Patterns of Groundwater Flow in Heterogeneous Systems

The presence of heterogeneity can exert a tremendous influence on patterns of groundwater flow. This heterogeneity may occur at a variety of scales, from large-scale lithological layering, to small-scale variations in permeability produced by subtle variations in grain size or compaction, or by variations in fracture spacing and aperture. Flow lines will be focused into more permeable zones, as shown in the video below.

This video shows the pattern of flow (indicated by the purple dye) in a laboratory sand box. A coarse layer at the bottom represents a permeable confined aquifer. Above the thin confining unit is a medium-grained unconfined aquifer with several gravel lenses. Flow is from right (high hydraulic head) to left (low hydraulic head).