Alongside rivers, peatlands or mires (flood mires) are embedded with periodically flooded areas. An important ecosystem service of them is to act as hydrologic „catch basin“ having a balancing effect on flood water, i.e. to prevent flood water rises or keep their levels low. This helps to lower discharge peaks. In Berlin, flooding is only a minor factor. However, official records listing some areas as flood-risk zones are here.
Whether a peatland can provide this balancing function and forms such a catch basin, or retention area for potential floods depends on its location in relation to possible flood-risk zones. Especially in the heavily built-up, urban areas of Berlin, such open spaces are very valuable, and one such rarity is illustrated at the example (see figure) of the peatland Tegeler Fließ Süd.