Ground-Water Monitoring Wells, Contamination, and Waste Management

Ground water in granular aquifers, fractured aquifers, and in karst systems, moves in response to hydraulic gradients from points of recharge to points of discharge. The horizontal gradient of the ground-water surface, the general shape of the water table, and the general direction of movement can be determined from a water-level contour or potentiometric map. The contours generally are based on the National Geodetic Vertical Datum (NGVD). However, in remote areas it is sometimes necessary to establish a temporary bench mark (TBM) and base line. The general direction of ground-water movement can be estimated by drawing flow lines perpendicular to the water-level contours. Results from tracer test studies can be used to support the interpretation of the direction of ground-water movement as shown by the water-level contour map.