The Hydrologic Cycle:
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/home.rxml
Precipitation:
http://www.cdc.noaa.gov/Drought/
General Information:
http://water.usgs.gov/
http://www.epa.gov/ow/
http://www.groundwater.org/index.htm
http://www.ec.gc.ca/water/en/nature/grdwtr/e_gdwtr.htm
-- excellent site!
Water Resources - excellent site (check out
the Biscayne Aquifer!):
http://sr6capp.er.usgs.gov/gwa/gwa.html
Photos illustrating groundwater and related phenomenon:
http://www.geo.duke.edu/geo41/gw1.htm
http://www.geo.duke.edu/geo41/gw2.htm
Karst Landforms:
http://daac.gsfc.nasa.gov/DAAC_DOCS/geomorphology/GEO_7/GEO_CHAPTER_7.HTML
http://daac.gsfc.nasa.gov/DAAC_DOCS/geomorphology/GEO_HOME_PAGE.html
http://www2.nature.nps.gov/grd/usgsnps/cave/cave.html#backtotop
http://www.goodearthgraphics.com/virtcave.html--
great photos of caves!
http://www.goodearthgraphics.com/under_earth.html--
great photos of caves!