Winter Flooding: Every region in the United States is at risk for winter flooding. While many people focus primarily on ice and snow during this time of year, it is important to also consider winter flood risks.
Ice Jams: Long cold spells can cause the surface of rivers to freeze, leading to ice jams. When a rise in the water level or a thaw breaks the ice into large chunks, these chunks can become jammed at man made and natural obstructions, resulting in severe flooding.
Snowmelt: A sudden thaw can produce large amounts of runoff in a short period of time. Because the ground is hard and frozen, water cannot be reabsorbed. The water then runs off the surface and flows into lakes, streams, and rivers, at faster rate causing excess water to spill over their banks.
Log/Debris Jams: Rivers and streams can carry many things downstream. From trees and vegetation to sediment. While much of this stream load is part of the natural riverine function, these items and this load can a/so be dramatically increased during flooding events. Floating objects and debris can be very dangerous and can cause damage, but this debris and sediment can a/so begin to deposit and begin accumulating in areas. This accumulation can change channel paths, depths, and compromise urbanized infrastructure.