aslan egdarnejad

One of the erosion control options in the downstream of the overflows is to use crushed stone to reduce the excess output energy and to minimize the amount of erosion and scouring in the downstream of the overflow. In this research, experiments were conducted to check the stability of the rock in the downstream of the spillway by changing the threshold angle. For this purpose, a triangular cup overflow with four different threshold angles was made of fiberglass. Experiments were carried out using a piled stone density with four different diameters in clear water. In each experiment, the flow depth was measured under the movement threshold conditions and then the stability number was calculated using the obtained data. The results of this research showed that the highest stability number related to the overflow with a threshold of 45 degrees and the lowest stability number was observed in the overflow with a threshold of 15 degrees. Also, the relative diameter of the aggregates is also an effective factor in the stability of the aggregates, and the stability number at the threshold of movement in the four angles of the triangular overflow threshold decreases with the increase of the relative diameter of the aggregates. In order to provide a relationship to estimate the relative diameter of the checkered stone, the variables of the investigation and the correlation coefficient of the results obtained from this relationship with the laboratory results for the triangular overflow were obtained as 0.85.

The results of the dimensional analysis by Buckingham method showed that the discharge coefficient(Cd), function "Ht/P" (represents the total hydraulic head ratio (total hydraulic head to the height of the weir)), "Sf" (represents the form factor of the weir) and "Nnp".Physical and numerical modeling was done in a rectangular flume with the length of 8 meters, width of 0.6 meters and height of 0.6 meters.The results of the study showed that creating an additional cycle has a positive effect on the TRTPIO weir, and it causes the discharge coefficient as well as its hydraulic performance to increase compared to the placement of the nappe breaker.creating an additional cycle and placing the nappe breaker on the labyrinth weir at the same time makes the TPTPIO weir with 4 nappe breakers have a higher discharge coefficient than other models.Quantitative evaluation of the results of this study shows that, for example, in the hydraulic head ratio of 0.24, the discharge coefficient of TRTPIO weir compared to TPTPIO weir, TPTPIO with 4 nappe breakers, TRTPIO with 4 nappe breakers, is 21, 8.5 and 21% have higher discharge coefficient; On the other hand, the Mattos-Villarroel weir has a higher discharge coefficient than the TRTPIO weir by 7.8%.The results of numerical modeling showed that with the increase of hydraulic head, the discharge coefficient decreases.while the increase of hydraulic head in labyrinth weirs causes an increase in the interference of nappe flow, energy loss, local submergence, and finally, a decrease in the hydraulic efficiency of the weir.

This research was conducted with the aim of evaluating the WOFOST for simulating the corn yield and water productivity in two different conditions of water amounts and nitrogen fertilizer supply.In the first research project, the factors of irrigation water amount in four levels and nitrogen fertilizer in four amounts and in the second project, fertilizer in four levels and fertilizer splitting were considered.The results showed that in the first projct, the accuracy of the WOFOST model for simulating water yield and water productivity was in the excellent and medium categories, respectively, while the accuracy of this model in the second project was determined in the excellent category for both aforementioned parameters.The efficiency of the WOFOST model for simulating yield in both project and water productivity in the second one was acceptable, but for simulating water productivity in the first project was in poor conditions.In the first project, changing the nitrogen fertilizer consumption from N1 to N4 caused an increase in the difference between yield in observation and simulation conditions.The amount of irrigation water had no effect on changing the WOFOST accuracy and error.In the second project, increasing the distribution of nitrogen fertilizer from T1 to T2 caused the error of this model to decrease from 6.5 to 3.6 percent.Based on the results, it is necessary to conduct more studies to use the WOFOST model to simulate corn in different amounts of irrigation water, but this model can be used to simulate corn in different amounts and splitting of nitrogen fertilizer.

In this study, the area under cultivation, average irrigation water and orchard yield were determined by field studies by researchers. Indicators of water consumption, virtual water, water productivity, virtual water consumed and water consumption intensity were obtained. Then, using irrigation planning, the amount of irrigation water was evaluated for the conditions of reducing water consumption in orchards. The best conditions for each crop were selected based on the results obtained and compared with the current conditions. According to the results, in most garden products, it is necessary to reduce water consumption compared to the current situation. The largest decrease was observed in peach, apple, nectarine and grape crops. The difference between water consumption for these products in the current and optimal conditions was 0.7, 6.4, 6.3 and 5.7 million cubic meters, respectively. The lowest difference between water consumption in the current and optimal conditions was determined in pomegranate and pistachio products with a difference of 0.12 and 0.35 million cubic meters. The average of virtual water consumed by horticultural products in Alborz province in the current situation is 0.0133 million cubic meters, which in the optimal case decreased to 0.0109 million cubic meters. Therefore, with the reduction of water consumption in orchards, the intensity of water consumption decreases from 0.33 to 0.26. This will save 19% of the province's water resources.

The AquaCrop model is one of the most widely used crop model that has been evaluated to simulate different crops. However, its accuracy in the simultaneous use of water stress and fertilizer in furrow irrigation has not been investigated. Therefore, the present study was accomplished using two factors: the amount of crop water requirement (at four levels W1, W2, W3 and W4, respectively, 120, 100, 80 and 60% of water requirement) and nitrogen fertilizer (at four levels N1, N2, N3 and N4 represent the application of 100, 80, 60 and zero percent fertilizer requirements, respectively). The required data, consisted of meteorological, soil, irrigation and nitrogen amounts, and crop characteristics, were collected in Seed and Plant Breeding Research Institute (in Karaj). Aforementioned data were used to simulate maize yield and crop water productivity. The results showed that the AquaCrop model for yield simulation (MBE = -0.15) and water efficiency (MBE = -0.32) had an overestimation error. The accuracy of this model for simulating grain yield and water productivity was 9% and 24%, respectively. With increasing water and fertilizer stress, the accuracy of the AquaCrop model for yield simulation decreased. The efficiency of the AquaCrop in simulating grain yield (EF = 0.92) and water productivity (EF = 0.47) was very favorable. Applying of the model in similar conditions is recommended for future studies.

Irrigation water and nitrogen fertilizer management have an effective effect on tomato yield and water use efficiency. So, it is important to know the best amount of irrigation and nitrogen fertilizer for tomato cultivation. Since doing farm researches need time and funds, it is necessary to use crop growth models like AquaCrop. Regarding that, data collected from Ismaeel Abad research station was used. The study was conducted there, irrigation was considered as four levels (E1: 50, E2: 75, E3: 100, and E4: 125 mm evaporation from pan class A) and fertility uses was considered as three levels (F1: 70, F2:100, and F3: 40 percent as fertility needed). At first, AquaCrop was calibrated without considering any fertility stresses using first year data. Then, F3 treatment in the first and second year was used to calibrate AquaCrop for fertility stress (40 percent as fertility needed). Results showed high correlation between observation and simulation values for yield (R2=0.915) and water use efficiency (R2=0.893). MBE, RMSE and NRMSE values showed a good precision for the model. The mentioned values were -0.02 (ton.ha-1), 0.42 (ton.ha-1) and 0.07 for yield, respectively, and -0.01 (ton.ha-1), 0.02 (ton.ha-1) and 0.03 for water use efficiency, respectively. Due to AquaCrop efficiency for simulating tomato yield (EF=0.41) and water use efficiency (EF=0.19), it is recommended to use AquaCop for simulating tomato yield and water use efficiency.

Determination of water requirement in irrigation and drainage projects and water management is important and plant coefficients are one of the key parameters in determining the water requirement.. Therefore in this study, Four-year lysimeter data of grass and three-year lysimeter data of winter wheat and weather data were in Esmaeil Abad in the Qazvin Agricultural Research Center applied to calibrate different methods of estimating evapotranspiration. So with use of these results winter wheat water requirement in each month was Available. Results indicated that annual evapotranspiration of grass, annual evaporation from pan evaporation and winter wheat evapotranspiration respectively were equal to 1296 mm,1703 mm and 550 mm during growth period. FAO 56 method was the best method compare to methods of Turc , Makkink , Priestly_Taylor, Hargreaves and Samani , FAO Blaney and Criddle and FAO 24 . Also results showed that calibration of methods can provide acceptable result in estimates of evapotranspiration of winter wheat. On the other hand, pan evaporation method which is the easiest and most practical method, with use of coefficients and some modifications could estimate evapotranspiration of winter wheat with acceptable accuracy. The value of Plant evapotranspiration coefficient (Kc) was determined equal to 0.29-1.09 and value of evaporationpan coefficient (KP) was determined equal to 0.58-0.88 and value of evaporationpan coefficient (Kcp) was determined equal to 0.26 -0.99.