The winter riverbed is the area a river takes up in winter. There is more precipitation in winter than in summer, which causes the river to expand outside its narrower summer riverbed. The water will remain in the winter riverbed until it flows back to the river naturally, soaks into the ground or evaporates. If we restore the winter riverbed in certain places, we give the river more room to flood safely. The natural relief or local levees protect the hinterland.

Tidal willow forests are forests of high-growing willows in the natural flood zones of large rivers.

In the context of the Sigma Plan, wetlands are marshy areas that are unaffected by the tides. The groundwater there is high in winter and drops in summer. The landscape can range from open water and reed beds to alluvial forests and wet grasslands.

A water barrier wall is an artificial elevation in the landscape in the shape of a wall created to protect the area behind it from flooding

A water barrier is an object or structure that is used to hold back water. Some water barriers are fixed. They can't be moved. Examples of this are levees, slopes, buildings or even street furniture. Other water barriers are mobile. They can be moved and are only activated when there is a risk of flooding.

TAW is the benchmark used for height measurements in Belgium. A TAW height of 0 metres is equivalent to the average sea level at low tide in Ostend.

Tweede Algemene Waterpassing (TAW) translates as second general water benchmark. It is the benchmark for height measurements in Belgium. A TAW height of 0 metres is equivalent to the average sea level at low tide in Ostend.