Under the action of gravity, surface water and groundwater always tend to 3\&I7o3V
flow from higher to lower elevations. Surface water will flow over solid and ?4MZT5 .
through permeable formations, and its volume and velocity are a function of #]FJx
the available supply and the fluid head. Groundwater can move only 38gEto#q
through a pervious material (fractured or fissured rock or soils with )dZ1$MC[
interconnected open voids), so its flow characteristic is also a function of Kma-W{vGD
formation permeability. Groundwater elevation varies as the supply source ETtoY<`#
varies and can be raised or lowered locally by increasing or decreasing the }tUr
V
local supply (naturally by precipitation or artificially by pumping a well or p#tbN5i[{7
irrigating). In general, over a large surface area, groundwater surface is a yU< "tg E
subdued replica of ground surface.