A Comparison of Delineation Methods for Wellhead Protection Area Case Study: Drinking Wells of Hamedan City

Well Head Protection (WHP) area, is a surface or subsurface area around a well which supplies extracted water from a well and therefore the pollutants entering the groundwater in this area would finally pump out from the well. In this study while introducing calculated fixed radious (CFR) method for determining WHP area of a single well, other conventional methods like analytical methods (Wyssling and KLF) and numerical models are also compared using nine pumping wells suppling drinking water for Hamedan city, Iran. The results indicated that by increasing the time of travel (increasing distance from a well), calculated fixed radious and analytical methods would lose their accuracy compared to the numerical modeling. CFR calculated values indicated under-protection on the upgradient side and over-protection on the downgradient side of a well head protection area. Moreover, in spite of the fact that the protection areas which calculated by KLF and Wyssling analytical methods, compared to the fixed radius method, are covering further area compared to the calculated protection area by numerical models, the narrow extended shape showed that the results does not cover considerable lateral distances of calculated protection area. Generally, the numerical models are the most accurate methods to draw well head protection area. In case of insufficient data, time, fund, and knowledge, however applying simpler methods like calculated fixed radius method and analytical methods would also lead to acceptable results.