Zazhor - blockage of the living section of the river at the beginning of ice age, causing the water level to rise.

Accumulation of drift ice, bottom ice and other types of in-water ice in the river channel during the fall drifting season and at the beginning of ice drifting, which constricts the living cross-section of the stream and leads to backwater (water level rise), reduction of channel capacity, or culvert openings and possible flooding of the coastal areas of the river.

Four stages of ice jam formation are distinguished:

1) cessation of drift ice transit and formation of immobile drift ice;

2) drifting of drift ice from a higher area and its accumulation under the ice;

3) compaction of drift ice (movement);

4) constriction of the channel water cross-section by a large amount of ice material and formation of a backwater level. The thickness of ice jam accumulations can exceed 10 m, and their length can reach 10-20 km, and the volume of squelch in the jam is from 3 to 100 million m3.