Project funded
by theEU–DGEnvironment
L
andsurfacerelevant
forapplication
Artificial surface
Agriculture land
Forest and semi-natural areas
Wetlands
F
inancialcosts
(C
apital
,
operation
&
maintenance
)
The Sigmaplan case study provides costs associated with large-scale floodplain
restoration: dyke heightening (€300 (wall on top) to €16 100/m (Quay wall));
inner dike adaptation (€770/m); outer dike construction (€840/m); outlet sluices
(€19 000/ha); inlet sluices (€4 000/ha). Engineering costs are typically 10% of
the investment cost and maintenance costs less than 1.5% of the investment cost.
D
esign
The slope of the river and floodplain is one of the most important parameters
when evaluating the retention potential of the floodplain: shallow slopes reduce
discharge peaks and prolong retention periods, while steeper slopes reduce the
effects of retention, especially when the flood wave is contained completely within
the channel (Habersack).
S
cale
This measure cannot be implemented in
catchments with a small area, as the
river will have limited or no floodplain.
A floodplain is the area bordering a river that naturally provides space for the retention of floods and rainwater. Floodplains have often been drained and in
many places they have been separated from the river by structures. They have also been covered by sediments. Restoration and management of floodplains aims
to restore their
retention capacity
and
ecosystem functions
, by reconnecting them to the river. It requires measures such as modification of the channel,
removal of sediment, creation of lakes or ponds in the floodplain, modification of agricultural practices, afforestation, plantation of native grasses, shrubs and trees,
creation of grassy basins and swales, wetland creation, invasive species removal, riparian buffer installation and development.
Case studies:
HYDROMORPHOLOGY
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