Results - TR00-140025

L nd

Obs WS 6000 cfs

ObsbsS 6S00 cf00

Obs WSer6100 cfs

Figure 19. Comparison of WSE's measured in the

physical model with HEC-RAS results near the ICS

Main Channel Distance (ft)

charge (see Fig. 16). HEC-RAS requires a fixed ice-

extended it to 300 ft upstream of the ICS to achieve

jam thickness at the head of a jam, and we used 1.5 ft

stable calculations near the ICS.

(i.e., the parent ice cover thickness) for all calculations.

Open-water conditions prevail upstream of a jam. Fig-

ure 21 shows that jam length decreases dramatically

Figure 20 shows the open-water profiles for the 100-

with increasing discharge, a combination of decreas-

year discharge (15,600 cfs) with and without the ICS.

ing ice volume and increasing jam thickness.

The effect of the ICS disappears beyond about 2500 ft

We determined the maximum water levels expected

upstream. Although the ICS raises the 100-year open-

upstream of the ICS by assembling the open-water and

water flood elevation at Kotecki Grove by about 0.6 ft,

ice-jam profiles for all discharges into a single data file.

ice jam conditions actually dictate maximum WSE at

Figure 22 shows typical results. Where the profiles

cross, the discharge that establishes the maximum WSE

Figure 21 shows ice-jam profiles at 4000, 7000, and

changes. Table 6 provides the maximum WSE, the dis-

10,000 cfs, with ice volume limited according to dis-

WS 15600 cfs - Llen 90 d

WS 15600 cfs - Plan 89

WS 15600 cfs - Plan 90

WS 15600 cfs - Plan 89

Figure 20. Comparison of open-water profiles at the

100-year discharge (15,600 cfs) with and without the

ICS (Plans 89 and 90, respectively).

Main Channel Distance (ft)

Western Governors University

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