نشریه دانش آب و خاک
سال سی‌ام شماره 1 (بهار 1399)

Implementation of research findings and their application in the field is a prerequisite for any improvement in quantity and quality of agronomic products. To investigate the effect of research findings on the wheat yield, two benchmark sites were chosen in the downstream Lands of Kharkheh River Basin, one with drainage (site 1) and another without drainage (site 2) system during 2013-14 and 2014-15 cropping seasons. Treatments were application of some research findings such as leveling, certified seed, appropriate amount and application time for fertilizer and  proper irrigation method as Research Management (RM) and farmer management as "Traditional Cultivation" (TC). Results showed that application of recommended package in RM treatment in 2013-14 increased the grain yield by 14 and 44% in sites 1 and 2 compared to TC treatment, respectively. While the values of the improvement in grain yield in the same sites for 2014-15 were 44 and 52%, respectively. During these two years the mean grain yields for RM and TC treatments were 4178.5 and 3321.0 Kg ha-1 in site 1, and 2976.5 and 1999.0 Kg ha-1 in the site 2, respectively. Based on the balance of a cropping season in 2013-14, the increased net benefit in RM treatment were 1.2 and 1.98 times more than the TC treatment in the sites 1 and 2, respectively. Application of the recommended package in 2014-15 increased the net benefit in RM treatment by 1.69 and 1.86 times more than TC treatment in the sites 1 and 2, respectively.

Computation of longitudinal velocity in the vertical direction and extracting the applied theories have been conventional manner from past years among the hydraulic engineers. In many previous investigations, the researchers have tried to extract some applied equations, separately, by dividing the flow depth namely from bed to water surface to various regions. As it is accepted by all of the researchers, the laminar sublayer zone has a linear velocity profile while out of this zone, the velocity simulation follows a logarithmic law which its accuracy in estimation of the velocity decreases by increasing the distance from the bottom of the channel. Also, it is not applicable for dip phenomenon which occurs bellow the free surface. In the current study, 12 experimental data series, operated under different experimental conditions, were collected from previous researches. Also, three common theories of log law, log- wake law, and modified log- wake law have been applied to simulate longitudinal velocity profile in the vertical direction. Finally, it is seen that the modified log- wake law has a better agreement with the experimental data, and also it can be operated for predicting the dip phenomenon bellow the free surface. For solving the equation of the mentioned theory, the factors of von Karman, wake strength, and shear velocity are assumed unknown. Then, the mentioned parameters have been extracted using a non-linear optimization technique of the least square curve fitting.

Recently, it has been shown that Artificial Intelligence (AI) methods such as Feed forward neural network and Support vector regression have great capability in modeling of non-linear hydraulic time series. AI methods offer effective approaches for handling large amounts of dynamic, non-linear and noisy data. Hence in this paper, seepage of Sattarkhan earth fill dam using two AI models of Feed forward neural network and Support vector regression was simulated, based on 2 scenarios with different combination of inputs. Afterwards, as a pre-processing method for improving the model performance, normally distributed noises with the mean of zero and various standard deviations were generated and added to the time series to form different jittered training data sets, for AI modeling of seepage. Further, as another method for improving the model performance, an ensemble post-processing model was developed using outputs of sole models. Non-linear neural averaging method was considered for model ensembling. The obtained results indicated that simultaneous application of the both jittering and model ensembling methods improved the model accuracy up to 32% in the verification step.

In recent two decades using the numerical models is common for simulating flow and sediment transport. Numerical models are valuable tools for estimating flow conditions and sediment transport, and are widely applied in water resources management. The main goal of this study is to develop one dimensional, unsteady, hydrodynamic model in which flow and sediment transport can be simulated as semi-coupled in river systems. In this research, the Saint- Venant’s equations are numerically solved for river systems and a semi implicit finite difference scheme is developed to solve the Saint- Venant equations for unsteady flow. The linear equations are produced based on the partial differential equations and the staggered technique. After solving the above equations, the computed hydraulic parameters in this part are sent to the sediment transport segment. The dynamic advection- dispersion equation and the sediment continuity partial differential equation are applied to calculate the suspended sediment and bed load transport rates, respectively. The Exner equation is then used to predict the changes in the river bed elevations. Finally, the model is compared to the Hec-Ras Model and the results show that the developed model has a good accuracy. There are differences in the predicted depth for scour and deposition, which are not unexpected due to differences in the bases of numerical models and between the equilibrium and non-equilibrium conditions of the Exner equation.

With respect to water shortage during the recent decades, subsurface irrigation method has been considered in arid and semiarid zones. Therefore, experimental design was performed as completely randomized blocks with four repetitions in Isfahan University of Technology. Then, the effects of different irrigation intervals of every day, every other day and once a week under the surface and subsurface irrigation on height, collar diameter, chlorophyll content and stomata conductivity of Zygophyllum fabago L. were investigated. The percentage of plant survival was also recorded six months after planting. The results showed that irrigation interval had a significant effect on height, chlorophyll content and stomata conductivity of the tested plant (P<0.05) and the height, diameter of the collar and stomata conductivity decreased by increasing the irrigation interval. While, the irrigation interval didn’t have a significant effect on the collar diameter (P>0.05). The highest percentage of survival (100%) was observed in subsurface irrigation treatment and control treatment had the lowest percentage of viability (70%). It could be concluded that the improvement of growth parameters and survived of Zygophyllum fabago were better with the subsurface irrigation than the surface irrigation.

Designing and implementing suitable cropping patterns are necessary to control the limiting factors and optimal utilization of available water resources. In the present study, cropping pattern optimization in Qazvin irrigation and drainage district has conducted considering the five levels of irrigation including I1, I2, I3, I4, and I5 (representing water allocation of 100, 90, 80, 70, and 65 percents of the crop evapotranspiration) and three different levels of cultivated areas including S1, S2, and S3 (representing, current cultivated area, 10 percents increase and 10 percents decrease in the crop cultivated area compared to the current conditions). Crops cultivation areas and water allocation were optimized using a linear programming method and the objective function was to maximize the benefit. The results indicated that the model in condition S2 allocated the most cultivation area to strategic crops and in condition S3 allocated the most cultivation area to economic crops. The condition S3I1 had the highest income (315 million rials) among the all scenarios. Water allocation alternative named I2, increased the economic productivity by average 0.82 million rials per cubic meter of water at all the cultivation area alternatives while maintaining income. Therefore, it was possible to allocate less cultivation area and a lower amount of water while earning more income. Also,  water allocation alternatives named I4 and I5 were not recommended due to reduced income and yield. Model had a limited cultivation area of water-consuming crops such as tomato, sugar beet, and the alfalfa under water shortage condition.

Increasing population and rising water requirements have raised the use of freshwater resources such as groundwater. Therefore, assessing the vulnerability of groundwater is a suitable method for identifying the vulnerable areas and protecting these resources. Shabestar plain in East Azarbaijan province is an active agricultural area and the use of groundwater resources in this plain is important due to the shortage of annual precipitation. In this study, the DRASTIC frame work was used to assess the vulnerability of the Shabestar plain aquifer. The amount of DRASTIC vulnerability index in the study area was calculated as 53.3to 118.3. Given that the weights of the DRASTIC frame work were somewhat expert, so the main purpose of this study was improvement of the DRASTIC by two methods of Neural Network and Neuro-Fuzzy. DRASTIC inputs were introduced as inputs of the both artificial intelligence models. The corrected DRASTIC index with nitrate concentration was considered as the outputs of the models. Nitrate values were categorized into two groups of train and test. After training the model the results of the model were evaluated at the test step with nitrate concentration. The results showed that the both artificial intelligence models had the high ability to improve the DRASTIC model. Nevertheless, the neuro-fuzzy model having a higher correlation coefficient with nitrate was a suitable method for assessing the vulnerability of Shabestar plain aquifer.

The performance of the existence emitters in micro-irrigation systems is on the basis of pressure dissipation and the inefficiencies of these systems in the pressure and discharge uniformity regulations have been reported by researchers. In this research, in order to improve emitters' efficiency in micro-irrigation systems, a new emitter named water volume control emitters was designed and evaluated. One hundred emitters were installed in the field condition on a micro-irrigation system and the applied water volume was measured until cutoff time. The experiments in pressures of 0.5, 1, 1.5, 2 and 2.5bar with three repetitions were conducted. In each repetition, the cutoff time of the emitter located in five positions at the first, third, mid, two-thirds and end parts of the lateral pipe were measured. Finally, the obtained results were evaluated on the basis of ASAE standards. In the field experiments, the maximum value of variation coefficient was obtained 3.3% in the pressure of 0.5bar (minimum pressure). Therefore, the system performance was evaluated in the excellent category in the all applied pressures. Also, the minimum coefficients of distribution uniformity (97.6%) and emission uniformity (91%) were obtained in the minimum pressure of 0.5bar so that these values were very favorable. In all of the pressure-discharge equations, the discharge exponent values were approximately estimated 0.55. The type of flow in emitters was turbulent. The appropriate performance of the mentioned emitters in creating a favorable water distribution uniformity showed that the change of view about emitters' operational mechanism and the developing new emitters with efficient mechanism can improve the efficiency of micro irrigation systems.

In this research, artificial honey bee colony algorithm, is used to solve single reservoir operation optimization problem. For this purpose, improved artificial bee colony algorithm is proposed using some modification in the basic algorithm. The simple and hydropower operation problems of Dez reservoir over 5- and 20-year time periods are solved using the proposed algorithm and the outputs are compared with the other available research results. In order to solve these problems, two different formulations are proposed in which the water release and storage volumes are considered as decision variables in the first and second formulations, respectively. If the first formulation of the improved artificial bee colony algorithm is used to solve the simple reservoir operation over 5 and 20 years, the objective function values are improved %9.94 and %55.266 than basic artificial bee colony algorithm, respectively. If the second formulation is used to solve simple reservoir operation over 5 and 20 years, the objective function values are improved %14.63 and %7.18 than basic artificial bee colony algorithm, respectively. In addition, if the first formulation of improved artificial bee colony algorithm is used to solve hydropower reservoir operation over 5 and 20 years, the objective function values are improved %7.76 and %26.47 than basic artificial bee colony algorithm, respectively. If the second formulation is used to solve hydropower reservoir operation over 5 and 20 years, the objective function values are improved %3.79 and %25.49 than basic artificial bee colony algorithm, respectively. Finally, comparison of the results shows that using the improved artificial bee colony algorithm leads to better results with low computational costs.

Due to the importance of groundwater potential maps in exploration, exploitation and management of groundwater resources, groundwater potential map of Balukhluchay watershed was prepared in this study. Therefore, 6 criteria along with12 sub-criteria, that affect infiltration and groundwater recharge, were used. Criteria and sub-criteria maps were prepared in raster format using existing base maps, WetSpa hydrological model and also RS and GIS techniques. Criteria and sub-criteria weights were determined using analytical hierarchy process (AHP) and groundwater potential map was prepared by combination of criteria and sub-criteria maps based on assigned weights. Results showed that 10.53 and 14.61 percents of the studied area had high and good groundwater potential respectively which were located in eastern and south-western part of watershed and were in relation with permeable rocks and low slope. Also, more than 50 percent of the area had low groundwater potential which was in relation with low-permeable rocks located in steep mountainous hills.

One of the economical energy dissipater structures applying in high spillways is flip-bucket which falling flow causes scouring in plunge-pool at downstream. In this research, the bed variation as a scour hole at the downstream of a siphon spillway has been investigated. Dimensions and position of the scour hole were analyzed both experimentally and theoretically. The experimental results showed that the maximum scour hole depth was a function of discharge rate and downstream tail water depth. Also, flip-bucket angle had the most significant effect on distances of upstream hill and scour hole bottom from the spillway. It was found that the scour hole length, distances of downstream hill end point and maximum scour from the spillway were affected by the hydraulic conditions but they were less effected by the flip bucket angle and bed particle size. Also, it was seen that the flip bucket angle had a significant effect on upstream hill height. The height of downstream hill height was a function of flow discharge and tail water. Applying Buckingham π-theory, three variable linear equations were extracted to predict the dimension and situation of the scour hole and hills. The comparison between the measured versus the predicted values showed a good agreement between them.

Climate change phenomenon has caused considerable changes in surface water and groundwater resources during the recent years. Groundwater is one of the important resources of the fresh water in every region and it is very important to investigate the effect of climate change on it.  In this study, the effect of climate change on water table changes in Sarab plain aquifer in the future time period of 2021-2050 was investigated using Atmosphere-Ocean General Circulation Model(AOGCM). For this means, the climate change data resulted from 16 models of AOGCM-AR4 under the emission senarios of A2 and B1 during two time periods of 1986-2015 and 2021-2050 wereweighted for the studied area.  Based on the weights of the climatic models and the amounts forecasted data by them for the future time period, the variations of the precipitation and air temperature were calculated with the probabilities of 10, 50 and 90 percent. The statistical model of LARS-WG was used todownscale the amounts of precipitation and temperature for the future time period. Using the precipitation-runoff models of NARX and MODFLOW the daily magnitudes of the runoff and water table fluctuations were estimated too. According to the results, water table will be declined about 0.0 to 10 meters comparing to the year 2001 in most of the aquifer areas under both scenarios. This decreasing trend is more visible under the scenario B1 comparing to the scenario A2.

In order to determine the effects of irrigation frequency on grain yield, yield components, and seed oil content of oilseed rape (Brassic napus L.), a field experiment was conducted at agricultural research station of Haji Abad, Iran. Four irrigation frequency treatments including irrigating the crop after 50 (T1), 75 (T2), 100 (T3) and 125 (T4) mm cumulative evaporation from the class A evaporation pan, were arranged in a randomized complete block design (RCBD) with three replications. Results showed that among the studied parameters, grain yield and 1000-garin weight (P<0.01), and number of pods per plant (P<0.05) were significantly affected by irrigation frequency. However, the pod length, number of grain per pod, oil concentration in the grain, and crop height were not affectd significantly. The T1 and T2 treatments had significantly higher grain yield, 1000-garin weight and number of pods per plant than the T3 and T4 treatments.There was no significant difference between T1 and T2 treatments for all of the studied parameters. However, T2 resulted in higher WUE than T1. It appears that canola irrigation after 75 mm cumulative evaporation from calss A evaporation pan which is equivalent to the irrigation frequencies of 14, 20 and24 days in November, December and January respectively, 16-20 days in February to early April and 9 days in late April to early May, would be approperiate and may be recommended for Haji Abad region.

In order to evaluate the effect of switching the furrow to drip irrigation methods on stem length, water used efficiency (WUE) and depth of root zone of Sultana grapevines, an experiment was conducted based on a randomized complete block design with four replicates in 2015-2016 growing season in Malayer, Iran. Treatments were: furrow irrigation (I1), combination of drip and furrow irrigation system (drip-furrow) (I2), bubbler irrigation (I3), drip 1: three dripper/plant (I4), surface-subsurface drip irrigation (I5), drip 2: five dripper/plant (I6) and drip 3: -eight dripper/plant (I7). The results showed that the drip irrigation caused significant decrease in the shoot length, leaf area and water consumption compared to the furrow irrigation. In the same order, the average of the mentioned parameters for furrow irrigation were 133 cm, 11.1 m2/vine and 5337m3/ha respectively, and for the drip irrigation, 121 cm, 6.5 m2/vine and 3625 m3/ha. These results indicated that there was positive correlations (R2) between the mentioned parameters. The treatments I6 and I7 had a yield of 31 and 29 ton/ha respectively, exceeding the furrow irrigation with yield 24 ton/ha. However, the other drip irrigation treatments showed less yield than furrow irrigation. The maximum WUE was evidenced by I6 treatment (10.3 kg/m3) and the minimum by furrow irrigation (4.9 kg/m3). The results showed that I6 with five dripper/plant, was the most efficient treatment, so it was considered an appropriate irrigation method to change from furrow to drip irrigation. At the end of the experiment, samples were taken from the vine roots revealing that the drip irrigation systems caused shallow roots.

Generally, intakes are used for conveying and diverting the flow within main channels and rivers. In this study, a flow field was simulated using FLOW-3D software. In addition, the flow free-surface variations were predicted using the Volume of Fluid (VOF) scheme. The flow turbulence was estimated by standard k-ε and RNG k-ε turbulence models. For instance, the MAE values for standard k-ε and RNG k-ε models to simulate the free surface profile were computed 0.166 and 0.201, respectively. The modeling results showed that the numerical model simulated the flow field with an acceptable accuracy. For example, the RMSE, MAE and R values for the simulated flow free-surface variations were calculated 0.164, 0.158 and 0.997 percent, respectively. Then, the effects of four flow division angles (30, 45, 75 and 90 degrees) on flow field pattern were considered. Regarding the modeling results, the highest depth-averaged velocity was obtained for the model with 45-degree. Among the models with division angles of 30, 45 and 75 degrees, the maximum shear stress was predicted for the model with 45-degree.