جستجوی مقالات مرتبط با کلیدواژه « qual2kw » در نشریات گروه « آب و خاک »

The Dez River, as the third largest river in the country, plays an essential role in the economic, social and environmental life of North Khuzestan. Also, it is very important because it supplies water to more than 125 thousand hectares from the Dez plain and the lands downstream of this plain to the place of Bituminous Dam and provides a significant part of the environmental needs of the Karun River. The purpose of this research is to investigate the trend of quality and pollution along the Dez River and evaluate the effects of urban, agricultural and industrial wastewater discharges on the trend of pollution and quality of the Dez River in 131 intervals based on the QUAL2KW model.

The QUAL2Kw model simulates the river in one dimension (one dimension along the length of the river) along with non-uniform permanent flow and can consider the effect of loading both point and non-point. In this model, in order to determine the concentration of qualitative parameters, the finite difference method is used to numerically solve the displacement-diffusion equation (Chapra et al., 2006). In this research, the QUAL2KW model was used to simulate the process of pollution and quality in Dez River. This model is able to solve the equations related to the river in both permanent and quasi-dynamic conditions. Also, simulate parameters such as dissolved oxygen, biochemical oxygen demand, temperature, ammonia nitrogen, etc. in the river network. In this model, the qualitative simulation is done based on the river course spacing. Spacing is done according to the hydraulic conditions of the river and the place of discharge of pollutants. Therefore, the distance between the regulatory dam and Bandaghir was divided into 131 intervals with variable lengths. In the calibration and validation stages of the model, it was determined that wide parameters such as flow geometry, river hydraulic conditions, water flow rate, aeration coefficients, pollutant entry points, nitrification rate, oxygen demand, etc. in the river are involved in qualitative modeling results.

The results showed that QUAL2KW water quality model is highly accurate in simulating quality parameters and pollution in Dez River. The trend of changes in quality parameters and pollution in the Dez River showed that this river is better in terms of BOD pollution due to the discharge of urban and industrial sewage, in terms of EC pollution due to the discharge of agricultural land drains (mainly sugarcane plan) and in terms of N-NH4 pollution It is in a critical condition due to urban and industrial sewage and drainage of agricultural land. Therefore, it is suggested that all sewage of Dezful city, sewage of fish farming, Haft Tepe complex and Pars paper factory be treated and then discharged, but regarding agricultural drains, corrective measures such as improvement in the type of irrigation systems, fertilizers , the cultivation pattern of the area, etc., should be done at the source.

The construction of a treatment plant as a solution for all polluting sources seems to be expensive and impossible. Therefore, it is suggested that all sewage of Dezful city, sewage of fish farming, Haft Tepe complex and Pars paper factory be treated and then discharged, but regarding agricultural drains, corrective measures such as improvement in the type of irrigation systems, fertilizers , the cultivation pattern of the area, etc., should be done at the source.

Today, one of the most effective ways to manage and protect surface water resources is to use the capacity of rivers to accept limits of pollution. In this study, the self-purification capacity of the Abbasabad river in Hamedan using the QUAL2KW model, based on the simulation of DO, BOD and COD parameters, taking into account the water quality standards in two areas for drinking (1.86 km) and agriculture (4.33 km) was evaluated. The accuracy of the simulated values was calculated through the calculation of statistical indices such as R2, SE, RMSE and NRMSE. The RMSE values in the validation stage for DO, BOD and COD values were calculated as 0.26, 1.82 and 2.62, respectively. The simulation results showed that the amount of dissolved oxygen decreased by -3.21% in the first period and by -1.66% in the second period. Also, the concentration of BOD and COD increased by 30.13 and 27.94% in the first period and by 70.84 and 60.81% respectively in the second period. Also, TMDL results showed that in the first period, the amount of input load should be reduced, but in the second period, it is possible to increase the input load. For BOD and COD parameters, the maximum load was calculated based on the agricultural standard at the two watersheds, as 49.80 mg/liter and 99.15 mg/liter.

Various wastewaters such as household, industrial and agricultural wastes are entered along the Dez River from different locations. Regarding the water scarcity crisis, a comprehensive study on quantitative and qualitative pollution and using management tools such as mathematical and computer models is needed to predict water quality of this river and to prevent its further pollution. In this research, the qualitative QUAL2K model was used for simulation of NO3-, PO4-3 parameters at seven stations; Chamgolak, Dolat park, third bridge, new bridge, floating bridge, fifth bridge and Gavmishabad. The calibration and prediction of the model was done using quality parameters of the river and other information obtained from the field studies. Also, root mean absolute error (MAE) and coefficient variation (CV) were used to validate the model by comparing the observation and prediction data. The results of the model represent the real conditions of the river to an acceptable level, which indicates the ability of the Qual2kw model for simulation of the quality parameters. Most of the river pollution is caused by urban sewage. According to the results, PO4-3 parameter during the studied period is considered to be threaten to aquatic life. But, according to water quality standard for agricultural use, there is no limitation for Dez River. The low discharge at the river downstream and the high loading of pollutants have increased the concentration of water quality parameters. According to the results of the EF, MAE and CV parameters, the model had the best fit for water nitrate.