This page provides a brief outline of, lists the main points of, gives links to figures for, and lists the assigned reading for a lecture in Dr. Bruce Railsback's GEOL 1121 class at the University of Georgia. This page is not intended as a set of lecture notes, and it cannot subsititute for a set of lecture notes. Familiarity with this page alone will not assure satisfactory grades on exams in the course.

Lecture 24 (Monday, March 25, 2002): Groundwater I (Physical Hydrology)

Brief outline of this lecture:
Porosity and permeability
The water table
Groundwater locations
     

Main points of this lecture:
Porosity and permeability are critical in controlling where groundwater is and where it flows.
An aquifer is a porous and permeable body of rock or sediment.
The zone of groundwater saturation is the pat of the earth in which non-mineral space is filled with water (or oil or natural gas) rather than air.
The water table is the surface at the top of the zone of saturation (in an unconfined aquifer).
The geometry of the water table is commonly a subdued replica of the land surface.
Most groundwater discharges into river (or into the ocean).
Groundwater is recharged or sesupplied by rainwater than has percolated down through the zone of aeration in soils.
Streams, rivers, lakes, ponds, and marshes are intersections of the water table with the land surface.
Groundwater usually moves in the downslope direction of the water table.
Most water in streams and rivers comes from groundwater discharge.
Extensive removal of groundwater results in a cone of depression in the water table.
The elevation of the water table can be inferred from the elevation of lakes, ponds, streams, and rivers, and from the depth to water in wells.
Such elevations can be used to construct a map of the water table in a given area.
Such maps can be used to predict the depth to which wells will have to be drilled to reach water.

Figures used in this lecture:
Porosity and permeability
Permeability of various materials
The water table and the zones of saturation and aeration
Where groundwater resides
Vertical cross-section of a typical groundwater system
The same groundwater system after extensive pumping
A topographic map of a hypothetical area
The same map with locations of a few wells and estimates of the elevation of the water table
The same map with one contour of a map of the water table
The same map with a map of the water table
The same map with estimates of depths to which wells would have to be drilled to reach the water table

Reading assignment: pp. 225--233 (to "other features . .").


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