FLOOD07843

• County: Statewide
• Basin: Statewide
• Title: Nationwide Summary of US Geological Survey Regional Regression Equations for Estimating Magnitude and Frequency of Floods or Ungaged Ssites 1993
• Date: 1/1/1993
• Prepared By: USGS
• Floodplain - Doc Type: Educational/Technical/Reference Information

The following infonnation
region:

is stored for each hydrologic

mle

Comment

The name of hydrologic region i:
Examples: AreaJ
Region_A
Southern Region
The name of the hydrologic region
specified is preceded by a $,
Examples: $Atlanta.citywide,
urban
$Georgia_statewide_
urban
The number of variables witbin the
region's equations.

The following infonnation is stored for each variable in a
region:

Name of hydrologic region

# of variables in equations

mlo Comment

Variable name Name of variable as it might appear in an
equation.
Examples: A
ST

Variable descriptor Description of the variahle,
Examples: Drainage.Area_(s,!-mi)
Basin_storage_(%)
Variable minimum Minimum value of variable. A floating
point.
Variable maximum Maximum value of variable. A floating
point.

FOR EACH OF THE RECURRENCE INTERVALS IN
ORDER (2, 5, 10,25, 50, 100,500):

Title Comment

Standard error for equation The calculated standard error for
the equation. A floating point
number, A 0.0 is entered if no
standard error data exists.

Equivalent years record The number of equivalent years
record for the equation. A float-
ing point number. A 0.0 is
entered if no equivalent years
record data exists.

Regression Constant, C The constant term of the regres-
sion. A floating point number. A
0.0 is entered jf no data for eUf-
rent recurrence interval exists.

-

Ti1Ie Comment

# of components in equation The number of components
(excluding constant) in the
regression equation. ALWAYS
>= 1. An integer. A 0,0 is
entered if no data for current
recurrence interval exists.

I
i
.
j
I
I
!
!
,
I

FOR EACH COMPONENT IN EQUATION:

mle Comment

Base Variable Index Index of base variables within the
list of name and descriptors
entered above. An integer.

Examples: I (for A)

2 (for S1')

A 0,0 is entered if no variable
exists for component.

Base Variable Modifier Modifier added to base variable
before the multiplier is applied,
A ftoating point number,

Base Variable Multiplier Value by which base variable is
multiplied, A ftoating point
number.

Exponent Constant The exponent constant for the
base variable, A ftoating point
number.

Exponent Variable Index The index (in the list of names
and descriptors entered above)
of the variable which appears in
the base variable's exponent. An
integer, A 0,0 is entered if no
exponent variable exists.

Exponent Variable Modifier Modifier added to exponent vari-
able

Exponent Variable Exponent The power to which the exponent
variable is to be raised, A ftoat-
ing point number.

EXAMPLE
ID Code: NS
State: North Somewhere
I of regions: 2
(Note - A variety of equations is used to illustrate the various
formalS that can be used, These equations are merely
examples.)
Region 1 's Equations:
RQ2 = 56.7Ao,335 SLO,235, standard error 46%,7 equivalent
years record
RQ5 = 64.IAo,224 (SL. 1.0p.345 (ST + 2,0)"0,234, standard
error 38%

RQIO = 72.4A 0.345A -0.02 (SUIOOO)O,234, 10 equivalent
years record
RQ25 = NO EQUATION AVAILABLE

192 Nationwide Summery 01 U.S. Geologlcol Survey Regional Regreaalon Equatlonelor Eatlmetlng Magnitude and Frequency 01
Flooda lor Ungeged Site., 1993