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O
bjectives
Planting flood-breaking hedgerows addresses several policy objectives. The primary target that justified their implementation
in the Lèze basin is
flood risk mitigation.
Indeed, the aim of flood-breaking hedgerows is to delay and spread out the
peak-flow of the river during flood events; by partially obstructing the flow, hedges can slow down running water. If the length
of the hedgerows network is sufficient, the measure can have a cumulative effect at the scale of the whole valley, leading to
decreased flows and reducing flood risks. Flood-breaking hedges also aim to reduce the energy of the river and its potential
for erosion, and help to filter nutrients; these contribute to improving the status of physico-chemical and hydromorphology
quality elements (under theWater Framework Directive), thus helping to prevent surface water status deterioration. Planting
hedges also contributes to maintaining and increasing
biodiversity
, through species diversity and by providing habitat
and connectivity.They also contribute to the provision of cultural benefits by recreating a traditional heterogenic landscape.
T
hemeasures
implemented
Flood-breaking hedgerows are composed of three to five rows of
native trees,shrubsorbushes
adapted to the local soil,
climatic and disease conditions. Hedgerows are planted on the floodplain
perpendicular
to the riverbed and are regularly
spaced (every 300 to 500 m). The trial site and plantation program were launched in 2009-2010 by planting two pilot
hedgerows. In total between 2009 and 2014, about 6km of hedgerows have been planted across the Lèze floodplain, with
a further 5km waiting for administrative approval. The objective is to reach
35km
by 2016.
© SMIVAL
Floodbreaking hedges obstructing the flow and slowing down running water
