نشریه فناوری های پیشرفته در بهره وری آب
سال سوم شماره 3 (پاییز 1402)

In Iran, pressurized irrigation systems cover a large area of agricultural land, but water use efficiency remains low because farmers tend to do deficit (over) - irrigation due to their lack of knowledge of crop water requirements. To address this issue, irrigation systems can be automated, and it is important to estimate crop water requirements accurately. This can be done based on soil moisture deficit or meteorological data. The water required can then be applied using a volume meter or by determining irrigation time based on the sprinkler flow rate. The study aimed to compare crop water requirement estimates based on soil moisture deficit and meteorological data, as well as the amount of water applied using volume and time-based methods.The study was conducted in the research farm of Razi University, Kermanshah, Iran, on a sprinkler irrigation system equipped with pressure and flow measuring devices, pressure switches, and electrical valves. The field was under corn cultivation, and four types of irrigation management were evaluated, which included a combination of two methods of determining crop water requirement (soil moisture deficiency and meteorological data) and two methods of irrigation application (time or volume). The four treatments were soil moisture - time (MT), soil moisture - volume (MV), weather - time (WT), and weather - volume (WV). The crop water requirement was calculated using the Penman-Monteith formula based on daily weather data. Soil moisture was measured at different depths one day before irrigation, and the soil moisture deficit was calculated to determine the crop water requirement based on soil moisture. The irrigation volume for each sprinkler in the irrigation cycle was calculated using equations that written in the paper.In the volumetric-based method (treatments WV and MV), the volume of water applied was measured using a water meter with a precision of 0.1 liters, and irrigation was stopped after passing the required volume of water. In the time-based method (treatments WT and MT), the irrigation time was calculated by dividing the irrigation volume by the average flow rate of the sprinklers (3 liters per second), and irrigation was stopped after the calculated duration. The actual sprinkler flow rate was calculated based on the volume of applied water and irrigation time in each treatment and irrigation round. Crop yield was measured at the time of harvest in the studied treatments and a control treatment managed by the Faculty of Agriculture. The irrigation treatments were not applied in the first month of the growth period due to field limitations.The results show that the crop water requirement calculated based on meteorological data at the beginning and end of the growing period was more than the method based on soil moisture. In total, the amount of crop water requirement calculated based on soil moisture was 8% more than the meteorological-based method. The volume of applied water in treatments of MT and WT was 14 and 8% more than in MV and WV treatments, respectively.The actual flow rate of sprinklers was different from the design flow rate due to irrigation situations in other parts of the farm. The average discharge of sprinklers (12 irrigation events) in WT, MT, WV, and MV treatments was 2.79, 3.03, 3.27, and 3.12 l/s, respectively. The irrigation time in volume and time-based methods also showed a significant difference. The irrigation time in MT and MV treatments was 10 and 18% longer than in WT and WV treatments, respectively. The study found that due to the non-uniformity of sprinkler discharge, applying irrigation by volume method is better than the time-based method. The results suggest that the MV treatment, which determined the amount of irrigation based on soil moisture deficit and applied it using a volumetric method, is a suitable option for automating sprinkler irrigation systems in the studied region.

Sediment deposition issues for reservoirs are important because the severe deposition could excessively decrease the reservoir lifecycle. Extreme storm events usually can carry a massive amount of sediment into reservoirs, and deposition will happen unless the incoming material can pass through sluice gates. When it comes with high concentration, the density current flow is prone to be generated, and the bottom outlets are the most effective sluice gate to release the sediment. Venting of turbidity currents is known as an efficient measure to prevent reservoir sedimentation and is applied in many reservoirs globally. It has several economic and ecological advantages compared with other evacuation methods. Dez Reservoir is one of the many reservoirs in Iran which suffer from sedimentation due to a lack of proper low-level outlet. Currently, the major issue which threatens the Dez Dam is the continual accumulation of silt in the reservoir near the dam endangering the operation of the entire hydraulic scheme. Mean annual sediment deposition in the reservoir is about 15 million tons. The elevation of sediment deposition has now reached to nearly 14 meters under the intakes of power stations (Research center of power Ministry, 2003). In this study, density current releasing through a proposed low-level outlet is considered as a proper solution to minimize the consequences of sedimentation.The aim of the study is to numerically assess the proposed low-level outlet. A high resolution 3-D numerical model is employed based on Navier-Stokes equations is employed to simulate the evolution of turbid density current in Dez Reservoir. Frist in order to calibrate the simulation model, Several models including various roughness height in combination with RNG and LES turbulence models were employed. Then, the flow depth and velocity results were compared with field measurements (KWPA 2007). In the next step, the proposed low-level outlet was added to the model and its impact on the behavior of turbidity current was investigated by using three turbidity current concentration and also three low-level outlet opening.The results indicated that using large eddy simulation turbulence model (LES) presents a higher accuracy than the simulation by comparing with the field measurements, so that the maximum error related to the calculation of the depth and velocity of the turbidity current is estimated to be 14.67 and 13.82%, respectively. In the next step, the proposed low-level outlet was added to the model and its impact on the behavior of turbidity current was investigated. Based on the simulated results the amount of sediments evacuated from the dam reservoir is directly related to the input concentration and the opening percentage of the low-level outlet. In such a way that by averaging the results for different inflow turbidity current concentrations, venting efficiency at the openings of 25%, 50% and 100% was calculated to be 15.4%, 20.8% and 25.1% respectively. In the next section of study, velocity profiles in the upstream sections of the low-level outlet were used in order to evaluate the water entrainment coefficient (Ew). It was found that as the opening low-level outlet increase from 25% to 50% and from 50% to 100%, the water entrainment coefficient increase 20% and 16% in avarage respectively.In a general point of view, The numerical results show good accuracy in simulating the evolution of the density current in the reservoir. Based on the simulated results, as the turbid density current approaches the low-level, water entrainment coefficient increases in avarage. Moreover water entrainment and also venting efficiency has direct relationship with low-level outlet opening and inflow density current concentration.Keywords: Reservoir sedimentation, Turbidity current, Sediment management, Venting efficiency, Reservoir outlet

The low inflow rate of water into the dam reservoirs causes sedimentation, leading to a decrease in the service life of dam. As a result, the performance of the dam in controlling floods and generating energy through water release downstream will be affected. Additionally, sediment deposition near the bottom outlets and turbines causes their burial, leading to difficulties in their operation and utilization. Installing inclined plates in the upper of bottom outlets is suggested as a new method to increase the amount of flushed sediments in pressurized flushing. Awareness of changes in the upstream flow pattern of the orifice is of great importance. In the present study, the effect of installing inclined plates on flow pattern changes in the upstream of the orifice was investigated using the Flow3D model. In this study, a numerical model calibration was performed using the results of experiments conducted in the hydraulic laboratory of the Faculty of Water and Environmental Engineering at Shahid Chamran University of Ahvaz, and the RNG turbulence model was chosen for conducting the simulation. The considered variables include plate width, plate installation angle, and plate installation distance to the orifice. In total, 5 scenarios (including the reference test (i.e., without installing plates)) have been defined for the numerical model.The results showed that the installation of inclined plates against the orifice led to the creation of vortexes and the development of a low-pressure zone, resulting in an increase in the volume of flushed sediment. Also, reducing the width of plates, increasing the installation angle, and increasing the installation distance of the plates will lead to a decrease in the intensity of eddies and a decrease in the range of low-pressure zone, which reduces the effect of installing inclined plates to increase flushed sediment volume.Based on previous studies, the amount of sediment output in pressurized flushing is limited and confined to the vicinity of the dam body. Therefore, this method is not used to revive the dead storage capacity of the dam reservoirs. Ancillary facilities such as bottom outlets and hydro-power plant outlets are located near the dam structure, and sediment entry into these facilities can have destructive effects. Therefore, providing methods to increase sediment discharge from near the dam body can be highly beneficial. Additionally, by creating a low-pressure zone in the upstream of the outlet, a suction effect is created, which can be useful in increasing the volume of sediment discharged during turbidity current discharging from the bottom outlet.

Drought is the most important abiotic stress in Iran, which leads to a significant decrease in plant yield. Crops need a lot of water. ‎Evaporation and transpiration determines the plant's water requirement. Water is one of the rare resources in Iran, which is affected ‎by the amount of rainfall. In Iran, the cultivation of maize has been greatly promoted in recent years, and its use in livestock and ‎poultry feeding and industrial uses has been noticed. Sunflower, as the main source of vegetable oil in the world, is of special ‎importance, which requires a lot of water. Plastic mulch is especially important in reducing water consumption in arid and semi-‎arid areas.‎An experiment was conducted as a randomized complete block design with three replications at the Research Farm, Agricultural ‎and Natural Resources Campus, Razi University, Kermanshah, Iran in 2016. The plants used in this experiment were maize and ‎sunflower. Treatments included plastic mulch between the rows, plastic coating on the plant (only in maize) and control (without ‎plastic). Treatments were applied at the beginning of the experiment and before germination.‎The plastic mulch between rows had the highest growth and yield of maize and sunflower than other treatments. In maize, plastic ‎mulch between the rows had higher biological yield, harvest index, number of seeds per row, ear weight, and 100-seed weight than ‎that of control, but there was no significant difference between plastic mulch between rows and plastic coating on the plant in terms ‎of mentioned traits. There was no significant difference among treatments in terms of number of rows per ear, ear skin weight, and ‎ear length. In sunflower, plastic mulch between rows had higher biological yield, head diameter, head weight, and 100-seed weight ‎than control, and there were no significant differences between treatments in terms of harvest index, and number of seeds per ‎head. ‎The results of this experiment show that by applying plastic mulch, especially ‎between the planting rows and before the seeds ‎germinate, while reducing the ‎length of the growth period and better use of moisture, the seed yield of maize ‎and sunflower can be ‎increased compared to not using plastic mulch by 38 and ‎‎41 percent, respectively. Other possible reasons for increasing grain yield ‎‎under the conditions of using nylon mulch included reducing evaporation and ‎increasing soil temperature at the beginning of the ‎growth period.‎

Indiscriminate exploitation of groundwater has caused a decrease in the groundwater level and as a result, has caused land subsidence in many areas. This problem is especially visible in arid and semi-arid regions like Iran, where water supply for agriculture, drinking, and industry is done from groundwater water sources, and in recent years, it has seriously threatened the aquifers of the plains as a serious danger. In this research, due to the importance of the problem, land subsidence in the Damghan Plain aquifer located in Semnan province was studied and investigated.In this research, the amount of subsidence was measured at the field, and then its spatial changes were investigated using conventional methods such as Kriging interpolation, Co-kriging, and inverse distance weighted interpolation (IDW). Also, the artificial neural network model was used to estimate and interpolate the amount of subsidence. Three statistical indices namely the coefficient of correlation (R2), the root mean square error (RMSE), and the mean absolute error (MAE) were used to compare the estimation of subsidence values using an artificial neural network model, kriging interpolation method, cokriging, and IDW. To perform interpolation using kriging, cokriging, and IDW interpolation methods, the variogram of land subsidence data was drawn. Also, in order to increase the accuracy of the mentioned models in predicting the amount of subsidence, the auxiliary variable of water level reduction was used.Using different functions such as circular, spherical, exponential, Gaussian, and linear models for plotting the semivariogram, results show that the Gaussian function with segment-to-threshold ratio (C0/(C0+C)) equal to 0.26 has better performance compared to other models. Also, the artificial neural network has a better performance compared to the kriging method and the inverse weighted distance method and has been able to reduce the RMSE error value in the validation stage by 17.6% and 31.3%, respectively. It has also increased the value of the R2 from 0.502 and 0.421 to 0.721.The use of the auxiliary variable of water level reduction has increased the accuracy of the models used in predicting the amount of subsidence. In this case, the comparison between the estimation of subsidence values using the artificial neural network model compared to the interpolation method of kriging, cokriging, and IDW shows that the artificial neural network model with a coefficient of determination (R2) of 0.860 and 0.751 and 0.015 and 0.017, has a better performance compared to the mentioned methods and reduce the amount of prediction error. Therefore, the artificial neural network model can be used with good accuracy as an alternative method instead of conventional interpolation methods to investigate the spatial changes of land subsidence.In recent years, the phenomenon of land subsidence has occurred in many plains of Iran due to excessive extraction of underground water, including Damghan Plain. In this research, by using the measured data of land subsidence in this plain, its spatial changes were investigated using kriging and cokriging methods (geostatistics method), inverse distance weighted method (IDW), and weighted IDW (deterministic method) in the whole plain. it placed. The research results showed:• Compared to circular, spherical, exponential, and linear functions, the Gaussian function can better estimate the spatial changes of land subsidence.• The results of the kriging method were better than the inverse distance weighted (IDW) method.• The artificial neural network model with Gauss function and two intermediate layers has better performance than other transfer models such as sigmoid, hyperbolic tangent, and hyperbolic Bade secant.• The use of artificial neural network model has increased the accuracy of land subsidence estimation compared to conventional methods such as the kriging method and inverse weighted distance method.

Undoubtedly, floods can be considered as one of the most effective natural hazards that cause many human and financial losses every year. A flood is defined as an overflow of water or its overflow in a river or spring, which is a threat to the life and property of residents near these sources. In simpler terms, any relatively high flow that impinges on natural or artificial banks in any direction of a stream is called a flood.  In this research, the effective criteria related to the estimation of flood design discharge in reservoir dams in 17 in Kermanshah province were identified and prioritized, and then in order to review and analyze the effective factors in estimating the flood estimation separately for each reservoir dam, were evaluated using 8 different multivariate decision-making methods.  Considering the large number of studied dams the four hydrological agents and comprehensive options such as design flood estimation in connection with the occurrence of hydrological events in the area by human origin, with natural origin, the quantity and quality of information and hydrometeorological data and the limitations of methods (statistical, experimental, models) were selected and prioritized with SAW, AHP, FAHP, VIKOR, TOPSIS, FTOPSIS, PROMETEE, Electre III methods. Based on the mentioned 8 methods, 22 criteria involved in estimating the flood yield of 17 reservoir dams were ranked.  In the SAW method, experimental methods with 6 rank 1, statistical methods with 5 rank 1 and physiographic parameters with 2 rank 1 are the most important effective criteria in estimating the flood entering the reservoirs of dams studied in this research. In the AHP method, hydrometric stations and the true limit of the basin were the most important effective criteria with 5 and 3 ranks, respectively. In the FAHP method, experimental methods with 6 and statistical methods with 5 ranks were recognized as two important criteria. In TOPSIS method, statistical methods, physiographic parameters and conversion of maximum flow to maximum instantaneous flow rate each with 1 first rank, and Fuzzy TOPSIS experimental methods, statistical methods and conversion of maximum flow rate to instantaneous flow rate with 6, 4 and 2 first rank respectively. In ViKor's method, only experimental methods have 1 rank. In the Electra method, the criteria of meteorological stations, the true limit of the watershed and experimental methods were evaluated as effective criteria with 1 rank. Finally, in the PROMETHEE method, only the experimental method with one item was ranked 1 rank.  The results showed that more than 76% of the dams have priority in the option of conditions and limitations of flood estimation methods (statistical, experimental, model, etc.) and 24% have problems in the option of quantity and quality and water and meteorological information.. The option that has more frequency than other option of the conditions and limitations of the flood estimation method (V4) of each reservoir dam. Based on the review of documents and documents of flood analysis and achieving the design flood in the studies of the first and second stages of reservoir dams of the studied dams, this conclusion is confirmed, in the statistical methods, the length of the statistical period is low and the frequency distribution function is not recognized properly. In addition, the use of experimental methods, which are mainly applied without recalibration of relevant coefficients and without necessary precautions and checks, is one of the weaknesses of flood estimation.