عنوان مقاله [English]
Background and objectives: Groundwater reserves in Iran is one of the main sources of water supply that in recent decades, the emergence of factors such as development, increased groundwater extraction and drought has reduced the quantity and quality of these resources. Therefore, proper management should be done to protect and sustain these valuable reserves and to avoid further negative consequences as much as possible. Lack of proper management in the operation of Birjand aquifer, the necessary conditions for subsidence, an irreparable accident, provides this plain. Therefore, given the importance of these valuable reserves, appropriate strategies for the sustainability of these resources should be considered. By increasing awareness about the quality of groundwater in this area and simulating the transfer of potential contaminants in these waters, we can understand the direction and speed of contamination transfer, determine the areas that are at risk of groundwater pollution in the coming years. Identification and analysis of aquifer status were evaluated in order to evaluate the effects of management scenarios.
Materials and methods: At first, numerical modeling of Birjand aquifer was performed. MODFLOW numerical simulation of Birjand aquifer area was performed in two permanent and non-permanent modes in 2011. Then the hydraulic conductivity calibration was performed on the mentioned date and validated for two years 1391 and 1392. Then, the necessary scenarios for the project, considering different points for wastewater discharge and artificial feeding, were defined. Finally, the effects of reduction, increase and decrease of 20% harvest on pollutant movement were investigated using MODPATH.
Results: The calibration results show that the observed and calculated mid-level error (RMSE) is 1.071 meters, which is desirable. Also, the level calculated by the model indicates the movement of groundwater in the direction of the dominant slope of the region, ie from east and northeast to west and southwest. Also, the way particles move corresponds to the groundwater gradient and in the general direction from east to west. The length of motion of the particle at a given time in the eastern part of the aquifer is less than the western part.
Conclusion:According to the applied scenarios, it can be concluded that increasing and decreasing the withdrawal of Birjand groundwater by 20% does not make a significant difference in the direction and route of pollutant transfer during 10,000 days, but the artificial feeding scheme has a significant effect on the transfer Leaves pollutant particles. Therefore, due to the problems in the groundwater of Birjand, the implementation of artificial nutrition plan for this city is necessary.