Proposed method: incorporation of fractured rock in aquifer vulnerability assessments

Groundwater from fractured rock aquifers serves as a source of drinking water around the world; however, wells in fractured rock can be susceptible to contamination. Aquifer vulnerability assessments are tools used for identifying the risk potential in groundwater sources, as well as efficiently allocating resources for source water protection. Existing methods include DRASTIC, GOD, EPIK, AVI, COP, and ISI. Some approaches do not consider risks posed by fractures, while others were developed for karstified regions; all are ill suited to fractured formations. This work proposes a new vulnerability assessment method incorporating quantitative portions of existing methods together with fractured rock characteristics. The proposed method is applied to a study area in Acton-Georgetown, Ontario; the DRASTIC and AVI methods are also applied for comparison. DRASTIC and AVI methods yield significantly different results from each other and from the proposed method. The proposed method demonstrates the heavy influence the fractured rock has on vulnerability, highlighting the need for its inclusion in vulnerability assessments.