Management Practices on Agricultural Non-Point Source Pollution (Aslanduz to Parsabad Spatial Range, 1993 to 2007)

Document Type : Research Paper


Department of Water Engineering and Management, College of Agriculture, Tarbiat Modarres University, Tehran, Iran


Recently, to control the adverse effects of agricultural management practices on surface water quality, it is essential to identify factors that affect the pollution of agricultural non-point source pollution. Therefore, the management of agricultural non-point resources pollution and prevention of non-point pollution transmission is one of the important ways to reduce surface water pollution, especially Rivers. In addition to the importance of environmental biology, the Aras River plays an important role in the lives of nearby people. Therefore, the comprehensive modeling of surface water system is a good approach for identifying and determining the amount of nutrient reduction caused by the application of management scenarios and it can be a useful tool to prioritize the design to improve the quality conditions and meet water quality standards in the water body. Therefore, any management strategy before implementation should be simulated in the form of simulated management scenarios and their efficiency. The main purpose of this study is simulation and evaluation of factors affecting on agricultural non-point pollution and the impact of land use management practices, such as land use management and chemical fertilizer consumption management under different scenarios, on reducing the load and improving the impact of non-point pollution and improving water quality on this river 60 km range using MIKE11 numerical model and evaluating their impact on reducing nutrient load.
Aras river, the largest river of northern Iran was selected as a case study in this study. The maximum flow in the studied area is 1100 m3/s at Aras dam and 2,600 m3/s at Moghan Dam site. However, the mentioned values may reach 32 and 180 m3 / s respectively in dry season respectively. In recent years, with the increase of adjacent agricultural land and low flow rates, the load of agricultural pollutant resources has been known as one of the main factors of Aras river pollution.
MIKE11 model, a one-dimensional tool with strong hydrodynamic to manage and evaluate the performance of river systems, beals, irrigation canals and … by the Danish hydraulic Institute (DHI) is developed. in this study was used to identify the factors affecting the agricultural non-point source pollution and management of simulation scenarios to reduce river pollution during the study area of hydrodynamic module (HD) module whit advection-dispersion (AD) is used.
The main data for hydrodynamic simulations and river quality include topographical maps, irregular triangle network (TIN), land use maps, hydrometer and qualitative studies of the study area from the regional water administration and agricultural jihad in Ardabil province. For hydrodynamic calibration of water level data and also on the research goals and data quality monitoring data, concerning the availability of water quality data, nitrate and phosphate were selected as water quality indices for calibration. The calibration station was used in the parsabad station from May 2007 to May 2008. In this study, Manning's roughness coefficient was used to resist the bed roughness.
To investigate the quality of water and to estimate the quality and load estimation of nitrate and phosphate pollution of the river, qualitative parameters were calculated monthly at the river section and a drain stream. Based on the processes governing the nitrate and phosphates and the results of sensitivity analysis in the river, the parameter of the applied fertilizer conversion factor is estimated as a calibration coefficient using the mass equilibrium method of solution in the river.
The results showed that the coefficient with Manning's modulus of 0.35 is better compared with other coefficients. The calibration results of the dispersion coefficient were determined based on the comparison of nitrate concentration and phosphate with the measured value at the parsabad station. Based on the Fisher's relation (Dx = m2 / s) in case a = 66.2 and b = 0.52 with RMSE of 0.81 mg / l and 0.08 mg / l, respectively, for nitrate and phosphate, respectively. In general, the average runoff run off of the region, % 10 / 2 and %3 / 7 of nitrate fertilizer and input phosphate were calculated. According to the results of the validation, the model performance with Manning roughness coefficient n and runoff coefficients are approved by water levels of nitrate and phosphate from June to December 2008.
In this study, land use observations and fertilizer use are used to determine factors affecting the sources of pollution in agricultural land. Agricultural and fertilizer fields were carried out as factors affecting the sources of agricultural pollution in the form of four scenarios in 1993 (scenario 1), 1997 (scenario 3), 2003 (scenario 3) and 2007 (scenario 4). Simulation results show that nitrate and phosphate loads in the aras river output increased from 730/4 kg /s and 58/6 kg /s in 1993 to 814.3 kg / s and 61.1 kg / s in 2007. Also, due to the increase in the amount of fertilizer, there has been a significant increase in agricultural pollution in the region. So from 1993 to 1997 (existing conditions) levels of nitrogen and phosphorus fertilizer in 320 kg / ha and 81 kg / ha in 1993 in 500 kg / ha and 120 kg / ha reached in 2007. Due to the above results, land use and fertilizer have a significant impact on the load of agricultural pollution; therefore, in the next step, it will be carried out to implement the measures of land use management and fertilizer. According to Aras River, agricultural water supplier 3 ranges (aslanduz, cultivation, industry and parsabad), the area land use was divided into 3 domains.
In the scenario of land use management, when agricultural planting is reduced, nitrate and phosphate loads have been greatly reduced in the Aras river output. in the first scenario, nitrogen and phosphorus charges were estimated at land use 540/72 kg / s and 50/83kg / s respectively.
also, nitrate and phosphate loads were decreased by 34 % and 16 / 8 % in comparison to the existing conditions, so it could be concluded that the reduction of non-point pollution due to low-level reduction of agricultural land.
4 scenarios were simulated to implement fertilizer management efforts. in scenarios 1 and 2 non-point pollution loads are reduced compared to the conditions available due to the decrease in the amount of fertilizer. however, in scenario 3 and 4, with increasing load loading, the load contamination of agricultural non-point pollution was significantly increased. In the scenario 4, given that the amount of fertilizers increased to 1.5 times. the nitrate and phosphate loads were also increased to 18/02 and 8/51 times as compared to the existing ones. Therefore, due to the results, the increase in the amount of fertilizer leads to more nutrient loss.
this study was conducted under different scenarios to investigate the effect of management strategies to reduce river water pollution in the aslanduz to parsabad. first, the factors influencing the pollution of agricultural pollution in the study area were then determined the effectiveness of management measures to control agricultural pollution with MIKE11 model. management practices were carried out in the form of land management scenarios and fertilizer. Managerial practices were carried out in the form of land management scenarios and fertilizer. different amounts of nitrate and phosphate were directly proportional to the use of land use and land use. simulation results show that the effect of different scenarios of fertilizer and land is similar in reducing the nutrient load of the same river.
so as to reduce the cultivation area under cultivation, pollution charges have been reduced and the maximum contamination of non-point pollution with 34 % in nitrate has been reduced. also, with an increase of 1.5 times the amount of fertilizer compared to the present situation, the nitrate increased by 18/02 % with the highest change