عنوان مقاله [English]
Delineation of the wellhead protection area for drinking water wells is an effective method to manage and protect water supply resources and it is important in public health. Therefore, this study aimed to determine the wellhead protection area to avoid contamination of drinking water wells, by drawing an area around wells that should be prevented the development and creation of any pollution in this area using a mathematical model. In order to drawing the wellhead protection area of 46 drinking water wells in Zarringol plain in Golestan province GMS7.1 software was used. For this purpose after providing conceptual model to determine the hydrodynamic coefficients of aquifer, the model has been run in steady-state and unsteady-state, and then it has been calibrated for one month in steady state and afterward for 5 years with seasonal stress in un-steady state. After ensuring the accuracy of the model, to determine the wellhead protection area for drinking water wells, the MODPATH particle locating was used. After providing wellhead protection area for1, 2, 3 and 5 years of the wells, the effect of various parameters on the form and how to extend wellhead protection area was discussed and evaluated. Based on the results of the study, determining the groundwater flow direction and hydraulic gradient are the most influential factors in the safety and privacy of a well since increasing hydraulic gradient causes narrowing and stretching of safety zone of well. The rate of pumping also is the other factor which could be effect, by increasing pumping rate the wide of safety zone of well will be increased, however it has no effect on the long of safety zone. The other parameters such as hydraulic conductivity and specific yield are next order of importance.