Fundamental Concepts of Groundwater Flow

This chapter introduces the basic concepts of groundwater flow through porous media and discusses the principal components of the hydrologic cycle. The concept of porosity is used as a measure of the water volume stored within subsurface porous materials. Water may be released from storage by simple drainage and through elastic changes in the groundwater or aquifer system. Frictional energy losses that result from flow within the porous media are expressed by the Darcy equation, which relates the rate of change in hydraulic head to the rate of groundwater flow into the water well. The groundwater flow system also is characterized mathematically by a combination of the mass balance equation and the Darcy equation. Both the three-dimensional and the two-dimensional horizontal forms of the mass balance equation are often used to quantify the groundwater that enters the water well through the intake pipes.