مجله مهندسی آبیاری و آب ایران
پیاپی 40 (تابستان 1399)

In this study with respect to the sensitivity analysis of transmissibility coefficient, storage coefficient and specific leakage of infinite and finite leakage aquifers in the unsteady flow state of groundwater, which was carried out using an analytical method, these results were obtained: 1. Withincreasing the coefficients of transmissibility, storage and specific leakage of infinite and finite leakage aquifer, the drawdownreduces. 2. In all of the examined sensitivity analysis, it was observed that the drawdown of infinite leakage aquifer is more than the finite leakage aquifer and the drawdown of finite leakage aquifer 2 is more than the finite leakage aquifer 1. 3. With increasing the transmissibility coefficient and specific leakage of infinite and finite leakage aquifer, the groundwater flow reaches earlier to steady state. 4. With increasing the storage coefficient of infinite and finite leakage aquifer, the groundwater flow reaches later to steady state. 5. Infinite leakage aquifer reaches the steady state later than the finite leakage aquifer and finite leakage aquifer 1 reaches the steady state earlier than the finite leakage aquifer 2.

Estimating the amount of sediment load that a specific stream can carry is one of the main subjects of sedimentary research. Shahroud River in Qazvin province is one of the important rivers in Qazvin Province which plays an important role in providing agricultural water in the region, especially providing water to the Sefid Rud dam. In this study, using the HEC-RAS model to study the erosion and sedimentation status of Shahrood River paid. Also, using maximum discharge measurements with a 25-year statistical period in Rajai Dasht hydrometric station located on Shahroud River and using Smada software discharg with different return periods and for calculating the hydraulic modeling of the river, were used. Finally, the model was run for 25 years (507.93 cubic meters per second). After calibrating the model for river hydraulic conditions and modeling inappropriate inappropriate flow conditions, the boundary information and depth were introduced into the model. Using the transfer of sediment ratios, the sedimentation capacity of Shiroud River was calculated. Comparison between the obtained results and the measured data showed that the Ackers-White equation with a mean error of 16% in the range was better than other functions.

Development of water resources projects are accompanied by several environmental impacts, among them, the changes in the natural flow regime and the reduction of downstream water flows. The assessment of environmental flow requirements in a river eco-system is a challenging practice. Ajichay River is the most important river of Urmia Lakes Basin, Providing 10% of entrance surface water flow to the lake. Therefore, Provision of environmental water requirements of this river is to be an important task. The main aim of the present study was to use different Eco-hydrologic methods to determine the environmental flow requirements in a typical perennial river, the Ajichay River. The overall results indicate that the FDC Shifting method is well adapted to the river condition. In order to maintain the Ajichay River at minimum acceptable environmental status (i.e. Class C of the River environmental management), an average annual flow of 1.52 m3/s is to be allocated along the river in the Akhula Station, located 70 km upstream from the Urmia Lake.

The long term experience of bridge constructing on rivers has led to conclude that in designing of bridges, only consideration of structural issues such as, geology, road conditions and traffic potential are not enough, and also, the effect of the hydrodynamic forces must be considered in designing of river bridges. In this research, the hydrodynamic forces that entered on bridge piers has been simulated with ABAQUS software to investigate the effect of different shapes of cross-section such as circular, semi-circular rectangular and elliptical with different L/B ratios, Reynolds number in both single piers and group piers with different G/D ratios (G shows the side by side distance of two piers) with respect to the fluid-structure interaction. It was concluded that the drag and lift forces considerably decrease because the cross-section shape has high adaption with the flow patter. So, the minimum drag force is shown in elliptical cross-section. In this cross-section, with increasing the L/B ratio, the drag coefficient also was decreased. In the group piers with tandem arrangement and circular cross-section, the two cylinders behave like a single body when L/D ratio is less than 2.5. In this cross-section, the L/D ratio of 3.2 is known as the critical spacing (L/D)c, and then after this spacing, the drag coefficient is decreased in three piers. The critical spacing is 2.6 and 2.3 for semi-circular rectangular and elliptical cross-sections respectively. After this spacing, the drag coefficient of each three piers in tandem arrangement is equal to the single pier one.

Rainfall-runoff process is one of the most important and complex phenomena in the hydrological cycle. Therefore, in its modeling, different perspectives for the development and improvement of predictive models have been presented. In this study, while introducing a combination of wavelet-group classification of data, its effectiveness for modeling the rainfall-run-off process in the Ghara-eos watershed was studied. At first, the rainfall and runoff time series were decomposed using a wavelet transform to several sub-basins to overcome its non-state. Then, these time subcircuits are considered as inputs of the grouped data collection method for predicting daily runoff. The efficiency of the combined model with DC and root mean square error (RMSE) were evaluated. The results of the validation of the models indicate that the highest amount of explanation coefficient and the lowest root mean of error for the single GMDH model were 0.65 and 0.07, respectively, and for the combined model of grouping the wavelet data The order is 0.91 and 0.05. The reason for the hybrid model's superiority to the single model is that the combination model of the grouping of wavelet data, instead of using the time series of rainfall and runoff data on a general scale, uses several time- Different decompositions are used as inputs in the model. Also, the results showed that the Wavelet-GMDH combination model compared to other composite models such as Waveline Artificial Neural Network (WANN) due to the GMDH model layer function, which includes binary combinations of input variables, and by selecting the number of optimal neurons in Each layer directs motion to the predicted data, has more efficiency and accuracy.

Accurate estimation of pollution decay coefficient is due to its effect on the oxygen consumption of the river’s solution of important issue, in managing the quality of water resources. The main purpose of this paper is to determine the decay factor of two rivers of Iran, named Talar and Babolrood Rivers. It has been done by measuring the field and elucidating the common empirical equations in two seasons of spring and summer. The qualitative parameters including DO, BOD, pH, EC, nitrate, phosphate and temperature in Talar River were measured in 5 sections of a total length of 4 km long, and in Babolrood River in 3 sections at a total length of 2.8 km, in May and August 2018. Then the decomposition coefficient was estimated using Streeter-Phelps Analytic Model. DO and BOD values were also analyzed in both spring and summer seasons. Based on the results in both case studies, the decay rate in summer was more than spring. The decay rate in Talar River was calculated equal to 1.57 in spring and 6.11 in summer, and in Babolrood, spring was 1.2 and in the summer was 8.34 (1/ day). Also, based on the slope changes, the dissolved oxygen content in both rivers increased in spring and decreased in the summer. In Talar River the BOD was equal to 4.34, in spring and 7.44 mg per liter in summer, and in Babolrood River in spring was equal to 2.5 and in the summer equal to 3.2 mg per liter.

In this study, to investigate the water quality of Gamasyab and Ghareh-Sou rivers in Kermanshah province, data from a 5-year statistical period during 2014-2018 was used. To evaluate the water hydrochemical properties, the water type and hydrogeochemical facies of rivers water were first determined using Stiff and Piper diagrams. Next, the controlling factors of the water chemistry of two rivers were determined using Gibbs diagram and Ionic ratios. Also, factor analysis and cluster analysis were used to determine the processes affecting the hydrochemistry of river water. Finally, to predict the possibility of dissolution and precipitation of some minerals, their saturation indices were estimated. The results showed that water type and facies are bicarbonate calcite in both rivers. Also, the main factor in changing the chemical quality of water in both Gamasyab and Ghareh-Sou rivers is water-rock reaction. According to the results of factor and cluster analysis, this factor can be attributed to the dissolution of (1) carbonate and evaporation (2) dolomite formations in the rivers watershed. However, the dissolution of carbonate formations due to their abundances and distributions two watersheds has a more significant effect on the change in water chemistry.This resulted an increase in some chemical parameters such as calcium, magnesium and bicarbonate in the water of these two rivers and also caused positive water saturation index for aragonite, calcite and dolomite minerals. Considering the low contribution of the second factor in changing the chemical parameters, the saturation indices for evaporative minerals of gypsum, halite and anhydrite is negative.

Bank erosion consists of two processes: basal erosion due to hydraulic force and bank failure under the influence of gravity. Because riverbank resistance force varies with the degree of saturation of bank material, the probability of bank failure is the probability of the driving force of bank failure being greater than the bank resistance force. . The degree of saturation of bank material increases with river stage; therefore, the frequency of bank failure is correlated to the frequency of flooding. Consequently, the rate of bank is a probabilistic phenomenon. In this research, a mathematical model was developed to predict riverbank erosion rate. This model is based on Duan (2005) approach. The model was used to compute riverbank erosion rate of a meander reach in the Zayande Rud river. The model result indicates that the rate of bank erosion at the ZayandeRud river is approximately 0.4 m/year, and bank surfaces are not stable

Seepage of diversion dams foundation and importance of its control, has always been of interest to researchers. In this study, seepage parameters and their control, were investigated experimentally, numerically and analytically. Results showed that using apron and cut off were effective on reduction of seepage discharge so that model with apron and two cut off for upstream head of 47 cm, seepage discharge about 60% decreased and occurrence of piping postponed. Investigations showed that outlet discharge had direct relation with upstream water head. Using a cut off on dam foundation showed the best performance on reduction of uplift force and reduced about 22%. Also application of apron and two cut off beside the control of piping, decreased exit gradient for upstream head of 75 cm up to 0.763. Results for model of apron and cut off on foundation in control of seepage discharge was so similar to model of apron and two cut off, so it is suitable alternative in terms of economic instead of apron and two cut off. Numerical model had good agreement with experimental model on simulation of exit gradient, uplift force and seepage discharge for whole models and error was less than 5%. Results showed, when cut off located at the center of apron, flow line was more symmetrical, potential line and potential changes under the apron were less. Also results compared with different analytical models and Khosla method showed more similarity with experimental and numerical results.

Soil and water salinity is one of the most important factors in reducing the yield of plants in arid and semi-arid regions, which tends to limit plant growth and its development. In saline soils, yield production directly influences by soluble salts in the root zone as well as by shallow water table depth. The first step for reclamation of such soils is reducing salinity to optimum level by leaching practice. Assessing the quantity of water required for this practice, as well as saving the applied water and proper use of water resources for optimal water management are of great importance for leaching process. The objectives of this study were to investigate theoretical models to predict ultimate salinity and to compare the predicted outcomes with experimentally obtained data. For this purpose, several field saline-sodic soil reclamation experiments were carried out in Jafir area, Khuzestan plain, Iran, by using double rings. All experiments were conducted by applying 100 cm water depth in four-25 cm intervals and intermittent ponding method. Four theoretical leaching models including series of reservoirs (SRM), numerical solution (NM), continuous column (TPTM) and secondary reservoir (SRBM) models were used to predict the ultimate salinity. All models outputs were then verified with the real data. Results indicated that among four examined models, the SRM and SRBM models provide more reliable outputs. Although the performance of studied models differed for different depths of applied leaching water, but considering the lower RMSE and RMSEn values of SRM model, this model is more suitable for forecasting the results of leaching and soil reclamation in the study area. This model could reasonably well estimate the designated final salinity.

Roughness estimation is one of error sources in flood simulation. In this study the flood was simulated in Atrak Olya, Chaylogh, Gelian and a part of Atrak river with different roughness coefficient using HEC-RAS ،GIS and HEC-GEO RAS and the effect of roughness coefficient on flood area, flood depth and velocity in different return period were studied. Results showed that for 100-year flood, the flood area and depth increased 1.1% and the flood velocity decreased around 4% for each 10 % increment of roughness coefficient. In addition, for each 10% decline in roughness coefficient, the depth variation was not considerable but the flood area decreased 1.1% and the flood velocity increased about 8.3%. The flood velocity to roughness variation was more sensitive than flood depth and area. Depth flood had the less dependence to roughness and it changes very low with more than 10% change in roughness coefficient. This trend is almost similar for all return periods

Kerman province with mean annual precipitation about 130 mm is categorized among dry provinces.Then producing the maximum agricultural products using minimum water consumption is highly important increasing soil water content and preventing of water deep.Percolation is one of the best ways to use water more efficiently in agricultural practices. In this regard using super absorbent gel is one of the newest methods that. Some studies have been carried on it.In a greenhouse test the effect of soil type , percent of soil moisture content and the amount of super absorbent in a purely random test of factorial with three factors : soil type ( heavy or light ) , percent soil moisture and the amount of super absorbent ( 0 , 100 , 200 , 400 , 800 , kg/ha ) , the effect of them evaluated on the height of maize , and surface of plant . The effect of soil type.  Percent of soil moisture and the amount of super absorbent showed significant difference on plant height and inflammation of leaf.The best results on growing factor of the plant achieved by using 400 kg of s.j in light soil with 60 % of soil water content.

This research investigates the factors affecting the quality and nitrate pollution of groundwater of Zeidoun plain in Khuzestan province. To this purpose, 25 agricultural wells were sampled and then the chemical parameters of water samples (including total dissolved solids, temperature, and cations and major anions) were measured. To investigate the factors influencing groundwater quality, compositiondiagrams, mineral saturation index and factor analysis method have been used.The results of this study showed that the groundwater has an unsuitable quality in the vast part of the study area. So that the salinity of groundwater is more than 3000 µmohs/cm in the middle and northern parts of the plain. Also, the concentration of sodium and chloride ions in these areas is more than 400 and 550 mg/l respectively. From the Nitrate pollution view point, groundwater contamination and pollution was occurred in central and northern parts of the study area. The concentration of nitrate in these regions varies from 15 to 100 mg/l. According to the results, the most important factors influencing the groundwater quality are water- rock interaction and pollution by agricultural activities and municipal wastes.

Groundwater resources in Iran, especially in the desert plains of southern Khorasan province are not in appropriate condition due to drought, increasing number of farming wells, and sustained pumping and they are subject to destruction and permanent groundwater withdrawal. This study mainly aims to investigate the factors affecting the groundwater withdrawal procedure in Sarayan plain (critical forbidden zone) located in South Khorasan province. In this research, groundwater withdrawal of Sarayan plain is investigated using SPI and GRI drought monitoring methods and fluid average, rainfall and drought effects. Also, using Arc GIS software, both drop and depth maps were drawn up for the years before and after the installation of a smart water meter for piezometric wells of the plain.The results indicate that the groundwater withdrawal reduction procedure has increased 14.36% during the 4-year period after the installation of the smart water meter compared to the 4-year period before its installation. The unit hydrograph of plain showed that groundwater withdrawal has dropped by 25 meters over a period of 23 years. Sustained groundwater pumping, the effects of successive droughts and consequent reduction of the aquifer recharge have been determined as the most important factors affecting groundwater withdrawal in Sarayan plain

Suitable water management in irrigation and drainage networks without mapping water requirement of different plants in macro levels is not possible. Iran was located in arid climate and has Drought problems and management of Drought, need to macro management of its water resources. In this study using meteorological data in Khuzestan, reference evapotranspiration and Wheat water requirement was determined in pilots. Finally different methods of mapping for example regression method, Inverse Distance Weighted and Co- Kridging were evaluated. In calibration stage power and logarithmic regression presented suitable results and have 8 and 16percent error respectively. Result show that ET0 and water requirement have significant relation with height. So these parameters have spatial continuity. In evaluating stage,  The result show that Co- Kridging method with  0.82 R2 (regression coefficient) , 0.66 d(Agreement index)  , 22.9 Root Mean Square Error  and 0.05 Normal Root Mean Square Error  and  5 percent Normal error  has lowest error in estimation of water requirement  of wheat and using this method can mapping water requirement with well accuracy. So Co- Kridging method is the best method between other methods. Use map obtained can has suitable conclusion from wheat water requirement changes in Khuzestan and manage crop pattern base of maps.

Precipitation is one of the most important hydrological events and its prediction can be used as a practical tool for optimum utilization and management of water resources. In the present study, artificial neural network (ANN) and wavelet-artificial neural network (WANN) were used for monthly precipitation perdiction at selected synoptic stations in Ardabil province, including Ardabil, Khalkhal, Meshginshahr and Parsabad during the 225 months for the years 1996-2016. For the short-term forecast of monthly precipitation (one month later), different scenarios were defined based on precipitation delays. Results indicated that the WANN model with the highest determination coefficient (R2) and minimum root mean square error (RMSE) was acceptable for all stations. The values of R2 and RMSE for Ardabil station were equal to 0.88 and 7.13 mm, for Khalkhal station were equal to 0.91 and 6.36 mm, for Meshginshahr station were equal to 0.92 and 6.97 mm and for Parsabad station were equal to 0.86 and 8.51 mm, respectively. In all stations, utilization of  the superior model (WANN model) with the combination scenarios i.e. rainfall delays, the minimum and maximum temperature improved the results of the model, but on the other hand, increased the computational cost of the model. Also, in all stations, the addition of relative humidity and wind speed as input variables somewhat reduced the performance of the model. The general results of this study showed that the WANN model with appropriate rainfall delays on a monthly scale can be utilized to predict monthly precipitation of selected stations in Ardabil province, including Ardabil, Khalkhal, Meshginshahr and Parsabad with acceptable accuracy.

Reduction of atmospheric precipitation and excess exploitation of groundwater resources in Shahdad plain caused severe changes in the system of water resources use in this region. Water is one of the most important inputs for agricultural production and efficient management of this rare resource is one of the most important fields of agricultural development. The purpose of this research is to identify the effects of price and non-price policies of irrigation water on the cropping pattern and gross profit of farmers in the Shahdad county of Kerman province. Irrigation water price policy (increasing costs of water extraction by increasing the cost of consumed electricity) and the non-price policy for irrigation water (reducing available water for farmers) was assumed with default, 5, 10 and 15 percent. To achieve these goals, a positive mathematical programming model with quadratic cost function and the Production Function with Constant Elasticity of Substitution was used. The required data were collected using simple random sampling method and completed 106 questionnaires in 2016-17. The results showed that by adopting a price policy for irrigation water, the areas under cultivation of products with less water consumption would increase and the areas under cultivation of other selected crops would be reduced. Gross profit model under scenario 100% increase in the costs of water extraction, decreased by 26%. Adopting a non-price policy for irrigation water under the 15% scenario has led to a reduction in areas under cultivation of all selected products and the gross profit model, by applying this scenario, is reduced by 48%. Therefore, the adoption of complementary policies such as rising prices of crops, the use of varieties with high yield and the use of new irrigation systems is suggested in conjunction with this policy.

Water is one of the important factors in agricultural sector and as the crucial factor of development and sustainability in agriculture, but nowadays water is limiter factor in this sector. Since the agricultural sector is the largest consumer of water, managing and increasing water efficiency is the most effective way to use the available water resources in this sector optimally. The purpose of this study was to investigate the various challenges and requirements in water management in Mazandaran province. The data of this qualitative study were collected using Delphi technique to reach group consensus. The population of the study consisted of 23 specialists in irrigation of agricultural. The study was conducted in three phases that finally presented 29 challenges and 24 requirements by experts. After eliminating the items with less than 80% agreement, there were 17 challenges and 17 requirements. The most important challenges included not choosing a suitable cropping pattern for each region and not using modern irrigation systems and most important requirements. These included were the use of agricultural mechanization and modern methods of irrigation and the role of agriculture education and extension.

Uniformity of water distribution is one of the most important factors in the evaluation of irrigation systems. The aim of this study was to investigate the uniformity of distribution (CU) and distribution uniformity coefficient (DU) in center pivot irrigation system with different distances of cans in radial direction and to obtain the relationship between these two coefficients. In this regard, three scenarios in the layout arrangement of cans were considered for evaluating the center pivot irrigation system in the Qazvin Megsal Cultivation-Industry. In the first scenario, the distance of 60 cans in a radial direction of 5 meters, in the second scenario, the area under irrigation of the system was divided into 60 equal concentric circles, and the location of each can placed middle of distance of circles, and in the third scenario, 15 cans were spaced 10 meters, 20 second cans The distance of 5 meters and 25 cans was spaced 2 meters in a radial direction. In the first case, all sprinklers were healthy and in the second case, 30 sprinklers was blocked to examine the effect of cans arrangement on CU and DU coefficients. The results showed that in the first case, the CU and DU coefficients for the first scenario were 84.4 and 79 for the second scenario, 83.9 and 74.8 and for the third scenario it was 80.9 and 73.5, respectively, and in the second case The CU and DU coefficients for the first scenario were 75.1 and 65.3, respectively, for the second scenario, 77.8 and 64.8, respectively, for the second scenario 82.8 and 73.7, respectively. It is not possible to use the formulas of the classical sprinkler irrigation method because the cans are weighed. In this study, using the measurements of CU and DU in the center pivot system and as well as the findings of other researchers, a linear regression relationship with a coefficient of 0.89 between CU and DU in irrigation was obtained. . Using this relationship, we can reduce the volume of Du calculations in irrigation.

Simulation of soil moisture distribution and redistribution, as well as knowledge about wetted dimension in drip irrigation can be considered as important criteria for improving the drip irrigation design. The experiments were carried out in a transparent plexy-glass tank (0.5m *1.22m * 3m) using three different soil textures (i.e. medium, heavy and fine). The emitter outflows were considered as 2.4 and 4 lit/hr with irrigation duration equal to 6hr. In this study, nonlinear regression method (i.e. Microsoft Excel Solver tool 2010) based on experimental data was utilized to develop empirical model for estimating the horizontal distribution of the wetting front in surface drip irrigation. Similarly, the radius of wetted bulb (in the distribution and redistribution phase) at different depths was estimated by optimizing the calculated coefficients of equations and finally, the full shape of the wetting pattern was simulated. The results of proposed models based on performance criteria showed that for distribution phase, the values of R2, RMSE and MAE varied between 0.7-0.89, 1.54-3 cm and 1.38-2.6 cm, respectively. Furthermore, for redistribution phase the R2, RMSE and MAE ranges were 0.6-0.92, 2.15-3.93 cm and 1.7-3.67, respectively. The comparison results of measured and simulated data revealed that proposed models can predict the shape of the moisture front in both distribution and redistribution phases with good accuracy.