APPENDIX B 



GLOSSARY 



Air mass - A widespread body of air, the properties of which can be 

 identified as having been established while that air was situated 

 over a particular region of the earth's surface and having undergone 

 specific niodi f ications while in transit away from the source region. 



Anticyclone - An atmospheric closed clockwise circulation. Because 

 clockwise circulation and high atmospheric pressure usually coexist, 

 the terms anticyclone and high are used interchangeably in common 

 practice. 



Artesian conditions - Ground water that is 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. 



Bathymetr ic - Relating to measurement of depths; usually applied to the 

 ocean. 



Bedrock - The solid rock, commonly called "ledge," that forms the earth's 

 crust. 



Chemical quality of water - The quantity and kinds of material in suspen- 

 sion or solution and the resulting water properties. 



Chlor ini ty - The chloride content of sea water, measured by mass, or 

 grams per kilogram of sea water, and including all the halides. 



CI imat ic year - A continuous 12-month period, April 1 through March 31, 

 during which a complete annual streamflow cycle takes place from high 

 flow to low and back to high flow. It is designated fay the calendar 

 year in which it begins. 



Continuous-record gaging station - A site on a stream at which continuous 

 measurements of stream stage are made by automatic equipment or made man- 

 ually at least once a day. These records are converted to daily flow 

 after calibration by flow measurements. 



Cubic feet per second (cfs) - A unit expressing rate of discharge. One 



cubic foot per second is equal to the discharge of a stream 1 foot wide 

 1 toot deep flawing at an average velocity of 1 foot per second. 



Cycloqenesi s - Any development or strengthening of cyclonic circulation 

 in the atmosphere. 



Cyclone - An atmospheric closed counterclockwise circulation. 



Seven-day ten-year low flow - The mean daily stream flow for seven consec- 

 utive days occurring on an average once in ten years. 



Degree day - Generally, a measure of the departure of the mean daily tem- 

 perature from a given standard: one degree day for each "f of departure 

 above or below the standard during one day. Degree days are accumulated 

 over a "season" at any point during which the total can be used as an 

 index of past temperature effect upon some quantity, such as plant growth, 

 fuel consumption, power output, etc. 



Pi ssolved sol ids - The residue from a clear sample of water after evapo- 

 ration and drying for one hour at l80''C; consist primarily of dissolved 

 mineral constituents, but may also contain organic matter and water of 

 crystal 1 izat ion. 



Drainage area of a stream at a specified location is that area, measured 

 in a horizontal plane, enclosed by a topographic divide from which direct 

 surface runoff from precipitation normally drains by gravity into the 

 stream above the specified point. 



Estuary - A bay, as the mouth of a riverj where the tide meets the river 

 current, 



Evapotranspiration - Discharge of water to the atmosphere by direct evapo- 

 ration from the land and by transpiration from plants. 



Extratropical cyclone - Any cyclonic-scale storm that is not a tropical 

 cyclone. 



Frequency - The rate of recurrence of an event in periodic motion: The 

 number of times a specified event occurs in a given series of observations. 



Ground water - Uater in the saturated zona. 



Ground-water discharge - The discharge of water from the saturated zone 

 by 1) natural processes sUch as ground-water runoff and ground-water evapo- 

 transpiration and 2^ discharge through wells and other man-made structures. 



Ground-water divide t A 1 ine on a water table on each side of which the 

 water table slopes downward in a direction away from the line. In the 

 vertical dimension, a plane across which there is no ground-water flow. 



Ground-water outflow - All natural ground-water discharge from a drain- 

 age area exclusive of ground-water evapotranspiration. 



Hardness, of water - The property of water generally attributable to salts 

 of the alkaline earths. Hardness has soap-consuming and encrusting pro- 

 perties and is expressed as the concentration of calcium carbonate (CaCOo) 

 that would be required to produce the observed effect. 



Hydraulic conductivity - A measure of the ability of a porous medium to 

 transmit a fluid. 



Hydrogeology - The science that deals with subsurface waters and related 

 geologic aspects of surface waters. 



Impermeable - Having a texture that -does not permit water to move through 

 it perceptibly under the head differences ordinarily found in subsurface 

 water. 



Induced recharcj e - The amount of water entering an aquifer from an adja- 

 cent surface-water body by the process of induced infiltration. 



Injection wel 1 - A well into which water is pumped. 



Isotherm - A line of ^ual or constant temperature. 



Isopleth - A line on a map connecting points at which a given variable has 

 a specified constant value. 



Knot - The unit of speed In the nautical system; one nautical mile per 

 hour. It is equal to 1.1508 statute miles per hour or 0.51'+'* meters per 

 second. 



Milliqrams per liter (mq/1 ) - A unit for expressing the concentration of 

 chemical constituents in solution by weight per unit volume of water. 



Palmer Drought Index - Provides a measure of drought severity as well as 

 duration. It treats drought severity as a function of accumulated 



weighted differences between actual precipitation and the precipitation 

 requirements, where the requirement depends on the carryover of previous 

 rainfall as well as on the evapotranspiration, moisture recharge and run- 

 off that would be climatically appropriate for the particular time and 

 place being investigated. 



Perennial stream - A stream that flows during alt seasons of the year. 



pH - The negative logarithm of the hydrogen-ion concentrations. Ordinar- 

 ily a pH value of 7.0 indicates that the water is at Its neutral point; 

 values lower than 7-0 denote acidity, those above 7-0 denote alkalinity. 



Recharg e - The amount of water that Is added to the saturated zone. 



Recurrence interval - The average interval of time between extremes of 

 streamflow, such as floods or droughts, that will at least equal in 

 severity a particular extreme value over a period of many years. 

 FrequencVf a related term, refers Eo the average number of such extremes 

 during the same period. The date of a drought or flood of a given magni- 

 tude cannot be predicted, but the probable number of such events during 

 a reasonably long period of time may be estimated within reasonable limits 

 of accuracy. 



Runoff - That part of the precipitation that appears In streams. It is 

 the same as streamflow unaffected by artificial diversions, storage, or 

 other works of man in or on the stream channels. 



Sal ini ty - A measure of the quantity of total dissolved solids in water. 



Salt-water encroachment - The phenomenon occurring when a body of salt 

 water, because of its greater density, invades a body of fresh water. 



Saturated thickness - Thickness of an aquifer below the water table. 



Saturated zone - The subsurface zone in which all open spaces are filled 

 with water. The water table is the upper limit of this zone and the water 

 in it is under pressure greater than atmospheric. 



Sedimentary rock - Rocks formed by the accumulation of sediment. 



Specific capacity, of a well - The rate of discharge of water divided by 

 the corresponding drawdown of the water level in the well (gpm/ft) . 



Stratified drift - A predominantly sorted sediment laid doun by or in 

 meltwater from a glacier; includes sand and gravel and minor amounts of 

 silt and clay arranged in layers. 



Ti 1 1 - A predominantly nonsorted, nonstrat I f led sediment deposited direct- 

 ly by s glacier and composed of boulders, gravel, sand, silt, and clay 

 mixed in various proportions. 



Tropical cyclone - The general term for a cyclone that originates over the 

 tropical oceans. Fully mature tropical cyclones range in size from 60 

 miles in diameter to well over 1,000 miles in diameter. 



Uater table - The upper surface of the saturated zone. 



Hater year - A continuous period October I through SsptanibEr 30 during 

 which a complete streamflow cycle takes place from low to high flew and 

 back to low flci'j. A water year is designated by the calendar year in 

 which it ends. 



Wind rose - Any one of a class of diagrams designed to show the distribu- 

 tion of vjind direction experienced at a given location over a considerable 

 period; it thus shows the prevailing wind direction. 



B=1 



