At this study، the optimum fertilizer application pattern by using of 15N isotope technique in different irrigation systems and the influence of the fertilizer application time on amino-N accumulation in roots has been investigated. The experimental design was a randomized complete block (sampling method) design with four main treatments (irrigation methods) and three replications (unit area 144 m2). Irrigation treatments include: T1; surface drip fertigation، T2; sprinkler fertigation، T3; sprinkler irrigation T4; furrow irrigation. In the middle of the each plot an area about 1- 2 m2 (15 plants) was allocated as isotopic sub plot. Results indicated that the least tendency to utilize the fertilizer sources was related to the fertigation treatments. Despite the highest root weight، treatment T2 is not recommended to use. The method of application of fertilizers in treatment T3 lead on to the highest nitrogen uptake efficiency and pure sugar. The method of application of fertilizers in T1 and T2 increase the rate of α-amino acid N in the sugar beet roots and decrease their quality. Treatment T4 produced relatively high quality roots that confirm the method of application of fertilizer in treatment T3. In the weather condition of central Iran، during the sugar beet growing season، the application of fertilizer should be begun 45 days after sowing seeds and must be completed within one month. Occurrence of isotopic fractionation phenomenon cause that the average percentage of labeled nitrogen fertilizer (Ndff %) in underground and aerial parts of the plant considered to be 20. 1 and 16. 1% respectively.

There is a need for proper water demand management since water scarcity is a fact in Iran due to the arid nature of the region. Seepage losses constitute the large amount of losses in agriculture. In some cases, the rising of underground water levels in adjacent lands to irrigation canal cause drainage and salinity problems for surface layers of soil.Therefore, it is important to find ways to limit losses through seepage. In Iran, empirical equations are mostly used to determine seepage in unlined channels in the most of the irrigation networks. In this study, the seepage losses in three earthen canals in Gazvin plain were determined by Ponding Test method and also the empirical equations were used to estimate the rate of seepage losses in these canals. Empirical equations such as Ingham, Davis and Wilson, Moritz, Molesworth – Yennidumia and Misra were evaluated with Ponding Test. The seepage rates obtained by the ponding test on canals No. 1 to 3 were determined to be 163.6, 567.7 and 379.5, respectively. Among empirical equations, Misra and Moritz methods found to have acceptable precision for channel seepage determination at the study area. Hence, these two formulas are recommended to be used.

Use of deficit irrigation to conserve water by minimizing leaching fraction during an irrigation season, or even across several irrigation seasons causes salt accumulate within the root zone. Naturally, salinization of the root zone is exacerbated when marginal waters are used. In this situation plants are experiencing simultaneously drought and salinity stress. Various mathematical models are exist for plants response to combined drought and salinity stress and its corporation in water uptake. The reduction functions are classified as additive, multiplicative and non coseptive models. Because transpiration is the largest component of the water budget in arid systems, the efficacy of models to simulate water and salt movement is depended on their ability to predict transpiration. In this study six different macroscopic reduction functions; Van Genuchten (additive and multiplicative), Dirksen et al., Van Dam et al, Skaggs et al and Homaee were evaluated in greenhouse condition using tomato data were exerted. This experiment was performed based on completely randomized design with three replicates and eight levels of salinity (0.75, 1.5, 2.5, 3.5, 4.5, 6, 8 and 10 dS/m) .Drought levels carry out as matrix potential during the experiment. The result of this study indicated that without salinity stress, all reduction function have a good agreement with measured data. Also, The result of this study indicated that the crop response to drought and salinity stress is additive low salinity level and is multiplicative at salinity level above 3.5 dS/m. among multi model, reduction function of Skaggs et al and Homaee's models were better fitness to measured data than the other functions.

Theta Probe is one of the new methods for measuring soil water content. Rapid measurement,high precision and direct measurement in field condition are important advantages of thi method. In this study, the effects of soil texture and compaction on water content measurement precision by Theta Probe (model ML2) were evaluated. For this purpose, three types of soil (sandy, loam and clay) were selected. Subsequently, 17 samples, from each type of soils, with various compaction and moisture content (between dry soils to saturated soil) were taken. Then, the Theta Probe was calibrated for each soil by linear and nonlinear techniques. Results of Theta Probe method compared with usual gravimetric method. The results indicated that ML2 Theta Probe have the highest precision (RMSE=% 2.7) in the sandy soil and precision of the Theta Probe have inverse relationship with clay content. Also, results showed that the effect of soil compaction on Theta Probe precision is very low and this effect increases by increasing in clay content. The correlation curves between results of Theta Probe method and gravimetric method showed the highest correlation (R2 =0.95) in sandy soil and the lowest correlation (R2 =0.91) in clay soil, Loamy soil had intermediate condition (R2 =0.93).