Stream restoration in the Netherlands Stream restoration in the Netherlands ––

two examples differing in scaletwo examples differing in scale

Roos LoebKarin DidderenPiet Verdonschot

Contents

� National survey on stream restoration

� Small-scale restoration: woody debris in the Jufferbeek

� Large-scale-project: restoration of the Geeserstroom

� Conclusions

Stream restoration survey – where?

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10

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upper course

middle course

lower course

upper&middle course

upper to lower c

ourse

middle&lower course

restoration projects per stream course

% o

f p

roje

cts

Stream restoration survey – measures

0

20

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60

80

remeander(active)

reprofile raise drainagebase

raisegroundwater level

developinundation zone

increase waterretetion/storage

hydrology & morphology

01020304050607080

low gradientbanks

fish migrationpaths

asymetricalprofile

plant wood onbanks

stream and bank arrangement

01020304050607080

change landuse

top soilremoval

buffer zones reduce inflowcontaminants

water quality

% o

f p

roje

cts

% o

f p

roje

cts

% o

f p

roje

cts

Stream restoration inquiry – monitoring

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hydrology

morphology

water quality fish

macrophytes

bank vegetation

macro!invertebrates

phytobenthos

unknownnothing

monitoring both before and after

restoration

Wood experiment in the Jufferbeek

� Free-flowing discharge� Removal of leaves and branches� 1-5% coverage of organic matter (naturally 25% wood, 25%

leaves)

� Effects� Habitat disappearance for stream-dwelling organisms� Homogeneity of habitats� Increased discharge� Bed-incisions and drought

� Wood addition could be a cheap restoration measure for a small part of a stream course

� Jufferbeek: upper course in the east of the Netherlands� 2 locations: upstream (control) and section with wood

addition (300 m)� Spring 2006: wood was added to a coverage 25%

wood section

control section

Wood experiment in the Jufferbeek

0%

10%20%

30%40%

50%

60%70%

80%90%

100%

Apr-05

Oct-05

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Apr-05

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Nov-07

c o n t r o l w o o d s e c t

cove

rag

e

fdetri cdetri silt leaves veg wood bran sand

Wood experiment in the Jufferbeek

finedetritus

coarsedetritus

silttwigsleavesvegetationsandfine gravel

flo

wve

loci

ty(m

/s)

0,40

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0,00 a b c dc c d e

Wood experiment

�2

�1.5�1

�0.50

0.51

1.52

2.53

E uk ie ffe rie lla c la r ip enn isN eo lim nom y ia spM id eop s is c ra ss ip esT ub ifex tu b ifexL accob iu s b ip un c ta tu sL im nod rilu s h o ffm e is te riC h ry sop ilu s spL eb ertia in aequ a lisT ub ific id aeN ep a c in e reaA u lod rilu s japon icu sP rod iam esa o livaceaV e lia c ap ra iP o tam o th rix b edo tiL eb ertia lin ea taN eum an ia v e rn a lisH yd ro chu s spP o lyp ed ilum sca la en umO ph id ona is se rp en tin aE lod es spL im nod rilu s p ro fund ico laA eshn a spM ic rop te rn a la te ra lisC e ra top ogon id aeS tagn ico la spB a th yom pha lu s con to rtu sH ippeu tis com p lan a tu sH yg ro tu s in aequ a lisH e loph o ru s a eq u a lisM o loph ilu s spN eph ro tom a spZ avre lie lla spC o ryn on eu ra c f an ten n a lisT aban id aeP lec tro cn em ia con sp e rsaG yrau lu s spB e raeod es m inu tu sS tem pe llin a spSpe rchon th ien em ann iG am m aru s p u lexB ae tis v e rn u sS egm en tin a n it id aA rrenu ru s c y lin d ra tu sC lado tan y ta rsu s spR ad ix o va taZ avre lim y ia spA n acaen a spS ia lis lu ta riaC lo eon d ip te rumP isid ium spG a lb a trun ca tu laP ro c lad iu s spP roa se llu s m e rid ian u s

taxon gewicht

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before after

nu

mb

ero

f m

acro

inve

rteb

rate

tax

a control

wood section

Taxon increase

Large-scale restoration: Geeserstroom

Before� Deeply incised, canalized, short length, limited slope� Eutrophication from agriculture and sewer overflow� No fish migration possible (weirs)

Large-scale restoration: Geeserstroom

Restoration measures� New, meandering stream bed (2005)� Close-off + diversion agricultural waters� Only 1 weir with fish ladder

Historical situation

Large-scale restoration: Geeserstroom

Historical situation

Large-scale restoration: Geeserstroom

110115max water depth (cm)

2770average water depth (cm)

8512max width (m)

97average width (m)

2110slope (%)

8.96.0distance to fish ladder (km)

after restorationbeforerestoration

Large-scale restoration: Geeserstroom

Roonboomdijk

0

0.05

0.1

0.15

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0.25

0.3

0.35

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0.45

Jan-

05

Apr-0

5

Jul-0

5

Oct-05

Jan-

06

Apr-0

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Jul-0

6

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Jul-0

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Oct-07

conc

entr

atio

nph

osph

orus

(mg

P/l)

DIP

DOP

Large-scale restoration: Geeserstroom

Roonboomdijk

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apr-0

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atio

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trog

enN

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DON

Large-scale restoration: Geeserstroom

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µ

m

� 3 common, (hyper) eutrophic taxa dominant (pioneer species)

2µ

m

5µ

m

Cocconeis placentula Achnanthidium minutissimum Gomphonema parvulum

Large-scale restoration: Geeserstroom

Diatoms

macroinvertebrates(dis)appearance

0.1

1

10

Hyd

raca

rina

Biv

alvi

a

Hiru

dine

a

Am

phip

oda

Meg

alop

tera

Odo

nata

Olig

ocha

eta

Tric

hopt

era

Gas

trop

oda

Col

eopt

era

Bra

chyc

era

Eph

emer

opte

ra

Isop

oda

Lepi

dopt

era

Pla

tyhe

lmin

thes

Nem

atoc

era

Chi

rono

mid

ae

Het

erop

tera

Rat

io a

ppea

red/

disa

ppea

red

taxa

Large-scale restoration: Geeserstroom

Index for rheophilic species Index for drought tolerant species

n.s.

Large-scale restoration: Geeserstroommacroinvertebrates

*

Conclusions

� Dispersion plays an important role in (re)colonisation; flying species reach restored stream more easily than non-flying species

� (Re)colonisation and vegetation development take time: long-term monitoring necessary

� Exceeding nutrient norms may hamper development of ecology

Conclusions

� Many projects in the Netherlands only focus on a small section of a stream, no restoration of entire catchments (+ problems from upstream sections)

� Most effort put into hydrological and morphological changes, little into nutrients

� Many projects are not monitored (especially not for biological targets). A before-after-control-impact monitoring would be best.

� Need for scientific research to gain do’s and don’ts in lowland stream restoration