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In most regions, rivers are not only a supplier of various uses of water, but they acts as the natural channels of transmission wastewater and sewage produced, So checking the quality of river water is important. The present study done based on analysis of water quality data at Shooshtar and Bandeqir stations located in Gargar river among 2002 to 2012 in Khuzestan province by drawing diagrams Piper and Wilcox, calculated residual sodium carbonate (RSC), the percentage of sodium occurred, and conducted to determine the trend in the data which has been used by Mann Kendall. To examine the correlation structure and the relationship between variables, method of principal component analysis (PCA) used. The results showed that the water of Gargar was kind of brackish water and it is heading to chloride. In addition, check the water quality of rivers based on RSC and Percent sodium indicated terms of theRSC water quality of stations in both is suitable for agriculture and the percentage of sodium water quality in Shushtar Station is appropriate and in Bndeghir station is unsuitable for agriculture. Study of trend quality parameters indicated Parameters Residual salts, electrical conductivity, bicarbonate, chloride and calcium have a significant ascending trend and Parameters, pH and flow rate have decreased significantly at the 99% level and along the river due to the entry of pollutants into the river and leads to reduce the water quality. In addition, The PCA results indicated the most important water quality parameters in the river Gargari, Parameters are SAR, SO4 and HCO3. baised on land use which is urban, and agriculture. Suggest that the use of fertilizer and agricultural fertilizers and sewage entering the River Shushtar Gargar, determining the cause the most three important parameters in determining the cause as the most important parameter in determining the water quality of the river.

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Nitrate loadings from agriculturalwastewater causes serious damage to water quality in many parts of the world. In this study, the removal of nitrate pollution of agricultural wastewater inKarun Agro-industry unitstudiedwith surface flow constructed wetland (FWS-CW) using hydroponic and soil as media. In order to investigate the effect of plant cultivated in CWs(floating and emergent cultivated), temperature and hydraulic retention time (HRT) on the performance of FWs-CW treating wastewater, nine parallel pilot-scale units of dimensions 3m in length and 1m in width and 0.8m depth were constructed. Continuous flow of wastewater introduced in the system from December 2012 until March. The three units were cultivated with vetiver on the floating platform, three units had soils as media and the rest were kept unplanted(Control).The study was divided into 6 phases of 6 months, using 3, 5 and 7days HRT. Averageweather temperature varied from about 8.92 to 31.25◦C. Concentration of nitrate measured at the inlet and outlet of the system and data analyzed using SAS to see the significance relationship between factors. The average nitrate concentration of the wastewater entering the unit was 20±3.76 mg/l. The results indicated that removal performance of the constructed wetland units different HRT and changes in temperature were significantly different. The treatment efficiencies of 3, 5 and 7days HRT were average of 14.24-37.52, 16.32-41.27 and 16.42-50.51%, respectively. Moreover, results from this study indicated that the emergent vetiver cultivated, floating vetiver cultivated and control wetland, removed 43.09,28.36 and 15.66 % nitrate respectively and a high removal rate regularly occurred in long-term operating(HRT=7days) efficiency in total CWs.

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For the determine the expected reactions of pollutants entering the river by the use of mathematical models is essential. These models are able to simulate the effects of existing and future loads and Help managers in their decision making. in the other words, Since the river water quality protection need to additional investments For the wastewater treatment or the collection systems and controls to create a drainage And may lead to limit the development activities in the river basin. Conservation of GarGar River, one of the branches of the Karun River and the water supply for domestic use, drinking, agriculture and aquaculture is the most important. The first step in managing water conservation awareness of the qualitative change them. Therefore, in this study a QUAL2KW mathematical model to simulate GarGar river quality was used. In order to model implement the necessary data for the years 91-1389 of Water and Power Authority, was prepared and In order to model implement the data divided into two categories: The first category (in Persian date Mehr 1389 -esfand 1390) in the calibrated model and The second category (in Persian date Ordibehesht 1391 -esfand 1391), available information was used for testing and verification. NO₃ and ₄NH parameters in GarGar river the simulation by model. validation results indicate The model have a good agreement with reality And according to studies conducted, The main sources of pollution in the river GarGar centers and villages can be named track wasteeffluent and sewage fish ponds inns and fish farming and agricultural drains.