When a river rises and overflows its banks, the water spreads over the flood plain and a layer of sediment is deposited after each flood. Over time the flood plain actually rises.
Flood plains can be hazardous environments but are extremely fertile lands.
In the Fraser River Basin where rivers meander through flat and wide valley bottoms, flood plains are common. Around small creeks, beaver dams create wetland environments of shallow water, sedge marches and willow swamps, which are important wildlife habitats. Nootka rose, grow mostly along stream courses or along the edge of lakes. Black cottonwood , Populus balsamifera ssp. The Secwepemc ate the cambium rarely.