Refugia are habitats where organisms retreat during a disturbance (e.g. flood, drought). Due to their reduced intensity of physico-chemical conditions, refugia allow organisms to withstand a disturbance. Despite their important ecological role, refugia are poorly studied and often neglected in practical management (e.g. river restoration). Through descriptions of field and laboratory experiments, this chapter illustrates the structure and function of flood refugia and emphasizes the role of the sediment regime in refuge provision.