Ice-jam flood level
Peak open water level
Low Tall Sedge
Submergents Emergents Submergents shrubs shrubs meadow
1. A dam upstream
temporarily increases the
flow in the regulated
2. The pulse of increased
water course
flow helps create an ice
jam further downstream
3. The ice jam floods the
perched basins
Figure 8.9: Ice-jam floods provide water and nutrients to maintain delta ponds.
(a) Higher flooding levels in spring break up reach the perched basins.
(b) An adaptation strategy: water released from the reservoir on the left increases the probability of ice jams and flooding
of the ponds.
Source: Based on Prowse and others 2002b
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CHAPTER 8 RIVER AND LAKE ICE 211