Conversion Factors, Datums, and Abbreviations and Acronyms


Conversion Factors


Multiply	By	To obtain
inch (in.)	2.54	centimeter (cm)
inch (in.)	25.4	millimeter (mm)
foot (ft)	0.3048	meter (m)
mile (mi)	1.609	kilometer (km)
square mile (mi2)	259.0	hectare (ha)
square mile (mi2)	2.590	square kilometer (km2)
acre-foot (acre-ft)	1,233	cubic meter (m3)
acre-foot (acre-ft)	0.001233	cubic hectometer (hm3)
cubic foot per second (ft3/s)	0.02832	cubic meter per second (m3/s)
cubic foot per second per square mile [(ft3/s)/mi2]	0.01093	cubic meter per second per square kilometer [(m3/s)/km2]
ton, short (2,000 lb)	0.9072	megagram (Mg)
ton, long (2,240 lb)	1.016	megagram (Mg)
ton per square mile (ton/mi2)	0.3503	megagram per square kilometer (Mg/km2)
ton per year per square mile [(ton/yr)/mi2]	0.3503	megagram per year per square kilometer [(Mg/yr)/km2]

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:


°C=(°F-32)/1.8


Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25 °C).


Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or micrograms per liter (µg/L).


Datums


Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).


Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).


Altitude, as used in this report, refers to distance above the vertical datum.


Abbreviations and Acronyms


Abbreviation or acronym	Definition
BCF	Bias correction factor
EWI	Equal-width increment
FNU	Formazin Nephelometric Units
MAE	Mean absolute error
MAPE	Mean absolute percent error
MSPE	Model standard percent error
NWIS	National Water Information System
RMSE	Root mean squared error
SSC	Suspended-sediment concentration
SSL	Suspended-sediment load
SSY	Suspended sediment yield
USGS	U.S. Geological Survey

First posted October 3, 2012