ABSTRACT
Under the action of gravity, surface water and groundwater always tend to flow from higher to lower elevations. Surface water will flow over solid and through permeable formations, and its volume and velocity are a function of the available supply and the fluid head. Groundwater can move only through a pervious material (fractured or fissured rock or soils with interconnected open voids), so its flow characteristic is also a function of formation permeability. Groundwater elevation varies as the supply source varies and can be raised or lowered locally by increasing or decreasing the local supply (naturally by precipitation or artificially by pumping a well or irrigating). In general, over a large surface area, groundwater surface is a subdued replica of ground surface.
