The part of a stream discharge that is not attributable to direct runoff from precipitation or melting snow. It is sustained by groundwater discharge and may be considered as normal day-to-day flow during most of the year.
A surveyed line that serves as a reference to which surveys are coordinated and correlated.
Unconsolidated material such as sand, gravel and silt, eroded from surrounding mountains and deposited in a valley
A technique used to collect information on groundwater level conditions by measuring selected wells throughout a basin. Specific and randomly selected wells are measured to provide the best aerial and vertical coverage in the basin