Editing Hydrology (section)

=== Groundwater ===
[[File:Building a map of groundwater countours.gif|thumb|250px|right|Building a map of groundwater contours]]
Ground water is water beneath Earth's surface, often pumped for drinking water.<ref name=USGS /> Groundwater hydrology ([[hydrogeology]]) considers quantifying groundwater flow and solute transport.<ref>{{cite journal|last1=Graf|first1=T.|last2=Simmons|first2=C. T.|title=Variable-density groundwater flow and solute transport in fractured rock: Applicability of the Tang et al. [1981] analytical solution|journal=Water Resources Research|date=February 2009|volume=45|issue=2|page=W02425|doi=10.1029/2008WR007278|bibcode=2009WRR....45.2425G|s2cid=133884299 }}</ref> Problems in describing the saturated zone include the characterization of aquifers in terms of flow direction, groundwater pressure and, by inference, groundwater depth (see: [[aquifer test]]). Measurements here can be made using a [[piezometer]]. Aquifers are also described in terms of hydraulic conductivity, storativity and transmissivity. There are a number of geophysical methods<ref name=Vereecken /> for characterizing aquifers. There are also problems in characterizing the vadose zone (unsaturated zone).<ref name=Wilson />