مجله پژوهش آب ایران
پیاپی 10 (بهار و تابستان 1391)

Cluster microforms are types of small scale bedforms found in the surface layer of some gravel bed rivers. These bedforms are comprised of discrete, organized groupings of particles that sit above the average elevation of the surrounding bed. In this study, flow and sediment characteristics were measured in a laboratory flume with and without the presence of clusters. Experiments were performed under steady flow conditions with clear water over uniform sediments. A statistical analysis using logistic regression was performed to examine the correlation between the occurrence of clusters and various combinations of measured parameters. It was found that clustering was best predicted by and parameters. It is thought that these variables work best at predicting the presence of clusters because they are descriptive of hydraulic and sedimentary conditions.

In this study, impact of climate change on sowing date, length of growing season and evapotranspiration of wheat in Behshahr area is evaluated. Detection of climate change was first evaluated by means of Mann-kendall and Sen Estimator trend tests. Results indicated that no significant changes were observed in precipitation for different seasons. Temperature, however, showed an increasing tendency in summer, autumn and winter seasons. Subsequently, changes in Maximum and Minimum temperature were then simulated using HadCM3 and CGCM3 climate projection models run under the IPCC scenario A2 were downscaled at local level using statistical technique for 2011-2040, 2041-2070 and 2071-2100 periods. Wheat’s phenological stages and length of growing cycle were estimated using the Growing Degree Day Index (GDD). Potential evapotranspiration (ETo) was calculated using Hargreaves – Samani method. For future periods, results showed that, temperature would increase by one to two degrees in all months by 2100. Under such conditions in the future, the appropriate sowing period will extend by 9 to 27 days and the growing cycle length will decrease by 4 to 14 days. Crop evapotranspiration will also increase during the growing cycle, but total crop evapotranspiration will reduce due to shortening of crop cycle duration.

Awareness of transported sediments and its temporal variation increase the precision of soil and water conservation projects and is an important indicator for determination of organic matter (OM) loss. Therefore, establishing the relationship between suspended sediment and OM content has a vital role in watershed management. Therefore, the present study was conducted in Educational and Research Watershed of Tarbiat Modares University (Kojour) with an area of 50130 ha to investigate temporal variation of OM and suspended sediment (SS) relationship in seasonal, monthly and storm scales for data set collected during autumn 2007 and spring 2008. For this purpose, water and SS samplings were made via depth-integration method and samples were then transported to the lab. SS was separated via decantation method. OM amount was also determined with loss on ignition procedure. The relationship between OM and SS in different time scales was evaluated by using different bivariate regression methods. Results of this study verified a high correlation between SS and OM in fall and winter seasons and December and January with respective correlation coefficients of some 0.90, 0.86, 0.95 and 0.95 (P<0.01), estimation and validation errors less than 37.18 and 36.90 and coefficient of efficiency more than 0.41. Whereas no significant relationship could be attained for spring and February, April and May, in evidence of small value of SS.

Soil erosion and sediment yield from watersheds are key limitations for achieving sustainable land use and maintaining water quality in streams, lakes and other water bodies. Studying soil erosion process and sediment yield and evaluation of dominant factors on erosion is therefore considered as one of the fundamental tasks in proper management of watershed resources. Insufficient information regarding the sediment yield during storms is also one of the old issues which mainly causes failure of soil and water conservation projects. In this research, development and analyzing rating loops of Chehelgazi watershed of Gheshlagh dam were investigated. To achieve the study purposes, the rating loops of 11 storm events from winter 2006 to spring 2007 were investigated. The sediment samples were taken immediately after measuring flow velocity with half an hour interval through intergration method for 11 storm events. The sediment yield was then determined for each study storm through laboratory analysis and applying SPSS13 and Excel software packages. The results of the study revealed that the rating loops in all storms followed the anticlock shape. This indicated that the entire sediment graphs with duration of 88 to 273 minutes in advance with an average interval of 1.5 to 2h preceded the hydrographs and also existence of sediment yield source in upstream parts of watershed.

Employment of Optimization technologies for improving the performance of is not a new idea and various kinds of technologies have been used for improving the productivity capacity of the reservoirs. As a general rule for these optimizing methods, decision variables are minimized or maxmimized for an objective function. This method has its own limitations. As the main aim in this paper, by combining genetic algorithms and fuzzy logic, the optimal outflow hydrograph is identified based on the inflow hydrograph for the reservoir of the Karun3 dam. For this purpose, using genetic algorithm, the optimal parameters are determined for Sugeno method in Fuzzy logic. In this problem, the objective function is defined as various goals pursued by flood controlling such as minimization of outflow peak, reduction of damages in downstream areas, flood storage, and maintenance and final level of water stored near optimal for resolving future water requirements, and the like are considered. Comparing the results to other methods, this method is promising at optimization of reservoir performance.

In this study, the effect of sedimentation behind Ogee Spillway on the characteristics of flow including upstream head and velocity, discharge coefficient, water surface profile, critical depth position and flow conditions downstream of a spillway, are investigated experimentally. The experiments were carried out by using an Ogee spillway with height of 25 cm and different upstream side slopes as 1H: 3V, 2H: 3V and 3H: 3V. The used sediment had a diameter of 0.4 mm and sedimentation heights in the range of 0-24 cm were considered. The results showed that the upstream flow depth and upstream flow velocity are increased by increase of sediment level upstream of spillway. As a result, the design head (He) will be increased. A change in He decreases the discharge coefficient of spillway. It was also found that the discharge coefficient changes from 2.25 for no sediment deposition (first stage of operation) to 1.69 for full sediment deposition in upstream reservoir. Thus, these results showed that the design of diversion weirs based on initial conditions is not accurate and causes major problems during operation of diversion weir.

Flood routing in rivers is a mathematical process. Its purpose is determination of downstream flood hydrograph. Solving the complete Saint-Venant equations for unsteady flow analysis is generally complicated. For this reason, the use of computer and developed commercial models is necessary. In contrast to these complicated methods, different simplified and approximate procedures of hydraulic and hydrological flood routing have been developed. These procedures with taking into account of some assumptions are capable of flood routing in rivers. In this research, the accuracy of two approximate methods of flood routing including Kinematic Wave and Muskingum-Cunge procedures in a case study in Doab Samsami river were considered and compared to each other. Results show that RMSE values for Kinematic Wave and Muskingum-Cunge methods are 0.845 and 1.401, respectively. In general, results obtained indicate that Kinematic Wave model is more accurate than Muskingum-Cunge model.

During a critical river flood event, a bridge deck may become partially or completely submerged by the flow. The deck submergence may be a critical situation for structural stability of river bridges. In this paper, the mean flow fields around a submerged bridge deck and the time averaged drag coefficient on it have been simulated by using Fluent software. The turbulence models considered are the standard, renormalization group (RNG) and Realizable. In these simulations for a fixed water depth on a deck, the effect of change of deck distance from the channel bed on the mean flow field around a deck and the time averaged drag coefficient on it, have been investigated. In these simulations, for a water depth constant in the deck upstream, the effect of change of deck distance from the channel bed, and water free surface on the mean flow field around a deck and the time averaged drag coefficient on it have been investigated. For the deck located near the channel bed (the deck distance from the bed equal to 0.5 times the thickness of the deck), Simulation results of RNG and Realizable turbulence models are in better agreement with experimental results. In other distances from the channel bed, standard turbulence model provides better accuracy. If the deck distance from the channel bed and free surface is significant

Using a finite element numerical model, the amount of coverage bending moment into concrete linings of irrigation canals were examined; based on minimum bending anchored into the concrete panels, the optimum structural dimensions of a trapezoidal canal were extracted. This study showed that the optimal size depends on the side slope and to the depth of the canal such that for canal depths greater than 4 meters, the optimal ratio of the depth of the canal to the width of bed is between 1 to 1.5. For canals with a 1:1 side slope, this ratio is around 1.5 and it is reducing by decreasing the amount of side slope, as for a canal with side slope equal to 1:2, the optimum ratio of depth of canal to width of bed approaching to one. This study also showed that the increasing of soil elasticity modulus has essential role in reducing of the amount of the anchored bending moments of concrete lining. In addition, the amount of acting anchor on the concrete cover has a direct relation to the canal side slope.

The hydraulic ram pump is a simple device for lifting water. This pump should be installed in a height lower than water source. The difference between pump and water source head causes pressure. This pressure closes waste valve of the pump and then opens the valve because of dropping of pressure. As waste valve opens and closes automatically, the pump works continuously. This pump works without electrical and fossil fules, but uses renewable energy, also made of polyethylene material. The experiment was performed according to a factorial layout in a complete randomized blocks design. Three factors studied in this research were height of source head (A), length of drive pipe (B) and diameter of drive pipe (C). In the experiment, the normal delivery of pump and discharge for action of 100 beats of the waste valve, were measured as indicators for analyzing and considered as dependent variants. The results showed that the main factors of source head and diameter of drive pipe had significant effects on pump output; Also effect of different levels of pipe length on output was significant. The results showed Instruction in AC was worthy of note.

Today, the management of flooding and surface runoff in urban areas is very important. In this study, adequacy of surface water collecting network in Masal city for passing the design flood is considered. The basic information about the climate, topography and land use provide for simulation of surface water collecting network using MIKE SWMM computer model. Hydrologic simulation in RUNOFF block was performed by entering the physiographic characteristics, pattern and the time distribution of precipitation for 10 return periods. For hydraulic simulation, the inputs from junctions and conduits characteristics were entered to EXTRAN block, and also the geometrical properties of the channel, grids, boundary conditions and outlets were fed to the model for simulations. The results showed that existing condition has not been able to pass design flood and this matter causes surcharge and flooding conditions in location of junctions more than 360 minutes. Therefore with technical and application considerations and with a trial and error procedure, adequate sizes of channels for passing design flood was determined so that in occurring of design flood, surcharge and flooding conditions have been omitted completely or become minimum (less than 15 minute) and according to that, the typical sizes of channels for passing design flood were proposed. Also in this, the sensitivity analysis of model was examined in RUNOFF block. Area and the percent of imperviousness with sensitivity index equal 2

In order to take into consideration the two dimensional infiltration (2-D) of water in furrows, the performance of Warrick two dimensional model was compared with Kostiakov-Lewis, Philip, and advanced HYDRUS-2D models. The accuracy of different methods was evaluated by comparing the measured furrow infiltration that was computed by input-output method. The results indicated that the 2-D Warrick model had the least error and Philip model had the highest error among the model tested. The absolute error (AE) and RMSE of the two dimensional Warrick infiltration model were obtained as 5.5% and 0.0031 m3 m-1 respectively. The absolute error of the Kostiakov-Lewis and Philip were 20.2% and 25.5% and their RMSE were 0.0042 and 0.0058 m3 m-1 respectively. Also the results showed that the difference between the two dimensional Warrick infiltration and the HYDRUS-2D models was 3.5%.

Cracking, uplifting and displacement of concrete canal lining would increase loss of water, decrease conveyance efficiency and produce tremendous economical damages to irrigation projects. This may be greatly due to high uplift pressure under concrete lining in areas where the groundwater level is high. Thus, provision of a filter-drainage system in such conditions is vital. In recent years, application of synthetic drainage materials in the form of geocomposite, as a replacement for conventional granular drainage materials have been considered. In the present study, performance of geocomposite as a filter-drainage material under concrete canal lining has been investigated in a laboratory model. The results of the investigations showed that a geocomposite layer of sufficient thickness is able to successfully reduce uplift pressure under the canal lining. As the weight of the concrete lining may itself cause some deformations and reduction in the thickness of geocomposite layer, such effect was also investigated. The results showed that weight of concrete lining would reduce the thickness of drainage layer, causing a substantial reduction between 2 to 8 percent in drainage capacity. Therefore, it was concluded that the effect of overburden pressure caused by the weight of lining must be considered when application of synthetic drainage layers is considered.

At river confluences, the flow patterns are very complex which cause deep scour bed, bank erosion and sedimentation. Such phenomena produce damage to hydraulic structures and change river morphology. Therefore, many studies were conducted to assess the location of scour depth in a sharp edge river confluence. The purpose of this study is to conduct experimental test to investigate the effect of curvature of downstream edge on sedimentation patterns at river confluence. Dimensional analysis was used to determine non-dimensional parameters, and then tests conducted with sharp downstream edge and three different radius of curvature of downstream edge, under different flow conditions. The results of this study show that as the radius of curvature increases, the maximum scour depth and point bar decreases significantly.

Qanat is a natural underground structure to drain and transfer ground waters, which has been used for more than 3000 years in Iran. There are more than 600 qanats in the megacity of Tehran and Sanglaj Qanat, located in the downtown, is one of the oldest qanats among all. The goal of this paper is to find some approaches to rehabilitate this qanat in order to use qanat’s potential in sustainable water resources management in cities. Therefore, the required water quality parameters were measured and monitored at first. According to the results, Sanglaj qanat’s water has been polluted and there are too many external threats. Using SWOT, an applied analytical method, the managing strategies were planned. Then, these strategies were prioritized by QSPM method. Based on the strategies with high priority, the final rehabilitation plan for Sanglaj Qanat was prepared. This plan includes two approaches to achieve the goals: sustainable water resources management and recycling.

For optimum use of water resources in irrigation and drainage networks, creation of simulation models by available data for the identification of effective parameters in groundwater resource system is useful. In this study, due to the existing high levels of groundwater table in Zarrineh-Rood plain at West Azerbaijan province, the impact of Zarrineh-Rood irrigation and drainage network on underlying groundwater resources is investigated. Groundwater surface variation under existing active irrigation and drainage network area as a recharge zone on the body of the plain was simulated through MODFLOW and the effect of increment in irrigation efficiency was investigated. The results of model calibration and verification indicate the reliability of the proposed model for the depiction of groundwater resources behavior under Zarrineh-Rood plain. The involved error in simulation of groundwater depth is less than 1.69 percent. After obtaining validated model water balance, the scenarios of increased irrigation efficiency as 10, 30 and 50 percents, were imposed over irrigation and drainage network area. Model results show that the groundwater table drawdown with increased irrigation efficiencies is about 0.5, 1.20 and 2 meter respectively. Moreover, due to the imposed increased irrigation efficiency scenarios, evapotranspiration is reduced about 12, 30 and 39 per-cent respectively.

Information on water quality and its temporal variations is necessary for sustainable water management. The focus of this research is identification of the long-term trends of water quality for the Chehelchay River, Golestan province. The data sets of twelve water quality variables recorded at the Lazoore river gauge station (located in the outlet of the Chehelchay watershed) during the period of 1350-1387 were analyzed. Non-parametric statistical methods (Mann-Kendall and seasonal Kendall tests) were employed for trend detection. The results indicated that, seven variables (sodium, chloride, SAR, sulfate, potassium, EC and TDS) demonstrate statistically significant increasing trend, four variables show no significant trend, and only one variable (bicarbonate) has a decreasing trend. Increasing trend of variables and thus river water quality deterioration could be attributed to factors such as land-use change, soil erosion and human wastes. Our study on land use changes, occurred in the Chehelchay watershed during the period of the study, showed that 2537 hectares of forested areas has been converted to croplands. Agreement between land-use change and water quality trends supports the hypothesis that land-use change is one of the most important factors causing deteriorating trends in the river water quality. This research reveals an urgent need for implementation of necessary management actions in the Chehelchay watershed to control pollution sources and protect river water quality.

In a laboratory study, concentration and formation of sediment load on the hydraulic jump was studied. Experiments were performed in a stilling basin of rectangular cross-section 0.5 m wide, 0.6 m height and 3 m long. Uniform sands of 0.6, 1.4, 4.1, and 5.6 mm with different concentrations were used in the experiments for various types of hydraulic jump with Froud number ranging from 3 to 9. The results indicate that the sediment size and sediment concentration makes no changes to the incoming super critical flow conditions and therefore, has no effect on the characteristics of the jump (sequent depth, energy loss and length of jump). However, the sediment loads are deposited in the sub critical zone (end of jump) and move downstream as bed load. The motion of the sediment is wave-like with a mild slope at the front followed by a raised bed of nearly uniform thickness terminating into a step. This sand wave performs a control section similar to the end sill in a stilling basin and keeps the hydraulic jump position at the beginning of the basin. The thickness and the position of the front of this sand wave are expressed as a function of upstream Froude number.

River flow behavior is one of the major problems considered in the design, operation and studies related to water resources. Recently, applying new techniques such as chaos theory in hydrology and water resources due to its innovation and ability has been considered. An application of chaos theory is characterization and quantitative analysis of river flow time series. The aim of this study is determining properties and prediction of Ahar-chai river daily flow during 19 years using the concepts of chaos theory. Chaos time series state space reconstruction is based on selecting two suitable parameters namely delay time and embedding dimension. In this study, average mutual information and false nearest neighbors method are implemented for estimating these two parameters. Correlation dimension method is used for determining the chaos ability and estimating the fractal dimension of daily river flow. The results of computations show that fractal dimension of 4 (chaotic low), with delay time of 65 days and embedding dimension of 13 for reconstruction the river flow dynamic state space, can be used. Local prediction algorithm for prediction of time series and correlation coefficient, and also Nash-Sutcliffe index and root mean square error are used for assessing the performance. Results illustrate good and acceptable accuracy of chaos theory in prediction of river flow.

Reservoir operation optimization is one of the most important issues in water resources management. In this study, reservoir operations of Doroodzan dam were carried out using SA optimization algorithm, yield model and Standard Operation Policy (SOP). For each method, a computer model was developed using FORTRAN. The decision variables in the SA model were the amount of water release in different months. The objective function is deficit of water requirement which was investigated as minimization form. Yield model was defined as an amount of water which in addition to supply drinking and industry demands, reservoir can supply agriculture water demand with a reliability of at least 80 percent. Results showed that all three methods fully supply drinking and industrial demands. The performances of SA algorithm and yield model in agricultural uses were better than the standard operation policy. Also the yield model supplies much more water for agricultural use than SA model. SA algorithm and yield model decreased water deficit 33.74 and 83.86 percent, respectively. Therefore, the yield model passes the best performance and the SA algorithm and the standard operation policy obtained the next positions, respectively

In this study, we investigated the effects of using fertilizers, chemicals, and herbicides over paddy fields on contamination level of the Zilakyrood river during 9 months of 2007-2008 period. Samples were taken in five points of the river. Phosphate, Nitrate, Ammonium, Mercury, Arsenic, Cadmium, Edifenphos, Butachlore and Dazinon of these samples were measured. The result showed that Nitrate and Ammonium were 14.45 and 0.34 ppm (below the critical level), but Phosphate fluctuated around the critical level (0.2ppm). Mercury was 5.6 ppb that was dramatically above the critical level. Arsenic and cadmium were 9.26 and 0.56 ppb respectively that were less than critical. Despite what has appeared in standars that mentions Edifenphos, Diazinon and Butachlore should not exist in surface waters, they were amounted to 2.66, 2.48 and 49.7 ppb respectively in this river.

In desert and dry regions such as Rafsanjan plain, use of the groundwater resources is more than surface water resources. In this research, MODFLOW and MT3DMS were implemented for a quantitative and qualitative modeling tools to investigate groundwater quality in Rafsanjan plain. The presented qualitative model for this aquifer was compared by observed data and calibrated. Then sensitivity analysis was preformed and this model was used to predict the next 2 and 5 years. Results showed that concentration of various parameters available in groundwater increase in the whole plain, increase in chloride (CL) and electrical conductivity (EC) being more than other parameters. Therefore, it was concluded that discharge and agriculture works should be decreased and recharge increased in this plain.

Kowsar dam is located on Khayrabad river, 60 km north-west of Dogonbadan, Kohgiloyeh and Boyerahmad province. Operation of this multi-purpose storage dam was started in 2003. Due to similarity of reservoir coefficient (0.41) of Kowar dam and Dez dam (located in Khuzestan province), three sediment measurements in 1983, 1997 and 2003 for Dez reservoir, and location of these two dams in Persian-Gulf watershed, the sediment distribution of Dez reservoir was used to predict sediment distribution pattern for Kowsar dam. The budget of sediments entering Kowsar reservoir is estimated as 475,000 m3/year and reservoir sediment distribution is predicted for 200-year periods for Kowsar dam. The results showed that when sedimentation rate becomes constant, the reservoir coefficient reaches a constant value of 0.59. About 632 years after the operation of Kowsar dam, sediments will reach turnouts level. Also, this dam will become full of sediments after 1437 years of operation.

One of the most important parameters in design of hydraulic structures is the instantaneous peak discharge. In this research, 20 empirical formulas that have been developed all over the world to estimate the peak discharge are evaluated in 26 hydrologic stations of western catchments of Iran. Instantaneous peak discharge data during a 42 year period at these stations were selected. Frequency analysis was performed on these instantaneous peak discharges by eight probability distribution functions, and after the best fit test, the instantaneous peak discharges with return periods of 2, 5, 10, 25, 50, 100, 500 and 1000 year were estimated by Log Pierson type III distribution. Homogeneity test of catchments under study was also done by Dalrymple method. Linear and non-linear regression analyses were done and the empirical formulas were calibrated for the region, and then the best formula was recommended. For the recommended models, the mean error for 20 to 1000-year return periods was between 21.67% and 34.67%. Among the most important results of the study is the inaccuracy of Fuler formula in estimating the instantaneous peak discharge in western catchments of Iran.

In this research, the effect of calcium carbonate, existing in natural environments, on removal, advection and dispersion of cadmium using batch reactor experiments, is studied. The results showed that 99.2% of Cadmium with initial concentration of 1.5 ppm will be removed by CaCo3 with concentration of 330 ppm. Regarding to high ability of CaCo3 in cadmium sorption and the existence of CaCo3 in soils and waters, one can conclude that CaCo3 has a great influence on self purification of natural environments and it must be considered in heavy metal transport transformation modeling. Firstly, by increasing salinity in the range of natural condition, sorption will decreased very fast but after the salinity of 2500 S/cm, the amount of this reduction will decrease. At last, the amount of sorption could be decreased by 50%. Investigation of Langmuir and Freundlich isotherms showed that the governing isotherm for cadmium sorption to CaCo3 on the basis of current data is Freundlich. Furthermore, comparing the linear and nonlinear methods in estimating Freundlich parameters show that the non linear sum of square of errors 0.3 of linear method. So it is better to use non linear method in estimation of parameters.

In this research, fuzzy based models were used for river discharge forecasting in lighvan watershed.To forecast the daily river flow, three parameters of the amount of rainfall, temperature, and daily discharge of Lighvanchai basin were used. Assessment of prediction results by using various error estimations methods such as Nash-Sutcliff Coefficient (CNS) showed that ANFIS model (CNS=0.998) was able to predict discharge of these rivers with higher accuracy and low dispersal than FIS model (CNS=0.993). It was also observed that by applying FIS model, daily air temperature affected the river discharge in two months of December (Azar) and April (Farvardin), and the accuracy of the model were increased. It can show the effects of air temperature on the variety of precipitation form in these two months.