Stream discharge, suspended sediment and erosion rates in the Red Deer
River basin. Alberta, Canada
!. A. Campbell
Abstract.
The study of the relationship between stream discharge and sediment load and
regional erosion rates in arid and semiarid environments is greatly complicated by the fact that
fluvial activity within the drainage basins of such areas is concentrated in perhaps one or two events
each year. Such patterns of fluvial activity present a major problem when attempting to estimate
suspended sediment rating curves. In most humid drainage basins much of the sediment load
originates with fluvial processes initiated by precipitation, or runoff, over large areas of the basin.
High discharges are then usually associated with large sediment loads. Under arid and semiarid
climates such situations are rare. Here, intense local convectional rainstorms, often falling on poorly
vegetated and highly erodible material close to the channel system, result in large imputs of sediment often accompanied by relatively minor changes in discharge in the main channel. This additional factor further complicates the problem and highlights the general fact that in most drainage
systems, in reality, the sediment yield is derived from a relatively small proportion of the total
catchment area. In regions of moisture deficiency such a situation almost always pertains. These
patterns are illustrated by data collected from the Red Deer River basin, Alberta, Canada. Here,
suspended sediment and stream discharge data, as related to surface erosion measurements and
regional erosion rates, show that typical rating curves significantly underestimate the occurrence of
high sediment concentrations and that in most years the sediment concentrations greatly exceed
those computed by rating curves. Such a situation poses potentially severe problems in terms of
design criteria for river management projects especially in the arid world.
Ecoulement fluvial, sédiments en suspension et vitesses d'érosion dans le bassin de la rivière Red
Deer, dans f Alberta, Canada
Résumé.
L'étude de la relation entre écoulement fluvial, transport solide et vitesse d'érosion
régionale en pays aride ou semi-aride s'avère très complexe du fait du type d'activité fluviale de ces
bassins versants, concentrée en un ou deux événements par an. L'établissement des courbes de
tarage de la charge en suspension dans un tel contexte soulève des problèmes majeurs. Dans la
plupart des bassins versants des régions humides, l'essentiel du transport solide est imputable à des
processus déclenchés par les précipitations ou le ruissellement sur de vastes étendues des bassins
concernés. Par conséquent, les volumes ruisselés importants sont généralement associés à des
charges solides élevées. Sous les climats arides et semi-arides, de telles situations sont rares. Dans
ce cas, des orages convectifs locaux de forte intensité, s'abattant souvent sur des matériaux très
sensibles à l'érosion et peu protégés par la végétation à proximité du lit du cours d'eau, se manifestent par d'importants apports de sédiments accompagnés souvent de modifications relativement
faibles du débit du lit principal. Ce facteur complémentaire tend encore à compliquer le problème
et met en lumière le fait général que dans la plupart des systèmes de drainage le transport solide
provient en réalité d'une proportion relativement faible de la superficie totale du bassin. Dans les
régions à déficit hydrique prononcé, cette situation prend un caractère presque permanent. Ces
phénomènes sont illustrés grâce aux données collectées dans le bassin de la rivière Red Deer, dans
l'Alberta au Canada. Dans ce cas, le transport solide en suspension et le volume d'eau ruisselé, mis
en relation avec les mesures d'érosion superficielle et d'ablation régionale, montrent que les courbes
de tarage classiques sous-estiment l'existence de charges solides élevées et que, la plupart du temps,
les charges solides dépassent de beaucoup celles qui sont estimées à partir de ces courbes de tarage.
Une situation de ce genre soulève des problèmes potentiellement graves en ce qui concerne les
critères de conception des projets d'aménagements fluviaux, plus particulièrement en pays aride.
244
Stream discharge, suspended sediment and erosion rates
245
INTRODUCTION
The study of the relationship between stream discharge and suspended sediment load
in arid and semiarid environments is greatly complicated by the concentration of
fluvial activity in many basins of such regions in relatively few major runoff events each
year. Years may pass between periods of bankfull or near bankfull discharge. Irregular
patterns of flow events make collection and interpretation of discharge data difficult.
A further problem, generally peculiar to dry regions, is the great difference between
the theoretical limits of the basin, the divide or watershed, and the effective area which
yields runoff and sediment (Dubief, 1953; Slayter and Mabbutt, 1964). The normally
determined physical boundaries of the basin are usually far larger than the actual
watershed. This is often due to interior depressions which in more humid climates
would become part of an integrated drainage system. In arid, or even semiarid regions,
such areas become non-contributory in terms of discharge or sediment yield and in
regions of low relief they are hard to define.
The factor of basin size appears to play a greater role in determining discharge and
sediment yield in dry climates. Small basins usually contribute higher proportions of
sediment yield per unit area than large basins (Gottschalk, 1964), partly because of
the greater likelihood of storm s entirely covering a small basin, and because high
intensity storms are usually of small size. A main factor causing problems in arid and
semiarid regions is the dominance of intense local convectional storms on highly
erodible areas close to the main channel that produce major inputs of sediment
without corresponding major increases in discharge. Sediment input is not related or
is poorly related to discharge.
Morphological controls are also important. Greater length of channels means
potentially greater losses are sustained in larger basins through channel infiltration and
even evaporation. Smaller basins typically have higher mean slope values and a greater
drainage density than larger basins: hence maximum peak discharges per unit area tend
to be higher in smaller basins. Sediment yields per unit area are also greater (Hadley
andSchumm, 1961).
Climate may be a critical factor in determining sediment yields. Melton (1957)
found drainage density increased with the percentage decrease in plant cover reaching
a maximum in semiarid conditions. Langbein and Schumm (1958)found sediment
yields, vegetation cover and annual precipitation combined to produce peak values in
the zone between the semiarid and the arid climates.
The general deficiency of water, the lack of a dense vegetation cover, and the fact
that weathered debris may be produced over some areas of an arid basin for considerable
periods before being removed means that discharge can actually decrease downstream
while suspended sediment load increases (Renard and Keppel, 1966). In semiarid and
arid climates, sediment concentration increases in streams at a far faster rate than in
humid climates (Leopold et al, 1964; Schick, 1970). Schick (1974), referring to
sediment concentration in arid regions, notes that significant increases occur as flow
length increases. For very small areas a doubling of the basin size may involve a onethird increase in sediment concentration; as the length of flow increases sediment
concentration may go up a hundred-fold (Schick, 1974). Increases in discharge do not,
however, because of the nature of precipitation and infiltration, increase at anything
like the rate of sediment concentration. These relationships also result from the
variability of precipitation which causes an accompanying variability in discharge. A
larger percentage of the load is carried in a few flow events often spread over a few
days or hours.
Semiarid and arid regions typically produce high suspended sediment yields per
unit area and they are subject to great discharge variability. Generally, the larger
the basin the less reliable will be any discharge-load relationship because of the
246
I. A. Campbell
constantly large fluctuation in the sediment-discharge producing processes and the
internally shifting nature of the sediment contributing area. As a result, large inputs
of sediment into the channel-systems are not generally accompanied by commensurately
high runoff. Rainfall of high intensity, which is usually the key generating factor in
erosion and sediment yield, is not necessarily nor usually high in total amount in dry
climates.
A further factor, probably true in many basins under all climates is most sediment
is derived from a comparatively small part of the basin (Gregory and Walling, 1973).
Typically, this is from the channel walls and valley sides. This again raises the
importance of drainage density, which, as noted by Melton (1957) and Gregory and
Walling (1973, p. 272), is usually high in most semiarid regions.
If these statements pinpoint some problems of sediment supply and discharge into
the channel system, what of the measurement values obtained from the events that do
occur? In most arid, and in many semiarid regions, adequate records of
hydrometeorological events are unavailable. Where they are it is often for areas that
have undergone significant human interference in the landscape with all the effects this
can have on runoff and sediment yields (Douglas, 1967).
These observations seem to indicate that, for a variety of reasons in dry climates,
great difficulty exists in attempting to define precise relationships between stream
discharge and sediment loads for any particular basin. The computation of erosion rates
based on such data becomes highly speculative.
WORLD AND REGIONAL EROSION RATES
There have been several attempts to produce maps showing regional or worldwide
patterns of erosion. A notable early attempt by Dole and Stabler (1905) is probably
still the standard against which others are gauged. As more data have become available,
there have been significant contributions by Fournier( 1960), Menard (1961),
Livingstone (1963), Corbel (1964), Judson and Ritter( 1964), Strakhov (1967), and
Holeman(1968).
Generally all use the same basic data, stream sediment loads (usually only suspended
load is used), though in some cases, (Livingstone, 1963; Corbel, 1964), solution load is
also used, to calculate sediment yield per unit area of basin. Empirical equations may
be derived to reflect variations in climate, relief and slope. The results, though
producing broadly similar patterns, often differ by an order of magnitude (Stoddart,
1969). Choice of basins, weighting of variables, human influences and other related
problems result in widely differing estimates. Interestingly, neither Fournier ( 1960)
nor Strakhov (1967), indicate that the semiarid regions produce the maximum sediment
yields while the data collected by Melton (1957), and Langbein and Schumm (1958)
indicate that they should.
The problem lies in the assumptions associated with the concept of sediment yield
per unit area. Apart from the previously noted effects of basin size on sediment yields,
especially in dry regions, the assumption that sediment is derived uniformly from a
basin is misleading. Gibbs (1967), for example, has claculated that over 80 per cent of
the suspended sediment of the Amazon, at its mouth, is derived from the Andes.
The problems involved in accurately determining regional erosion rates are immense
even presuming that the data on which they are based justify the exercise.
In the arid and semiarid regions of the world these problems are very important. In
these regions much of the data needed to calculate sediment yield and erosion rates are
lacking and the semiarid world faces the problem that relatively minor changes in
climate, to which the area is prone, have drastic effects on sediment yield. These
climatic variations effect the entire basin hydrology. Also, and of immediate social and
economic importance, increased human pressures placed upon these fragile areas makes
Stream discharge, suspended sediment and erosion rates
FIGURE 1.
Canada.
247
Location and physical characteristics of the Red Deer River basin, Alberta,
it imperative that accurate information on sedimentation, siltation and erosion be
available so that successful engineering and land use schemes can be developed.
An example of the specific problems encountered in calculating regional erosion
rates, sediment yields and other related components of the basin in a semiarid climate
is shown for the Red Deer River basin in Alberta, Canada.
THE RED DEER RIVER BASIN
The Red Deer basin occupies an area of about 43 000 km2 of south-central Alberta,
Canada (Fig. 1). Within its perimeter are parts of three of the major physiographic
zones of Alberta and western Canada; prairies, foothËls and mountains (Fig. 1). Its
source area in the Rocky Mountains includes glacial and non-glacial fed streams that
originate at elevations up to 3500 m. In its 780 km length from its headwaters to the
Alberta-Saskatchewan boundary the river transverses four ecosystems that reflect
changes in climatic environment typical of this section of Alberta (Fig. 1). These
ecosystems trend generally north-south, corresponding to the gradual east-west rise in
elevation and its accompanying climatic zonation (Fig. 1). The eastern half of the
basin receives generally less than 350 mm of precipitation each year while the western
half generally gets well over 400 mm annually. The basin can be divided i n t o a humid
(or sub-humid section) and a semiarid section. Most of the basin lies within the Bsk
region of Kôppen though parts of the western and northern sections come within the
Z>Z>/category. The mountain section lies within the Highland climates.
On the basis of discharge records from gauging stations, and for the purposes of this
discussion, the Red Deer can be considered as consisting of four sections (sub-basins)
delimited by stations at Sundre, Red Deer, Drumheller and Bindloss (Fig. 1). The
248
I.A.Campbell
TABLE 1.
Mean annual discharge and contributary areas Red Deer River, Alberta
Gauging Mean annual
station
discharge
[m 3 /s] '
Incremental
measure
for sub-basin
[m 3 /s]
Sundre
34.27
Red Deer 51.55
Drumheller
60.05
Bindloss 69.12
Total/Mean
69.12
34.27
17.28
49.60
25.00
2442
8873
20.60
440
61
8.50
9.07
12.30
13.10
13414
18271
31.20
42.50
19
15
69.12
100.00
43000
99.90
50
Mean annual
discharge as
a percentage
of the total 2
Contributing Contributing Mean
area as a
area
annual
percentage runoff
[km 2 ] 3
of the
[mm]
total 4
5.60
1. As measured at the station (Alberta Research Council 1972).
2. Calculated as the amount that each station gauges as a percentage of the total measured
at Bindloss.
3. The area as determined by the outline of the sub-basin between successive gauging stations,
or, in the case of Sundre, above Sundre to the outlines of the watershed.
4. Calculated as the amount of the area above each station as defined in (3) expressed as a
percentage of the total.
respective contributing areas and discharge data are shown in Table 1. Evidently a
very minor portion of the basin contributes much of the total discharge. The
mountain and foothills section above Sundre, about 6 per cent of the total area,
contributes almost 50 per cent of the total mean annual discharge and Bindloss, over
40 per cent of the Red Deer Basin, contributes only about 13 percent of the mean
annual discharge. These results reflect the climatic variation of the basin, and are seen
in the mean annual runoff values (Underhill, 1962), shown on Fig. 1.
Table 1 shows the calculated runoff values derived from dividing the basin area into
the mean daily discharge values in m3/s and multiplying these by the number of seconds
in a year of 365 days. The values are close to those obtained by Underhill (1962).
Geology
Most of the Red Deer basin is formed within Upper Cretaceous and Tertiary deposits
(Green, 1970). Only in the mountains and parts of the foothills are rocks older than
Cretaceous exposed. These consist of Devonian and Upper Palaeozoic limestones and
shales. The Upper Cretaceous lithological units are very uniform. They consist almost
entirely of shales, poorly indurated sandstones, thin clay ironstone beds, and coal
seams. Many beds are rich in bentonite. The surficial cover consists of a variable
thickness of deposits largely associated with the Wisconsin glaciation. These comprise
till, lacustrine deposits, and glacial outwash and small patches of post-glacial eolian
deposits (Atlas of Alberta, 1969). In places surficial deposits exceed 75 m, but over
much of the basin they are less than 30 m thick; often post-glacial erosion has removed
them entirely.
The valley of the Red Deer, at least downstream of the foothills, is entirely postglacial though in places the river has reexcavated portions of its old pre-glacial course.
Post-glacial erosion has been rapid. The river is incised over 100 m into the prairie
surface (Fig. 2) and much of this cutting has occurred within the last 10 000 years.
This rapid rate of downcutting was aided initially by glacial meltwater released as the
continental ice-sheet retreated and ablated. Erosive processes were enhanced by the
ïi
S
o
c
m
jo
S»
5
o
3
|
i
I
I
I
i
250
I.A.Campbell
unconsolidated glacial deposits and the generally incompetent nature of the shales
and sandstones that dominate the regional bedrock.
A combination of the dry climate in the southern and eastern portion of the basin
and its adverse effects on vegetation cover, and the highly erodible bedrock have
produced extensive areas of badlands along the Red Deer stretching from Nevis, (near
Red Deer), to Atlee, (near Bindloss), (Stelck, 1967). This stretch is shown on Fig. 2
as one of marked valley incision. These badlands play a major role in the sedimentdischarge relationships of the river. They contribute massive amounts of sediment
from a very small area of the basin (Campbell, 1970a, 1973, 1974).
The badlands regional significance and their role in the sediment load-discharge
patterns of the Red Deer River are seen in the maps produced by Stichling (1973). He
showed that the suspended sediment concentrations of the Red Deer were anomalously
high for the prairie region. The Red Deer recorded average annual values in excess of
1000 mg/1. based on the formula.
annual suspended load
=—
a
annual stream flow
Adjacent basins showed values below 400 mg/1. The map of suspended sediment
yield (Stichling, 1973) showed, however, that the Red Deer was identical to its
neighbours with values of between 51 and 250 tons mi - 2 year -1 (17.8 — 87.5 Mg
km - 2 year -1 ). The discrepancy between the two maps illustrates the effects of
averaging sediment yields over an entire drainage basin when in actuality the sediment
was derived from a relatively small part of the Red Deer basin and where large areas
within the basin boundaries contribute neither runoff nor sediment to the river.
concentration =
SUSPENDED SEDIMENT RATING CURVES
Suspended sediment rating curves have been used to predict stream loads where longterm data are lacking. One early attempt was by Campbell and Bauder ( 1940) with
their 'silt-discharge rating curve'. The technique involves plotting a line through data
points on a graph relating load and discharge. Many variations are in vogue and
usually logarithmic values are used. Seasonal climatic effects and other
hydrometeorological factors often produce a considerable degree of scatter.
The derivation of accurate prediction curves could be of great value where long-term
records are not available. But they are subject to certain problems in terms of their
derivation and interpretation. The values most used are simple plots of log load
against log discharge with load generally considered the independent variable. Abrahams
and Kellerhals (1973), however, noted in their study of four Canadian prairie rivers
(of which the Red Deer was one,) that load is not the originally measured variable; it is
usually concentration that is measured. Since load is computed from concentration and
discharge, L = CQ, this amounts to correlatingx withx xy and it may produce
erroneous conclusions concerning C (Benson, 1965).
Abrahams and Kellerhals (1973) using multiple linear regression for the eight
month summer period only, to avoid problems associated with river-icing, found that
an equation of the form
logC = «+Mog<2
produced a reasonably close relationship between concentration and discharge. The
Red Deer, however, produced problems in their predictive model. They noted that
'... the rate at which fine material is supplied to the river and to the
immediate vicinity of the channel is independent ofQ (my italics), and
that most of this material is moved downstream immediately on rising
stages.'
Stream discharge, suspended sediment and erosion rates
TABLE 2.
Bindloss
251
Predictions of load and concentration from rating curves for t h e Red Deer at
Average error in predicting mean
monthly concentration [%}1
Average error in predicting
mean monthly load [%] 2
Error in predicting sediment
load in 7 - 8 summer months
1967
1968
1969
1970
1971
49.5
40.6
35.5
42.6
52.0
45.2
41.7
29.7
43.8
50.6
5.9
-52.2
2.6
-52.2
54.6
After Kellerhals et al (1974)
1. Using rating curves for 1967-1969 period
2. Using rating curves for 1970-1971 period
(Abrahams and Kellerhals, 1973, p. 104). They attributed this independency to the
badlands upstream of Bindloss.
Kellerhals et al. (1974) came to simUar conclusions. Observations on the Red Deer
showed that predictions of sediment transport from rating curves gave errors that were
consistently large, generally between 35 to 50 per cent for mean monthly
concentrations and between 30 and 50 per cent for mean monthly loads (Table 2).
They further found that rating curves for the Red Deer significantly underestimated
the recurrence of high sediment concentrations. Table 3 shows that for virtually
every year used, the highest concentrations and the mean of the ten highest
concentrations observed exceeded those computed by the rating curves. High sediment
concentration was consistently underestimated and statistical tests showed that the
number of days recording high concentrations were significantly greater than the
number computed.
For stations with short or unreliable records, or both, and for streams like the Red
Deer where major local inputs of suspended sediment are unaccompanied by similarly
high discharges, the potential predictive error for sediment rating curves, sediment
yields or allied information becomes very large.
Table 4 gives some indication of the effects of local injection of sediment into the
Red Deer River to show its lack of relationship to discharge values. At Red Deer,
the correlations and other values show generally that the two factors are well-related.
At Bindloss, however, this pattern becomes less clear and the level of correlation drops.
When the Bindloss load and discharge data are treated independent of the contributions
from Red Deer the relationship between load and discharge is poor. The slope of the
regression is near zero indicating that load and discharge show little correlation except
in a very general sense.
CALCULATING DENUDATION RATES FROM SEDIMENT LOADS
The sediment load transported by a stream can be used as a measure of the denudation
rate of the basin using a formula of the following type:
denudation [m3 k m - 2 year *]
total stream load [Mg]
area [km ] X specific density
There are clearly several sources of potential error, some major, involved in the
conversion.
The measurement of actual total stream load is difficult, except within certain limits.
Typically only suspended sediment load is measured and even this is difficult to do
accurately unless stringent sampling procedures are followed. Additional weighting
I.A.Campbell
o
o
o
o
I
o
as
m
-3399
^H
-5000
252
É
OS
•S
c
3
3
Ou
I
S
3
lis
-^ _
J3
C
-£
"•a
»>
S .2
as
•v,
^ i
.—I
^
rH
;z3
i—i
1—4
-^ "S
M
C
tD
c 4J
S c
•si's
3
as
Stream discharge, suspended sediment and erosion rates
r^
—*
O
•a
>.
&
i-i
fU
.5
e
3
S
•a
E
•2 I
1
e -a
c
tu
c3 cfl
t/î
â
s
5 5
o .5
o .S ers
2 « "»
s -a
ï3 tu ^
tu Q
~
'3 & .2
Oï tu P « 8 »
o c r
— - CQ
w>
_
2
50*2
tu
S T3~
k M
60 0 *
o a
O £2
•^i"
W
•4
<»f
SS
"3
m
< .S
H «
â
60 C
S, ^
<u o M
ta
•c
o
A- 7 j ^ i ^» 5
^ td o 13
,_ n M —
o«
&3I1
a*. 03
a tu o
tU tso CD t 3 =* — a
ra
£
M a> t i *te
M a) "d
.S
-c! .5 tu
.g
°
Q
" -O o
-a
.S » û
«
"3
CD
^
_^ -ri "T3
" £ *a Pi g -a ai
_ sc 13
g *o-* »c c£JÛ*dOr o c « tu 3
60 £< 60 S- 6 0 ^" ; M « " ^ 1> ES SP S* S
o Vs
(D XJ
° 3 ° §
i—I
£« Wï g - . g
g'e
h-3 V5 G J
253
254
I.A.Campbell
TABLE 5.
Erosion rates and correlation Red Deer badlands, July 1969 - October 1976
Plot
Number of
values
Correlation
r2
Regression
slope
Mean surface
change July
1969-October
1976
[mm]
1
2
3
4
5
6
7
8
9
15
15
15
15
15
15
15
15
15
-0.72
0.85
0.74
-0.82
-0.77
-0.08
-0.57
-0.82
-0.90
0.52
0.72
0.56
0.68
0.60
0.00
0.33
0.67
0.82
-0.15
0.33
0.14
-0.19
-0.16
-0.01
-0.10
-0.22
-0.40
-23.5
29.3
5.1
-37.8
-34.3
- 6.9
-28.3
-27.4
-63.1
* mean surface lowering — 31.6
* mean of negative values only
factors may be added to allow for bed and solution load if these are not determined.
The calculation of basin area is fairly easy though determination of effective area that portion of the basin that actually produces the sediment — may be difficult.
Specific density of parent lithological units varies over a wide range and is a possible
major source of error. Corbel (1964) suggested that a figure of 2.5 be used as a measure
of specific density. This means each cubic metre of sediment source material would
have a mass of 2500 kg. Hadley and Schumm (1961), however, used a conversion
factor equivalent to 881 kg/m3 in their study of sediment yields from badlands in the
Cheyenne River basin, Wyoming. Dole and Stabler (1905) used a value equivalent to
2643 kg/m3 in their classic study. Schumm (1963), for comparative purposes, retained
the same value in his study of the disparity between present erosion rates and orogeny.
Campbell (1970a) on the basis of mean bulk density samples from the Red Deer
badlands, found that a value of 1826 kg/m3 represented a reasonable average. That
figure is retained here. These figures represent values commonly used for the
determination of suspended sediment conversion from some lithological unit, or units.
If, however, the sediment yield is mainly derived from a weathered mantle, or a soil,
then they are probably far too high and a value near 1.0 ( 1000 kg/m 3 ) may be more
applicable.
The result is a possible three or even four-fold variation in conversion depending on
the values used. Such a variation would produce a similarly high range of regional
erosion rates if applied to the same set of suspended sediment load data.
RED DEER BADLAND EROSION RATES
Detailed measurements of erosion in the Red Deer badlands have been in progress
since 1969. The techniques employed are described elsewhere (Campbell, 1970b,
1974). During the study period, and on the basis of 3375 point measurements, the
mean erosion rate has been 31.60 mm. The study period is slightly longer than seven
years so the mean erosion rate is 4.51 mm/year.
Measurements are taken within 9 — 1 m2 plots with 25 sample points in each.
Readings are taken twice each year, in spring and autumn. Fifteen sets of readings for
each plot are available to date. Some statistical presentation of the collected data is
given in Table 5. Of the nine plots two (numbers 2 and 3) were sited on alluvial fan
surfaces to show rates of aggradation. These values were not included in the erosion
rate calculation.
Stream discharge, suspended sediment and erosion rates
255
Given a mean erosion rate of 4.51 mm/year the equivalent in suspended sediment
yield using a conversion of 1826 kg/m3 (Campbell, 1970a), produces a rate of
8.23 kg/m2 or about 8230Mg km" 2 year -1 . Comparative areas of the western United
States show mean annual erosion rates of between 15 and 45 mm (Hadley and Schumm,
1961), which are 3 to 10 times higher than the rates obtained here. Schumm (1956a)
quotes erosion rates of 20 — 38 mm over a two year period in the badlands of North
Dakota. This area is highly analogous to the Red Deer badlands.
In fact, the rates of erosion in the Red Deer badlands are lower than might be
expected. Strakhov (1967) gives data for mechanical erosion of from 0.OO1 to
4.00 mm/year in large basins, but in extensively man-altered small basins the rate
rises to 85 mm/year. Bridges and Harding (1971) found erosion rates on spoil heaps
in South Wales (United Kingdom) in the order of 24 mm/year and Schumm (1956b)
found erosion rates on badlands in New Jersey to be between 10 and 35 m m in a 10
week period!
A summer only study in 1968 using runoff plots (Campbell, 1970) gave mean
sediment yields of 1.40 kg/m2 for badlands surfaces. The data shown on Table 6
indicate that 1968 was a low year for sediment production and runoff so the mean
annual values found for the 1969-1976 period of 8.23 kg/m2 are reasonable.
For the Red Deer badlands, with an estimated area of 800 km2 (which is probably
high), an average erosion rate of 4.51 mm/year would produce a sediment yield of
6.58 X 106 Mg. Table 6 shows, on the basis of available information on sampled
suspended sediment, the mean annual load at Bindloss is 3.31 x 106Mg. About 900
per cent probably originates in the stretch of river between Red Deer and Bindloss,
(that stretch lined by badlands). On that basis, the mean annual sampled load at
Bindloss should be about 2.92 x 106 Mg if sediment already in the river at Red Deer is
ignored.
The difference between the calculated annual sediment yield from the badlands and
the mean annual suspended sediment load of the river is in the order of t w o times.
There are several possible explanations for this.
(1) The measured erosion rates for various reasons (instrumental) are too high.
This is possible but measurements made in similar areas show the erosion rates are not
unreasonable and in fact are conservative.
(2) The measurements are biased towards highly eroding surfaces rather than
being truly representative of the surface in the badlands. This is possible because it is
unfeasible to sample all units, slope angles, divide distances etc., which all in theory
effect erosion rates. The data (Table 5) show a 10-fold variation in erosion rates.
Plot 9 erodes quickly, at a mean rate of 9.00 mm/year, whereas Plot 6 lowers at only
about 1.00 mm/year. Plots 1,4,5,7 and 8 are consistent; their average is only 30.26 mm
over the total period, or 4.32 mm/year, slightly less than the 4.51 mm/year average
rate for all eroding plots. The rates measured seem reasonable given the natural
variations.
(3) The total amount eroded does not get into the Red Deer immediately. This
problem of 'sediment-delivery ratio' is a very real one. Roehl (1962) found for some
basins in the southern and southeastern United States, that it varied between about
90 and 3 per cent. Given the intermittent nature of runoff in the region, erosion,
entrainment and deposition of the same material frequently occurs within a short
distance. While there is no extensive build-up of deposits Table 5 does show that of
the two fan surfaces one underwent a net aggradation of almost 30.00 mm. This would
amount to 4.18 mm/year and, if it were a general tendency, the 'sediment-delivery
ratio' for the badlands would be only about 8 per cent. There is no field evidence to
suggest this, and the second alluvial fan surface (Plot 3, Table 5) accumulated only
5.10 mm in total. The Red Deer may act as a major storage system for sediment
derived from the badlands. Figure 2 shows a conspicuous 'hump' in the river long-
256
I.A.Campbell
m
~-<
<
z
Z
o
\£>
-H
\£>
-H
Z
z
z
z
^
=3
c3
•is
T3
S
«
•"*
O
"O ,
^<*£>
O ^
°
• O T J X
C S "
g-"S M
« o •S « >>
es "g SG- ^<""-—.
O _C « g en
Ï
fins
111?
JI
2s;
5 -s ""
« -a »
c c Q
Stream discharge, suspended sediment and eorsion rates
257
profile downstream of Nevis — the upper limit of the badlands. This may represent
incoming sediment being delivered at such a rate that the river is incapable of removing
it except at periods of major flood.
(4) Sediment sampling procedures at Bindloss may not be measuring correctly
the total suspended sediment. Sediment is sampled at Bindloss by the Water Survey of
Canada. The station has been operating for about 45 years. Most Alberta streams are
ice-covered from about mid-November to early or mid-April, making sampling difficult.
At Bindloss, usually no suspended samples are taken in the winter four months and
very few reading are taken in March. These months typically are ones of low flow and
low sediment loads. Break-up and melting are often rapid, occurring within a few days.
In 1974, mean daily discharge rose from 27.4 m3/s on 11 April to 328.48 m 3 /s on
16 April during the break-up period. Mean concentration of suspended sediment rose
from 107 to 8700 mg/1. in the same period (Water Survey of Canada, 1976, Suspended
Sediment Data for 1974).
In order to determine daily load of the streams, an average concentration, L, is
determined for each 24-h period and combined with the mean daily discharge, Q, to
give the daily transport rate. The Water Survey of Canada gives this rate in short tons/
day. L [short tons/day] = 2.7 Q [cfs] X C [g/1.]. Samples measure instantaneous
concentration (CI), and the rivers are sampled often at irregular intervals. Measurement
frequency is determined by the prevailing transport rate and its variability (Kellerhals
etal., 1974), e.g., in 1974 the Bindloss station took the following number of samples,
January (1); February (1); March (1); April ( 17); May (31); June (30), July (24);
August (16); September (15); October (15); November (11); December (6).
Interpolation between the observed, often irregularly spaced CI values is used to
produce estimated values for non-sampled periods. Because these values are given in
terms of C(average concentration) and because L is, to a degree itself a function of Q,
high Q values tend to produce high C values, especially in streams like the Red Deer that
receive massive amounts of sediment from comparatively low runoff events. The
sediment sampling programme may therefore produce errors.
(5) Any combination of some or all of these may be true.
EROSION RATES IN THE RED DEER BASIN
If the mean annual suspended sediment load as measured at Bindloss is distributed
evenly over the Red Deer basin, the regional erosion rate becomes 0.0397 mm/year
assuming a conversion factor of 1826 kg/m3 and an average annual load of
3.31 X 106Mg at Bindloss with a basin area of 43 000 km2. This value of mean annual
denudation is between the values of 0.021 and 0.04 mm/year (clastic load only) shown
by Slaymaker and McPherson (1973) for the Red Deer, and is between the regional
values of 0.0205 and 0.204 mm/year shown by Founder (1960). The mean annual
load at Red Deer is about 12 per cent of the total load measured at Bindloss, that is,
about 400000 Mg. It is derived from the basin above the town of Red Deer, an area
of 11315km 2 . This produces an average yield of about 35Mg k m " 2 y e a r _ 1 a
representative figure for mountains and foothills in this region. Strakhov ( 1967) shows
this portion of the Rocky Mountains as producing between 50 and lOOMg k m - 2 y e a i - 1 .
Luk (1975), found that sediment yields in the foothills and mountain section of the
Bow River watershed in southern Alberta varied from 16 to 146 Mg km""2 year - 1 . The
load measured at Bindloss minus the amount passing at Red Deer is about 2.92 X 10 6
Mg/year. In theory it is derived from an area of about 31 600 km 2 . This would give an
average sediment yield of about 70 Mg km - 2 year -1 .
But, of the total 31 600 km2 below Red Deer, about 800 km 2 of badlands, 2.5
per cent of the area below Red Deer town and less than 2.0 per cent of the entire basin,
has the potential to produce the total suspended sediment load measured at Bindloss.
258
I.A.Campbell
Calculations of regional erosion rates and sediment yields should be related only to
the characteristics of the portion of the basin producing it (Wigham and Stolte, 1973).
It is unreal and unwise to estimate regional erosion rates based on suspended load data
where nothing is known of the erosional patterns within the basin.
REFERENCES
Abrahams, A.D. and Kellerhals, R. (1973) Correlations between water discharge and concentrations
of suspended solids for four large prairie rivers. In Fluvial Processes and Sedimentation,
(Proceedings of Hydrology Symposium no.9), pp. 96 — 113: Nat. Research Council of
Canada.
Atlas of Alberta (1969) Government and University of Alberta (University of Alberta, Edmonton),
162 pp.
Benson, M.A. (1965) Spurious correlation in hydraulics and hydrology. Hydraul. Div., Proc. Amer.
Soc. Civ. Engrs. J. 91, 3 5 - 4 2 .
Bridges, E.M. and Harding, D.M. (1971) Micro-erosion processes and factors affecting slope
development in the Lower Swansea Valley. Trans. Inst. Brit. Geogr. Special Pu bl. no. 3,
65-79.
Campbell, I.A. (1970a) Erosion rates in the Steveville badlands, Alberta, Canad. Geogr. 14,
202-214.
Campbell, I. A. (1970b) Micro-relief measurements on unvegetated shale slopes. Prof. Geogr. 22,
215-220.
Campbell, I.A. (1973) Accelerated erosion in badland environments. In Fluvial Processes and
Sedimentation (Proceedings of Hydrology Symposium no.9), pp. 1 8 - 2 5 : Nat. Research
Council of Canada.
Campbell, I.A. (1974) Measurements of erosion on badlands surfaces. Z. Géomorphologie,
Supplementband 21, Geomorphic Processes in Arid Environments (Proceedings of the
Jerusalem-Elat Symposium), pp.123-137.
Campbell, F.B. and Bauder, H.A. (1940) A rating-curve m e t h o d for determining silt-discharge of
streams. Trans. Amer. Geophys. Un. 2 1 , 6 0 3 - 6 0 7 .
Corbel, J. (1964) L'érosion terrestre, étude quantitative. Ann. Geog. 73, 385—412
Dole, R.B. and Stabler, H. (1905) Denudation. US Geo! Survey Water Supply Paper 294,
78-93.
Douglas, I. (1967) Man, vegetation and sediment yields of rivers. Nature 215, 9 2 5 - 9 2 8 .
Dubief, J. (1953) Essai sur L'hydrographie superficielle au Sahara, vol.1, Direction du Service de la
Colonisation et de l'Hydraulique: Direction des Etudes Scientifique, Algiers.
Fournier, F. (1960) Climat et Erosion.' la Relation entre l'Erosion du Sol par l'Eau et les
Precipitations Atmosphériques: P.U.F. Paris.
Green, R. (1970) Geological Map of Alberta: Research Council of Alberta, Map 35.
Gregory, K.J. and Walling, D.E. (1973) Drainage Basin Form and Process: Edward Arnold,
London.
Gibbs, R.J. (1967) The geochemistry of the Amazon River System. Bull. Geol. Soc. Amer. 60,
561-590.
Gottschalk, L.C. (1964) Reservoir Sedimentation. In Handbook of Applied Hydrology (edited by
V.T. Chow), pp. 1 7 - 1 to 1 7 - 3 4 : McGraw Hill, New York.
Hadley, R.F. and Schumm, S.A. (1961) Hydrology of the Upper Cheyenne River Basin: B. Sediment
sources and drainage-basin characteristics in Upper Cheyenne River Basin. US Geol. Survey
Water Supply Paper 1531, 137-198.
Holeman, J.N. (1968) The sediment yield of major rivers of t h e world. Wat. Resour. Res. 4,
737-747.
Judson, S. and Ritter, D.F. (1964) Rates of regional denudation in the United States. / . Geophys.
Res. 69, 3 3 9 5 - 3 4 0 1 .
Kellerhals, R-, Abrahams, A.D. and von Gaza, H. (1974) Possibilities for using suspended sediment
rating curves in the Canadian sediment survey program. Studies in River Engineering,
Hydraulics and Hydrology: Alberta Cooperative Research Program in Highway and River
Engineering, Edmonton, Alberta, 86 pp.
Kellerhals, R., Neill, C.R. and Bray, D.I. (1972) Hydraulic and geomorphic characteristics of rivers
in Alberta. River Engineering and Surface Hydrology: Report 7 2 - 1 , Research Council of
Alberta, Edmonton, 52 pp.
Langbein, W.B. and Schumm, S.A. (1958) Yield of sediment in relation to mean annual precipitation.
Trans. Amer. Geophys. Un. 39, 1076-1084.
Stream discharge, suspended sediment and erosion rates
259
Leopold, L.B., Wolman, M.G. and Miller, J.P. (1964) Fluvial Processes in Geomorphology:
Freeman,
San Francisco.
Livingstone, D.A. (1963) Chemical composition of rivers and lakes. US Geol. Survey Prof. Paper
440G. 64pp.
Luk, S.H. (1975) Soil erodibility and erosion in part of the Bow River basin, Alberta. Unpublished
PhD Thesis, University of Alberta.
Melton, M.A. (1957) An analysis of the relations among elements of climate, surface properties
and geomorphology. Office of Naval Research Technical Report II (Project N R . 389—042),
102 pp.
Menard, H.W. (1961) Some rates of regional erosion. /. Geology, 69, 1 5 4 - 1 6 1 .
Renard, K.G. and Keppel, R.V. (1966) Hydrographies of ephemeral streams in the Southwest./.
Hydraul. Div., Proc. Amer. Soc. Civ. Engrs. 92, 3 3 - 5 2 .
Roehl, J.W. (1962) Sediment source areas, delivery ratios and influencing morphological factors.
In Land Erosion (Proceedings of the Bari Symposium), pp. 2 0 2 - 2 1 3 : IAHS Publ. no.59.
Schick, A.P. (1970) Desert floods: interim results of observations in the Nahal Y a e l Research
Watershed, southern Israel, 1965-1970. In Results of Research on Representative
and
Experimental Basins (Proceedings of the Wellington Symposium), pp. 4 7 8 — 4 9 3 : IAHS
Publ. no.96.
Schick, A.P. (1974) Formation and obliteration of desert stream terraces - A conceptual analysis.
Z. Géomorphologie Supplementband, 21. Geomorphic Processes in Arid Environments
(Proceedings of the Jerusalem-Elat Symposium), 88—105.
Schumm, S.A. (1956a) The role of creep and rainwash on the retreat of badlands slopes. Amer. J.
Set 2 5 4 , 6 9 3 - 7 0 6 .
Schumm, S.A. (1956b) The evolution of drainage systems and slopes in badlands a t Perth Amboy,
New Jersey. Bull. Geol. Soc. Amer. 67, 5 9 7 - 6 4 6 .
Schumm, S.A. (1963) The disparity between present rates of denudation and o r o g e n y . US Geol.
Survey Prof. Paper 454H, 13 pp.
Slaymaker, H.O. and McPherson, H.J. (1973) Effects of land use on sediment p r o d u c t i o n . In
Fluvial Processes and Sedimentation, (Proceedings of Hydrology Symposium no.9)
pp. 1 5 8 - 1 8 3 : Nat. Research Council of Canada.
Slayter, R.O. and Mabbutt, J.A. (1964) Hydrology of Arid and Semiarid Regions. In Handbook of
Applied Hydrology (edited by V.T. Chow), pp. 2 4 - 1 to 24—46: McGraw Hill, New York.
Stelck, C.R. (1967) The record of the rocks. In Alberta - A Natural History (edited b y W.G. Hardy)
pp. 2 1 - 5 1 : Evergreen Press, Vancouver.
Stichling, W. (1973) Sediment loads in Canadian rivers. In Fluvial Processes and
Sedimentation
(Proceedings of Hydrology Symposium no. 9), Nat. Research Council of C a n a d a , pp. 3 9 - 7 2 :
Nat. Research Council of Canada. _
Stoddart, D.R. (1969) World Erosion and Sedimentation. In Water, Earth, and Man (edited by
R.J. Chorley) pp. 4 3 - 6 4 : Methuen, London.
Strakhov, N.M. (1967) Principles of Lithogenesis, vol. 1: Oliver and Boyd, L o n d o n .
Underhill, A.G. (1962) Report on the effect of a change in the vegetation on run-off and erosion
characteristics of Alberta streams: Water Resources Division, Alberta D e p a r t m e n t of
Agriculture, 57 pp.
Water Survey of Canada, Environment Canada, Sediment and Surface Water Data for Canadian
Rivers, Ottawa, Canada.
Wigham, J.M. and Stolte, W J . (1973) Sediment yield estimate from an index of p o t e n t i a l sediment
production. In Fluvial Processes and Sedimentation (Proceedings of Hydrology Symposium
no. 9), pp. 9 6 - 1 1 3 : Nat. Research Council of Canada.