WSP07478

• File Number: 8272.600.60
• Description: Colorado River Basin Salinity Control Program - Basin Member State Info - Utah
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 3/1/1982
• Title: Salt Uptake in Natural Channels Traversing Mancos Shales in the Price River Basin - Utah
• Water Supply Pro - Doc Type: Report/Study

t'-'
o
~
CO

Qs

Surface flow rate in the river
in ds

a and b

Constants determined
regression based on
observations

by a
field

In this relationship, salt loading is divided
among three flow paths and varies expo-
nentially with respect to flow.

Langbein and Dawdy (1964) suggested that
watershed chemical weathering can be de-
scribed according to Nernstls law and pro-
posed the functions:

dL/dt

(Cs - C)
C
s

(1. 8)

DA

in which

L Dissolved mass
t Time
D = Maximum rate of dissolution
Cs Saturation concentr"t~nn
A Drainage area undeL L0l1sideration

By simple mass balance differencing, Equation
1.8 may be represented as:

Q(Co -Ci)

(Cs - C)

Cs

(1. 9)

DA

in which

Ci "" Concentration of influent water
(wflter. in the river channel enter-
ing the area drained by the sub-
basin of area, A)

Concentration of effluent water
(water leaving the subbasin of
area, A)

Algebraic manipulation of Equation 1.9
yields:

Co

Co

C (1 + c, Q/DA)
s l
----r + QC IDA
s

, , , (1.10)

Equations 1.8 to 1.10 are nearly the same as
those proposed by Jurlnak et a1. (1977) 13
years later.

I

From studying the total salt load per
square mile in various large watersheds,
Langbein and Dawdy (1964) observed that on a
log-log plot the annual salt load increases
linearly with annual runoff up to approxi-
mately 3 inches (Figure 1,4). Thereafter,
loads begin to decline.

Hendrickson and Krieger (1964) and Toler
(1965) in separate studies of Southeastern
U.S. streams described a hysteresis effect in
the pattern of salt concentration during
storm events. Depending upon whether the

log scale

5
"
~
1
'e 5
Ii
....
..
c
~

_ _15.9 -.!o~sl!..Q:..m~-y!.a:. _ _ _ _ _ _ _ _ _ _ _ _ __

I
1 3" of annual runoff
I
I
I

log scale
3,69

"
c
o
-'
c;
en 0.1
0,1

Mean Annual Runoff (inches)

Figure 1.4.

Salt load versus annual surface
runoff (taken from Langbein and
Dawdy 1964),

stage is rIsIng or falling, different concen-
trations were observed for a given water flow
rate. The A.llthors attribute the hysteresis
effect to t- iJl1"~ variation in the salt dis-
solution process, changes in the rate of
surface runoff, and the inflow of relatively
constant quality groundwater. Toler (1965)
observed that the hysteresis can be clockwise
or counter-clockwise depending upon the
variability of the quantity of groundwater
inflow.

From a study of the Hubbard Brook
Experimental Forest, New Hampshire, Johnson
et a1. (1969) proposed the following model
for stream water chemistry based. upon mixing
and mass balance:

C

C
s
1 + S Q + Ca

, . , , ' , , ' (1.11)

in which

s

Constant

C
a

Rainwater concentration

Cs

Groundwater concentration minus
rainwater concentration

Salinity concentrations predicted by the
model were consistently higher than those
observed in the prototype system.

Gibbs (1970) identified three major
mechanisms contributing salt loadings to
rivers: 1) atmospheric precipitation, 2)
mineral dissolution, and 3) evaporation-
crystallization. Rivers vary greatly in how
salinity sources divide between precipitation
and rocks as illustrated in Table 1.1.

Pionke and Nicks (1970) applied salini-
ty/flow models to ephemeral streams in
Oklahoma. Flow and salinity, as functions
of time for two typical storms on the West

5