This lecture introduces the idea of flow continuity and the derivation of the Laplace equation for computing seepage in soil. The concept of equipotential (or head) lines and flow lines are introduced. Flow nets are briefly introduced.

Critical Questions to Consider:
1) What are the two main assumptions made in deriving the Laplace equation? What do you think about them?
2) Why would we want to know the total head at any point in a soil mass where seepage is occurring?