a. h. nazemi

Evapotranspiration (ET), a major component of the hydrologic cycle, is important in water resources management and irrigation scheduling. Nowadays, due to the lack of the lysimetric data in weather stations, the ET values calculated by the standard FAO Penman-Monteith model ( ) are used as benchmark values of grass reference crop. Also, the Penman-Kimberly model is widely applied for computing the alfalfa-reference crop ET ( ). In the present study, the meteorological data from 6 weather stations located in the Sistan-Va-Baluchestan Province covering a period of 10 years were used to calculate the and values. Then, the to  ratios were computed for all six stations during the studied period. The Penman-Kimberly model at Mirjavah station had the worst result compared to other stations. The NS coefficient values for this station are the lowest (0.07) and the SI and RMSE values for this station are 0.43 and 2.48, respectively, which is the highest value among the study stations. Finally, the contributions of the energy balance and aerodynamic components on the final ET values were determined using the Penman-Kimberly model, which showed the important influence of both components on the ET process. Consequently, the use of radiation-based models e.g. Priestly-Taylor model in these stations should be carried out by special care.

In many irrigated areas, shallow water table causes water logging and salinity of the soils, thus usually subsurface drainage systems are used to control this situation. In most cases, subsurface drainage systems discharge a large amount of water and salt to the environment, hence drainage water management is necessary to prevent this situation. Drainage is an action that ensures the sustainable use of land, in addition to increasing the performance. The traditional view in the drainage systems’ design, has known the drainage aim, unique to increase the yield and improve the grown environment and does not examined the environmental impacts of drainage projects. Today, this attitude has lost its position in the new approaches, in addition to agricultural and industrial purposes, environmental goals of the drainage projects are also examined. In this study the quantity and quality of output drained water from the drainpipes as compared to the time were simulated using the method system dynamics analysis, and were compared to in vitro model data. The effect of changing the depth of drainage pipes, distances between drainage on the drained water volume, and the amount of output salt were investigated. For the experiments in this study, the physical laboratory model of Water Resources, in the Faculty of Agriculture, University of Tabriz was used. Physical model is a rectangle cube-shaped container, metal-glass, with 2 m length, 1 m width and 0.5 m height. In order to determine the position of water table in the soil, 20 piezometers were put at the bottom of the model. Four reticulated metal pipes with a diameter of 2 cm were embedded as drainage pipes in the model. Tests were performed with depths of 0.4, 0.3 and 0.2 m from the soil surface, and three distances of 1.4, 1 and 0.6 m between the drains. In the upper part of the model, a sprinkler irrigation system consisted of four lateral and eight water sprayers, were placed at the height of 0.6 m above the soil surface: they were used to produce precipitation and irrigation practices. In this research, the VENSIM programming software, which is one of the most appropriate programs for dynamic evaluation of systems was used for modeling. This software shows the performance of the system during the simulation, with repeated solving of various equations in the system, by limited different methods. In order to evaluate the performance of the systems, various tests on water table level, drainage water quantity, salinity of drained water and groundwater salinity were done. The water table level increases through time and remains constant at a steady state. The output discharge from drains also increases during time and reaches to a steady state by fixing the water table and reducing its fluctuations. The salinity of drained and groundwater decreased during the experiment and approached to the amount of irrigation water salinity (0.45 dS/m), due to the mixing of irrigation water with low salinity groundwater with the higher salinity. The salinity of output drainage also decreases causing reduction of the groundwater salinity. Drainage volume, and the amount of drainage water EC, were measured in order to investigate the effect of changing the depth and distance between drainage pipes on the quality and quantity of the drainage water in each establishment. By increasing the depth and distance between drainage tubes, the length and depth of the water lines, towards drain pipes, increases and the share of groundwater participating in the output drainage increases, which leads to the increase of output’s salinity. This increase in depth and distance, also increases the soil storage volume in the drainage pipes, and increases the discharge of drainage water. The simulation data were compared with the measured values and correlation coefficients for output discharge, salinity of drainage water, water table level and groundwater salinity in trial mode (drain spacing: 1.4 m, depth: 0.4 m), which were 0.75, 0.92, 0.98 and 0.97, respectively. In addition, the values of the RMSE statistical indicator for these parameters were obtained as 0.1875 mm/min, 0.1684 dS/m, 0.0081 m and 0.0825 dS/m, respectively, indicating that the simulation results have the higher accuracy. The evaluation of quantity and quality of drains’ discharge cumulatively shows that the increase in drains’ depth and spacing causes the increase of the volume of drainage water and salt.

Due to advection phenomenon, energy balance in vegetation covered field's changes and some additional energy is transferred from the barren lands to vegetation covered sites by air sensible heat flux. This phenomenon increases the evapotranspiration. The present study was conducted to investigate the advection occurrence in the field of maize as a spring crop, and winter wheat as a fall crop at the Agriculture Faculty Research Station of Tabriz University. Mentioned crops for were planted in a 1.6 hectares’ farm, equipped with a lysimeter at its middle, for two years. These crop's evapotranspiration was measured by the lysimeter during the growing season of each plant. The advection phenomenon occurrence was investigated using the methods of energy balance in the field surface, Priestly-Taylor coefficient, the ratio of evapotranspiration obtained from advection energy to vegetation surface evapotranspiration (Rad) and Bowen's ratio () on different days after planting of each crop. Observation data of the temperature showed that there was a sensible heat gradient between the lysimeter and surrounding areas. Negative values of the sensible heat flux, Rad and Bowen ratio on some days of plants growing season showed that the advection extra energy had affected the crops evapotranspiration values. Results showed that the advection effect on maize evapotranspiration was more than that on wheat evapotranspiration. In the study region except of regional advection, local advection could be occurred due to small size of cropped fields, different irrigation schedule and depth of adjacent farms, and fallow duration of some farms.

In order to determine effective parameters on Aji Chay river pollution and the aquifer of Tabriz plain located in eastern part of Urmia Lake and better management and controlling of water resource quality, principal component analysis, artificial intelligence techniques (neural networks and decision tree M5) and geostatistics (Kriging and Cokriging) through water quality data analysis (Cations, Anions) in the period of 2001 to 2013 have been used. Statistical multivariate analysis has an ability to process a big range of data, and is known as a quantitative method in order to manage water quality of the East Azarbaijan province’s rivers. Determination of the water quality parameters would result in costs reduction and aiming the monitoring, controlling, and protection of water quality. The results show that M5 method presents simple linear relations in predicting chloride and salinity, also the decisions for categorizing decision tree algorithms are clear and extractable. Also the results of geostatistics showed that Tabriz plain's aquifer is in a bad condition from qualitative viewpoint compared to the last years, and in western part of the plain due to extreme well extraction, salinity in outlet from 9000 in 2001 to over 11000 (µmhos cm-1) in 2012 has been increased.

In this research the wetting pattern of soil under subsurface drip irrigation was investigated through field experiments on two layered soil at the level and sloping lands, and the interaction and individual effects of the sloping and layered soil conditions on the wetting pattern were studied. Comparisons between observed soil moisture profiles in the level and sloping soils clarified that by increasing the application duration, the wetting patterns of the sloping soil showed more adaptation with that of the level soil. The results indicated that the effect of soil anisotropy was declined with increasing the water application duration. Due to high hydraulic conductivity value of the sublayer soil, the wetting front showed an inflection after reaching to the boundary of the two layers, so that the vertical expansion of pattern was increased and the wetting bulb transformed to an ellipse. The HYDRUS 2D software was applied to simulate the wetting patterns at the same conditions of filed experiments. The radial distance of the soil wetting fronts in the different angles from emitters were compared with corresponding simulations in order to evaluate the model accuracy. Results showed that HYDRUS simulations had a good agreement with observed data with Root Mean Squared Error (RMSE) value of 2.47 cm, correlation coefficient (r) value of 0.82 and model Coefficient of Efficiency (CE) value of 0.24 for the layered level soil. Also the values of these statistical criteria for sloping layered soil in the same order were 4.03 cm, 0.75 and 0.36 respectively. Generally, these results confirmed reliable ability of HYDRUS software for simulation of water movement in the studied conditions.

Irrigation is necessary for the crop growth and determining crops water requirement is essential for supplying it. In arid and semi-arid regions, air temperature plays a fundamental role in evapotranspiration process. In this study, the temperature occurrence probabilities at the levels of 50%, 65% and 80% were applied for calculation of evapotranspiration. The Penman-Monteith FAO and Hargreaves equations were used to calculate the evapotranspiration in Tabriz area. The results showed that the Wakeby distribution function had the best adaptation with the temperature data set in the study area. Using different levels of probability for temperature in determining reference evapotranspiration in the Penman-Monteith FAO method, negligible effects were seen in the obtained results so the averaged temperature data was enough for calculations at the cases that there were no needs for precise values. It was concluded that the Penman-Monteith FAO equation was not sensitive to small changes in temperature values, on the contrary in Hargreaves model, using different levels of temperature probability had significant effects on the calculated reference evapotranspiration values. Finally, results of the both methods were compared with the exact evaporation data obtained from pan and the pan coefficient was obtained for each method and suitable pan coefficient values of 0.63 and 1.22 were determined for methods of Penman-Monteith FAO and Hargreaves models, respectively.

From the mathematical point of view, the FAO Penman-Monteith equation shows a homographic function related to the wind speed. The homographic function has horizontal and vertical asymptotes. In this issue horizontal asymptote is applicable; because the vertical asymptote occurs for negative values of wind speed but the negative sign indicates the direction of the wind speed and only the absolute values of the quantities are used. By increasing wind speed from zero, evapotranspiration will increase until it reaches to a limited asymptote value. This value is the horizontal asymptote of the fractional function of FAO Penman Monteith equation. In this research the effect of wind speed variations on the evapotranspiration amounts was analyzed, with considering the mathematical framework of the Penman-Monteith equation. Meteorological data from three weather stations, including Tabriz, Isfahan and Rasht were used in this research. Results showed that in the FAO Penman-Monteith equation, wind speed effect on evapotranspiration is nonlinear and variation in evapotranspiration amounts is more at low wind speeds than high values of wind speeds. As a general result, evapotranspiration has tended to asymptote homographic function and the rate of increasing in evapotranspiration is reduced by wind speed increasing.

Imperfect knowledge due to unpredictable climatic conditions leads to uncertainty in decision making in agriculture. Therefore, a probabilistic analysis of the various possibilities besides increasing flexibility in decision-making can also enhance the reliability of decisions. Using Tabriz Synoptic station’s data, the values ofthe crop (TriticumAestivum L.) evapotranspiration and effective rainfall in mid to late season in the study area (Tabriz plain) were estimated. Analyzing the effective rainfall and crop evapotranspiration as probabilistic variables, a reliable method for estimating the irrigation water requirement was described using the “probability distributionfunctions”.By examining 12 different probability distribution function, it was found that the log normal distribution function achieves the best results for the monthly precipitation data with values greater than 30 mm, but there is no unique probability distribution function for evapotranspiration data.This method can also provide a general formula for calculations of irrigation water requirement with different probability levelsduringthe growing season. Results showed thatthe reported values of irrigation requirement in the NETWAT program that is atthe 50 % probability level andused in most of irrigation projects in Iran, were different the calculated values in this study.According to similar reports in different researches, the represented method is recommended for more precise estimation of irrigation water requirements (with different probabilities) especially in critical situations (with high evapotranspiration and low rainfall values) or for crops that are sensitive to water stress in 80% probabilitylevelor higher.

Because of the importance of canola as a major oil plant and its compatibility with different climatic conditions, an experiment was conducted in the Agricultural Research Station of Tabriz University to determine its lysimetric evapotranspiration. Lysimetric evapotranspiration was measured 583.6 mm in the study region. Results showed that there was 23.36 percent difference between lysimetric evapotranspiration and potential evapotranspiration resulting from FAO Penman-Monteith method. A relationship for crop coefficient was obtained based on the days after planting and radiation absorbed by plants and was corrected with temperature and leaf area index. The durations of growing stages of spring Canola including initial, development, middle and end stages based on percentage of land cover and LAI were obtained equal to 25, 35, 20 and 20 days, respectively. Also the mean values of crop coefficients were determined for the initial, middle and the end stages of growth equal to 0.72, 1.45 and 0.66, respectively. There was significant difference between crop coefficients resulting from this study with the recommended values in the FAO 56. In this study, changes in the ground cover percentage, LAI, plant height and evapotranspiration were investigated on different days after planting.

Determination of hydraulic head loss is one of the most important components of designing drip irrigation systems. For having an optimized water distribution in drippers, it is necessary that head loss in each section should be in predetermined range. In recent years, fluent software has been used greatly in hydraulic science and fluid mechanics for evaluation of different flow regimes. The mentioned software has fantastic capabilities andits advantages have been proved in solving different fluid problems, mass and heat transfer. In the current study we tried to simulate hydraulic behavior of water flow in drip irrigation manifolds. Thus, three manifolds with same 18 meter length and outer diameter of 32, 40 and 50 millimeters which have 8 outlets with 2 meter intervals have been set. Validation of mentioned model has been done by comparing its result with observed values, measured in laboratory and computed results by Darcy Weisbach formula. In these experiments, pressure distribution was measured in three manifolds with different diameters and inlet pressure of 0.8, 1.0 and 1.2 bar using digital piezometer. Results showed that fluent software and Darcy Weisbach formula by having maximum relative error of 1.1268 and 0.5720 and correlation coefficient of 0.99959 and 0.99993, respectively in comparison of measured head loss are suitable models for simulation of water flow in manifolds and also are the appropriate and accurate methods in hydraulic simulation of water flow in drip irrigation systems.

Evapotranspiration، as a major component of the hydrologic cycle، is important in water resources development and irrigation planning. This paper aimed at investigating the abilities of Adaptive Neuro-Fuzzy Inference System (ANFIS) to estimate daily reference evapotranspiration (ET0). The daily climatic variables such as air temperature، relative humidity، wind speed and solar radiation from two weather stations (Salvatierra and Zambrana) in Spain equipped with electronic sensors for collecting of climatic data، were used as inputs to the Neuro-Fuzzy model to estimate ET0. Comparisons were made among the estimates provided by the ANFIS، Artificial Neural Networks (ANNs) and following the empirical models: Hagreaves – Samani، Ritchie، Makkink and Turc. The comparisons revealed that the ANFIS models (with RMSE between 0. 276-0. 437 mm) could be employed successfully in modeling evapotranspiration process. The ANNs (with RMSE between 0. 298-12. 5 mm) were also found to perform better than the empirical models in this regard.

Groundwater has always been considered as one of the major sources of drinking and agricultural water supply, especially in arid and semi-arid areas. Ground water systems simulations because of their inherent complexity are not readily possible. The goal of this research is prediction of groundwater level fluctuation in Shabestar Plain, West of East Azerbaijan province, using artificial neural networks (ANN). The 9 years data sets (1380-1388) from 15 piezometers that uniformly disperse on the whole plain is applied for ANN model training. The four inputs ANN model were monthly data set from temperature, rainfall, Daryanchay discharge, groundwater level in each piezometer with one month delay (t0-1). The groundwater level was the only output of the ANN model. The results of this research showed that the ANN model with TRAINLM training function and with TANSIG activation function are capable to monthly prediction of groundwater level in 3 years period with high accuracy R2=99.63, RMSE=1.43 in training step and R2=99.16, RMSE= 1.167 in validation step in study area.

In the present study, the width and height of steps, also the slope and height of spillways are considered as varied parameters, and has been tried to represent a comprehensive method for optimal designing of stepped spillways. For this reason, a complete program has been written in Matlab programming environment. In this program, Genetic Algorithm has been used for optimization. A stepped spillway with optimized dimensions was designed instead of a smooth spillway of Saroogh Reservoir Dam, which is located in West Azarbaijan province. The results showed that the replaced stepped spillway led to increase the energy dissipation and declined the dimensions of energy dissipator at toe of the stepped spillway. Also, for a constant discharge and varying slope, the variation of optimum height of steps was negligible. The sensitivity analysis of objective function showed that the relative energy dissipation on the stepped spillway for a constant discharge was independent of optimum height of steps and it was decreasing by increasing the slope of spillway. Also, increasing the discharge led to decrease the energy dissipation and increased the optimum height of steps for a constant slope. Results show with the slope 11.3 (%) and discharge 422 m3/s, the proper step height is 1.6 m and energy dissipation is 60.42 (%). With the same slope but discharge 776.9 m3/s (design discharge), proper step height is 2.25 m and energy dissipation is 43.7 (%).

Achieving the full potential of drip irrigation requires optimizing its effective operational parameters. For a given soil، knowing the temporal evolution of the wetted volume can contribute to a proper determination of emitter spacing and duration of irrigation as a function of the root zones soil volume. To investigate the optimal drip management practices، numerical and analytical simulations are easy and inexpensive approaches. In this study، the physical properties of the soil for simulation of wetting front position in drip irrigation were determined. Then، in order to calculate Van Genuchten model parameters، soil water characteristic curve was determined by means of a pressure membrane apparatus. Also، for solving the Philip and Ben-Asher equations، some computer programs were provided using Mathematica 7. 0. The HYDRUS 2D was used for numerical simulations. Statistical comparisons of the simulated and observed radial distances from emitters were employed to evaluate the accuracy of the analytical and numerical models. Results showed that HYDRUS 2D output with relevant root mean square error of 3. 32572 and correlation coefficient of 0. 9607 had a better agreement with the observed wetting front data in comparison with other methods and، in general، it’s the best method for simulating of wetting front in drip irrigation.

During a survey on pests of pine trees، Pinus mugo Turra، in April 2010 in Mashhad، a colony of an aphid was observed in abundant populations on the seedlings، belongs to the subfamily Cinarinae and family Lachnidae، being identified as Cinara pini (Linnaeus، 1758). The blast sequence to C. pini in the gene bank showed that the species was most similar to C. atlantica with 93% similarity. The mean length of adults was 2. 69± 0. 06 mm. The base of last antennal segment has fewer than 4 setae. The final rostrum segment is longer than the basal diameter of cornicles or slightly longer than the second tarsal segment of hind legs. Investigations on the biology of the aphid under greenhouse conditions of 25±2 ˚C، 45±5 RH، and 16:8 (L: D) showed that prematurity development time lasted 10 days. Intrinsic rate of increase (rm) was 0. 197 ♀/♀/day and the net reproductive rate (R0) was 30. 67 ♀/♀/generation. The reproductive period of aphids was 12. 61 days during which a total of 36. 75 nymphs per female were deposited. The total length of a generation was 26. 20 days.

In this paper, the MSM2 model was evaluated based on the field data measured at the agricultural research station of the University of Tabriz. The model was evaluated by data obtained from cultivated SC704 hybrid maize in a lysimeter. Comparisons between measured values of soil water content, maize evapotranspiration, grain yield and top dry matter with those predicted by the model showed the good estimation accuracy of the model. Also the comparisons between evapotranspiration estimation method of MSM2 model with conventional methods, considering single and dual crop coefficients, showed that the MSM2 model method had better accuracy than the conventional methods.

Numerical models are frequently used for simulation of water movement in soils. Soil water flow simulation models require a description of root water uptake as a sink term. In this study, two water flow models including the proposed SWMRUM model and the HYDRUS software were compared based on the field measurement in an apple orchard. Probe-type time domain reflectometry (TDR) was used to measure soil volumetric water content within radial (R) and depth (Z) vectors. Root water uptake model includes root density distribution function, potential transpiration and soil water stress-modified factor. A root water uptake sink term was developed, and entered into a soil water dynamic model to enable simulation of water flow in soil via numerical solution of Richards equation. The outputs from the two models were compared against the measured water content data. Simulated and measured water contents were in excellent agreement. Analysis of residual errors, differences between the measured and simulated values, was performed to evaluate the model performance, based on the maximum error (ME), root mean square error (RMSE), coefficient of determination (CD), modeling efficiency (EF), and coefficient of residual mass (CRM). Results showed that maximum root water uptake was 0.04 m3m-3d-1 at 25-30 cm depth and the minimum was 0.005 m3m-3d-1 at 80 cm depth.

Wind drift and evaporation are the main sources of water losses in sprinkler irrigation systems. A proper understanding of factors affecting these losses and estimating their amounts can be useful for reducing water losses and improving irrigation efficiency. It seems necessary to develop a model to estimate these losses in order to increase application efficiency of widely used center pivot irrigation systems. In this research a 25×25 m2 network of catch cans at 1.25 m spacing was prepared in the field. Commonly used Nelson R3000, Senninger LDN and Nelson D3000 spray sprinklers with various nozzle sizes, pressures and elevations were installed at the center of the network. Experiments were conducted at the various weather conditions and the needed climatologic data were measured simultaneously. Water losses were computed in terms of volumetric difference between the emitted water from spray nozzles and the received water on the soil surface. Using statistical analyses several equations which enable to estimate wind drift and evaporation losses were derived. From conventional methods, Frost-Schowalen, Keller-Bliesner and Playan et al methods were considered and their accuracies were investigated in comparison with the experimental data. Results showed that the proposed new equations estimated water losses satisfactorily and they calculated wind drift and evaporation losses more accurately than the mentioned methods.

Water hammer is one of the destructive hydraulic phenomena that occurs in the form of pressure waves in the Pressurized fluid flow systems such as pumping stations، water and oil pipe lines، and hydro-electric installations. Due to importance of water hammer and its destructive effect on pipeline networks، this phenomenon was studied in this investigation by using experimental and numerical models considering two different cases، with and without surge pipe. Data collected for different discharges in arbitrary time intervals were compared with results of CFD numerical model. After determining the optimum network and proper turbulence model the effect of unexpected stopping of water valve on fluid motion and reaction between water and structure was simulated using Fluent software. After testing k-ε and RSM turbulence models، the k-ε Realizable model found to be the best model. Finally، the results of the numerical model were compared with those of experimental model using the statistical analysis، R2، RMSE and RE. The results showed a good agreement between CFD numerical model and experimental model. So CFD model can be used as a suitable numerical model for computing maximum and minimum pressure.

Double ring and tension infiltrometer are simple, fast and suitable instruments for determining soil hydraulic conductivity. The effect of land slope on soil properties such as saturated and unsaturated hydraulic conductivities has been reported by various researchers. The aim of this study was to estimate and compare soil hydraulic conductivities at different slope gradients under steady state and transient flow regiones. Field experiments were conducted in a loamy soil with different slope gradients in Gonbad research station, Hamadan, Iran. Soil surface slope gradients, of 0 (level), 10, 20, 30 and 40 degree were selected in this station. For each slope gradient, water infiltration experiments were carried out using a double ring and a tension infiltrometer at tensions of 0, 6, 9 and 15 cm in three replications. Totally 60 infiltration experiments were carried out. In steady state, values of saturated and unsaturated hydraulic conductivities were estimated using Reynolds et al. and Ankeny et al. procedures, respectively. In transient statevalues of the hydraulic conductivity, for different land slopes and water pressure heads, were calculated from the parameter of the second term of Philip’s two-term equation, Results indicated that the hydraulic conductivity values for both steady state and transient flow regines were decreased with increasing in tension and slope gradient values. The higher rate of hydraulic conductivity decreases was obtained for lower tensions. In steady and transient state, by increasing in slope gradient from 0 to 40 degrees, decreasing of hydraulic conductivity in 0 tension was 4.1 and 3.7 times more than these in 15 cm tension, respectively. The fitness between the Gardner exponential model and steady state flow procedure was higher than that of transient flow procedure. In all experiments, values of relative difference of hydraulic conductivities were less than 7% that indicated good fitness between the steady state and transient flow procedures

In order to determine and analyze the head losses caused by the combined effect of entrance resistance and approach flow convergence to drains, some known models were studied. The field data of an existing sub-surface drainage system were applied for evaluating the models and selecting the best one. The hodograph solution was employed to compute the water head, directly above the drain, while the Oosterbaan model was used to validate the hodograph results. Total head loss between two drains, was determined using Ernst equation. The results showed that increasing total head loss caused reduction of hydraulic head in approach flow region in a non-linear manner. Application of Youngs and Hoffman equations as well as EnDrain program based on energy and Darcy equations could simulate drain discharge to some extent. Hoffman equation gave some promising results among the others in term of R (0.928), RMSE (0.0007) and SI (1.09).

Flow routing is a mathematical procedure for predicting volume change, speed, and shape of a flood wave in a channel as a function of time which is of great importance in river engineering, flood control and hazard reduction, river conservation, and modeling of flow in weirs and reservoirs. The solution of flood routing can be carried out using hydrologic or hydraulic procedure depending on conditions and existing information. In this research, hydraulic routing was carried out using 4-point finite difference Muskingum method based on St Venant dynamic wave equations. Furthermore, Muskingum linear and nonlinear hydrological approaches were applied for the purpose of comparing results of the methods and the parameters of Muskingum models were estimated using least square errors procedure. Along the reach of Mehranrood between Lighvan and Hervi hydrometer stations using upstream input hydrographs (Lighvan station) and downstream output hydrographs (Hervi station) 3 flood events were selected for flood routing. In hydraulic routing procedure, output hydrograph was obtained using input hydrograph and hydraulic characteristics of the reach. Hydraulic characteristics used in this method were longitudinal slope, side slope, bottom width and length of reach. In hydrologic routing procedure, one of the input flood hydrographs associated with the related output one were used for estimation of linear and nonlinear Muskingum models parameters. The resulted parameters then were used to evaluate the goodness of fit of the models by application of the two other input and output flood hydrographs. Results showed that hydraulic flood routing using dynamic wave method (4-point finite difference Muskingum method) was more compatible with the observed output hydrograph than Muskingum hydrological methods. Weak efficiency of the linear Muskingum model was also observed in comparison with the nonlinear one.

In order to evaluate performance of the center pivot irrigation systems, an understanding of water application characteristics of these systems is necessary. A new model and its computer program are developed to calculate applied water depth and coefficient of application uniformity of center pivot systems. The model uses water distribution pattern of stationary single spray nozzle as an input and simulates center pivot overall water distribution pattern. For this purpose, two static and dynamic square grids are considered. The static grid is obtained by dividing irrigated field to square components. The dynamic grid is resulted from adapting a grid with square components on water distribution pattern of single spray nozzle and is moved with moving spray nozzle on the center pivot lateral. Dynamic grid is moved over static grid. Water depths received in the field are determined in static grid components via considering water applications rates in dynamic components. Distribution patterns are overlapped in areas covered by adjacent spray nozzles. The model outputs are water depths received in the field in all components of the static grid and water application uniformity coefficient. In order to evaluate and validate the model performance, several experiments were conducted in the field and the model was run for the same conditions. The results showed high accuracy of the model in simulating water distribution patterns of the center pivot irrigation systems.

Use of mathematical models as efficient tools in solute transport studies and management in porous media is usual. The present model by making use of the governing equation for two - dimensional solute transport in a porous medium expresses the ion adsorption effect on solute transport in a saturated semi infinite porous medium.This model has been solved analyticaly under the first type (Dirichlet condition) and the third type (Cauchy condition) boundary conditions. In solute transport by diffusion, the third type boundary condition shows the solute concentration at the boundary or on the soil surface more than that of the first boundary condition. In advection – dispersion solute transport, the solute concentration distribution curves resulting from the first and third boundary conditions because of advection predomination are approximately identical. The effect of ion adsorption on the medium,s solid matrix is evaluated by retardation factor in the model. The retardation factor greater than one causes retardation in solute transport, distribution and dispersion in the medium. The effect of ion adsorption on solute concentration distribution is independent of the selected boundary condition and depends on the modes of solute transport and dispersion in the medium, so as the rate of this effect in advection – dispersion solute transport is more than in diffusion transport.