water management in the netherlands_tcm224-303503.pdf

8/20/2019 Water Management in the Netherlands_tcm224-303503.pdf

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Water Management

in the Netherlands


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| Rijkswaterstaat2


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Water Management

in the Netherlands


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| Rijkswaersaa2


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Waer Managemen in he Neherlands | 3

PrefaceHaving he righ amoun o waer or waer users, a he righ ime, in he

righ place, and a socially accepable coss is one o he key arges or he

Minisry o Inrasrucure and Environmen.

Today’s ground rules or he disribuion o waer in he Neherlands

originae rom he 1980s, more specifically rom he second Policy

Documen on Waer Managemen. A he ime, he enire waer

inrasrucure was reviewed. The conclusion was ha large-scale

invesmens in he waer inrasrucure were no necessary and ha good

managemen would suffice o opimise he benefis o our waer

disribuion sysem.

Our inrasrucure and he ground rules sill suffice, bu he capabiliies

have been sreched o he limis. Climae change and sea level rise promp

a re-examinaion o our waer managemen. The resilience o he main

waer sysem, he waer inrasrucure and he ground rules are up or

reconsideraion. Waer usage has also changed and new aciliies areneeded. We can only respond o he orecased climae changes i we are

ully conversan wih he way he main waer sysem works. The quesion is,

are we sill amiliar wih he background, he operaion and he rules o our

waer managemen? This bookle seeks o conribue o answering ha

quesion. This is also an excelen opporuniy o offer our collegues rom

abroad an overview o he specific siuaion o waer managemen in he

Neherlands, a counry ha would no be inhabiable wihou our flood

deences and waer managemen srucure.

I hope you will enjoy reading i.

Luizen Bijlsma

General Director, Rijkswaterstaat, Centre for Water Management


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Preface 3

Introduction 7

1 The development of water management in the Netherlands 11

The hisory o he ormaion o he Neherlands 11

The hisory o waer managemen in he Neherlands 13

2 System and functioning 21

Managemen o he reshwaer elemen o our waer managemen sysem 22

Componens o our waer managemen sysem: 26

– The Meuse 26

– The Rhine and is disribuaries 27

– IJsselmeer area 31

– Souhwesern Dela 31

– Regional waerways 36

Limis o waer managemen 36

3 Safety 37

4 Excess of water 41

5 Water shortages and drought 47

6 Salinisation 53

7 Water quality 59

8 Future developments 65

Physical and socieal changes 65

Consequences o climae change or waer managemen 69

9 Towards ‘climate-proof ’ water management 71

10 The Water Act and its legal instruments 75

Publication information 80


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Introduction Waer managemen in he Neherlands is a complicaed issue. Also,waer

disribuion hroughou he counry is ar rom sraighorward. The

challenges or waer policy makers are significan and he discussions abou

hese challenges requen. Tha is precisely why i would be pracical i

he paries involved could share an unequivocal body o knowledge and

a vocabulary ha everybody undersands.

As he work o many waer managemen auhoriies and waer users is

usually limied o only one par o our waer sysem, i is ofen difficul o

undersand he sysem as a whole and all is inerconnecions. There is

also someimes a disored percepion o he possibiliies ha exiss in

channelling waer. The need o have an overview o our waer managemen

sysem and is uncioning is indispensable in presen discussions. I is

imporan o know why hings are organised he way hey are and o

undersand he aspecs closely relaed o he disribuion o waer, such assaey, excess o waer and shorages, drough and salinisaion. I is also

imporan o know which issues and botlenecks o expec i climae

change persiss.

This bookle describes waer managemen and waer disribuion in he

Neherlands as well as he problems relaed o flooding, waer shorages,

saey, drough and salinisaion. The descripion o our waer managemen

sysem includes a shor hisory o he geological creaion o he Neherlands

and an accoun o he inervenions ha ook place over he cenuries oproec he counry rom highvolume river discharges or sorm ides.

Land reclamaion and oher hydraulic engineering projecs, such as he

excavaion o channels o he sea and he canalisaion o rivers, are also

briefly discussed.

We also look a waer disribuion, ocusing on he main waer sysem,

he regional sysem and he ineracion beween hem. Waer disribuion

under normal circumsances is disinguished rom waer disribuion in

he even o flooding or waer shorage.


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The relaion wih saey and salinisaion is explained as well. Finally, we discuss he curren botlenecks and he problems we can expec as

a consequence o climae change and soil subsidence. Where relevan,

he various hemes will be relaed o he designaed users.

This bookle may be used by everyone involved in organisaional issues

o waer managemen in he Neherlands: waer managemen auhoriies

and policy saff o municipal councils, provinces, waer boards and cenral

governmen, as well as people who use our waer sysem, and oher

ineresed paries. The aim is o provide basic knowledge on waer

managemen and waer disribuion in he Neherlands. Hopeully his

knowledge and inormaion will conribue o a clear discussion on solving

curren and uure botlenecks. We hope i will also conribue o insigh

and undersanding o hose abroad, who are ineresed in he pariculariies

o waer managemen in he Neherlands.


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1 The development ofwatermanagement inthe Netherlands

The hisory o he ormaion o he Neherlands

A he end o he las Ice Age, around 10,000 years ago, he Norh Sea was

a large lowland plain. As emperaure increased he sea level rose and afer

a ew housand years, he Norh Sea was on he doorsep o wha we now

call he Neherlands. River waer came o a hal behind barrier bars ha

he sea had creaed. Sil setled and plans flourished in he warmer climae,

orming a layer o pea on windborne sands deposied during he previous

period.

For cenuries hese layers o pea accumulaed, paricularly where hebarrier bars ormed a coninuous line, as i did in Holland. However, sorm

ides washed away enire areas o pea, afer which marine clay deposis

were ormed. This happened mosly in he souhwes o he Neherlands.

In he eas and souh he coarse and fine sand deposis rom he ice ages

sill occur on he surace. Here we also find he hilly areas o he Veluwe,

he Urechse Heuvelrug, he Hondsrug and Salland, which are ormed

by laeral moraines lef behind by he ice ages. These high grounds are

criss-crossed by a muliude o sreams ha provide naural drainage.

In he norh we also find boulder clay.


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7000 BC 5500 BC

This mixure o boulders, gravel and loam was so heavily compaced by he

glaciers o he las ice age ha i became impermeable, which has is effecon oday’s waer managemen.


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The hisory o waer managemen in he Neherlands

Living on he edge o land and waer offers many benefis, which is why our

ancesors sayed here despie he inrusive sea, rying o learn o live wih

waer. Excavaions near Vlaardingen in he lae 1990s proved ha waer

managemen was already par o lie beore he Common Era began.

Dams, shee piling and culvers were uncovered ha are clearly indicaive

o waer managemen inervenions. People in he norh ereced arificial

dwelling mounds called erps several cenuries beore he Common Era

began.

Gradually, we became more enerprising. The Middle Ages saw he

reclamaion o he pea bogs. Channels and diches were dug rom he

levees ino he elevaed bogs in order o drain hem. As an uninended

effec, exposure o air caused he bogs o se and oxidise.

While his was a slow process, in ime he surace level dropped unil i

lay beneah he level o he river on he oher side o he levee. Dikes and

mills became necessary o drain he excess waer ino he rivers.

In he souhwes, he bogs were no drained bu excavaed or heir saldeposis. This ype o surace level reducion gave easy access o he

sea: large pars o he bog were washed away, or insance during he

S. Elisabeh Flood o 1421, which creaed he Biesbosch. Large esuaries

were ormed around he cores o islands.

In he norh, his had already happened several cenuries beore. Here he

sea had breached he barrier bars in 1170, washing away he bog siuaed

behind hem, and hus creaing an inernal salwaer lake: he Zuiderzee.

Shorly aferwards, in he 13h cenury, he inhabians o he sal meadows

in Groningen and Friesland decided o link he mounds or ‘erps’ on whichhey lived by building a series o dikes.

Even afer he Middle Ages, sea levels coninued o rise and land coninued

o subside. Dikes had o be raised coninually. Bu waer managemen a

imes also ook he offensive: in he early 17h cenury, we sared draining

he lakes and ponds ha had been creaed by exracing pea. The las o he

inland lake reclamaion projecs, Haarlemmermeer, was drained around

1850. By hen, powerul seam-driven pumping saions had been developed

ha enabled us o drain his large lake.


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Soil map o the Netherlands: high grounds with wind-borne sand deposits drain into low-lying

grounds with Holocene deposits.


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Diking in he souhwes and norh (he Dollard) reclaimed large srecheso land rom he sea, undiscouraged by disasrous sebacks in he orm o

periodic sorm surges. The area along he major rivers o he Neherlands was

also subjec o regular flooding, ofen caused by ice dams: ice floes snagged

on he shore, impeding subsequen floes unil he blockage became so grea

ha he waer orced is way over or hrough he dikes.

In he course o he 17h cenury, he Waal became he main disribuary o he

Rhine. Almos 90 percen o he Rhine’s waer discharged hrough he Waal

o he sea. This drasically reduced he discharge o he Rhine isel and o is

oher branch, he IJssel. In order o sop his process, as well as or miliary

and socio-economic reasons, he Pannerdensch Kanaal was dug in 1707.

The succession o evermore powerul water-related interventions resulted in continual

subsidence o low-lying areas o the Netherlands, while the sea level continued

to rise ever aster (mean sea level [m.s.l.]).


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How the Pannerdensch Kanaal restored the discharge through the Neder-Rijn and IJssel.

In he 18h cenury, he rivers sared o have difficulies discharging ino

he sea. The Maasmond a Brielle siled up and shallows were also ormed

upsream. Ye i would sill be anoher cenury beore his was correced by

river inervenion works.

The 19

h

and 20

h

cenuries saw more drasic inervenions, such as hedigging o he Nieuwe Merwede, he Bergsche Maas and he Nieuwe

Waerweg, and he consrucion o weirs in he Neder-Rijn designed o

creae a differen disribuion o he Rhine’s waer over is disribuaries.

The Neherlands earned inernaional renown wih he Zuiderzee Projec,

which began wih he Asluidijk (1927-1932) and he reclamaion o he

Wieringermeer, he Noordoospolder, Ooselijk Flevoland and Zuidelijk

Flevoland. Equally impressive is he Dela Projec, buil in response o he

disaser ha hi he souhwes Neherlands in 1953. The Dela Projec inparicular confirmed our repuaion as conrollers o he sea, especially

once he planned dam in he Ooserschelde was alered in such a way ha

he sea will only be kep ou i here is he hrea o a repea o he 1953

disaser.

Many o he inervenions, however, have a downside which we only

sared o undersand in rerospec such as, or example, he ecological

consequences o he Dela Projec. This undersanding was incorporaed

ino he inegraed waer managemen policy launched in he 1980s.

Meanwhile, all hese inervenions have caused us o orge ha he seaacually inended o coninue shifing our coasline urher easwards.

Where i would have ended up by now is difficul o say.

Pannerden

Pannerdensch Kanaal

Schenkenschans

Lobith

Arnhem

Waal

Aerdt

Pannerden

Schenkenschans

Lobith

Arnhem

Waal

Aerdt


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The inrusion o he sea would have been couneraced by he rivers,

which would have coninued building up heir delas. Bu evidenly

he Neherlands would have looked very differen had hese inervenions

no aken place.

Fac is ha he coas now lies where i is. And ha we decided in 1990 ory and mainain he coasline here. This is why we have been so busy ever

since wih sand replenishmens, boh on he beach, he oreshore and in

he litoral zone. Moreover, a he urn o he millennium some evens

occurred ha urned our views on waer managemen upside down. High

discharge volumes rom he rivers Rhine and Meuse in 1993 and 1995 led o

he Space or he River programme. In addiion, excepional droughs in

2003 and early 2005 underlined he imporance o designaing areas where

waer can be sored as a buffer capaciy.

Southwestern Delta below sea level (dark blue). Right: situation in the event o flooding;

lef: situation in the event o flooding i no interventions had been made in our water system.


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Water BoardsIn he early Middle Ages, he wesern par o he Neherlands was a boggy

pealand. For people o work and live on ha land, i had o be drained.

In hose days, he villagers did ha hemselves by digging a dich, building

a dam or consrucing a dike. From he 11h cenury onwards, his gradually

changed. The people who owned he land were ofen no longer villagers

bu large landowners who lived in ciies, casles or esaes. Moreover,

here was a growing insigh ha he consrucion o dikes and waer

drainage were maters ha wen beyond he realm o a village.

In he 13h cenury, people wih common ineress in sae waer

managemen ormed co-operaives, resuling in he firs waer boards.

Their co-operaion no only involved working ogeher, i also implied

paricipaion in governance, which makes he waer boards he oldes

orm o democraic governmen in he Neherlands. The waer board

Hoogheemraadschap van Rijnland, esablished in 1232, is he oldes waer

auhoriy ha is sill in uncion.

There used o be several hundred waer boards, bu in he las cenury

heir number has been reduced considerably. Nowadays here are 26 lef.

Rijkswaterstaat

A he end o he 18h cenury, parliamen decided o esablish a powerul

cenral organisaion o preven he counry rom being flooded by he sea

and rivers. Shipworms were atacking he wooden seawalls and

quaysides, harbour mouhs were siling up, and ice dams were causing

flooding. Counermeasures were aken, bu hey ofen only provided

solace on a very local scale and caused new problems elsewhere. I was

ime or cenralised waer managemen on a naional level. On March 27,1798, an ‘Agency or Public Works and Waer Managemen’ was

esablished, comprising a presiden, an assisan and a draughsman.

Nowadays Rijkswaersaa is he implemening agency or he Minisry o

Inrasrucure and Environmen. Rijkswaersaa adminisers he naional

road nework (3,260 km), he naional waerways nework (1,686 km) and

he waer sysem (65,250 km2), including he Duch par o he Norh Sea.

The legal insrumens a he diposal o our waer auhoriies are

presened in chaper 10.


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Overview o the area administered by the 26 regional water boards.


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Biurcation point (‘T-junction’) at IJsselkop, seen rom the south.

The ship is approaching rom the IJssel.


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2 System andfunctioning

The Neherlands could be considered as a gaeway or waer. All he waerha is carried across is borders by sreams and rivers mus be discharged

ino he sea. The same applies or rainwaer, which makes is way o he sea

overland or underground. In he eas and souh, his happens naurally.

Due o he relie o he land, waer on high ground finds is own way down.

Bu in he fla low-lying areas ha also lie below sea level, waer needs a

helping hand.

We gradually ried o urn his gaeway ino a conrol panel: a pumping

saion here, a lock here, dams, dikes and weirs everywhere. This has

resuled in a mosaic o rivers, canals, lakes and (dammed) esuaries,inerlaced wih a sysem o diches, own canals and channels. Generally we

manage he operaion o our main waer sysem quie well. We direc waer

rom he Rhine and Meuse o locaions o our choice. A subsanial amoun

is sored in Lake IJsselmeer, so ha i can be used laer on or he

producion o drinking waer, irrigaion purposes and much more. We make

sure ha here is sufficien waer in he canals o allow shipping o coninue

and we use i o comba saline inrusion o groundwaer and o keep

seawaer a bay.


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Managemen o he reshwaer elemen o our waermanagemen sysem

However small our counry is, i sill is par o our inernaional river

basins: Rhine, Meuse, Scheld and Ems. All he waer ha flows down

hese rivers passes hrough our counry on is way o he Wadden Sea and

he Norh Sea.

As his bookle ocuses only on he reshwaer elemen o hese river basins

and on he ransiional area (he souhwesern Dela), he Scheld and Ems

will no be discussed. The discussion o our waer managemen sysem will

address he ollowing:

rivers wih accompanying canals in he same river basin,•

IJsselmeer area,•

souhwesern Dela, and•

he smaller, regional waerways on high grounds and in low-lying areas.•

In order o undersand how our waer managemen sysem works, he waer

sysems hemselves need o be explained. A waer sysem comprises variouscomponens which inerconnec o a high degree, paricularly in he waer

managemen sysem o he Neherlands. They influence each anoher, hey

are co-dependen and moreover hey are sensiive o ranser o problems

relaed o waer qualiy and quaniy. To undersand ha

inerconnecedness properly, his paragraph will firs describe he naure

and characer o he various componens.

Water rom high grounds flows to the sea as surace water as well as via groundwater streams.


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High groundsRain ha alls ono high grounds parly infilraes where i ell, while he

remainder flows o lower-lying areas by way o sreams. The infilraed waer

also seeps down, which causes marshland o develop a he oo o he high

grounds. These areas reac differenly in summer and winer. In summer,

he groundwaer level is low as a resul o he evaporaion surplus, which

causes he ground o absorb mos precipiaion, and run-off is limied.

In winer, he soil is sauraed and rainwaer is discharged immediaely.

River A river can be ed by melwaer, precipiaion and groundwaer. In summer

(wih zero or only a small precipiaion surplus and litle melwaer),

he river sream is narrow. In imes o a large precipiaion surplus and/or

a lo o melwaer, he river can become so wide as o cover he enire flood

plains (he area beween he summer dike and he winer dike).

The ‘river system’ component.

Polder A polder is an area ha is proeced rom ouer waer by a dike and ha has

a conrolled waer level on he inside o he diked area. Any waer enering

he polder (rain, seepage waer) ha is no used or sored, has o be pumped

ou. To do his, he waer is firs pumped ino he polder oule.


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Lay-out o our water management system.


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Diagram o the components ‘polders’ and ‘reclaimed land’.

Streams between components The differen componens (high grounds, polders and rivers) canno be

seen in isolaion rom one anoher. There is consan inerchange:

he river supplies waer o he lake, he lake discharges waer ino he sea

and he polder drains waer ino he lake, as well as absorbing i in he

summer. The waer level in he lake influences he seepage waer andgroundwaer flows. In shor, everyhing is inerconneced.

Interconnectedness This inerconnecedness is he basis or managemen o our main waer

sysem. Under normal circumsances, i seams obvious ha waer in every

componen is a he level we wan i o be and ha i flows where i is

needed. However, in periods o excess rainall in our own counry and in

counries upsream, or during prolonged periods o drough, we have o

consanly conrol and manipulae he sysem o coninue serving all waer-relaed ineress. We do his according o scenarios and agreemens,

which will be discussed in deail in he ollowing paragraph.


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The interconnectedness o the water system components.

Componens o our waer managemen sysem

Rivers and canals

The days when he rivers could deermine heir own course are long gone. We have aken various measures o conrol waer disribuion.

Key ools are he weir a Driel, which deermines o some exen how much

Rhine waer flows o he IJssel, he Neder-Rijn and he Waal; he sluice gaes

in he Asluidijk, which enable us o regulae he waer level in Lake

IJsselmeer; and he Haringvlie and Volkerak sluice gaes, which allow us

o deermine hrough which ‘exi’ he waer will flow ino he sea.

The Meuse

The Meuse is a rain-ed river and, as a resul, i ofen goes hrough periods wih litle discharge. In order o reain wha waer here is and o mainain

shipping, seven weirs were consruced in he 20h cenury: a Borgharen,


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Linne, Roermond, Beleld, Sambeek, Grave and Lih. They are almos alwaysin operaion, being opened only when he discharge volumes are high.

This mosly occurs in winer, when here can be so much rainall in he river

basin ha he Meuse canno cope wih his discharge. This happened,

or example, in 1993 and 1995.

Where he Meuse crosses he border a Eijsden, i is almos immediaely

divided ino hree channels: he Zuid-Willemsvaar, he Julianakanaal and

he Grensmaas (he srech o Meuse in he border region o he Neherlands

and Belgium).

In he Grensmaas, we aim a a minimum flow o 10 m3/s or ecological

reasons, bu in dry periods his canno be mainained. Shipping along

he Julianakanaal mus remain possible a all imes, requiring 20 m3/s o

compensae or losses a he locks a Born and Maasbrach. In dry periods,

waer ha is used hrough operaion o he locks is pumped back again.

The canals in Midden-Limburg and Noord-Brabant The provinces o Limburg and Noord-Braban rely on he Meuse or heir

waer supply. According o several reaies wih Belgium since 1863,he Neherlands is obligaed o discharge a minimum o 10 m3/s ino he

Zuid-Willemsvaar via he supply culver a Maasrich. In reurn, Belgium

is obligaed o redirec 2 m3/s, plus anyhing exceeding he obligaory

10 m3/s ha is discharged o he Neherlands a Lozen. Incidenally, par

o he Meuse waer is already divered near Liege, which Belgium uses o

supply he Alberkanaal.

Waer managemen o he canals in Midden-Limburg and Noord-Braban

is laid down in a waer agreemen ha aims o ensure ha he supply and

discharge o waer is disribued equally among he areas managed by heregional waer boards.

The Rhine and its distributaries The Rhine crosses he Duch border a Lobih. The firs biurcaion poin

is near he Pannerdensche Kop. Here he river splis ino he Waal and he

Pannendersch Kanaal, which flows ino he Neder-Rijn.

Eas o Arnhem, he IJssel branches off rom he Neder-Rijn. The weir in

he Neder-Rijn near Driel is operaed in such a way ha Rhine waer can be

discharged ino he IJssel or as long as possible a 285 m3/s and ha hereis always 25 m3/s lef or he Neder-Rijn. The remainder goes o he sea

hrough he Waal.


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This disribuion o waer discharge guaranees a reasonable navigaion

deph on he hree river branches. In addiion, he power saion Harculo

near Zwolle receives sufficien cooling waer and here is enough waer

available in Lake IJsselmeer o mee agriculural requiremens in he norh

o he Neherlands during dry periods.

This ideal scenario can be mainained on average or a leas nine monhs

per year. However, i he discharge a Lobih is less han 1,300 m3/s, i isimpossible o direc 285 m3/s o he IJssel. Even so, a discharge o 25 m3/s

is sill mainained over he Neder-Rijn.

Detail o the subsystem o the Meuse and the canals in Midden-Limburg and Brabant.


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As he discharge rises above 1,300 m3/s, he weirs a Driel, Amerongen and

Hagesein are gradually opened and he discharge hrough he Neder-Rijn

increases, while approximaely 285 m3/s coninues o flow hrough he

IJssel. I he Rhine has a discharge over 2,400 m3/s, he weirs are ully

opened and he disribuion o waer discharge can no longer be

manipulaed.

The Amsterdam-Rijnkanaal and the Noordzeekanaal The Amserdam-Rijnkanaal and he Noordzeekanaal are o major

imporance or shipping connecions beween IJmond, Amserdam

and Germany and or regional waer managemen. The canals mus be

considered as a single sysem. The map shows he cachmen area or

his sysem. The green area is drained direcly, he yellow area can also

be drained indirecly hrough he Noordzeekanaal by way o he inle

Oranjesluizen (locks) near Schellingwoude. On average, 60 percen o he

waer in he sysem is supplied by regional waer discharged by he waerboards (he green area). The sysem drains ino he Norh Sea a IJmuiden.

When he sea level is low, he waer flows hrough discharge sluices

Catchment area o the subsystem o the Amsterdam-Rijnkanaal and Noordzeekanaal.

Green drains directly, yellow indirectly


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(maximum 500 m3/s). When he sea level is high, he IJmuiden pumpingsaion, which is he larges in Europe (maximum 260 m3/s), is pu ino

operaion.

Waer can be supplied hrough locks a Wijk bij Duursede and

Schellingwoude. The quaniy supplied by Lake IJsselmeer depends o

a large exen on he flushwaer managemen or he Lake Markermeer.

The amoun ha is supplied a Wijk bij Duursede in dry periods in is urn

depends on he amoun o waer ha can be subraced rom he Waal a

Tiel, as he discharge in he Neder-Rijn is needed o mainain he waer

levels downsream.

Waer is wihdrawn rom he Amserdam-Rijnkanaal and he Noordzeekanaal,

or regional waer supply and drinking waer purposes.

This is aken ino accoun in he managemen o he sysem as navigable

deph is o be mainained. I he level o Lake Markermeer permis flushing

o he Vech and waer supply via Muiden, waer can also be direced ino

he Amserdam-Rijnkanaal. In ha case, less waer has o be divered rom

he Waal hrough he Neder-Rijn.Many ships are locked a IJmuiden. This causes salwaer o flow ino

he Noordzeekanaal, creaing a salwaer gradien rom IJmuiden o he

connecion wih he Amserdam-Rijnkanaal. Ecologically, his salwaer

gradien provides he Noordzeekanaal wih unique ecological characeris-

ics. Because here is an inle poin or drinkingwaer in he Amserdam-

Rijnkanaal we mus ensure ha salwaer incursion does no advance any

urher. To ha end, a minimum flow o approximaely 30 m3/s is aimed

or a Diemen. I possible, waer rom Lake Markermeer is also used a

Schellingwoude o hal salwaer incursion.In prolonged periods o drough, waer rom he Amserdam-Rijnkanaal is

also used o comba salinisaion o he polders in he province o Zuid-

Holland. During dry periods waer rom he Hollandsche IJssel is oo saline

or his purpose, because he salwaer ongue has advanced oo ar ino he

Nieuwe Waerweg. This arrangemen o provide he polders in he province

o Zuid-Holland wih waer rom he Amserdam-Rijnkanaal was made in

he lae 1980s in a Waer Agreemen eniled Small-scale Waer Supply

Provisions. I sipulaes ha a sysem o pumps and pumping saions direc

approximaely 7 m3/s o reshwaer o he polders o Zuid-Holland duringperiods o waer shorage.


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IJsselmeer area This waer sysem comprises lakes IJsselmeer, Markermeer, IJmeer and

Randmeren. This is he larges reshwaer basin in Wesern Europe and

uncions as a buffer which, during periods o drough, can supply waer

o many o he norhern pars o he Neherlands.

I is also a naure reserve o naional and inernaional imporance.

Is primary uncion is o discharge waer rom he river basins o IJssel,

Overijsselse Vech and Eem.

Lake IJsselmeer – and in he summer monhs, Lake Markermeer – is

primarily ed rom he IJssel. From April o Sepember, he arge level on

hese lakes is 0.20 m below mean sea level (m.s.l.), while during he

res o he year a level o 0.40 m below m.s.l. is mainained. There is

usually enough waer o mainain his level. In he winer monhs,

Lake Markermeer discharges he majoriy o is excess waer ino Lake

IJsselmeer, while in he summer mos o i flows weswards o flush he

Noordzeekanaal. In spring and auumn he direcion o he waer discharge

changes depending on he weaher condiions and he waer levels.

Excess waer rom Lake IJsselmeer is discharged ino he Wadden Sea viasluice gaes a Den Oever and Kornwerderzand.

Lake IJsselmeer provides significan waer volumes o he provinces o

Friesland and Groningen, as well as he norhern par o Noord-Holland

and large pars o Drenhe and norhwes Overijssel. In addiion, waer inle

poins or he producion o drinking waer are locaed a Andijk and

Enkhuizen. However, he quaniies involved here are relaively small.

The key waer inle poins or he Schermerboezem are locaed on Lake

Markermeer a Luje-Schardam, Schardam and Monnickendam. Finally,

waer rom Lake IJsselmeer can be le in a Muiden and Zeeburg o flush he Vech and he Amserdam canals, respecively. During periods o drough,

a sequence o prioriies comes ino operaion (see page 52), which

deermines he order in which he scarce supply o waer will be allocaed o

he users. For he IJsselmeer area his sequence has been laid down in he

regional sequence o prioriies eniled ‘Waer disribuion in he Norhern

Neherlands’.

Southwestern Delta

The souhwesern Dela is demarcaed by he Nieuwe Waerweg/NieuweMaas, he Biesbosch and he Scheld esuary. I is a complex sysem o

inerconneced and muually influenial resh- and salwaer waerways.


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Some waerways are sagnan, ohers are idal.

The Rhine, Meuse and Scheld converge here. Waer disribuion is largely

regulaed by he Haringvlie sluice gaes, which are operaed in such a way

ha he Nieuwe Waerweg can discharge 1,500 m3/s or as long as possible.

In his way, we atemp o counerac salwaer incursion and prevensalinisaion o he Hollandse IJssel, he mos imporan waer inle poin

or he mid-wesern par o he Neherlands o which is locaed a Gouda.

Moreover, he operaion o he Haringvlie sluices aims o ensure a

minimum waer level in he Hollandsch Diep o 0 mere Amserdam

Ordnance Daum (NAP), in order o susain navigaion o and rom he

seapor o Moerdijk.

During discharges a Lobih up o 1,100 m3/s, he Haringvlie sluice gaes

are compleely closed, excep or he sal drains and fish passages. When he Rhine discharge is beween 1,100 and 1,700 m3/s, he gaes are

open a low ide or 25 m2 i he sea waer level is lower han he waer level

Detailed map o the southwestern Delta.


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on he landward side. In his way, an average flush rae o some 50 m3/sper ide is mainained in he wesern par o he Haringvlie.

A discharge raes beween 1,700 and 9,500 m3/s, he sluice gaes are

gradually opened and a discharge volumes over 9,500 m3/s, he gaes are

ully opened. However, hese operaion rules are no always sufficien o

mainain a arge discharge o 1,500 m3/s a Hoek van Holland. During

periods o low flows and when he Haringvlie sluices are compleely closed,

he Nieuwe Waerweg receives he discharges rom he Lek, he Waal and

even he Amer, minus he waer ha is drained a he Volkerak sluice gae

and he flush rae o he Haringvlie.

A he momen, he Haringvlie sluice gaes sill orm a solid barrier

beween he sea and he Haringvlie, and as such hey block he passage o

(migraory) fish such as salmon and rou. The Haringvlie sluice gaes will

be lef ajar in 2010 in order o creae a more naural dela. This means ha

he gaes will no longer close during rising ides, bu will remain ajar on

he condiion ha he reshwaer inle poins do no become salinaed.In his way, a gradual ransiion rom seawaer o river waer will develop.

Moreover, migraory fish will be able o pass hrough he sluice gaes.

This measure is in line wih he implemenaion o he Waer Framework

Direcive and he Bird and Habia Direcives (Naura 2000).

Wih he excavaion – and subsequen deepening – o he Nieuwe Waerweg

o ensure access o he por o Roterdam, salwaer moved urher and

urher inland, which compromised he waer supply o Delfland. To supply

resh waer o Delfland, a pipe wih a capaciy o 4 m3

/s was insalled romhe Brielse Meer o Delfland, passing underneah he Nieuwe Waerweg.

In combinaion wih he exising capaciies or leading 10 m3 hrough he

Lopikerwaard or Krimpenerwaard, he area can now mee is own waer

demands.


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Lake Volkerak-Zoommeer was creaed in 1987 as a resul o he decisiono keep he Ooserschelde in an open connecion o he sea.

To reain sufficien idal range, he surace area o he Ooserschelde

was reduced wih he help o he Philipsdam and he Oeserdam. By

disconnecing he Lake Volkerak rom he Haringvlie and flushing he

sysem wih reshwaer rom he Hollandsch Diep and he rivers in

he province o Braban a resh waer lake was creaed.

Since 1994, excessive amouns o nuriens and a long reenion ime in

his lake have creaed opimal condiions or blue-green algae blooms.

Blue-green algae adversely affec he aquaic environmen by producing

oxins. In addiion, when hey die off in lae summer, hey produce a

errible smell. This causes inconvenience o residens, holiday-makers and

ouriss almos every year, while armers canno use reshwaer rom he

lake or irrigaing heir crops. In 2004, a sudy was iniiaed o ideniy

soluions o his problem. The research resuls led o he conclusion ha

he necessary improvemen in waer qualiy canno be obained i Lake

Volkerak-Zoommeer remains a reshwaer lake. Only i he lake is

salinaed again and limied idal dynamics are resored, waer qualiy

will improve sufficienly or he algal blooms o disappear.


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Overview o all ‘water valves’ in the main water management system.


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Regional waterwaysIn addiion o he main waer sysem, here is also a dense nework o

diches, sreams and canals in he Neherlands ha belong o he regional

waer sysem. The main waer sysem and he regional waer sysems are

inerconneced a several locaions. In he even o excessive rainall, he

regional sysem drains ino he main sysem, while he regional sysem can

be ed by he main sysem in periods o drough.

In low-lying pars o he Neherlands, he waer ha eners he sysem has a

variey o uncions, he mos imporan o which is mainaining he waer

level o preven subsidence o pea bogs. In addiion, flushing is used o

guaranee good waer qualiy. In higher areas, he waer is supplied

primarily or irrigaion purposes. The map on page 35 provides an overview

o he ‘waer valves’ in he main and regional sysems.

Limis o waer managemen in he even o exreme

discharge volumes

Under normal circumsances, our waer sysem works well.

Problems such as saey, waer shorages, flooding, waerlogging and

salinisaion usually only occur under exreme circumsances. The ac ha

problems occur is no surprise given ha he margins or waer disribuion

in and beween he various elemens o he sysem are small. In he even o

exremely low river discharges, every weir along he Neder-Rijn is opened

and he sluice gaes on he Haringvlie and Asluidijk remain closed, bu

ha is all we can do o regulae or direc he disribuion o waer. The same

is valid or exremely high discharges, when we can do nohing else buopen all he sluice gaes as wide as possible.

The ollowing chapers deal wih saey, flooding, waer shorages and

drough, salinisaion and waer qualiy in he curren siuaion.

Chaper 8 provides a glimpse ino uure developmens and heir poenial

consequences, and Chaper 9 discusses he policy and managemen

documens ha indicae how we inend o adap our waer managemen

sysem o climae change effecs.


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3 Safety

Dunes, dams, dikes and he Dela Projec enable us o live saely in ourlow-lying counry. The sandards ha he waer deences have o mee are

laid down by law. Ironically, he gradual developmen o he sysem wih

which we gained conrol over he waer creaed a saey risk in isel. River

waer ha is orced o remain in a limied space beween dikes can only rise

in he even o higher discharge raes.

We have exchanged as i were he inconvenience o a large area o weland

or a virual guaranee o land ha is permanenly dry, bu a he risk ha

waer levels will be much higher han beore in he even o a flood. This

hrea has increased even more by subsidence and sea level rise. As hepopulaion behind he dikes has grown and invesmens in housing and

businesses run ino he billions, he consequences o a dike burs would be

disasrous. In he disribuaries o he Rhine, waer disribuion relaes o

saey in ye anoher way. The ‘regulaory valves’ in he main sysem are

operaed in such a way ha he chance o flooding is equally high in all

disribuaries. Managemen and mainenance o he river beds and winer

beds mus ensure ha his coninues o be he case.


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What is safety?Dikes and dunes ensure ha we may eel sae. All he dunes and he mos

imporan dikes are called primary waer deences, because hey proec us

rom flooding by he sea, he main rivers or Lake IJsselmeer and Lake

Markermeer. The secondary deences are also imporan, bu i a dike in his

caegory collapses, he consequences are no as dramaic – alhough he

inhabians o Wilnis may hink differenly. There, he ring dike o he

Groo-Mijdrech polder burs in Augus 2003 and he srees in he Veenzijde

esae were covered by hal a meer o waer. Ye, in erms o saey, Wilnis is

o a differen order han wha we are discussing here. I he primary waer

deences were breached, he consequences would be considerably greaer,

Jus how sae we are behind he waer deences depends on where we live.

The Flood Deences Ac indicaes he saey sandards or every dike ring

area. The sandard is higher i more economic aciviies ake place wihin

he ring and i he number o inhabians is high. Oher imporan acors

are he size o he area liable o flooding; he heigh o which he waer may

rise and wheher he flood waer will be resh or saline.

The sandard is expressed in a probabiliy per year ha a criical waer level will occur, e.g. 1:1,250 per year. The requiremens or a flood deence

srucure in erms o heigh and srengh are derived rom ha sandard.


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How is safety determined? The saey o lakes, rivers, he river dela and he sea are each deermined

by differen acors:

Lakes waer level, wind (wind acion and wave run-up)

Rivers waer discharge and, o some exen, wind

(wind acion and wave run-up)

River dela river inflow, sea level, wind (wind acion and wave run-up)

Sea ide and wind (wind acion and wave run-up)

Safety, for whom? The Dela Commitee, esablished afer he disaser o 1953, has laid down

our curren proecion policy. However, since hen, a number o issues have

changed. Considerable invesmens were made in he areas behind he

dikes and he number o people living here has increased significanly.

These developmens are no likely o sop any ime soon. In addiion, all

climae scenarios orecas by he Royal Neherlands Meeorological Insiue

(KNMI) show a rise in sea level and river discharge volumes. In shor, he

hrea and he poenial consequences o a flood are on he increase. A large-scale flooding will cause widespread damage and long-erm

disrupion o our sociey.

Tha is why here is growing suppor or an alernaive approach o saey.

We should no longer ocus on he probabiliy o a ailure o our waer

deences, bu on he risk (i.e. probabiliy muliplied by consequences)

o acual flooding. This provides greaer insigh ino he possibiliies o

limiing he consequences o flooding. The riskbased approach shows ha,

despie all our effors, he risk can never be reduced o zero. By implicaion,

he naional governmen canno be held solely responsible or proecionagains flooding. However, he prevenive approach o high-waer

proecion remains pre-eminen in waer managemen policy. In order o

map he risks o flooding, he governmen, provinces and waer boards are

implemening he programme Flood Risks and Saey in he Neherlands.

For each dike ring, he probabiliy o flooding and he flood damage is

expeced o be mapped ou by 2010 – aking he presen siuaion as he

basis or calculaing probabiliies.


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| Rijkswaersaa40


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4 Excess of Water

A cellar ull o waer is upseting. A layer o waer on he road is a nuisance.No more and no less. In any case, our saey is no a risk.

We have caused par o he problem ourselves, by gradually paving or

asphaling more land and coninually choosing o build residenial esaes

a locaions where waer also likes o ‘reside’ now and again. The Naional

Adminisraive Agreemen on Waer (NBW) includes an agreemen ha

waer managemen mus be in order by 2015, indicaing how ofen flooding

or waerlogging may occur.

Wha is excess o waer?

Excess o waer is he collecive erm or siuaions in which we are aced

wih large amouns o waer in he orm o precipiaion or groundwaer,

bu wihou i endangering our lives. In mos cases, he problem is

emporary, such as afer a heavy rainsorm or flooding.

Excess of water caused by rain

Heavy rainall occurs mosly beween Sepember and March. This is alsohe period when he rivers carry more waer. Excess o waer ha occurs as

a combined effec usually affecs low-lying areas, where he waer gahers


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and rom where i is difficul o pump ou because o high waer levels. The same is valid or polders. In sal meadows, he problem is worse

because he waer also comes up hrough he ground.

Excess of water caused by groundwaterIn areas wih high groundwaer levels, excess o waer can occur whenever

here is insufficien drainage and he waer ges ino crawl spaces or

basemens. A requen problem is sponaneous seepage under dwellings,

which is difficul o solve wihou drainage or pumps.

What is waterlogging? Waerlogging is a specific erm used or a sae o he soil whereby he waer

conen in he soil prevens enough aeraion or specific aciviies. Ground

may be regarded as waerlogged when he waer able o he ground waer

is oo high o convenienly permi an anicipaed aciviy, like agriculure.

Waerlogging can also be cased by excessive rainall.

Overview o interconnected causes o flooding.


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Wha causes waer flooding and waerlogging?

Flooding and waerlogging are caused by:

• insucient ability to store rainwater; reasons include more intensive use

o land, increase o paved suraces, reduced sorage capaciy.

• the excessive level of outer waters, making it impossible to drain water

swifly rom he upsream area which leads o sagnaion.

• alterations in spatial layout. Sometimes we built residential areas at

locaions ha used o be sorage basins. In ha case, higher groundwaer

levels alone can cause damage.

• subsiding ground levels caused by shrinkage, seing and oxidation of

pea bogs. The resul is ha waer level and ground level more rapidly

coincide wih one anoher. In addiion, he heigh difference beween

groundwaer and surace waer in higher-lying waerways or lakes

increases, resuling in more seepage waer.

As or regional waers, flooding occurs when waer levels are so high ha

he sreams, lakes or waerways burss heir banks. In he main waersysem, floods are deemed o occur i naional waerways are no sufficienly

capable o soring or discharging regional waer discharges. Given ha

naional waerways are he final link in he discharge chain, i is imporan

ha hey are no he weakes links, oherwise hey will cause excess o waer

in upsream regional waer sysems. On he oher hand, i is equally

undesirable ha regional waer boards should shif heir drainage problems

ono he naional waerways. Agreemens beween waer auhoriies

concerning such maters are laid down in so-called waer agreemens.

Naional waerways can cause flooding and waerlogging in wo ways.Direcly, when waer flows over is banks, and indirecly, when high waer

levels on naional waerways block discharges rom regional waers.

There are differen causes o flooding and waerlogging in polders, on high

ground, in urban areas and in areas beween he rivers and he dikes.


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| Rijkswaersaa44

Weir in the Neder-Rijn at Driel.

PoldersIn polders, excess o waer can be caused by:

• limited storage capacity, which means that water cannot be collected

• overly rapid discharges into storage basins, that cause these to overow • insucient drainage capacity to pump water to larger storage basins.

This causes problems i large amouns o waer need o be drained and/or

i he receiving waer has a high level and he discharge head increases

• extra seepage water caused by high water levels behind the dike, which

causes waerlogging.

High groundOn high ground, flooding and waerlogging are caused by:

• stagnation in discharges due to high water levels downstream or inreceiving waers

• overly rapid discharges, resulting in increasing water discharge levels.

This increase is emporary, because he waer hen flows o low-lying

areas.

Urban areasFloods caused by rainall ofen occur in ciies or indusrial esaes, where

almos all rainall drains ino he sewer. This is usually a combined sewer or

wase waer as well as rainwaer, even hough segregaed sewer sysems orseparae rainwaer discharges are gaining ground. During heavy rainall,

sewers canno cope wih he amoun o waer and overflow, resuling in


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srees being flooded. Much worse, someimes cellars are flooded as well.Moreover, i a combined sewer overflows, public healh may become an

issue.

Areas outside the dikesIn areas ouside he dikes, floods are simply caused by high waer levels.

I is someimes necessary o accep excess o waer. I he operaion o he

main sysem requires ‘closing he ap o he regional drainage sysem’, local

flooding will occur. This will, however, preven poenially less conrollable

flooding elsewhere and hus jeopardizing saey.

Who is affeced by floods?

In order o deermine wheher he sysems operae as hey should, i is

necessary o know he requiremens or waer sysems.

Managemen goals have been se or his: a paricular waer level mus no

be exceeded more han once in a cerain period o ime. An assessmen o wheher he sysem is uncioning properly does no so much ocus on he

exen o which he level is exceeded bu on he requency wih which his

occurs and, paricularly, or how long.

Regional waer boards assess heir waer sysems according o he operaing

sandards sipulaed in he Naional Adminisraive Agreemen on Waer,

on he basis o which hey can deermine wheher measures are required o

keep damage due o flooding and waerlogging a an accepable level.

The operaing sandards indicae how ofen flooding is allowed o occursaisically. Differen sandards apply or differen designaed land uses.

Grassland, or example, may be waerlogged once every 10 years, land on

which greenhouses are buil only once every 50 years and in buil-up areas

flooding is no o happen more han once every 100 years.


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5 Water shortagesand drought

Even his boggy land near he sea experiences waer shorages once in a while. Tha is o say, reshwaer shorages. The very dry summer o 2003

and he dry spring o 2005 are he mos recen examples.

Plans wihered in he fields, ships could only be parially loaded, power

saions were limied in heir inake o cooling waer, naure suffered rom

drough. In order o prepare or he nex period o drough, he “sequence

o prioriies” – which indicaes he order in which waer will be allocaed

o specific users – was adjused.

Wha is waer shorage and drough?

We speak abou drough when here is a long-erm shorage o areaspecific

waer, which causes every process ha is dependen on he waer cycle o

suffer. Drough maniess isel in a shorage o moisure in he soil’s roo

zone, in exremely low waer levels in rivers, and even in dry waerways.


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| Rijkswaersaa48

Wha causes a waer shorage?

A waer shorage can be caused by a severe lack o rainall or low river

discharges. The lack o sufficien inrasrucure o supplemen he shorage

in rainall may also be a cause. Occasionally, available waer is no properly

disribued. Finally, he waer can be o inerior qualiy: oo saline

(or agriculure, drinking waer and indusrial processes), oo warm

(o be used as cooling waer) or oo pollued.

Aside rom all his, shorages can arise even when here is no drough,

simply because demand exceeds supply.

Who is affeced by waer shorages?

Waer shorages manies hemselves in hree ways. A shorage o moisure

in he soil is mos common. This means ha here is no enough waer or

plans, suning heir growh. Secondly, a shorage can occur in he surace

waer, meaning ha waer levels canno be sufficienly mainained. Thisresuls in a lack o waer or agriculural purposes and flushing. The inabiliy

o mainain waer levels can have a negaive effec on he sabiliy o dikes,

engineering srucures and oundaions. Bogs can become oxidised. In he

hird place, a consequence o insufficien waer o he correc emperaure

and qualiy is ha power saions have no cooling waer, drinking waer

companies have o close heir inle poins and armers and horiculuraliss

canno irrigae heir crops.

The diagram besides eaures drough regions and heir characerisicdrough-relaed problems.


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Northern Netherlands Salinisaion along he Wadden Sea coas, drough-relaed problems on he islands.

Northeastern Netherlands

Dry areas due o a lack o waer supply inrasrucure.

Centraleastern Netherlands

Groundwaer relaed drough.

Supply rom he IJssel and he Vech in cases o drough.

Eastern Netherlands

Presence o hilly areas where

waer supply is impossible.Central Netherlands

Shorage o cooling waer in he

Amserdam-Rijnkanaal/ Noordzeekanaal,

no oher drough-relaed problems.

Northwestern Netherlands

Few drough-relaed problems,

occasional deficiencies o he

waer supply sysem.

Western Netherlands

Salinisaion and small-scale waer supply.

Southwestern Netherlands

Salinisaion.

Southeastern Netherlands

Presence o hilly areas where waer supplyis impossible.

Supply rom Germany and Belgium.

Southern Netherlands

Waer shorage in hilly areas where waer supply is impossible. Dependen on waer supply rom

Belgium, hough no agreemens exis o ha end. In dry periods, hereore, he waer supply is

significanly limied.

Area around the major rivers of the Netherlands

Few drough-relaed problems, occasional deficiencies o he waer supply sysem.


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| Rijkswaersaa50

sufficienly mainained. This resuls in a lack o waer or agriculuralpurposes and flushing. The inabiliy o mainain waer levels can have

a negaive effec on he sabiliy o dikes, engineering srucures and

oundaions. Bogs can become oxidised. In he hird place, a consequence

o insufficien waer o he correc emperaure and qualiy is ha power

saions have no cooling waer, drinking waer companies have o close

heir inle poins and armers and horiculuraliss canno irrigae heir

crops.

Shorages are someimes characerised by large regional variaions.

Differences in soil moisure can be due o meeorological condiions,

soil ype, land use, managemen o surace waer levels and seepage waer.

Shorages in surace waer are mosly down o limied possibiliies in

reshwaer supply. In he downsream river areas, his is direcly relaed

o sal incursion.

A shorage o waer affecs almos every secor:

Agriculture

Waer shorages lead o lower producion. Crop yields can be down by 10

percen in an average dry year. However, his does no necessarily equae o

economic damage. Damage caused by salinisaion only accouns or one

percen o he overall drough-relaed damage. This is due o heavy flushing

and o he ac ha armers and horiculuraliss op or drough-relaed

damage raher han sal damage. A subsanial par o he losses caused by

waer shorages are he indirec resul o choosing o preven moisure

damage. By oping or deep drainage, armers and horiculuralissimplicily accep ha hey will someimes lose crops due o waer shorages.

Shipping

Low waer levels mean ha ships can carry less cargo. These limiaions

become relevan i he Rhine’s discharge level alls below 1,250 m3/s.

This occurred recenly in 2009.

Energy sector

Producion is usually limied once every wo years. However, he reasonor his is high river waer emperaures raher han low discharge levels.


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NatureChoices in spaial developmen and subsequen adjusmens o waer

managemen have occasionally creaed arificial siuaions ha have made

ecosysems vulnerable o drough. Moreover, ragmens o naure already

suffering rom drough are acing even harder imes as hey barely have any

reserves o draw on.

How do we respond o periods o drough and waer

shorages?

Periods o drough can someimes las so long ha i is no longer possible

o serve every designaed use. This orces us o choose: who or wha akes

prioriy in he disribuion o scarce supplies o river waer? This choice is

no made all over again each ime bu crieria are laid down in a ‘sequence

o prioriies’. These prioriies were drawn up in response o he excepional

drough o 1976, and updaed afer he summer o 2003 when drough was

almos as inense (see box on page 52).

Unorunaely or shipping and he oher secors in caegory 4 he waer

level in rivers, canals and harbours is he leas o our concerns when waer

is in shor supply. I needs be, armers and horiculuraliss who culivae

capial-inensive crops and acories using process waer (caegory 3) are

also ignored, so as o allocae only waer o he producion o drinking

waer and o power saions (caegory 2). Ulimaely, all ha remains are

he ineress o he firs caegory: saey and he prevenion o irreversible

damage.


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The sequence o prioriies in he orm o a diagram:

Category 1 Safety and the prevention of irreversible damage

1 sabiliy o flood deence srucures

2 setling and subsidence o pea bogs and moorland

3 naure dependen on soil condiions

akes precedence over:

Category 2 Utilities

1 drinking waer supply

2 power supply


Category 3 Small-scale high-quality use

1 emporary spraying o capial-inensive crops

2 process waer


Category 4 Others (economic considerations,

also in terms of nature)

1 shipping

2 agriculure

3 naure, as long as no irreversible damage occurs 4 indusry

5 waer recreaion

6 lake fishing


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6 Salinisation

‘Sal eners he Neherlands hrough he ron door and underneah hedoorma.’ As long as he Rhine carries sufficien amouns o waer, he ron

door (he Nieuwe Waerweg) will remain closed, bu underneah he doorma,

which is as wide as he coasline is long, here are many gaps ha allow

salwaer o come o he surace. Salinisaion is a problem or many secors.

Wha is salinisaion?

Ground waer in he norhern and wesern pars o he Neherlands is slowlybecoming salier. This insidious process called salinisaion akes place in

wo ways. The sal orces is way inland via surace waer, known as exernal

salinisaion, or i works is way up hrough he soil in groundwaer, which is

called inernal salinisaion.


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Extend o salinisation during the drought o 2003.

Wha causes salinisaion?

External salinisation There is only one locaion where resh and salwaer are in direc conac

wih each oher: Hoek van Holland. The exen o which seawaer can orce

is way inland depends primarily on he relaion beween he river dischargeand he sea level. Wih an average discharge level o he Rhine and an

average ide a sea, he salwaer ongue reaches he Willemsbrug in

Roterdam. Exreme evens o sal waer incursion will only happen when

he sea level is high while he Rhine carries a limied amoun o waer.

Incidenally, some inle poins already become salinaed i he waer level

o he Rhine is low and he sea is a a regular level.

The Haringvlie sluice gaes play a key role in couneracing exernal

salinisaion hrough he Nieuwe Waerweg. By keeping he gaes closedeven a low ide and when he Rhine discharge is low, all river waer is

direced o he Nieuwe Waerweg. As long as here is a minimum flow o

he sea o 1,500 m3/s pas Hoek van Holland, he mouh o he Hollandsche

IJssel will no become salinised. However, i is no possible o guaranee

such a minimum discharge. Under excepional condiions, exernal

salinisaion can occur in he Haringvlie and he Hollandsch Diep, even i

he Haringvlie sluice gaes are shu igh. The sal orces is way hrough

he ‘back door’ via he Nieuwe Waerweg and hen hrough he Spui and he

Dordsche Kil. This exreme even o salinisaion occurred in he auumnso 2003 and 2005, when river discharge levels were very low while he sea

level was significanly higher due o a sorm.


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During dry periods, however, he discharge rom he rivers will decrease, which resuls in an increase in exernal salinisaion. And his in urn reduces

he capaciy o keep inernal salinisaion under conrol.

Internal salinisationIn mos pars o he Neherlands, deep groundwaer is brackish o saly.

Wih he excepion o he coasal zone, his is caused by sea waer ha

remained in he underground when he sea rereaed. Originally, his

marine groundwaer was pracically immobile, bu as a resul o land

reclamaion and drainage groundwaer sared o move. In heir urn,

baches o groundwaer were brough ou o heir sable siuaion and

sared o move in an upward direcion, in cerain places breaching hrough

he surace or enering ino he surace waer. This orm o salinisaion is a

process ha is virually irreversible. Even i he sea level remains he same,

Cross-section o the western part o the Netherlands, highlighting how seawater and deep

brackish groundwater seep into surace waters in deep polders.


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he process will coninue or cenuries. Sea level rise and soil subsidence will only accelerae his process. I is mos prevalen in he wesern and

norhern pars o he Neherlands. Furher inland, he influence o sea level

rise is less pronounced. For example, in polders as Groo-Mijdrech in he

province o Urech, which do suffer rom inernal salinisaion, sea level rise

has no impac on he waer sysem.

In deep pars o polders and reclaimed areas such as he

Haarlemmermeerpolder, saline groundwaer can end up as seepage waer in

canals and breach hrough he surace as naural aresian wells (see figure

page 55). To comba inernal salinisaion, reshwaer is pumped ino he

polders. On he one hand, his is carried ou o provide couner pressure o

saline seepage waer and on he oher hand, o flush he waercourses.

In his way, waer in regional sysems is mainained a a cerain chloride

concenraion. However, his requires suficien good-qualiy waer in he

main waer sysem. During dry periods, however, he discharge rom he

rivers will decrease, which resuls in an increase in exernal salinisaion.

And his in urn reduces he capaciy o keep inernal salinisaion underconrol.

Who is affeced by salinisaion?

Salinisaion is only a problem i users are hindered or damaged by he ac

ha he chloride conen in he waer rises above a cerain concenraion.

AgricultureSalinisaion is a direc hrea o agriculure. Agriculure is bes served by

waer wih a low chloride conen. Wha armers or horiculuraliss will

accep, depends, however, on he crops hey grow. For example, rui rees

are more sensiive o higher chloride conen han sugar bee or grain.

Halophye arming is, o course, indifferen o salinisaion, bu his secor

only accouns or a limied marke. Wihin he secor, here are possibiliies

o making use o brackish waer, or insance o produce crops ha are rich

in proein as an alernaive o impored animal odder. In areas where

salinisaion is already a problem, alernaive sources o reshwaer arebeing considered o comba urher salinisaion.


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Shellfish fishingMussel seed fishing requires he presence o reshwaer/salwaer

ransiions and esuarine condiions. Oherwise spa all will decline

significanly. In general, shellfish culivaion depends on good qualiy

salwaer, which is why shellfish culivaors benefi rom he salinisaion

o reshwaer bodies and he resoraion o esuary dynamics.

Drinking water companiesDrinking waer companies need waer wih low chloride conen in order

o produce good qualiy drinking waer. In areas where salinisaion is

imminen, hey spread he risks as widely as possible by using boh surace

waer and groundwaer sources, or by desalinaing high-chloride conen

waer.

Energy companies and industry For energy companies and oher indusries, he availabiliy o resh cooling

waer is essenial or heir producion processes.

Insallaions are buil on he basis o reshwaer inake, which is a condiionor he selecion o consrucion maerials. Salinisaion increases reamen

coss o process waer.


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Freshwater is not always good and saltwater is not always badWha a user calls resh or saline waer depends on he purpose waer

has o ulfil, and on how users appreciae he qualiy o he waer.

For he drinking waer secor and or indusry, waer qualiy sandards

are high. The Duch sandard or he chloride conen in drinking waer

is 150 mg/l, while he European sandard is 250 mg/l and he sandard

adhered o by he World Healh Organisaion is 300 mg/l.

While here is no evidence ha levels in excess o hese sandards

consiue a public healh risk, hese limis are based on organolepic

judgemen by ase panels. Indusry also employs a 150 mg/l sandard

or process waer, while he sandard or cooling waer depends on he

selecion o maerials or cooling insallaions. Seawaer can be used

or cooling i insallaions are purpose-buil.

The chloride sandard or irrigaion waer or agriculure depends

primarily on he crops being grown. For insance, differen sandards

are used or growing rui and or growing poaoes. While here are

no clear sandards or irrigaion waer in he Neherlands, he Culural

Technical Handbook (1988), or example, defines a sandard o

300 mg/l or rui culivaion and 600 mg/l or poaoes.

Apar rom he ‘official’ chloride sandards, user percepion also plays a

key role in deciding wheher o use waer o a paricular qualiy. This is

deermined by knowledge and experience, as well as by he available

means and by he necessiy o using waer. For insance, armers in he

Flevopolders (Ooselijk Flevoland and Zuidelijk Flevoland) use waer wih

a higher chloride conen or irrigaing bulbs han armers in he wesernpar o he counry would accep.


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7 Water quality

Drinking waer companies, horiculuraliss, he leisure indusry, fishermen,everyone, in ac, and naure as well, benefi rom good qualiy waer.

The user deermines wha consiues ‘good’: each designaed use ses is

own crieria. As a consequence, qualiy almos always plays a role in he

disribuion o waer. Freshwaer is used in deep polders o flush ou seepage

waer ha is high in chloride and nurien conen. Waer supplies are

required o comba drough. Bu in naure reserves, even i hey are already

oo dry, waer is usually only welcome i is qualiy is close o he waer

qualiy in ha area.

Polder waer ha comes rom he main sysem carries nuriens along and,in many cases, oher chemical subsances as well. This poses exra qualiy-

relaed problems, especially or he sagnan waers in he main sysem such

as Lake IJsselmeer/Lake Markermeer, Krammer/Volkerak and a number o

canals. Also in he low-lying pars o he Neherlands, where he need or

waer inake alernaes wih he need or discharge and he pressure o

seepage waer is rising, qualiy complicaions pile up.


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Wha is good waer qualiy?

In general, reshwaer can be regarded o be o beter qualiy i i conains

ewer nuriens, oxins or sal. Visually, i is imporan ha i is ransparen,

while high oxygen conen adds o he qualiy. Finally, i is also imporan

ha waer qualiy has no adverse effecs on waer organisms and plans.

Differences in qualiy are influenced by a series o acors: he waer

composiion changes depending on is origin and on he land use, soil ype

and groundwaer flow resuling in seepage or infilraion, in he area where

he waer originaes rom. Finally, waer qualiy is closely linked o he

quaniy o waer: conaminaion is less noiceable when highly dilued.

Wha causes poor waer qualiy?

Nuriens and oxins reach surace waers along a number o ways.

A primary source is leaching and run-off rom agriculural areas, bu

effluens rom wasewaer reamen plans, le alone unreaed dischargeso wasewaer, also conain high levels o phosphae and nirae.

Furhermore, rivers can carry polluans and nuriens and even

amospheric polluion will be deposied on land and waer.

Nuriens ener surace waer even aser i drainage is inensive.

For ha mater, leaching o nirogen does no only affec surace waer

bu groundwaer as well. High nirae concenraions can cause problems

i he groundwaer is used or he producion o drinking waer.

In all o his, a disincion needs o be made beween sagnan and

running waers. Lakes, canals and diches are generally more sensiive o

europhicaion han rivers and sreams. Nurien concenraion in sagnan

waers is largely deermined by exernal polluion, such as amospheric

deposiion, supply via sreams, pumping saions, rivers and wasewaer

discharges. In rivers and in closed esuaries such as Lake IJsselmeer and

Haringvlie ha are primarily supplied by large rivers, he concenraion is

also deermined by wha hose rivers supply rom across our borders. In he

Norh Sea, he concenraion is also deermined by he influx o nuriensand, in paricular, by he level o niraes in he rivers. The key source o

releases or sreams on high sandy ground is leaching and run-off rom


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J.L. Hoogland pumping station at Stavoren. This is also an inlet point or

the regional water system.

agriculural land. The patern o rainall has a cerain influence as his

depends on groundwaer levels and on he exen o which he soil is

sauraed wih waer. In addiion, i is also imporan in which season he

polluion occurs.

Chemical subsances can have an adverse effec on waer organisms and

plans in surace waers, such as reduced growh or ewer offspring,

resuling in a reduced number o organisms. Some organisms even disappear

compleely. Birds and mammals risk being affeced by consuming waerorganisms such as algae and waer fleas ha are conaminaed by oxins.

Waer qualiy in he Neherlands has improved significanly in recen

decades and likewise effecs o conaminaion have decreased. Neverheless,

new and largely unknown groups o subsances keep appearing, effecs

o which may be even more significan. Examples include anibioics,

medicines and subsances ha disrup he hormonal balance. These

subsances originae rom effluens o wasewaer reamen plans, as well

as rom manure ha evenually makes is way rom arable land ino surace waer.


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The concenraion o conaminaed subsances in he Norh Sea droppedsignificanly in he 1980s and 90s, bu i appears ha his decline has now

haled.

Wha problems are linked o poor waer qualiy?

EutrophicationEurophicaion primarily occurs in areas ha have o deal wih a manure

surplus. Ye europhicaion can also occur in areas wih litle or no

agriculure, i hese areas are flushed wih non-area specific waer

originaing rom anoher area ha is rich in nuriens. This can be waer

ha is used o mainain waer levels, or waer ha is pumped hrough o

supplemen waer shorage somewhere else. Also, he enire coasal region

is affeced by europhicaion. In some places his reveals isel in algal

blooms.

Toxicity The concenraions o well known subsances such as heavy meals, PCBs,PAHs declined in recen decades, bu his decline has now come o a hal.

Pesicides remain a problem, especially in regional waers. Ye he effecs

are no generally caused by subsances alone. Hydromorphological

condiions also play a role. This calls or an inegraed approach in

he managemen o waer sysems.

Specific risks occur a peak loads during uninenional releases. Such

releases occur regularly in he Meuse, affecing sensiive species or causing

hem o disappear alogeher. The conaminans ha flow ino he Norh Sea can lead o disrupion o

he hormonal balance or o bio-accumulaion in organisms, hus affecing

he ood chain. Promp deecion and hereore monioring o hese ypes

o subsances – new subsances appear on a regular basis – and o heir

effecs on organisms and he ecosysem is necessary. These problems should

be ackled by ollowing a river basin approach and a inernaional level.


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Control device or excess water on the right bank o the rivers Lower Rhine and IJssel.


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8 Future developments

The Neherlands is geting weter, dryer and salier. The sea level is rising. While rainall is geting heavier a imes, i may also a oher imes hold off

much longer. Soil subsidence coninues, due o boh geological influences

and human aciviies. Land use is changing as well, he economic secors

are coninuously changing and, socieally speaking, new demands are made

on waer. All his can hardly indicae anyhing else han he necessiy or a

change in waer managemen and waer use.

Physical and socieal changes

ClimateSince he early 20h cenury, average emperaure has risen by approximaely

0.74°C. I is highly probable ha we also conribue o his rise: burning o

ossil uels, deoresaion and cerain indusrial and agriculural aciviies lead

o an increase in he concenraion o greenhouse gases in he amosphere.

Model calculaions indicae ha he emperaure could rise rom beween

1.1°C o 6.4°C beween 1990 and 2100. Increases o more han 2°C will

probably be accompanied by subsanial changes, because he sea level willalso rise significanly, here will be more periods o drough and hea and

occasionally exreme precipiaion will occur.


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Since he climae scenarios o he programme Waer Managemen in he21s cenury were firs published in 2000, several new global and regional

climae models have been drawn up. Based on his recen knowledge,

he Royal Neherlands’ Meeorological Insiue (KNMI) ormulaed our

scenarios in 2006. These scenarios assume a maximum emperaure

increase o 2°C by 2050.

Four climate scenarios by KNMI (2006).

The general picure resuling rom all our scenarios is ha global warming

is proceeding. As a resul, we will have more mild winers and warm

summers. In addiion, winers will become weter on average and we

can expec more exreme periods o heavy rainall.Especially in summer, here will be heavy downpours, while in conras,

he number o rainy summer days will decrease. I he air flow paterns

above wesern Europe change (he ‘plus’ scenarios), winers will become

significanly weter and summers much dryer.

Litle will change in erms o wind, which will remain as changeable as i

is now. Moreover, all our scenarios have in common ha sea level will

coninue o rise.


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Soil subsidence and salinisationIn a large par o he low-lying areas in he Neherlands, soil subsidence

is expeced as a consequence o soil setlemen and oxidaion o pea.

The larges subsidence is expeced in Groningen due o exracion o naural

gas and in Flevoland due o setling. On he oher hand, a small increase in

ground level is expeced in he souh easern par o he counry due o

econic iling (see figure on page 68). The quaniy o suberranean sal

will increase due o he ollowing hree causes: a ime-lag effec o pas

reclamaion projecs, soil subsidence and sea level rise. As a resul, seepage

waer pressure will increase and seepage waer ha rises rom he ground

will become more saline. A considerable increase is expeced in he coasal

zones o Zeeland, Friesland and Groningen in paricular, ye some polders in

he provinces o Noord-Holland, Zuid-Holland and Flevoland will be

affeced as well. Only in a limied number o locaions sal concenraions

will decline due o increased surplus rainall, which will counerac he

ime-lag effec.

Economic and spatial developmentsIn coming decades, residenial and commercial developmens will coninueo expand heir claims o public space in low-lying areas. As ransporaion

o reigh over long disances is cheaper by shipping, he expansion o

he inernal waerways will coninue.

Waer recreaion has become a significan acor boh socially and

economically and will jus increase in scale and inensiy. The demand

or elecriciy will coninue o increase as well. This means ha more power

saions will be buil, someimes in places where his conflics wih waer

relaed ineress.


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The expected subsidence and rise o ground level up to 2050.


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Consequences o climae change or waer managemen

KNMI scenarios orecas ha he minimum emperaure increase will be

1°C. In a wors-case scenario, he summers will become considerably dryer

as well, which will have an impac on river discharges, moisure defici and

salinisaion.

River discharges All scenarios envisage ha he average discharge o he Rhine will increase

in winer (up o +12 percen and decrease in summer (up o –23 percen).

The same applies or he Meuse, wih a maximum increase o 5 percen in

winer and a maximum decrease o 20 percen in summer.

Moisture deficit and drought I here is no srucural change in he air flow paterns above Wesern Europe,

he average summer precipiaion will increase by 3 o 6 percen. However,

i easerly winds prevail, rainall could easily decrease by 10 o 19 percen.

Aside rom his, he chance o exreme drough is greaer because a highemperaures evaporaion will exceed whaever exra rain may all.

Salinisation The combinaion o sea level rise and lower river discharges in summer will

ineviably lead o increased salinisaion. The salwaer ongue will penerae

urher inland and he number o days ha reshwaer inle poins canno

be used will increase. A he same ime, he amoun o waer ha can be

aken rom our main waer sysem in order o comba inernal salinisaion

in he regional waer sysems will decrease, while he need increases.

Flooding and waterlogging The Neherlands will experience more requen periods o exreme

precipiaion, which will be longer in winer and shorer bu more inense

in summer. Exreme precipiaion can lead o flooding and waerlogging.

In conras o drough, his ofen occurs locally or regionally because

rainall can vary significanly rom place o place.

Along he Amserdam-Rijnkanaal/Noordzeekanaal, he Twenhekanalen

and he Veerse Meer, he poenial o hese waer bodies being he cause orflooding is negligible. While he chance is also sligh along he Hollandsche

IJssel, i a dike will breach, his will affec a significan area. The upper


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Sluice gates in the Haringvliet Dam. Together with the sluice complex in the Asluitdijk and the

one at IJmuiden, and with the weir at Driel, these sluice gates are key to the regulation o the

discharge and distribution o reshwater.

course o he Hollandsche IJssel, he Meppelerdiep, he Zuid-Willemsvaar,

he Wilhelminakanaal and he Lake Volkerak-Zoommeer are a a greaer risk

o being he cause o flooding wih possibly subsanial damage.I we don’ maximise reenion and sorage in regional sysems, bu insead

drain exra rainall by increasing discharge capaciy, hen he upper course

o he Hollandsche IJssel, he Twenhekanalen and he Beuwepand o he

Amserdam-Rijnkanaal migh no be ready in 2015 o deal wih expeced

waer discharges or he period up o 2050.

SafetyI he climae develops according o he scenarios, he normaive condiions

or he Rhine (16,000 m3

/s) and he Meuse (3,800 m3

/s) have acually beenexceeded already, a leas according o he 2008 sudy eniled Climae

Change Resilience o Waer Land he Neherlands. Ye, he chance ha he

dikes along he rivers in he counry’s easern and cenral areas will burs is

very small, paricularly i by 2015 all he measures planned in he conex

o he Space or he River programme are implemened. A key assumpion,

however, is ha in imes o very high discharge volumes, he discharge

disribuion over he Waal, he Lek and he IJssel will be changed in such

a way ha he Lek is spared. The sudy also showed ha i climae change

develops according o he more drasic scenarios, here is a reasonablechance ha he surcharge sandard or he Rhine o 18,000 m3/s will be

exceeded somewhere beween 2040 and 2045.


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9 Towards ‘climate-proof’water management

The changes ahead o us promp he quesion wheher our waer sysem willsill uncion effecively in he uure. Differen sudies have shown ha he

key poin o atenion or waer managemen up o 2050 is he supply o

reshwaer o he souhwesern par o he Neherlands. According o wo

o he our KNMI climae scenarios, he periods o waer shorages and low

river discharges increase significanly, which raises he demand or waer,

while he supply decreases, parially due o he salinisaion o he mouhs

o he rivers Rhine and Meuse.

Are hese shorages so severe ha hey warran a reconsideraion o waer

managemen or waer disribuion? And apar

water management in the netherlands_tcm224-303503.pdf

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