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THE GENERATION OF SPRING PEAK
SHORT-TERM METEOROLOGICAL
HAROLD
F. HAUPT
flows recorded over a 25-year period in Benton Creek, a
were studied in their relation to meteorological events. More
rallrl-on-snnw than by clear-weather snowmelt; the two types of peaks differ
Ch,trai:te1 1stLCS. Two rather simple techniques were used to calculate the gerler:ltn/e
and the hypothetical outflow of water from a snc)wIJaC:k
data on spring peaks on two regional subbasins were corlSldlere~d
4
Short-term meteorological conditions-usually lasting less than
accelerate streanlflow during the rising stage of spring runoff in the northern
Mountains.
Heavy rain falling on the snowpack may directly contribute excess water to snowmelt runoff in
some years. In other years, a stationary airmass accompanied by continuous warm temperatures
about a
lead to a very high rate of heat transfer to the snowpack and indirectly
':If'£"'AI~~r':ltl£"''1.n of melt and runoff. These contrasting types of events, because of
often
about
peaks on small drainages.
flow runoff on mountain streams has
attention has
to the concurrent meteorology. -------~-J
methods for determining the frequency and magnitude of peak
were pUbll~)nea
excellent volumes by Bodhaine and Thomas 1964, and Thomas, Broom,
1963.
There was need for an ensuing study of ambient rainfall-temperature events in relation to
runoff, covering their relative frequency of occurrence, their synchronization with maximum
conditions, and their generative capacity.
This paper deals with such relationships on small subbasins. Detailed information was
obtained from an analysis covering hydrometeorological records collected on a small forested
watershed in northern Idaho. Somewhat less extensive records from two regional subbasins are
also discussed.
QUALIFICATIONS OF THE STUDY WATERSHED
Scarcity of weather data has been the main deterrent to studies of this kind. For the northern
Rocky Mountains, as for other regions of heavy snow accumulation, climatic and streamflow
data are scanty. Coverage by rainfall-temperature reporting stations in mountainous terrain
However, long-established facilities on Benton Creek within
Priest
Idaho, are an
Here the cOlnblnaltloln
on)xrmll:v to a
"'<1.o,n+ ...... o ....
River Experimental
included
runoff, classification
of interdependence
and determination of an index of
the snowmelt season was
1"7-="rl
nrf'\l'-="rlnr-="c
nr-f',,,, ... rf .....,rY
'Clr'l'=1
1965 according to the
\Q>~'")1-.1:T,a
at
station
of peak
Station
not converted to
to
Dn~vallellce of adiabatic conditions in
spring
fallen as snow. A
volume was arbitrarily
as
if the
totaled more than 0.50 inch during a
than 0.50 inch of rain fell, the
was listed as
by snowmelt.
Int·A~,rfAl"'A"t",rit:.nr'A of multiple peaks in the same season was given careful consideration
magnitude. A late-season
peak" coasted" downstream, in
on the recession of an earlier rise streamflow. This contributed to est:alJi!lS,nnlerlt
volume, but such a
was rejected in the analysis as a true me;aSl1re
1-" of a short-term
To isolate the event and ellmlJnalte
·nro't- ...... rr the
r r A ....
l r n l '... r""'\r1"'Jl1r"A
rY\«:l'r)C11~r..:.ri
"".o...... ,o., ...·n ... '["""'" "'n ..... n "••
" ... If--I.-t- .....
M
0.04
inches for a forest
and Tmax is the daily maximum temperamaximum temperature recorded at
station
sequence
volumes
56
50
4-22
5-13
1
5-16
64
.547
.511
.443
.436
.366
.314
.314
.246
.00
.06
.07
.00
.00
.00
.06
.14
Surface
meltEq. 1
(4)
Rainfall
meltEq. 2
(5)
7.32
6.64
6.68
8.88
9.80
7.92
5.56
8.20
7.36
.00
.01
.01
.00
.00
.00
.01
.02
.04
8.08
.04
Maximum
7.32
6.71
6.76
8.88
9.80
7.92
5.63
8.36
.77
1.02
.36
1.52
2.43
.99
7.80
.14
7.61
6.98
3.64
.80
.96
.88
.84
1.04
2.84
MaximUlll temperature sequence
6-day
rainfall
Surface
n1elt1
(11 )
Rainfall
meltEq.
(13)
Index of
outflow
potential
(14)
-----------lnches------------
3.06
0.66
.36
7.36
8.84
0.10
.06
.04
.00
8.67
6.51
8.01
,/"",.1"'1"0,1""\.0'"
of maximum rainfall
0.4
snow data from
Benton Springs Coooeralt1\i'e Snow
of Engineers (1960) used
..L'~LAI;-'
maximun1
flood
of a
that even when
maximum observed rainstorm
rain-an-snow formula, calculations yielded a flood crest
snowmelt alone. They attributed this to concurrent meteorological
When a low-temperature rainfall-producing airmass is
as operaless heat must be considered available for snowmelt than under clear-weather
z-",..,LL ....
...........
0r'\'t"\r1-,f-tr'\"t"\IC'
vV_1Ll\-JYI.UI..lV.Llu.
SU1PPJreSSlIJLg influence of rainfall on ambient air temperatures
ON SPRING PEAK CONDITIONS IN TWO
by
LL1IVAL''vU\. .lVA.
L"-A-I'uJl,--'J.""<"""" ;::)\.JDJ:)}-\;:)[l"l;:)
.l,
on Boulder
incomplete
three stations were cOlnblne:d
semblance
continuous seasonal record of rainfall data
of rainfall inforn1ation
\vas the U. S. Weather Bureau Monthly Climatological Data. Stream records were obtained from
Papers and Idaho State water resource summaries
the S. ue:01()j;!JCal
and magnitude of
volumes was
in test
of streamflow regimes on Benton Creek and two
drainages. In statistical
comparisons of the timing of spring peak volumes, coefficients of correlation were found to be
very low-that is, .117 for Benton Creek vs. Boulder Creek and .526 for Benton Creek vs.
South Fork of the Clearwater River. Agreement was
of
by mclgUtItlLQe
and the time of
peak on Benton
rise and fall on the other stream. The spring
with the
or fourth
",",-1"l:"\~"'1"f",",-""" between Benton
coefficients
.992
the
streamflow
elevation rarlge~-re~;pC)nClea
11nth"'l"n-tttu
QUl"lf"I-'l"Anl'";rp>fi
" ' " ' - ..A . . .
,allo1"f'"'- .....
on Boulder
capacity of
volume weather
(Boulder
stations)
Year-month
(6)
5
60
5
.428
.00
50
5
.730
.565
48
5
5
.081
.075
.053
.039
.038
8
57
5
47
5
5
44
.017
exceeded
,627
.580
.256
.435
.16]
.156
.107
.51
Year-month
capacity of
weather event
(11 )
49
1.
more than one-half of the spring peak volumes
associated with ">~n,..-.
,,. ...... '..,--..."7
J.1.1''''~J.J.J.J.\.~1.J.1. spring discharge, for years of rain-an-snow
with the ending day of maximum rainfall than it was, for years of
the ending day of maximum temperatures.
3. In some years heavy rainfall, accompanied by relatively high air
the generation of spring peak runoff, whereas in other years heavy rainfall
SU1Jo]~es:seffect on air temperature, so that snowmelt contribution to runoff was
spring peak volumes did not occur.
The highest peak runoff of record was a snowmelt event.
VII"'JIII\JIII',,,"-,\1
I.VUl1l-".,..lUI.UJ.vJ.
Creek-South
ClearlDater River
1. Three-fourths of all the spring peak volumes studied
snowmelt alone; in the South Fork, 52 percent of the
n-un-()n··sniOW events.
Boulder
floods