Investigations of Groundwater Flow Systems in Big Creek and Big Otter Creek Drainage Basins, Ontario

Big Creek and Big Otter Creek are two small streams that drain southward into Lake Erie. Five hydrostratigraphic units can be defined in the glacial deposits. The upper permeable zone of the carbonate bedrock is regarded as the sixth. This latter zone is considered to be a continuous hydrostratigraphic unit because of the pattern of potential distribution.In these near-surface materials there are only two orders of flow systems—local and intermediate—with no evidence for regional flow toward Lake Erie. Recharge and discharge zones have been recognized both from potential distribution and field observations. Finite element analyses were used to verify the flow patterns in several sections.The pinch-out of aquifers accounts for anomalous locations of discharge zones (flowing wells) as shown in the theoretical models of Freeze and Witherspoon (1967).Most water-level data were obtained from drillers reports of domestic wells in the bedrock. The water-levels in such wells provide a close approximation of the hydraulic potentials in the aquifer. Of 331 such water wells, only three had reported water levels that were anomalous according to the potentiometric map of the bedrock aquifer unit. On the other hand, data from seventeen carefully installed piezometers confirmed the interpretation of potential distribution and thus the pattern of groundwater flow systems.