6.1 Using Polar Coordinates

Radial flow can be described using a polar coordinate system, where r is the radial distance from an origin (a pumping well) to an observation point (Figure 17). The position of the observation point is defined by r and an angle, θ, measured from a horizontal axis (polar axis) in a counterclockwise direction (Figure 17). When conditions are isotropic and homogeneous, the water bearing unit is horizontal, and the open area of the pumping well fully penetrates the unit, the angle θ becomes unimportant as all flow is horizontal and thus is the same on every radius (Fetter, 2001).