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F.4 HYDROLOGY
F.5
Large supplies of ground water are available from the R River outwash plain alluvium,
glacial moraine, and from underlying sandstones in the area. The general course of deep
ground-water flow is to the southeast. The regional gradient broadly parallels the trend
of the topography and the surface drainage. The natural surface drainage of the immediate
site area is mainly to the southeast, toward the river.
The R River tributaries close to the site area are S Creek, 8 km northwest, and
T Creek, 5 km southwest. The B River flows parallel to and east of the R River, joining the
R 24 km downstream from the site area.
The ground-water levels near the site are relatively flat and slope toward the river
during normal river stages. During periods of high river flow, there may be some reversal
of ground-water flow near the river. These reversals would be of short duration and infiltration
of water from the river would be limited. The gradient toward the river is
re-established after the high water recedes.
River flow information based on data from the R River gaging station is as follows:
Number of years of record 40
Average annual flow, Z/sec 120,000
Minimum recorded flow, A/sec 6,200
Maximum recorded flow, A/sec 1,300,000
River flow and temperature data pertinent to the reference site are shown in
Figures F.4.1 and F.4.2, respectively.
Flow duration data for the R River calculated in the vicinity of the reference site are
shown in Figure F.4.3. Based on these data, the flow is expected to exceed 50,000 Z/sec 90%
of the time and 27,000 R/sec 99% of the time.
The average river velocity at the site varies between 0.5 and 0.8 m/sec for flows below
280,000 Z/sec. The river drops about 3 m from 2.4 km upstream to 2.4 km downstream of the
site. Rapids frequently occur in this stretch of the river.
I II I I I I -
40- " 00
1000 - \ MAXIMUM ENVELOPE 35-
5/ --- 90 - MAXIMUM ENVELOPE
-
, CAVERAGE
2 0- -- ,VERAGE
25'~- - 9V0A' A
10 m 20 - 7n.
9 50 K 1 - 60
S
20 -
- AVERAGE
10 - 50 -
10 -MINIMUM ENVELOPE 4 MNI MUM P
I I I I I I I I
0- 30 -
JAN FEB MAR APR MAY JUNE JULY AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEP OCT NOV DEC
FIGURE F.4.1. Daily Average and Extreme FIGURE F.4.2. Daily Average and Extreme
River Flows at the Reference Site Water Temperatures at the Reference Site