رضا لاله زاری

The main problem of water resources planning is the inappropriate allocation between different consumers. Water allocation planning is a complex, multi-variable, and multi-constraint problem, which requires advanced optimization methods to be solved. Classical optimization methods are facing some limitations such as being trapped in local optimum points, and difficulties in handling different variables. In this paper two of these methods including particle swarm optimization, PSO and multiobjective non-dominated sorting genetic algorithms, NGGAII were explored and their efficiency in optimization water reservoir operation problems is compared. Dealing with the necessary of multiobjective programing accuracy, two single objective models was developed separately using PSO to verify the NSGAII results.

Estimating the parameters of infiltration equation and Manning’s roughness coefficient are essential for the optimal design and evaluation of surface irrigation systems. The present study was carried out to calibrate these coefficients for a closed-end border irrigation system with four series of field information. In this regard, the hydraulic surface water flow is simulated using zero-inertia model by WinSRFR simulation model that linked to the particle swarm optimization algorithm for repetitive calculations. The objective function of the optimization problem was the minimization of the difference between the calculated and measured times of advance and recession phases, and four coefficients of the modified Kostiakov equation and Manning’s roughness coefficient were considered as decision variables. The sensitivity analysis of the developed model showed that the coefficient b of infiltration equation in the recession phase and the Manning’s roughness coefficient in the advance phase have the most errors in the predicted results. The results showed that based on the optimized parameters in the model, the values of root mean square error, RMSE, were obtained between 3.77 to 12.86 minutes and the coefficients of residual mass were varied between -0.099 and 0.003 to predict the advance and recession times in the four experimental irrigations. Based on results, with optimization of WinSRFR model, there is accessibility to achieve in application efficiency and distribution uniformity about 86 and 84 percent, respectively (with adequacy about 100 percent) by flow variable (inflow rate and cutoff time).

The main problem in surface irrigation systems is the low irrigation efficiency due to poor management, inaccurate estimation of design parameters and inadequate design. Losses in surface irrigation include deep infiltration and runoff, which is one of the ways to increase the efficiency of border irrigation, using closed-end mode in irrigation systems. This research was conducted to evaluate the effects of geometrical variables (slope and length of border) and flow control (inlet flow rate and cut-off time) on application efficiency and uniformity of water distribution in closed-end border irrigation system. The length, slope, inflow rate, and cut-off time are considered as the decision-making variables for developing the multi-objective genetic algorithm based on the non-dominated sorting. For this purpose, three irrigation borders with closed-end system were considered in the Ramshir network. The optimization algorithm for calculating the objective functions involves maximizing the minimum water depth and minimizing the infiltration depth in a modeling loop. The optimization algorithm was linked to WinSRFR 4.1.3 software to calculate the objective functions. The results showed that the best combination of inflow rate and the cut-off time for 75 mm of required water depth was 1.9 lit/s/m and 150 min, respectively, which increased application efficiency and distribution uniformity to 79 and 78 percent. Furthermore, the application efficiency in the closed-end border irrigation system is higher (30% to 50%) than the open end method in different scenarios.

Groundwater resources, as one of the most important factors in sustainable development, need to be intensely considered. Numerical models such as Modflow and MT3D is an applied tool for simulation and management of groundwater flow and solute transport. In this study, Shahrekord aquifer modeling is provided by the use of monthly data’s including hydraulic heads, depletion volume of the wells, springs and qanats, precipitation values. This model has been developed based on the assessment of the hydraulic conductivity and specific yield coefficients in the calibration process. The study year was divided to 12 monthly stress period for calibration (10 periods) and verification (2 periods). The results showed that the hydraulic conductivity from 6 to 16 m/day and specific yield from 0.03 to 0.07 were varied. The predicted water table in calibration process in comparison to observed values of water levels on piezometers with variance of 0.63. These results confirm the need model of groundwater flow prediction. Moreover, Effective molecular diffusion coefficient, longitudinal dispersity and distribution coefficient were calibrated to achieve acceptable variance between observed and calculated nitrate concentration. The most contaminant particles are in the south zone of aquifer where is the nearby urban wastewater wells. Moreover, the central and south parts of plain have the suitable situations for groundwater discharge because of the high amount of transmissivity.

The estimation of soil moisture plays an essential role in the hydrologic modeling, drought prediction and management, climate change analysis, and support of agricultural decision making. Therefore, by use of meteorological parameters variations in the future period, effect of climate change on soil moisture status were investigated by use of three models of AOGCM and emission scenarios namely B1, A2 and A1B. So, firstly, the values of temperature, rainfall, relative humidity, wind speed and radiation were determined by these three scenarios and AOGCM models and secondly downscaled by the LARS-WG model and change factor method. Results of the present study showed that the values of temperature, relative humidity, wind speed and rainfall would increase in average by mean of 8%, 7%, 1% and 5% respectively, in the future period (2020-2039) in comparison with the baseline (1992-2011) and also temperature and relative humidity would increase in average by 30% and 19% in the future period (2080-2099) as compared with the baseline. Also, soil moisture at the depths of 30 and 60 cm were determined by use of meteorological parameters, soil and water data in SWAP model for future and base line periods. The results showed that the soil moisture in the future period of 2020 would increase as compared with the baseline, but in the future period of 2090 would decrease. Furthermore, the 5th and 21th weeks of the wheat growing season were determined as drought stress warning weeks for the Faroub and Soleimani farms, respectively.

Optimized water allocation may be considered as a valuable solution to increase the productivity of water resources in arid and semi-arid areas. To achieve this purpose, the main resources of water consumption in Baghmalek plain (Khuzestan province) for duration of October 2013 to September 2014 and also water table heights for nine years (2002 to 2011) were evaluated. In this study, the final model was developed by combining the two cropping pattern multiobjective optimization and groundwater simulation models. Also, groundwater flow was simulated for addressing optimal discharge scenarios based on finite difference numerical approach using Modflow software. Study years were divided into 36 seasonal stress periods and hydraulic conductivity, specific yield and recharge were calibrated in these periods. The results showed that the flow model had an acceptable simulation accuracy by variance error of 3.05 and 3.92 in calibration and verification processes, respectively. Furthermore, the prediction of water table after the optimal discharge scenario indicated that the May and June months were the main periods of groundwater management.

The price of water in agriculture plays an important role in the water allocation management. Therefore, the optimum strategies of cropping pattern could be designed when water price analysis are considered in a predetermined economic framework. In the present study, a programming model was developed using the genetic algorithm for optimal water allocation in the eastern north of Khuzestan province that is suffering from water deficit. Maximization of benefit per cost ratio was defined as the objective function by a linear equation and the feasible domain of the problem was limited to water resources, cultivated lands, irrigation systems, and economic parameter constraints. In the developed optimization scheduling, there is the set of solutions with the great potential to maximize the net income of cropping pattern in the water shortage condition. Three scenarios of water price including 0, 200, and 500 Rials/m3 have been considered to compare the allocated water, water use efficiency, and net benefit per drop indices for each crop. The results show that by imposing deficit irrigation and an increase in costs, the volume of allocated water together with the efficiency of water usage for tomatoes is increased by 7% and 0.07 Kg/m3, respectively. Furthermore, the same conditions lead to an increase in the cultivated area of wheat and maize. Analysis of evaluation indices indicated that by increasing the price of water, the model decreased the allocated water in vegetables and increased the water usage efficiency and benefit per cost ratio in beans.

Water resource management is a main driver to increase economic productivity for an agricultural area. Under water shortage condition, efficient use of available water is necessary for required sustainable crop production in arid and semi-arid area. Therefore, a combination procedure of mathematical modeling and optimization techniques has been developed for water allocation to maximize the economical productivity and total efficiency of an irrigation scheme.Optimization model is presented using multiobjective genetic algorithm and evaluate by two objective functions. Water use efficiency, cropping pattern, reduction of irrigation losses, effective use of rainfall and cultivated area are considered in the objective functions of the model. Irrigation water requirement for each growing stage and cultivated area have been considered as decision making variables. For field study, the main crops of Baghmalek plain and their related area, the cost of agricultural inputs and final price of crops were collected in farming year 2013-2014. The results show that the optimal cultivation area allocated among various crops is decreased for maize, melon, tomato and onion in drought condition. Tomato, bean and onion have obtained more volume of total available water, respectively. Tomato in relative yield and net benefit ratio, vegetable in the percentage of allocated water and bean in effective use of water have the minimum values of evaluation parameters.

Groundwater is the largest resource of water supplement and shortages of surface water supplies in drought conditions that requires an increase in groundwater discharge. Groundwater flow dependson the subsurface properties such as hydraulic gradient (water table gradient or head loss in artesian condition) and hydrodynamic coefficients. The flow treatment is analyzed with an accurate estimation of effective parameters in groundwater equation. This function is obtained using the continuous equation. Inlet and outlet flows of a cell are equal to storage amounts in the continuous equation. Analytical solution of this equation is complex, so numerical methods are developed including finite element and finite difference methods. For example, Feflow is a groundwater modeling tool that makesuse of finite element method (Reynolds and Marimuthu, 2007). Modflow as a finite difference three-dimensional model simulated underground flow under steady and unsteady conditions in anisotropic and non-homogeneous porous media. Modflow is designed to simulate aquifer systems in which saturated-flow conditions exist, Darcy’s Law applies, the density of groundwater is constant, and the principal directions of horizontal hydraulic conductivity or transmissivity do not vary within the system. In Modflow, an aquifer system is replaced by a discretized domain consisting of an array of nodes and the associated finite difference blocks. Groundwater modeling and water table prediction by this model have the acceptable results, because many different informations of water resource system are applied. Many people and organizations have contributed to the development of an effective groundwater monitoring system, as well as experimental and modeling studies (Lalehzari et al., 2013). The objective of this paper is investigation of hydraulic and physical conditions. So, a numerical model has to be developed by PMWIN software for Bagh-i Malek aquifer to calculate hydrodynamic coefficients and predict water table in the future. Bagh-i Malek aquifer located in Khuzestan province is mainly recharged by inflow at the boundaries, precipitation, local rivers and return flows from domestic, industrial and agricultural sectors. The discharge from the aquifer is through water extraction from wells, springs, and qanats as well as groundwater outflow and evapotranspiration. In this study, conceptual model of Bagh-i Malek aquifer on the framework of finite difference numerical approach has been used in simulating groundwater flow treatment. Water table data of 8 piezometers was collected for the 10 year duration from 2002 to 2012. The study years are divided into 40 seasonal stress periods with daily time step. Hydraulic conductivity, specific yield and recharge were calibrated in these periods. Verification was made between the simulated and measured hydraulic heads in the next calibration year. To simulate the groundwater table elevation in this study area, the PMWIN model is used. Bagh-i Malek aquifer is considered as a single layered aquifer, and therefore only the horizontal hydraulic conductivity is estimated. Modflow was used to simulate both steady state and transient flow systems. In steady conditions it is assumed that the total of time simulation is a time period and it does not change inlet data in the modeling duration. In unsteady conditions,the duration of study is divided into some stress periods that data is changed in every period. Estimation of hydraulic conductivity is the first step of calibration process at steady state conditions. The correct assignment of hydraulic conductivity has a main effect on other parameters accuracy. Hydraulic conductivity mapping indicated that the maximum values are in the Eastern North (6-7 m/day) of the aquifer. The twice calibrated parameter is specific yield in unsteady conditions. Specific yield mapping indicated that the values vary from 0.03 to 0.08 and are maximum in the Southern regions of the plain similar to hydraulic conductivity. The results confirm that the flow model has the tolerable simulation accuracy by variances of 3.1 and 3.84 in calibration and verification processes, respectively. The sensitivity of the flow model to decreasing the hydraulic conductivity is more than increasing it. 50 percentage declined into the hydraulic conductivity causes the increase of the variance from 3.1 of initial value to 44. Mapping of calibrated hydraulic conductivity showed that the Eastern North of aquifer has the higher transmissivity and discharge capability in comparison to Southern parts. At last, the result show that the Bagh-i Malek aquifer model is sensitive to recharge, hydraulic conductivity and specific yield, respectively.

The procedure that is to be selected for a sustainable maintenance of open channels in agriculture largely depends on the type of supervising process and the availability of its appropriate device. In this paper, social acceptance and technical problems related to the contractor, farmer, taskmaster and supervisor were taken into consideration. The study was carried out in conveyance channels of agricultural regions in Lorestan province (Delfan Palin), which is 19 km long, from 2007 to 2010. The layouts of structures were performed with 6 to 8 cm thickness and trapezoidal section by gravel, sand and concrete mix. The main problem and influencing factor for desirable utilization are the wrong change in predetermined section scheme and technical failure to perform, respectively. After the classification and assessment of the problems, some solutions which have more positive effects on the next stages of channel construction were suggested.

The uniformity of water distribution by sprinkler irrigation is an important design factor that affects water use efficiency and leaching of solutes. The irrigation application uniformity is affected by changes in wind speed and its direction, sprinkler characteristics and variations in operating pressure. The purpose of this paper is to present modified equations for evaluating the pressurized irrigation systems based on non-dimensional infiltrated depths. The equations have been obtained by four data groups including the average of the measured depth values in any quarter. Coefficient of uniformity, CU, distribution uniformity, DU, application efficiency, Ea and deep percolation ratio, DPR are selected indicators to evaluate the sprinkler irrigation system. The suggested method is compared to the traditional approach for assessment the evaluation indicators, also collected data from a wheel-move system in Chaharmahal & Bakhtiari province. The relation between CU and DU was analyzed for 3 scenarios of the average depth. The results show that the application efficiency was estimated 12% less than previous equations because of using four average values. Coefficient of uniformity and distribution uniformity in wheel-move system was calculated 0.78 and 0.66, respectively.

Advance velocity is an important factor in surface irrigation system design and simulation. Volume balance is a simple model based on continuity equation used in surface irrigation design and management. In the past volume balance models, it is generally assumed that the upstream depth of surface water is constant and equal to normal depth. This initial assumption may cause significant errors in computing advance flow. In this paper, a modified volume balance (MVB) model is developed to predict the advance curve in furrow irrigation. In the suggested method the upstream surface, water depth is actual depth and variable in time. Predicted advance distance of VB, VB-ZI and MVB was compared to the observed data obtained for the three furrow lengths of 60, 80 and 90m. Evaluation indexes indicated that the modified volume balance equation is more accurate than the previous equations by RMSE 9.26, 7.37 and 6.76 respectively. Sensitivity analysis showed that the inlet discharge has the greatest effect on the model and the model is more sensitive to decreasing the discharge amount than to increasing it.

Alternative sustainable water sources must be identified when water demand is increased. Artificial groundwater recharge for water reuse are supply augmentation methods in water limited areas. Monitoring the present solute transport process is necessary in determining possible threats to drinking water supplies in the future. In this study the groundwater flow is investigated to represent movement and quality transformations for a modeling period of 5 years (Sep. 2002 to Oct. 2007). Total dissolved solids, TDS, concentration as aquifer water quality index was simulated using Modflow and MT3D models in two direct and indirect recharge scenarios. The model has been calibrated under steady state and transient conditions. Hydraulic conductivity and specific yield in flow model and transverse and longitudinal dispersivity and molecular diffusion coefficient in solute transport simulation was calibrated by first four years and was verified with observed data in last year. Seven urban wells were selected as the observation points and the calibrated model was used to evaluate the vulnerability of aquifer on wastewater recharge. The results show that the developed numerical model is capable of simulating the TDS concentration in porous media. Direct and indirect recharge methods increase the average of water table about 4 m and 2 m, respectively. The effect of contaminant transport with concentration of 2000 mg/L is approximately in distance of 200 m. Also, deep percolation of agricultural lands had more effect than advection, dispersion and diffusion terms to groundwater contamination.

Evaluation procedures have been developed for effective design and management of irrigation systems. Furrow irrigation is one of the main types of applying water in agriculture. In the present study, a new procedure for field evaluation of water distribution in furrow irrigation is proposed. For this purpose, application efficiency (Ea), water requirement efficiency (Er), deep percolation (DP) and tail water ratio (TWR) have been introduced based on the average of the non-dimensional infiltrated depth values in the four data groups. The relationships between coefficient of uniformity, CU and distribution uniformity, DU have been described by opportunity time values of each quarter and using the linear equation instead of infiltration function. The proposed method was compared to other procedures by 9 scenarios of field data with different discharges and lengths. The results show that the evaluation indicators of furrow irrigation depend on the hydraulic characteristics of the soil and the opportunity time. Also, there was no observed any significant difference on the suggested indexes values and classical performance indicators.

Nowadays, in order to reduce the effect of unwanted factors and gather information related to land cover, vegetation indices were used. In this study, the effects of NDVI and VI indices on land cover and runoff curve number of Mansourabad watershed were investigated by using Geographic Information System (GIS) and Remote Sensing (RS). Land cover map was prepared by using vegetation indices and Landsat satellite images. In addition, the results of classification of these two indices and corresponding percentage with surveying data were compared. After that, runoff curve number map was prepared by combining land cover map with land use and soil hydrology group maps and by utilizing SCS table in the GIS environment. To assess the accuracy of each curve number map obtained from each index, runoff peak discharges computed by HEC_HMS model were compared by the measured amounts. The result of the classification showed that NDVI index with Kappa coefficient equal to 0.83 was better than the VI index with Kappa coefficient equal to 0.74 for land cover. These results were verified by lower error percentage between the measured and observed maximum discharge for NDVI index.

An accurate design of drip irrigation requires water quality analysis that helps attain a better emission uniformity coefficient. This study examined aquifer qualitative parameters in the north of Khuzestan province to assess the applicability of groundwater in trickle irrigation systems. For this purpose, interpolation technology was used to map chemical parameters collected from 104 deep wells. At first, predicted values of each element were compared with the observed data using RMSE index to select the optimum interpolator technique. Interpolation and spatial analysis was carried out using geographical information system software in different layers. Evaluation factors including sodium adsorption ratio, SAR, total dissolved solid, TDS, total hardness TH, and Langelier saturation index, LSI, which are often directly estimated from water analysis data such as calcium, magnesium, bicarbonate, potassium, and sodium. The results showed that the LSI was positive in 90 percent of wells. Total hardness in many parts of the study area was higher than 300 mg/L (very hard water), which indicated strong possibility of carbonate sedimentation and emitter clogging. Also, total dissolved solids in the south of the region was higher than 2000 mg/L.

Air pollution has harmful effect on human health and the environment. Accordingly, considerable effort has been put to analyze the air pollutants. One important issue is the spatial distribution of these pollutants. Dispersion of the pollutants released from sources on the ground is mostly driven by the planetary boundary layer where turbulent flow causes mixing of the content of the stationary ground layer of atmosphere with higher moving layers and thereby clears out the pollutants rapidly. To predict the dispersion of air pollution in the atmosphere, researchers investigate the behavior of plume rise under certain conditions. Two factors critically affect the result of the test: primary plume rise and its dispersion. In this work, we study the effective height of emission which determines the dispersion of the pollutants. The height of the plume has been subjected to semi-empirical and to more accurate numerical studies. These approaches suffer from some shortcomings. For instance, the gravitational effects and fluctuations of the wind speed are neglected. Numerical approaches are typically based on a Gaussian plume rise model so called ISC3 (published by EPA). In this paper plume rise of emission of an air pollutant is simulated using Fluent software which allows one to input natural wind velocity profile and to consider the gravity. Another advantage of this approach lies in the usage of turbulent kinetic energy (TKE) and temperature profiles. In this work, theoretical plume rise using the ISC3 model were being calculated at first. The calculated values of xf and ∆h are equal to 437.85 m and 50.87m, respectively. Then, the dispersion was being simulated accordingly using Fluent and the results were compared with those of the numerical studies.

Shahrekord aquifer is depleted by almost 800 deep and semi-deep wells, the majority of which are agricultural wells and some have urban usage. In southern parts of the plain, the water table has fallen strongly because of immoderate discharge and decreased the quality of water by urban wastewater. The main objective of this study is investigation of subsurface dam construction and its effects on water table in consumption locations, reduction of deliveries costs and interception of contaminant transport. Therefore, the Shahrekord aquifer model was simulated with hydrodynamic coefficients calibration by PMWIN5.3 Software. The southern outlet of plain (near Bahram-Abad village) was selected to study subsurface dam construction, then a horizontal-flow barrier in this place was set with mean hydraulic conductivity equal to 0.5 m/day. Water table situation and nitrate concentration were analyzed using ArcGIS9.2 software before and after dam construction. The results showed that the subsurface dam rises groundwater level in 4 kilometers distance of upstream areas. Also, the available volume of water increased about 1.5 Mm3. Nitrate concentration didnt show to be considerably different from the initial state. But, it is likely that contamination in the storage resource will rise because it is located near Shahrekord water treatment plant and also due to the discharge of wastewater wells.

As furrow irrigation is practiced on a large percentage of farm fields in Iran، the design and operation of this system calls for improvement. As collecting the necessary data to predict of advance and recession curves in a furrow requires field accurate measurements. These operations are costly and time consuming and the use of approved models is advantageous. The main objective of this study was evaluating the hydrodynamic، zero inertia، and kinematic wave models prediction by field observation using the SIRMOD software. Sensitivity analysis for this software was performed by employing three input parameters: discharge، Manning''s roughness coefficient and furrow slope. Field experiment performed at the Research Farm of Faculty of Water Sciences Engineering، the Shahid Chamran University of Ahvaz. Data were collected from three furrows، 60، 80 and 90 meters long، with three replications and three discharges of 1. 0، 1. 25 and 1. 5 liters. sec-1. Four indices: 45 degree line (a)، model average prediction error (Er)، regression coefficient (R2) and average relative error of model (Ea) were used to evaluate the model’s predictions. The results of sensitivity analysis indicated that the SIRMOD software was sensitive to variations of input parameters. The predicted values of advance phase for all models were more than the observed values، but، generally، the amounts of (a) and R2 indicated that the hydrodynamic and zero inertia models had better performance in prediction of advance phase compared with the kinematic wave model. Moreover، the hydrodynamic and zero inertia models، as in the advance phase، predicted the regression phase better compared with the kinematic wave model.

More than 98 percent of the earth’s drinking water supply comes from groundwater. It needs protection from possible contamination, especially in urban areas where wastewater production is high. Most area of Shahrekord plain is under the cultivation and irrigation water comes from the groundwater. Furthermore, urban sewage discharges to the groundwater, in some parts of the Shahrekord plain. In this study, 18 wells were selected for water sampling. The effects of landuse were evaluated on Total Dissolved Solids (TDS), Total Hardness (TH), Electrical Conductivity (EC), Nitrate (NO3–), Nitrite (NO2–) and Sulfate (SO42-). The samples were selected in different seasons; spring, summer and autumn 2004. A Nested Complete Randomized Design (NCRD) was used for statistical analysis with 18 samples per plot. The results show that there were significant differences (P<0.05) between value of NO3–, NH4+ concentration and EC in farmlands and urban areas. There was no observed any significant difference on the NO2–, pH and TH value. It was higher in farmlands than in urban areas. The result shows that there are a significant difference (P<0.01) on NO3– concentration in different seasons.

It is necessary to care the quantity and quality of the water resources especially in arid and semi-arid regions. Shahrekord plain where it has a 551 Km2 total area, groundwater is discharging almost 255 MCM annually and uses for drinking and agriculture. The main objective of this study was classification of groundwater quality and comparison with the drinking water standard limits in Shahrekord aquifer. Some of the chemical properties such as Cation, Anion, Electrical Conductivity (EC), Total Hardness (TH) and Total Dissolved Solids (TDS) were measured in four times (Spring and Autumn 2004 and 2005). The results show that the some of the chemical concentration in North-Western part (NWP) of the aquifer including Ca, Mg, SO4, HCO3, Cl and Na was lower than Southern part (SP). Bicarbonate in the Anions and Calcium in the Cations has the maximum values; however they are lower than the standard limits. Water type was assigned as Calcium Bicarbonate in terms of available ions combination in Shahrekord aquifer. The TH in the wells varies from 150 to 300 (mg/lit /CaCo3). The water quality is classified in hard water category base on TH. The result shows that there wasn’t considerable difference in TH and TDS values on spring and autumn seasons. The maximum nitrate concentration is about of 37 mg\lit in agricultural landuse of northern sites. Result shows that Total Hardness (TH) and Total Dissolved Solids (TDS) in southern parts and Nitrate concentration in northern parts have maximum values concentration. This subject shows that the source of these water quality parameters is difference together. Azotic fertilizer seepage of agricultural lands increase Nitrate contamination and urban wastewater had most effect to provide the chemical concentration and Total Dissolved Solids.

At present nitrate contamination of groundwater is a significant problem. In the past decades, nitrogen fertilizers have been widely used without considering negative impacts on the soil andecology. The nitrate easily reaches the surface and subsurface water. The objective of this study was to investigate nitrate contaminant distribution using Geographical Information System (GIS). Accordingly, 10 observation wells were selected out of 500 operational wells and water sample collected during (12 months) of July 2007 to June 2008. In total, 120 water samples were analyzed for nitrate concentration. The results show that nitrate concentration in the central parts of the plain is lower than northern and southern parts and did not change during the year. The most contaminated region of the aquifer is located in the southern part where it is contaminated by the urban wastewater wells in the vicinity of the aquifer. In the summer, the nitrate concentration is increased due to high agricultural activities and consumption of nitrogenfertilizers. The results indicate that the nitrate leachs during irrigation and so it affects the water quality.