Fluvisols are common in periodically flooded areas such as alluvial plains, river fans, valleys and tidal marshes, on all continents and in all climate zones. They occupy some 3.5 million km2 worldwide, of which more than half are in the tropics.
Fluvisols are young soils that have fluvic soil properties. For all practical purposes this means that they receive fresh sediment during regular floods (unless the land was empoldered) and (still) show stratification and/or an irregular organic matter profile. Fluvisols in upstream parts of river systems are normally confined to narrow strips of land adjacent to the actual riverbed. In the middle and lower stretches, the flood plain is wider and has the classical arrangement of levees and basins, with coarsely textured Fluvisols on the levees and more finely textured soils in basin areas further away from the river. Fluvisols show layering of the sediments rather than pedogenic horizons. Their characteristics and fertility depend on the nature and sequence of the sediments and length of periods of soil formation after or between flood events.
Fluvisols cover areas over 5% of the total land area of Europe. Fluvisols are present in nearly all regions, forming dominant soil reference group.