A formation, group of formations, or part of a formation that is waterbearing. Artesian conditions, Occurrence of ground water under sufficient pressure to rise above the level at which it is encountered by a well, but which does not necessarily rise to or above the surface of the ground.-Base flow, Sustained or fair-weather flow. In most streams, base flow is composed largely of groundwater discharge. Bed material, Sediment deposited on the surface of a stream bed. Carbonate hardness, Hardness of water due to calcium and magnesium bicarbonate and (or) carbonate. Clay, Sediment composed of particles having diameters less than 0.004 mm. Color (of water), A visual effect due to material in solution. Cone of depression, The depression, roughly conical in shape, produced in a water table or piezometric surface by pumping (or artesian flow). Correlation, coefficient of, A measure of the degree of relationship between variables. Numerically, the coefficient of correlation (r) ranges from 0 (no correlation) to ± 1 (perfect correlation). The sign is positive if the dependent variable (ordinate value) increases with increases of the independent variable (abscissa value); negative if the dependent variable decreases with an increase in the independent variable. Discharge area, Area of land or body of surface water where ground water discharges naturally directly from the zone of saturation. Dissolved solids, Residue from a clear measured sample of water after evaporation and drying for 1 hour at 180°C. Expressed as parts per million. Drainage area, The area above a specified location that contributes water to a stream. It is measured in a horizontal plane, which is enclosed by a topographic divide in such a way that direct surface runoff from precipitation normally would drain by gravity into the stream above the specified point. Flow-duration curve, A cumulative frequency curve that shows the percentage of time that specified discharges are equaled or exceeded. Fluvial sediment, Fragmental material transported by, suspended in, or deposited by water. Gaging station, A particular site on a stream, canal, lake, or reservoir where systematic observations of gage height or discharge are obtained. A primary gaging station provides a long-term sample of the rate and amount of flow in the hydrologic province for which it serves as an index station. A secondary station provides a short-term sample of rate and flow in an area, which, through correlation techniques, can be related to flow at a primary gaging station. A partial-record station is a particular site where limited streamflow data are collected over a period of years. Ground water, The part of subsurface water that is in the zone of saturation. Hardness, The effect of calcium, magnesium, and other cations having soapconsuming and encrusting properties. Expressed as the calcium carbonate (CaCOs) equivalent in parts per million. m IV GLOSSARY OF TECHNICAL TERMS Mean annual flood, The flood having a recurrence interval of 2.33 years. Micromicro, Prefix meaning 10~12 ; symbo...