FLOOD05589

• County: Statewide
• Community: Statewide
• Stream Name: All
• Basin: Statewide
• Title: Ephemeral Streams Hydraulic Factors and Their Relation to the Drainage Net
• Date: 1/1/1956
• Prepared For: State of Colorado
• Prepared By: USGS
• Floodplain - Doc Type: Educational/Technical/Reference Information

EPHEMERAL STREAMS

11

Figure 9 presents the data for suspended load at
various discharges (the suspended-sediment rating
curve) measured at two Geological Survey sediment
stations. The same section is used for both discharge
and suspended-load measurements at the Domingo
station on the Rio Galisteo. For the other example, the
sediment station is located 11 miles downstream from
the gage on the Rio Puerco at Cabezon. Because no
major tributaries enter in this reach of the stream, the
sediment and discharge records may be considered
essentially comparable.
The data from sediment measurements in small
ephemeral streams are shown on figure 10, along with
curves for the two sediment stations. In each arroyo
cross section we measured only a single flood, \vhereas
in regular sediment operations each measurement

represents generally a different hydrograph rise or
different day. Nevertheless, lines drawn through our
meager data agree very well with the sediment-rating
curves of the regular sediment stations. Furthermore,
the scatter of our data obtained by wading measure-
ments (fig. 10) is no greater than that for the stations
(fig. 9). This suggests that the suspended-load rating
curve at a given cross section in a western ephemeral
stream can be approximated by a series of measure-
ments during one or two floods.
The relation of suspended load to discharge has bee"
expressed as

L=pQ'

where L is suspended load in tons per day (Leopold and
.\1addock, 19.53). Values of j (slope of the suspended-
sediment rating curve) for arroyos range from 1.09 to

Rio Galisteo at Domingo. New Mexico

100,000

.
.
.

>-
<<
o
~
w
~
on
z
o 10,000
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ci
<<
g
"
z
w
"
o
w
on
,
o
w
o
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on
=>
on

.
.

,. :-

1000

.

.

.
I .
100 ~-.
.'+:.
~.
,-.

1
.-
I
.

10

10

100

DISCHARGE, IN CUBIC FEET PER SECOND

10

100

1000

{'
....
9.4.-1.
i??L
.0
"

.

500

Rio Puerco at Cabezon, New Mexico

'I'
.....
.'"
o
'"

1000

,.
.

I
.

FIGl'RK 9.-Suspended.sediment rating curves for Rio Galisteo at Domingo, N. MH., and for Rio Puerco near Cabezon, N. Mex., measured one-fourth mile above the
mouth of Chico Arroyo.