Iranian Water Research Journal

Abstract The total specific surface area is a factor that can relate micro-scale properties to macro-scale physical and chemical properties of a porous medium. Soil moisture characteristic curve (SMCC) is a fundamental and hydraulic feature of the soil; it is a very important quantitative expression in modeling water flow, water uptake by plants root, and transported salt at run off in the unsaturated soils. In this study, the effects of soil specific surface area (SSSA) on soil characteristic curve was evaluated in 30 soil samples. The SSSA was measured by using the BET method and also pressure plate apparatus was used to measure the soil moisture characteristic curve. Analysis of data showed positive significant correlation between SSSA with measured soil moisture values corresponding to pressures exerted by pressure plates.

Abstract In this study, the AquaCrop model was calibrated and validated to estimate yield and water productivity of canola (cultivar Hyola 401) under farm conditions. The experiments were carried out in two farms with an area of one (field A) and four (field B) hectares with a silty loam soil under furrow irrigation in Dehloran, Ilam province. Seeds were planted in both fields during November 10 to 21, 2010. Field data including water balance components, plant growth and development stages, biomass and yield were measured during the growing season. The data collected from field A were used for model calibration and the data collected from field B were used for model validation. Amount of consumed water and grain yield for the four-hectare farm (field A), were 426.9 mm and 1900 kg/ha, respectively. They were 381.2 mm and 1650 kg/ha for one-hectare farm (field B). The model predicted the yield for the four-hectare and one-hectare farms 1837 and 1509 kg, respectively. The measured value of water use efficiency (WUE) for the fields A and B were 0.44 and 0.43 kg/m³ while the predicted values by AquaCrop model were 0.43 and 0.39 kg/m³, respectively. The obtained results showed a good agreement between measured and predicted values of soil water content, root depth and biomass in the studied fields.

Abstract Determining the accurate values of the return flow fraction from different uses is essential for optimal allocation, management and operation of water resources. The goal of this research was estimation of return flow coefficients from domestic, industrial and agricultural demands and also contribution of these return flows in surface flow. For this purpose, calibration technique and Genetic Algorithm were used. MODSIM is a river basin management decision support model that was used as a simulation model. In this research by Custom Run capability of MODSIM, i.e. coding in VB programming language into the model, the calibration of considered coefficients was provided. The calibration was done for 3 different objective function. Results showed that the most appropriate and logical coefficient was obtained in the 3rd calibration state, i.e. calibration with an objective function that included RMSE of surface flow discharge and RMSE of groundwater level. The return flow fractions of domestic, industrial and agricultural demands for Shian sub-basin in the western part of Iran are obtained 87, 76 and 18 percent, respectively.

Abstract Reservoir operational rule curves are equations that can balance reservoir system parameters in each period by considering previous experiences of the system. These equations include variables such as inflow, storage capacity, and released water from the reservoir that are commonly related to each other with some constant coefficients in a predefined linear and nonlinear pattern. In the recent years, evolutionary algorithms in general and genetic algorithm (GA) in particular have been applied to develop optimal operational rule curves with predefined pattern. Genetic programming (GP) is an evolutionary algorithm based on GA, which is capable to calculate optimal operational rule curves without using predefined operational patterns. In this paper, at first, first- and second-order rule curves which depend on the inflow and storage volume of Karaj and Bazoft reservoirs have been extracted for the meeting downstream water demands and hydropower energy generation objectives, respectively. In following, operational rule curves by the GP, without any predefined mathematical pattern have been extracted and compared with the GA results. The GP rules improved the objective functions of the first- and second-order rule curves by the GA in supplying downstream demand 12.39 and 7.29 percent, respectively.. Similarly, the hydropower energy generation has been improved by 51.62 and 47.76 percent in the first- and second-order rule curves, respectively.

Abstract For accurate estimation of unit hydrograph ordinates is very important in watershed management, many different methods have been developed for this purpose. Recently, Transfer Function (TF) model has attracted the attention of researchers, because it requires a very small number of parameters, omits negative values and also is robust against oscillations. After estimating the model parameters, the values of unit hydrograph obtain and then runoff would be estimated. For evaluating the performance of the TF model, it has applied on two case studies, namely Lighvan (in Iran) and Potomac (In North America) basins with two events in each basin and the obtained results were compared with the results of the traditional Least Square method. Root mean square error (RMSE) and coefficient of determination (R²) were used to evaluate the model performance. The R² values of the TF model for the estimated unit hydrograph of Lighvan basin and Potomac basin were 0.99 and 0.98, respectively. The results showed that the TF model with decreasing oscillations and omitting the produced negative values presented accurate results in estimating unit hydrograph and flood hydrograph ordinates and this method can be used in other watersheds

Abstract Accurate estimation of side weirs’ discharge coefficient is an important issue in practical and economical design of these structures. In this study, the discharge capacity of labyrinth side weirs was estimated using adaptive neuro-fuzzy inference system (ANFIS) model. The target output of the present study was the discharge coefficient of labyrinth side weirs. Correlation tests indicated that the governing dimensionless parameters are almost independent. Results also showed that the apex angle of labyrinth weir is the most effective parameter on discharge coefficient compared with the others. The results of error analysis indicated that among different methods developed for estimating the labyrinth weir discharge coefficient, the relations presented by Emiroglu et al. (2010) and the developed ANFIS model in this study had the maximum and minimum error values, respectively. It is observed that the developed ANFIS model, presented more accurate results compared with the relations suggested by the other researchers for estimating the discharge coefficient of triangular labyrinth side weirs.

Abstract Accurate design of Spillways as one of the main parts of dams is an important issue in the stability and safety of dams. Determining the characteristics of flow hydraulic by using physical models is too expensive and time-consuming. In this study, two-dimensional flow over ogee spillway was simulated by solving Poisson functions of stream and pressure using the Finite Element method and analyzing k-ε turbulence and volume of fluid models in Finite Volume technique. Also a comparison was made between the results of numerical models and measured values in order to investigate the accuracy of the models in calculation of water free surface profile and flow velocity. The average relative error in velocity calculation using Finite Element and Finite Volume approaches was obtained 2.09% and 0.93%, respectively. The corresponding values for free surface profile were obtained 1.25% and 0.72%, respectively. The results showed that the Finite Volume approach had better performance than the Finite Element method in modeling flow hydraulic over the ogee spillway.

Abstract Estimating the pressure on various parts of dams’ foundation and controlling the seepage and uplift force are one of the most important issues in designing of dams. In this research, the hydraulic behavior of cut-off with different penetration depths for two types of soil layering and three conductivity coefficients was studied experimentally. Seepage and piezometric pressure were measured at 28 points of physical model. Then, the water flow was simulated by Seep/W software in the same soil conditions and the values of seepage and pressure were estimated. Average relative errors for discharge and hydrostatic pressure estimation were obtained 0.28% and 1.4%, respectively, that shows good agreement between numerical and experimental results.

Abstract Monthly water balance models (monthly Rainfall-Runoff models) are considered as the main tools in the evaluation and long-term planning of water resources. The main structure of these models included continuity equations for soil moisture storage, subsurface water and sometimes groundwater. Variables considered in the modelling of water catchments consist of surface runoff, precipitation, evaporation, and in some of cases, monthly average temperatures. Since there are too many unknown parameters in the monthly water balance equation used in the modelling process, using auxiliary relations is inevitable. These equations are usually empirical and recommended as default in the models. In this paper, the used relations in the structure of the Budyko model for estimating the contribution of groundwater in base flow, soil moisture and evaporation were optimized. The uncertainty of the result in both traditional and optimized models was evaluated using GLUE method. The results indicated an improvement in the optimized model performance and uncertainty compared to the common traditional model in three different watersheds.

Abstract Water shortages in arid and semi-arid regions necessitate new methods for supplying water from available resources. Underground dams and subsurface intakes have recently attracted the attentions for water exploiting in these regions. A couple of this type of intake has been constructed in a few seasonal rivers, but their performances for different river discharges and porous media have not been evaluated. In this study, the effect of river subsurface flow rate and cut-off on subsurface water diversion was experimentally investigated. The results showed that with increasing the upstream flow rate, the diverted flow rate (through drains) increased at first and then tended to a constant value gradually. The particle size of the porous medium had a significant effect on the rate of flow through drains, so that the increase of particle size caused to increase diverted flow rate, significantly. It was also shown that without the cut-off, the water diversion efficiency decreased about 40%. Furthermore, an equation was developed for determining the diverted flow rate based on the experimental observations and dimensional analyses.

Abstract Optimization of conjunctive water use in hydro-systems considering quality constraints, due to the complexity of the resulting nonlinear problem solution, are addressed within a short-term horizon by researchers. In this research, an optimizing model was proposed for long-term conjunctive use of water at the basin that maximizes the hydro-system operation reliability and considers TDS as a water quality index. In the proposed model, by the use of model decomposition and aggregation among different parts of the model, and developing a linearizing algorithm, modeling and analysis of large hydro-systems (at the basin scale) within a long-term horizon is provided so that the water quantity and quality deficits are minimized. Results of model application to Zayandehrud watershed in a thirty year period (2001-2030) showed the improvement of water quality at the Gavkhuni wetland up to 50% in dry and high demand months. Model prescribed operational rules have supplied water demands with 68% reliability along the Zayandehrud River. Model application to Zayandehrud hydro-system shows a meaningful improvement in the water supply with suitable quality in the river for agricultural and environmental demands. However, more detail of this improvement must be determined by other models that operate in smaller spatial and temporal scale, based on the results of the presented long-term model in this study.

Abstract Bridge failures due to scour at bridge abutments have clarified the importance of scour depth prediction. Most of bridge abutments are located in the floodplain. Also, one of the common cases in a floodplain is vegetation. Velocity and shear stress distribution in compound channels are not uniform and the obtained results from rectangular channels cannot be used for compound channels. In this study, based on experimental observations, dimensional analyses and multivariable non-linear regression, a dimensionless relationship for prediction of scour depth at vertical wall abutment terminating in the vegetated floodplain of a compound channel is suggested. The results indicated a good agreement between the experimental observations and predicted values by suggested relationship. For suggested relationship, coefficient of determination (R²) was 0.94 and root mean square error was obtained 0.79 centimeters.

Abstract Helleh, Shapur and Dalaki Rivers are the most important rivers in Fars and Bushehr provinces of Iran. In this study, water quality data of Helleh, Shapur and Dalaki Rivers includes 15 parameters at 24 stations in a seasonal base during the years 2007-2008 were analyzed by Multivariate Factor Analysis technique. The obtained eigenvalues from analysis of evaluated parameters to the main factors showed that the first five factors explain about 83% of variation between the stations. The most important parameters were found electrical conductivity, total hardness, Strontium, dissolved oxygen saturation percent, water temperature, and nitrate regarding to the first factor with 26.167% of the total variance. The second group was included total Iron, Manganese and turbidity related to the second factor with 16.133% of the total variance. Finally, Cesium and Lithium pertained to the third factor explained 15.276% of the total variance. The results of calculating the composite water quality index and ranking the stations showed that the water quality of the stations Tange Chogan, Sarkhon and Cheshmeh Sasan had the best quality and the stations Shekastian, Banejaberi and Dargahi, which are under the influence of evaporitic formations, salt domes, salt springs, and agricultural activities, had the worst water quality. The results showed that the Factor Analysis technique can properly use for finding the most influential parameters and ranking water quality of monitoring stations.

Abstract Water security is a vital issue that may threat by contaminating drinking water of a city, for example through a terrorist attack. In the absence of a proper managing safety in water distribution system, the number of victims of such terrorist attack can reach to whole of city population. In a passive defense approach, the first step for any integrated public alert system and contaminant controlling is rapid detection of contaminant source. Observations from a set of monitoring points are used to detect the contaminant source. The optimal number of required monitoring points and their pattern is a challenging task that closely depends on the potential injection points, the amount and characteristics of injected pollution. The best monitoring system corresponds to the pattern that minimizes (a) the required number of monitoring points, (b) the affected population at detection instant, and (c) the undetected cases. In this study, the fast multi-objective evolutionary algorithm, NSGA-II, is coupled with the simulation model, EPANET, to find a trade-off curve among the conflicting objectives. Monte Carlo simulation is used to incorporate uncertainties in injected pollution. The Nash bargaining solution is utilized to find the equilibrium point of the obtained trade-off curve. In order to demonstrate the efficiency and capabilities of the proposed methodology, the water distribution network of Lamerd City is modeled and the best monitoring points are determined.

Abstract Nayshabour aquifer in Khorasan Razavi with arid and semi-arid climate, have an important role in agricultural production by using groundwater resources. In this study, the required equations for estimating water table variations are obtained using the groundwater balance model. Since there are too many variables in the objective function of water consumption, in this study, PSO optimization algorithm (Particle Swarm Optimization), a Meta heuristic method which requires less computation and is more efficient, was used to determine the optimized crop pattern and intensification. Model results based on a normal year (2008) showed that in order to minimize the drawdown in the water table, with rainfall equal to average annual rainfall of the region, farmers only permitted to exploit 359 million cubic meters from the Nishabour aquifer that this water volume can irrigate only 59706 hectares that it is 48789 hectares less than the current status. So that 48802 hectares of cropping land reduced and only 183 hectares of land were added for planting tomatoes.

Abstract Among hydraulic structures, water level control structures have a significant role in increasing water efficiency and decreasing the water consumption. Due to the diversity of hydraulic structures and operational methods, many different models have been developed for controlling and characterizing the behavior of various structures. In this research, CanalMan model is used to simulate the operation of control structures in Foomanat Irrigation Networks, located in the west of Guilan province. A canal in F2 unit, named as BP19, is chosen for field studies and simulations with the selected model. The canal has been visited before the irrigation season for considering its condition. More visits have been done after starting the irrigation season to see the status of the canal and operation hydraulic structures and the required data for the simulation were measured. Then the operation of different control structures such as Amil, Sector gate and Labyrinth weir were simulated and their behavior investigated to choose the best suitable water level control structure. Based on the Molden and Gates criteria, among the considered control structures, the Amil with average values of 100%, 82% and 27% for the indicators of delivery efficiency, adequacy and justice, respectively, had the best performance in control and regulation of flow in the considered canal.

Abstract Hydraulic jump is a kind of the rapidly varied flow that during this phenomenon the flow profile changes from supercritical to subcritical and causes substantial energy dissipation. In this research, hydraulic jump characteristics, including length of jump and roller length of jump within the stilling basin with different adverse slope (0, -0.6, -1.3 and -2%) and three different roughness (1, 4 and 10 mm) were investigated. Results showed that these characteristics on stilling basins with adverse slope and the rough bed were reduced respect to the classic jump situations. The experiments were performed on rough beds in different conditions where the Froude number varied between 4.9 and 7.8. In this research, the total length and the length of roller part of the hydraulic jump were decreased about 39.6 and 32.3 percent, respectively.

Abstract Sometimes the pollution occurs as a sudden event, either intentionally or unintentionally and it may become a water quality crisis. Despite the damage that can occur due to the sudden pollution, little research has been done in this area. Damage caused by the entered pollution in reservoirs can affect the water resource system in two ways: (1) Damages that are caused due to lack of water allocation, and (2) damages that are caused due to consumption of polluted water. Those damages are in contrast with each other. Thus, the crisis should be managed in a way that the least damage occurs in the water resource system. This paper investigates the crisis management due to the sudden entrance of a 30 m³ MTBE load to the Karaj dam. To simulate MTBE advection, dispersion, and vaporization, the latest process is added to the CE-QUAL-W2 model. After that, the multi-objective optimization hybrid algorithm, NSGAII-ALANN, is used to extract the best set of decisions. According to the results, if pollution enters the reservoir in the summer, by using one of the driven policies, by a 36% reduction in demand meeting, allocated pollution decreases by 60% and also maximum concentration decreased by 76%. These results for winter are 38%, 51% and 67%, respectively. Similar results are extracted for other seasons.

Abstract Knowledge of the suspended sediment distribution is important for calculating suspended load in streams and rivers, because in the large depth flows, the suspended load comprises up to about 80% of the total load. Until now, many equations have been proposed by researchers for estimating the suspended sediment distribution in open channels. In this study, these equations have been assessed and the best equation has been selected among 9 empirical equations by using statistical analysis. For this purpose, the most reliable experimental data have been used. The results showed that among considered equations, the Einstein and Chien’s equation (developed in 1952) had the most agreement with the experimental data (RMSE=0.048, R²=0.988, EF=0.988, and ME=0.086) and presented the most accurate estimation of suspended sediment distribution. Inversely, the results showed that the McTigue’s equation and Willis’s equation had the least accuracy and don’t recommend using them for estimating the suspended sediment distribution in open channels.

Abstract Due to shortage of facilities and tools, continuous monitoring of sediment load is not possible in most rivers and therefore the rating curve is usually used to estimate the sediment discharge. It has been proven that adding some other time related variables are necessary to improve the precision and accuracy of the rating curves. In this study, using a 7-parameter equation proposed by Cohen et al., multivariate sediment models for five hydrometric stations of Qazzaqli, Pounel, Keshvar, Gelinak and Bande Shah Abbasi, have been developed based on the recorded data during 1968– 2002. Then, these models have been evaluated using precision and accuracy indices. Furthermore, the effects of different watershed physiographic factors on the precision and accuracy of the rating curves has been investigated. Results showed that the average values of precision and accuracy indices across five stations were 1.958 and 3.488, respectively. This indicates the satisfactory performance of multivariate models in comparison with original single variable sediment rating curves. Also the mean annual flow discharge had the highest correlation with accuracy and precision indices which can be related to high frequency of its recorded data.

Abstract Fluctuation of water level leads to variation of soil moisture regime around canal and cause destruction of the canal side slopes. In this study, stability of side slope of the earthen canal with two different slopes in presence of water table level was studied by using numerical and physical models. Then cut off is considered as a method for controlling failure. The results showed that the seepage surface and piezometric pressure near the side slope are two important factors in stability of side slope of earthen canals. In order to control the destruction of the earthen canal with steeper slope the sheet pile should be installed below the level of the bottom of the canal, but for milder slope the penetration depth of cut off up to the level of the bottom of the canal is adequate. The results showed that the numerical model had good agreement with experimental results in simulation of total pressure, discharge and phreatic line as the average error in estimating the total flow and pressure in the numerical model in comparison with experimental model were, 5.66% and 2.08%, respectively.

Abstract Nowadays, computational intelligence models have shown high ability on prediction of time series. The main purpose of this paper is to evaluate the performance of six artificial neural network based models for simulation of precipitation and subsequent drought condition in Yazd station and identifying the best one. In order to evaluate the performance of models two criteria: Root Mean Square Error (RMSE) and Correlation Coefficient (R) were used. The results showed that the dynamic structures of artificial neural network including recurrent network (RN) and Time Lag Recurrent Network (TLRN) showed better performance with R=0.77 and 0.78, respectively. Comparing the performance of RN and TLRN models indicated that, however both of the models had the similar performance, but the TLRN network was the best one.

Abstract Three-side spillways are one type of dam outlets that despite of their hydraulic limitations and construction problems, under specific topographical conditions selected as one of the best options in storage dams. Considerable energy losses, great turbulence and hard stroking on bed and walls of lateral canal are some of undesirable hydraulic features of these spillways. Due to the complexities of fluid flow and the impact of scale, physical models do not provide a clear understanding of the physics governing the flow. In the complex flow and structures, is necessary to be considered, the laboratory studies, along with the numerical studies. In this study, Three-dimensional flow field in the three-side spillway and the end sill, have been investigated by using FLOW-3D software with finite volume method and RNG(k-e) turbulence model. Comparison of numerical results with experimental data showed that this model have a good ability to prediction three-dimensional flow pattern over this kind of spillways.

Abstract Gravity current occurs due to entrainment of a fluid with bulk density in a fluid with specific density . Impacting of dens flow mass with stagnant fluid, the gravity current penetrates into stagnant fluid and the plunge depth occurs. In this research, hydraulic parameters of density current and bed slope of the stagnant fluid, which affect on the plunge point, have been investigated. In all of the experiments, plunge depth was measured in the various discharges of density current and different of density 6, 9, 13 and 16 kg/m³ at three slopes 8, 12, and 16 percent. The results showed that the slope has a minor effect on the height of the plunge point. In a certain density, when the inflow of the density current is increased, the height of plunge point is also increases for different slopes. Based on experimental data and using dimensional analysis, an equation is presented for simulating the height of plunge point. Comparison between data obtained from the new equation with the measured data, showed that the new relationship can estimate actual data with good accuracy. The relative difference between the data obtained from the new equation and measured data was 0.91%. Comparisons are made between this new equation and the equations presented by other researchers using the whole data available in the literature. The results showed that the new equation had more

Abstract As the water resources are limited and about 40% of world’s farmlands use dry farming systems, improving the management of dry farming has great importance. The main purpose of this research is to investigate the impact of precipitation variability on annual yields of dry farming Wheat. The area under consideration is the province of Hamadan. All the probable time periods of precipitation have been considered and the impact of different periods of precipitation in 3 main cropping seasons (Autumn, Winter and Spring) was assessed on annual yields of dry farming wheat. Then the most effective period of precipitation on annual yields of dry farming wheat specified and the annual yield-effective precipitation regression relationship has been defined and calculated for this period. The values of annual yields of dry farming wheat were calculated based on a distribution function fitted to annual yield data and compared with values obtained from regression relationship. The results showed that the most effective period of precipitation on annual yield of dry farming wheat in all conditions, is March 30th to May 7th. Also, the results of annual yield-effective precipitation regression method in estimating of annual yields of dry farming wheat were similar to results of the distribution functions method with a correlation coefficient of 99%.

Abstract In this research, a part of the distribution network in Lar city was selected for the calculation of real loss volume and leakage indicators in the network. Magnetic flow meter, data logger, and digital Dickson pressure gauge were installed at the input of the network. The pressure and flow rate were recorded in 15 minutes time intervals. Then, on various stages of research real water loss and leakage performance indicators, including ILI, UBRL and TIRL were calculated. Based on the results, the real water loss was between 12.1-18.7% with an average of 15.5%. The Technical indicator for real losses (TIRL) during measured periods were in the range of 97.2-188.5 lit.d^-1.con^-1 with the mean of 147.5 lit.d^-1.con^-1. Unavoidable background real losses (UBRL) were between 34.2-44.6 with the mean of 40 lit.d^-1.con^-1 and infrastructure leakage index (ILI) was between 2.8-4.2 with the mean of 3.6, which indicate that the network condition is undesirable. The mean recyclable leakage for each connection is 107.5 lit.d^-1.con^-1, which considering the number of service connections (18100), the total recyclable leakage in water distribution network in Lar city is 710199 m³.year^-1.