Under the action of gravity, surface water and groundwater always tend to \IL; }D{
flow from higher to lower elevations. Surface water will flow over solid and "ITC P<+
through permeable formations, and its volume and velocity are a function of E$u9Jbe
the available supply and the fluid head. Groundwater can move only ~ RdD6V
through a pervious material (fractured or fissured rock or soils with Ux Gr+q
interconnected open voids), so its flow characteristic is also a function of $`KddW0_
formation permeability. Groundwater elevation varies as the supply source *8QESF9
varies and can be raised or lowered locally by increasing or decreasing the KC"#
local supply (naturally by precipitation or artificially by pumping a well or N }$$<i2o
irrigating). In general, over a large surface area, groundwater surface is a %1Ex{H hb
subdued replica of ground surface.
