Water management of a floodplain on carbon rich soils: Evidence from the Borgfelder Wümmewiesen

By project NACAO

Published on 18 October 2024

Germany

Bremen

About this good practice

The Borgfelder Wümmewiesen are a regularly flooded floodplain landscape on carbon-rich soils and one of Bremen's largest nature protection sites (689 ha). Wide, extensively farmed meadows and pastures, crisscrossed by ditches and dotted with still waters, characterize its appearance. The floodplain is used by farmers as pastureland or for haymaking. It is home to many animal and plant species. There is long-standing experience in actively managing the water level, including complete flooding in winter, thereby reducing carbon emissions from peat soils while achieving biodiversity conservation goals at the same time.

Conservation measures since 1987 include the restoration of ditches, the creation of small bodies of water, and relocating the summer dyke to connect 25 hectares to the river Wümme as a floodplain. The water level has been actively managed since the 1990s. Two dam keepers (an ornithologist and a farmer) operate the dam in close consultation with the supervising foundation nordwest natur and the nature conservation authority. In recent years changing climate conditions (and water regimes) have become a fundamental challenge

The south of the area is mainly owned by WWF/Northwest Nature Foundation. It can be dammed and is characersied by extensive use, very rare plant species and late breeders (quail, corncrake). The north is predominantly private, less waterlogged, extensive to semi-intensive use. Here are fewer rare plant species, but more meadow birds.

Resources needed

Mainly: (i) Financial resources to purchase land and capacity for close coordination with landowners. (ii) Investments to adapt the water system (restoration of ditches, creation of small bodies of water, relocating dykes to reconnect the floodplain to the water flow). (iii) Operation of dams.

Evidence of success

For each management objective -- (i) biodiversity conservation (e.g. rare meadow birds like the snipe), (ii) carbon sequestration (peat soils), (iii) agricultural use (cultural landscape) -- there are indicators of sucess. This includes extraordinary high breeding sucess of very rare meadow birds (e.g. snipe) and populations of very rare plant species (e.g. cuckoo pink), reduced carbon emissions from peat soils and and ongoing semi-intensive agricultural use of parts of the site.

Potential for learning or transfer

There are trade-offs and synergies between the three management objectives: (i) biodiversity conservation (e.g., rare meadow birds), (ii) carbon sequestration (peat soils), and (iii) agricultural use (cultural landscape). Carefully targeted water management allows for leveraging synergies. In many places in Europe, however, this will first mean creating the necessary conditions by adapting and renaturalizing heavily modified watercourses and ditches, reconnecting floodplains, and installing technical measures to control water levels.