60
ERDC/CRREL TR-02-14
7
SURVEY CONDITIONS
The weather and flow conditions were conducive for conducting the bathy-
metric surveys, which could be carried out on the scheduled dates. Flow condi-
tions in the reach essentially were in accord with the CWCP schedule for flow
release from the Fort Peck Dam and are typical of the winter flow regime for the
river (Fig. 40).
14000
12000
10000
8000
6000
4000
2000
0
1-Oct
22-Oct
12-Nov
3-Dec
24-Dec
14-Jan
4-Feb
25-Feb
18-Mar
8-Apr
29-Apr
Date
Figure 40. Discharge from the Fort Peck Dam, 1 October 1998 to 1 May 1999.
Weather
The winter of 1998-99 was relatively warm for the Fort Peck reach for north-
east Montana. The accumulated total of freezing degree-days (AFDD) for March
1998 through March 1999 was about 1648. In contrast, March 1996 through
March 1997 was one of the coldest periods, with 3060 AFDD.
Other factors that may have affected the river system include the relatively
wet fall, which potentially increased the water table. The higher water table may
have increased the gradient towards the river, with ramifications along the bank.
Also, the snowfall was above normal, increasing the amount of water entering the
system either as runoff or ground water during the spring thaw. Figure 41 shows
the precipitation measured in the Culbertson area for September through Decem-
ber for 19801998.
Freeze-up occurred along the river during late December. At the Culbertson,
Tveit-Johnson, and Vournas sites, it occurred on December 20. At the Mattelin
and Pipal sites, it began on the evening of December 20 and was completed on
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