Flood defense in the Netherlands

13 Pages·2011·0.27 MB·English

by  Toine Smits

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Flood Defense in The Netherlands
Hein T.C. van Stokkom a , Antonius J.M. Smits b & Rob S.E.W. Leuven c
a Ministry of Transport, Public Works and Water Management, Arnhem, The Netherlands
b Radboud University Nijmegen and Erasmus University of Rotterdam, Netherlands
c Institute for Wetland and Water Research, Radboud University Nijmegen, The Netherlands
Available online: 22 Jan 2009
To cite this article: Hein T.C. van Stokkom, Antonius J.M. Smits & Rob S.E.W. Leuven (2005): Flood Defense in The
Netherlands, Water International, 30:1, 76-87
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International Water Resources Association
Water International, Volume 30, Number 1, Pages 76–87, March 2005
 2005 International Water Resources Association
Flood Defense in The Netherlands
A New Era, a New Approach
Hein T.C. van Stokkom, Ministry of Transport, Public Works and Water Management,
Arnhem, The Netherlands, Antonius J.M. Smits, Radboud University Nijmegen and
Erasmus University of Rotterdam, The Netherlands, and Rob S.E.W. Leuven, Institute
for Wetland and Water Research, Radboud University Nijmegen, The Netherlands
1
1
0
2
ust Abstract: Intensive land use and far-reaching regulation of the fluvial hydrosystem in the past
g
u century have reduced the hydromorphological resilience of the Rhine and Meuse river basins. Because
A
2 the hydromorphodynamic processes could be controlled to a greater extent, residents of the riverine
1 2 areas lost their sense of the natural dynamics of river systems, and further urbanization of areas prone to
3:2 flooding took place without the potential dangers being recognized. It was particularly in the low-lying
at 1 polders of the Netherlands that the potential damage from flooding increased tremendously over time.
] The high water discharges of the rivers Rhine and Meuse in 1993, 1995, and 1998 caused a considerable
n
e change in governmental policy, public awareness, and international cooperation in terms of flood
g
me protection and inland water management. The Dutch government is currently trying to achieve sustain-
Nij able water and river management by developing and implementing a new approach to flood defense. In
eit addition to the implementation of technological measures, the government aims to create more space for
sit the rivers, combined with objectives from other policy areas, including the restructuring of rural areas,
r
e development of the ecological infrastructure, surface mineral extraction, land use and other area-
v
ni specific projects such as housing schemes. This approach is not confined to the Netherlands: similar
U
d concepts have recently been introduced at various other locations in the Rhine and Meuse river basins. The
u
o new approach requires land-use changes and introduces new scientific research issues relating to land and
b
d water use, hydromorphology, river management, and socio-economics. This paper discusses this new ap-
a
R
[ proach and related scientific developments.
y
b Keywords: sustainable flood defense strategies, hydromorphology, habitat restoration, socio-eco-
ed nomics, public-private enterprises
d
a
o
nl
w
o
D toric overview of geographic and hydrological aspects of
Introduction the Netherlands and described the organizational and leg-
islative developments of water management. Originally,
Located in the delta formed by the Rhine and Meuse the water boards, Netherlands oldest democratic institu-
rivers, the Netherlands has a long history of adapting the tions, took care of flood protection and land reclamation.
natural water and river systems to user functions such as However, the water boards tended to focus on regional
housing, agriculture, and shipping. Figure 1 provides an interests, which sometimes led to controversial manage-
overview of the Rhine and Meuse river basins. The “ever- ment measures regarding public interest on national level.
lasting fight” against floods in this small country, much of it Since 1798, the overall responsibility and coordination of
situated well below sea level, is legendary. Large parts of water management in the Netherlands has been a task of
the Netherlands are still subsiding, while the sea level is the national government (Van de Ven, 1976), and the Di-
rising. Approximately 25 percent of the country is currently rectorate-General of Public Works and Water Manage-
situated below mean sea level (by up to 6.7 m). Without ment was created to fulfill this task.
the dikes and dunes along the coast, 65 percent of the The spectacular technological developments of the
most densely populated part of the Netherlands would be past century allowed far-reaching alterations to be intro-
flooded every day. Huisman et al. (1998) presented a his- duced to the hydrosystem in the Rhine and Meuse river
76
Flood Defense in The Netherlands: A New Era, a New Approach 77
The above developments came about gradually. Tech-
nological innovations made it possible to alter the
hydrosystem in favor of particular user functions and people
started to lose their sense of the natural hydrodynamics of
river systems and the related threat of flooding. Further
urbanization of areas prone to flooding was undertaken
without recognizing the potential danger. It was particu-
larly in the delta, in the low-lying polders of the Nether-
lands, that potential flood damage increased tremendously
in the course of time. After the near floods of 1993 and
1995, the countries along the rivers Rhine and Meuse re-
alized that the traditional approach to land and water man-
agement had to be fundamentally changed, an awareness
that was further raised by the high water discharges of
1998. The need for innovation of flood defenses and wa-
1 ter management in general appears to be widely accepted
1
0 in the Netherlands. However, much more is required, as
2
st was recently stated by the Secretary of State for Trans-
u
g port, Public Works and Water Management: “It will de-
u
A mand creativity, energy, time and money. Protecting the
2
2 Netherlands from floods will require repeated investments
21 over a long period of time” (Anonymous, 2000a).
13: Within the context of an international agreement, it
at was decided that considerable efforts would be made in
]
n the near future to restore the resilience of the Rhine and
e
g
e Meuse river basins (Anonymous, 1995). Each country was
m
Nij to select the appropriate measures to restore the
rsiteit Fkrimivge2u rasr neRd 1 h.3 iTn6e,h0 e0a R0n dhk imnMe2e ,a urnsedes pMaerceetu is1ve,e3 lby2a.0 sT ianhnse dw s o9itu3hr5 sc uekr-mfma,co erue tashrp eleaecsnt igovtfeh 1lsy8 .o5 f , 0Ft0ho0er hrwiyvhdeorrlo ebm.a Uosirpnp ,ht ofor lnooomgwi ct,h atelh repe ecsriolsuipenentccrtieiev soe fo otfh ft eht heree R lrehivvianenre t b rpiavasreitnr osb faa tsshi nea
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v extensive data on hydrology, water quality and land use see Middelkoop
Uni and Van Haselen (1999) hinagv eth mesaed em ceoanssuirdeesr a(bAlen opnroygmreosuss i,n 1 s9e9le8cat)i,n agn adn dth iem cpoleumnterinets-
d
u of the Meuse river basin are expected to follow soon.
o basins. In the short term, these alterations benefited agri-
b
ad culture, navigation, and flood protection. However, the
R Flood Defense Standards: Design Water
[ large-scale reclamation of wetlands and the regulation and
y Discharges and Design Water Levels
b harnessing of rivulets reduced the hydromorphological re-
d It took some time for people to recover from the anxi-
e silience of both river basins. This meant that the water
d ety caused by the floods of 1993 and 1995. In 1995, some
oa and sediment discharge patterns were affected in such a
wnl way that periods of high or low precipitation rates are now 2d5ay0s,0 d0u0e p etoo ptlhee w qeuree setvioancaubatleed s ftraobmili tthye oirf h doimkeess ftohra st ohmade
Do immediately reflected by extreme high or low water lev- been exposed to protracted flooding and had become satu-
els in the river. The large-scale draining of agricultural
rated with water. The estimated economic damage to ag-
land and the expanding urbanized areas, consisting almost
riculture, industrial activities, and private enterprises
completely of impervious materials, caused rapid run-off
amounted to about US$ 1 billion. As a result, the Dutch
of rainwater and subsequent high water discharge peaks
government adopted a policy aimed at minimizing the po-
in the river. River regulation schemes and the embanking
tential damage, raising public awareness, improving inter-
of floodplains augmented this problem (Dister et al., 1990).
national early-warning systems, and developing measures
For instance, the length of the river Meuse downstream
to increase flood safety levels, preferably in an interna-
of Grave, the Netherlands has decreased by nearly 30
tional context. The government immediately decided to
percent due to meander cut-offs (Middelkoop and Van
initiate the so-called Delta Plan for Large Rivers (Olsthoorn
Haselen, 1999). In addition, the morphological resilience
and Tol, 2001), which stipulated that all river dikes had to
of both river basins was affected by the large numbers of
be adapted to meet current standards. However, as a re-
sluices, weirs, dams, groins, and fortified riverbanks, which
sult of the near floods in 1993 and 1995, the design dis-
impeded the replenishment of the bed load. In the Rhine,
charge in the river regions of the Netherlands will end up
this has resulted in ongoing riverbed erosion at several
being higher than those used up to now as a basis for
locations (Anonymous, 1993).
calculating dike heights (design water levels).
IWRA, Water International, Volume 30, Number 1, March 2005
78 H. van Stokkom, A. Smits, R. Leuven
The design discharge is derived using a statistical analy- norms are significantly higher, for instance 1/2,000 up to 1/
sis of discharge peaks that have occurred in the past (Silva 10,000 in the “Central Netherlands” dike ring, a region includ-
et al., 2001). For example, measurements in the Rhine at ing the cities of Amsterdam, The Hague, and Rotterdam, and
Lobith (where it enters the Netherlands, Figure 1) have the area they enclose. This is associated with the greater
been taken since the year 1901. First, a so-called homog- economic interests and population densities, but also with the
enization of the flow measurements series is conducted. difficulty in predicting storms at sea, which carry a higher risk
The Rhine catchment area has changed a great deal in the of victims, and with the fact that seawater is salty and thus
course of time, which has resulted in changes to the river’s causes greater damage in the event of flooding.
discharge characteristics: the same precipitation pattern In 2001, the design water levels were reviewed within
in the catchment area now leads to a different flood wave the context of the flood management legislation. For the
at Lobith, in terms of height as well as shape, than was Rhine branches, it was decided to increase the design dis-
seen at the beginning of the 20th century. In order to de- charge at Lobith from 15,000 to 16,000 m3/s. Without the
rive the design discharge under the present circumstances, implementation of further measures, this also means higher
discharge peaks measured in the past have been corrected design water levels. If the design discharge at Lobith is
to accommodate alterations in the catchment area that known, then the design water levels on the Rhine branches
1 have occurred in the 20th century. can be calculated, using two-dimensional computer mod-
1
0 In terms of height, width, and slope, dikes are designed els simulating water discharge and water levels in the river
2
st to withstand the discharge of floodwater for a pre-deter- (Silva et al., 2001). The design discharge is set at the up-
u
g mined length of time, based on specific technical guide- stream boundary of the model at Lobith. The model then
u
A lines. The design water level forms an important starting calculates the discharge across the three Rhine branches
2
2 point: the water level that the dike must be able to hold and the corresponding water levels.
21 back safely. This water level has a certain probability of
at 13: osecnc ufrorri ntgh et hvaatr cioourrse dspikoen dres gtoio tnhse. lTehveesl eo fle pvreoltse cotfi opnr octheoc-- Room for the Rivers
]
n tion, which can be regarded as safety standards, are set In its Fourth Memorandum on Water Management,
e
g
e forth in flood management legislation. Additionally, fac- the Dutch government stated that engineering measures
m
Nij tors such as wind set-up and wave run-up are taken into that are sustainable are preferred to meet the desired level
rsiteit cTborhaninss cihdhaeesrs ar tenisoeuanlr,t lefyod r ai nwll thhhiaecv hdi iank gce e arri tnsaaginfse fitrnye tenhboeo raamrred ao isfs om1f/ a1thi,n2et5 aR0ihn pieneder. oschrfe osauaslfeded tby de (e dAseingvonisn edydims aconhudas ri,gm 1ep,9 lp9er9me)v.e eTnntheti das wmnehewiacn hrso, udthneasdtp omitfe er taahsiesu irinengs-
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v
ni year. In other words, the probability that the river water will and reinforcing dikes. Thus, expanding the floodplain of a
U rise above the design water level must not be higher than 1/ river by moving dikes further inland is preferred to raising
d
u 1,250 in one year. In the western part of the country, safety the dikes (Figure 2). Taking the effects of climate change
o
b
d
a
R
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y
b
d
e
d
a
o
nl
w
o
D
Figure 2. Overview of measures aimed at increasing water discharge capacity, roughly ranked in order of decreasing efficiency: (a) moving dikes
further inland, (b) constructing river bypasses, (c) lowering groins, (d) dredging the riverbed in sections of the river where sedimentation occurs,
(e) removing obstacles such as non-flooding areas in the floodplain, summer embankments or ferry ramps, (f) lowering floodplains, for instance
by digging side channels, frequently combined with land-use changes from agriculture to habitat restoration and recreation
IWRA, Water International, Volume 30, Number 1, March 2005
Flood Defense in The Netherlands: A New Era, a New Approach 79
Table 1. Evaluation of flood defense projects executed within the framework of the INTERREG Rhine Meuse Activities (IRMA) program
(Van Rooij and Van Wezel, 2003)
Transnational Effect on Effects on Public Degree of
Project cooperation water discharge landscape quality participation innovation
Rhine River
Restoration of river confluences
Kinzig and Schutter (G) + + ++ + +
Restoration of Rhine meanders and
floodplains along the Rhine river section
Kunheim and Marckolsheim (F) + + ++ 0 ++
Infiltration of rainwater in urban area of
Neuenberg am Rhein (G) 0 0* + ++ 0
Realization and management of retention
areas along the Rems River (G) + + + ++ +
Infiltration of rainwater in rural area of
Massenbachhausen (G) + + + + ++
Dike relocation Worms-Bürgerweide (G) ++ ++ ++ + +
1 Realization of retention areas along the
1
0 Alzette River (L) + + ++ 0 +
2
st Floodplain rehabilitation (Klompenwaard)
u with construction of side channels (NL) + ++ ++ + +
g
u River dike relocation, creation of side channel
A
2 and floodplain lowering location Bakenhof
2 along Nederrijn River (NL)1 + + ++ + +
21 Adaptation of railway abutment in floodplain
3: at Rosandepolder along Nederrijn River (NL) 1 + ++ 0 ++ ++
1
at Meuse River
n] Demonstration projects focused on widening of
e
g floodplains along the Meuse (border B-NL) ++ + + + ++
e
m Reconstruction of weirs and dredging of river
Nij bed of the Haute Meuse (B) ++ + 0 0 +
rsiteit S aclonawtdc hrdemovweitnantl io(zGfa r)tiaoinnw oaf treirv ruulent-so ifnf bthye r Refuohrre sRtaivtieorn ++ ++ + ++ +
e
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ni B: Belgium; F: France; G: Germany; L: Luxembourg NL: The Netherlands; 1: see also Table 2; *: requires up scaling
U
ud (increased rainfall and rising sea levels) into account, ing the water discharge capacity as well as the storage of
o
b merely raising the dikes is pointless in the long term. More- water (called “Meuse works” for the Meuse river; “Room
d
a over, periodically reinforced and raised dikes may give lo- for the Rhine Branches” [RVR]” for the Rhine branches;
R
y [ cal authorities and citizens a false sense of security, resulting “Integrated Exploration of the Lower River regions” [IVB]
d b in extensive private and public investments for structures for the downstream sections of the Rhine branches and
de in the hinterland. Therefore, the Dutch government has Meuse; and “Water Management in the Lake IJssel Re-
a
o initiated a shift from “traditional” flood protection policies gion” [(WIN] for the lake IJssel region) (Anonymous,
nl
w (i.e. merely dike raising and draining polders) towards cre- 2000b; 2000c; Van Leussen et al., 2000; Silva et al., 2001).
o
D ating increased water discharge capacity, i.e., creating All of these studies have made it clear that water man-
more room for the river. Changing land-use functions and agement can no longer been seen as a separate issue,
creating more room for the river is difficult but effectively unrelated to nature conservation policies and spatial plan-
anticipates future developments. Within this context, con- ning. As the Dutch government puts it: “By opting for room
crete management measures have been formulated, some for the river, possibilities elsewhere in the river regions
of which had already been considered earlier, while oth- will need to be found for a number of activities. Room for
ers were new. With respect to the projects included in this the river will not be able to exist without consequences for
plan, particular attention was given to increasing the wa- the public planning policy in the rural areas” (Anonymous,
ter discharge capacity of the rivers and other goals within 2000a). The results of these studies are being used in some
the framework of the Action Plan on Flood Defense for surveys at regional and national levels to determine the
the Rhine (Anonymous, 1998a). The INTERREG Rhine appropriate set of measures for each river section in the
Meuse Activities (IRMA) program of the European Com- Netherlands. The Directorate-General for Public Works
mission has provided additional funding to implement these and Water Management bears the overall responsibility
projects (Table 1; Van Rooij and Van Wezel, 2003). for selecting and implementing the appropriate flood de-
Studies carried out in the Netherlands during the pe- fense measures along the Rhine branches and the river
riod 1995 to 2002 have examined the options for increas- Meuse in the Netherlands. The decision-making process
IWRA, Water International, Volume 30, Number 1, March 2005
80 H. van Stokkom, A. Smits, R. Leuven
will take place within the context of the national Key Plan- can be derived from these previous figures; the highest
ning Decision procedure, which includes public participa- estimate will then be around 15 cm (Silva et al., 2001).
tion in the decision-making process, and provides the
legislation (including expropriation if necessary) required New Approach
to implement the selected measures. For centuries, spatial planning in the low-lying Neth-
The Dutch government realizes that policies and man- erlands has been a matter of separating land and water
agement measures can only be successful with sufficient and maintaining this separation. The Netherlands has ben-
public support. Therefore, local and regional authorities as efited from this, considering the fact that two-thirds of the
well as non-governmental agencies are involved in these gross national product (around US$ 2 trillion annually) is
studies. In the meantime, additional spatial planning poli- generated domestically (Anonymous, 2000a). However,
cies and legislation have become operative (since 1995), climate change increases the likelihood of floods and other
protecting the (remaining) floodplain area against building water-related problems (e.g. droughts and rising sea level).
and housing projects (Anonymous, 2001a). In addition, the population density continues to grow, as do
the potential of the economy and, consequently, the vul-
nerability of the economy and society to flood and drought
Climate Change and a New Approach to Water
11 Management in the 21st Century disasters. These developments add up in terms of safety,
0 creating a growing risk with even greater consequences.
2
st Climate Change As such, the safety risk is growing at an accelerated pace
u
g Future climate changes could influence precipitation (safety risk equals probability of flooding multiplied by
u
A levels to such a degree as to result in extreme discharges flood damage). In 1999, the Secretary of State for Trans-
2
2 in the Rhine and Meuse. Under such circumstances, how- port, Public Works and Water Management and the presi-
21 ever, it can also be assumed that flooding and/or supple- dent of the Union of Water Boards established the Advisory
13: mentary water storage measures along the upper Rhine Committee on Water Management in the 21st Century
at would lead to an upper limit to the discharge in the down- (Anonymous, 2000a). This Committee was charged with
]
n stream direction. Developments in the levels of precipita- developing recommendations for desirable changes to the
e
g
e tion in the central and northern sections of the Rhine and water management policy in our country, focusing on the
m
Nij Meuse catchment areas in particular will influence the level consequences of other water-related problems such as
rsiteit osaitfsi o dtnias kscihhnoagwr gfsleo tsho iadnti ,nt ahgse sa uNlomentighn egtrh laea 4nU°d psCp. Ateernm R aphpeiprnareto uixnrietmo i nactcoern easanisdaele yirn-- c2wl0ai0mte1ar, ttemh icashn Caanoggmeemm, eriintsttei neing p rstohedea ulNceevedeth lsseo ramlnaend d glsau.ni dTde hslieun beDssiu fdtoecrnh fc uget.ou vIrne-
e
v
ni the next century (the highest estimate for the climate ef- ernment enacted these guidelines in the new approach to
U fect in 2100), a discharge increase at Lobith of 18,000 m3/ ensure safety (mainly flood risk management) and to re-
d
u s around 2100 cannot be ruled out (Silva et al., 2001). If duce the other water-related problems in the 21st century.
o
db floods and storage measures along the Upper Rhine are This approach comprises:
a
R not taken into account, a 4°C temperature increase would 1) Awareness; citizens are insufficiently aware of prob-
[
y mean a discharge at Lobith of more than 19,000 m3/s. lems associated with water. The government will im-
b
d However, one must also remember that the Lower Rhine prove communication on the nature and scope of these
e
d imposes a limit on the amount of water that can reach the risks and, in addition to its own efforts, will offer indi-
a
o
nl Netherlands: 17,500 to 18,000 m3/s, which is the estimated viduals the opportunity to contribute to risk reduction.
w discharge rate at which flooding can occur along the Lower 2) Three-step-strategy; the need for a new approach to
o
D Rhine (Silva et al., 2001). ensure safety and reduce water-related problems
For the last 1,000 years, sea water levels measured founded on a number of underlying principles;
along the Dutch coast have become higher and higher. • anticipating instead of responding;
This is not solely caused by the sea level rise, but also by • not shifting water management problems to others,
subsiding coastal areas. The combination of these two ef- by following the three-step strategy (retaining, stor-
fects is called relative sea level rise, and it amounts to 20 ing and draining) and not shifting administrative re-
cm per century. It is expected that this trend will continue sponsibilities to others;
in the near future. Like river discharges, the consequences • allocating more space to water in addition to imple-
of climate change on sea level must also be taken into menting technological measures.
account. Various scenarios have been developed for this 3) More room for the river; in addition to implementing
situation. The mid-range estimate of a 1°C increase in technological measures, allocating more space for the
temperature around the year 2050 would cause a relative (occasional) storage of water is required. Wherever
sea level rise of 25 cm. The highest estimate of a 2°C possible, this space must also serve other objectives
increase corresponds to a sea level rise of 45 cm around that are compatible with water storage.
2050. The sea level rise in 2015, the year envisioned for 4) Spatial planning; the primary goal is maintaining the
achieving sustainable flood defense in the Netherlands, discharge capacity of the river by legislation prevent-
IWRA, Water International, Volume 30, Number 1, March 2005
Flood Defense in The Netherlands: A New Era, a New Approach 81
ing non-river-linked human activities (such as housing
and industrial estates) in the floodplains and by adapt-
ing municipal zoning schemes. Furthermore, within the
context of spatial planning, a so-called “water test” is
being added to the present legislation. This test must
examine the future effects of proposed zoning schemes
on water systems and prevent the gradual decrease in
the space allocated to water caused by land-use, infra-
structure, housing and other projects (Anonymous,
2001a). For the Rhine branches, a study has been
conducted focusing on water storage areas or dike re-
location based on a possible future design discharge of
18,000 m3/s (Project Group Resilience Study, 2002).
Subsequently, a study has been initiated on the pros
and cons of so-called “emergency storage areas” (Fig-
1 ure 5) in order to cope with discharges even higher Figure 3. River dike relocation, creation of side channel, and flood-
1
0 than 18,000 m3/s or potential dike breaches (Commis- plain lowering in Bakenhof along the Nederrijn river at Arnhem. For
2
st sion Luteijn, 2002). details on the efficiency of this project see Tables 1 and 2
u
g 5) Knowledge; the new water management approach
u co-operation. Thus, a cross-border decision support sys-
A imposes new demands on the coordination and distri-
2 tem is under development and the respective dike design
2 bution of knowledge and on education relating to wa-
21 ter and river management (e.g. including new insights concepts and parameters are being compared and attuned.
13: in social studies, spatial planning and public adminis- This co-operation has also led to a computer-assisted model
at tration). for improved calamity management (Anonymous, 2001b).
] Furthermore, a bilingual magazine is issued periodically to
n 6) Responsibilities; the government, provincial authorities,
ge inform the public of the progress being made. During the
e water boards, and municipal authorities are all respon-
m successful cross-border conference in November 2001 in
Nij sible for ensuring safety and limiting water-related prob- Nijmegen, the Netherlands (Smits et al., 2003), civilians,
rsiteit ltieammspkslse. amAndednm ctiaontoiiopstnerr aoatftiiv omen ea magsruuesertem se.en Ansut srr eeav brioaepuwitd th haaens dd bi evefeifsnei occntoi vnoe-f yinogu pnrgo ppeoospallse ,f aonr dim scpireonvteisdt sf lwooodrk perdo tteocgteiothne ar wina dreenveeslso.p-
ve In the context of the ICPR a so-called “Rhine Atlas”
Uni dleugcitseladt itoon a fsosre sas r athpeid s iumitpalbeimliteyn otaft itohne oref l e“vroaonmt p froers ethnet was published (Anonymous, 1998a). This is a collection
d of maps showing the potential damage that would result if
u river” projects and to see if this legislation needs to be
dbo adapted. a breach of the dikes should occur along the river Rhine.
a The purpose of this “Rhine Atlas” is to increase the aware-
R 7) Investments; developments in terms of climatic change
[ ness of decision-makers involved in spatial planning, flood
y and land subsidence, as well as the new approach, re-
b management and water management. The total amount
d quire repeated additional investments in both the na-
e of potential damage was found to add up to 100 billion US
d tional and regional water management systems.
oa dollars for the entire catchment area of the river Rhine,
wnl 8) Ifnloteordn aptriootneaclt cioono paenrda tiwoant;e irn tmerannaatigoenmale cnot ompuersat tiboen ionn- including US$ 80 billion for the Dutch section.
Do tensified. In the above list, the second point (three-step-strat-
egy: retaining, storing and draining) is of particular interest
Regarding the last point, considerable efforts have been
because it extends beyond the borders of the Netherlands
invested and clear results have been obtained. In particu-
and can be applied to small and large stream corridors,
lar, the cooperation within the International Commission
even to the level of entire river basins. In fact, other Rhine
on the Protection of the river Rhine (ICPR) and the politi-
and Meuse riparian states have already adopted similar
cal agreement on a mutual approach between the German
concepts (Hooijer et al., 2002; Van Rooij and Van Wezel,
Nordrhein-Westfalen region and the Dutch province of
2003). Because the catchment areas of these two rivers
Gelderland and the Directorate-General of Public Works
are located in more than one country, flood control inevi-
and Water Management deserve to be mentioned here.
tably became a matter of co-operation between the rel-
This agreement was prolonged for another five years by
evant authorities. Flanders, France, Germany, Luxembourg,
the respective governments on May 23, 2002. Although
the Netherlands, and Wallonia submitted a joint flood con-
the specific measures on both sides of the German-Dutch
trol program to the European Commission within the frame-
border may differ in character (such as that the new dikes
work of its INTERREG II-C initiative. This INTERREG
to be constructed in Germany are one meter higher than
Rhine-Meuse Activities (IRMA) program was approved
required by Dutch standards), the exchange of informa-
on December 18, 1997. Besides the European Union mem-
tion, knowledge and views has led to an open and fruitful
IWRA, Water International, Volume 30, Number 1, March 2005
82 H. van Stokkom, A. Smits, R. Leuven
ber states mentioned, Switzerland was also participating way (in terms of navigation). Recently, there have been
in this program on a project basis. The main objective of attempts to restore the dynamic hydromorphology of small
the IRMA program was to prevent damage caused by streams and rivulets at several locations in the catchment
floods for all living creatures in and important functions of area of the Rhine and Meuse (Nijland and Cals, 2001).
the catchment area of the rivers, and therefore create a Harnessing structures have been removed from the banks
balance between the activities of the population in the ar- and in some cases wooden constructions or tree trunks
eas, the socio-economic developments and sustainable have been deliberately placed in the stream to increase
management of the natural resource water. the hydromorphodynamics (Figure 4). While at first, these
The program has been completed at the beginning of experiments merely aimed to improve biodiversity by re-
2003. During the six-year period of IRMA (1997-2003), storing the morphological diversity of the hydrosystem, a
almost 153 projects were carried out in the catchment area morphologically diverse hydrosystem with riparian veg-
of the Meuse and Rhine (Van Rooij and Van Wezel, 2003). etation also retains water in the catchment area. More-
Table 1 gives examples of innovative flood management mea- over, it provides better conditions for the replenishment of
sures and evaluates the efficiency, transnational coopera- groundwater supplies and bed load, reducing riverbed ero-
tion, and public participation of some representative IRMA sion (in contrast to some river systems, the Rhine is a
1 projects in various parts of the Rhine and Meuse basin. sediment-poor hydrosystem). These advantages are lack-
1
0 The innovative character of the new approach lies in ing with the traditional methods of retaining water (by
2
st the way this three-step strategy is implemented. In con- means of sluices and small dams). At present, several
u
g trast to the traditional approach, which primarily involved projects are being carried out in the Rhine catchment (e.g.
u
A engineering measures (such as dikes, sluices, weirs, and Alzette rivulet) and Meuse catchment (e.g. Niers rivulet)
2
2 dams), solutions are now preferably sought in restoring to stimulate the interaction between water flow and sedi-
21 the natural hydromorphological processes of stream cor- ment (hydromorphological processes), with financial sup-
13: ridors, expanding the floodplains with previously reclaimed port from the European Union and various ministries of
at land and adapting user functions. The following section the Rhine and Meuse riparian countries (Van Rooij and
]
n illustrates this new approach with some practical examples Van Wezel, 2003).
e
g
e related to small rivulets (catchment area) and sections of
m
Nij the rivers Rhine and Meuse. Midstream and Lower River Sections:
rsiteit Implementing the Three-step Strategy TesepmeIcpnio atrlhlaeyr miilnyi d tShsttero erNaimnetg ha eWnrdlaa lntoedwrs e a–rn pddai srDtcseh loaafry gtiehnseg or Rifv ueinrn foblofafwsiinn –g
e
v
ni Catchment Area: Retaining Water by Restoring rivulets should be preferably fine-tuned in time and add up
U Rivulets to the expected discharge of the main stream. In addition
d
u Although water boards and river managers have ac- to water retainment in the upper parts of the river basin as
o
db quired great expertise in regulating rivulets and rivers, they described in the previous section, water should be stored
a
R have little experience in reversing this process without in- temporarily in the rivulet systems themselves or, for in-
[
y creasing flood risks and adversely affecting the water- stance, in medium-scale retention areas such as at Noord-
b
d
e
d
a
o
nl
w
o
D
Figure 4. Examples of small-scale experiments aimed at inducing hydromorphodynamics in formerly regulated streams. Left photograph; in
order to stimulate the interaction between water flow and sediment, tree trunks are fixed in the bank of a rivulet (left photograph; “Sandbach”
Iffezheim, Germany) or wood debris is deliberately left in a stream (right photograph; ‘Geul”, Maastricht, the Netherlands). In both cases, the
channel becomes shallower and wider, and the water discharge decelerates
IWRA, Water International, Volume 30, Number 1, March 2005
Flood Defense in The Netherlands: A New Era, a New Approach 83
and Zuid Meene along the Vecht rivulet (4.25 106 m3), measures along a river section to meet the desired increase
landed estates along the Regge and Dinkel rivulets (0.17 in water discharge capacity (Van Schijndel, 2003). The
106 m3), Starkriet along the Aa rivulet (0.25 106 m3), and user can also choose how to divide extra discharge at Lobith
Bossche Broek along the Dommel rivulet (8 106 m3) (Van over the various Rhine branches in the Netherlands. Apart
Rooij and Van Wezel, 2003). Retention and storage of from the net hydraulic effect of each combination of mea-
water may also provide solutions to problems of extreme sures, the toolbox estimates the total costs and environ-
droughts (e.g. likelihood of extreme low water levels due mental effects. It also contains a selection of aerial and
to climate change). ground pictures of most of the measures. When the user
Another example of retention by habitat rehabilitation has defined the total set of measures the toolbox produces
instead of building dams, but on a larger scale, is to be a summarized report on all the effects. This tool has proved
found along the so-called “Grensmaas,” the section of the to be very powerful, not only in the development of alter-
river Meuse which forms part of the border between Bel- native strategies and planning measures but also in com-
gium and The Netherlands (Van Leussen et al., 2000). municating with the people and authorities involved. It gives
This river section is being transformed into a natural river- various stakeholders the opportunity to evaluate their vi-
bed, which functions as a natural retention area. Modified sion on the design of the Rhine delta. By using this toolbox
1 gravel extraction is used to widen the floodplains, and an the efficiency of the measures A through F in Figure 2
1
0 attempt is made to restore the original hydromorphological could be ranked roughly (Silva et al., 2001). For instance,
2
st processes. There is no navigation on the “Grensmaas.” It all options for setting back dikes (300 to 600 m over a
u
g is limited to an existing shipping canal parallel to this river length of 1 to 5 km) cost less than US$ 0.63 million per
u
A section. The “Grensmaas” project is a joint Dutch-Bel- mm water level reduction. Groin height reduction can con-
2
2 gian undertaking (Van Rooij and Van Wezel, 2003). tribute to a decrease in the water level in the Waal end
21 IJssel river varying from 5 to 15 cm. On the Nederrijn,
13: Increasing the Water Discharge Capacity of the this is a maximum of 10 cm. The costs of groin height
at Main Stream reduction are relatively low and the efficiency of this mea-
]
n Land reclamation has severely reduced the original sure is intermediate. On average, the removal of 60 bottle-
e
g
e floodplain areas of both Rhine (Havinga and Smits, 2000) necks can reduce the water level on the Waal and
m
Nij and Meuse river (Van Leussen et al., 2000). At some lo- Nerderrijn/IJssel river some 20 cm and 10 cm, respec-
rsiteit cdnauetceik otsno”s )u, (rtVbhaaenn r Aidvelepvrhebleeondp, mh2a0es0n 2tbs)e .( cFsoormo-cmea l etlhexditsr e“pmheyresdlpyrea cuctoliinvcse bt,r omicttteleaed-- tathibvauentl myU. eSTn$hts e2 a .cn5od ms tthsil eloi rofe nwm tioodv emanloi norgef ftaehnrardny dUreaSemp$pe 7sn 5ivn amgr yitl hlfireoo nbm rf ioldergs aes
e
v
ni sures that increase the storage capacity of the riverbed highway bridge. The costs of excavation embankments
U are now preferred to raising dikes (Anonymous, 2000a). and small-scale setting back of dikes are usually in the
d
u Thus, downstream of the Rhine tributaries, proposed mea- order of US$ 5 million per project, but it can run up to over
o
db sures concentrate on creating more room for the river. A US$ 20 million if many homes must be relocated.
a
R number of possibilities can be identified for creating more In parallel to the planning and design processes, quite
[
y room for the river to increase the cross section or the a number of projects along the Rhine branches in the Neth-
b
d water discharge capacity of the river (Figure 2). These erlands have already been carried in recent years. Figure
e
d measures range from (a) moving dikes further inland; (b) 3 shows an innovative “room for rivers” project that com-
a
o
nl constructing river bypasses; (c) lowering groins; (d) dredg- bines river dike relocation, creation of side channel and
w ing the riverbed in sections of the river where sedimenta- floodplain lowering. Table 2 gives estimations of the costs
o
D tion occurs; (e) removing hydraulic obstacles such as and effectiveness of some projects. For the next decade,
non-flooding areas in the floodplain, summer embankments, the Dutch government has set aside about US$ 3 billion
bridge abutments, or ferry ramps; and (f) lowering flood- for “room for the river” projects. Additional funds will be
plains, for instance by digging side channels, frequently made available in due course for the construction of so-
combined with land-use changes from agriculture to habi- called emergency storage polders in the upper part of the
tat restoration and recreation (Pruijssen, 1999; Nijland and Dutch section of the Rhine river (Figure 5) and for long-term
Cals, 2001; Buijse et al. 2002; Nienhuis et al., 2002). measures relating to design discharges of 18,000 m3/sec.
Close cooperation with water boards, governmental
agencies, municipal and regional authorities, institutes, uni-
versities, non-governmental bodies, and interested civil-
ians has yielded an inventory of large numbers of options
for measures along the branches of the river Rhine in the
Dutch part of the basin (Silva et al., 2001). These options
have been screened and collected in a so-called “toolbox,”
a user-friendly decision support system that enables the Figure 5. Schematic representation of detention polder for tempo-
river manager or stakeholders to design combinations of rary or emergency storage of river water in the hinterland
IWRA, Water International, Volume 30, Number 1, March 2005
84 H. van Stokkom, A. Smits, R. Leuven
Table 2. Estimated costs and effects on water level of innovative projects to reduce flood risks along the Rhine River branches in the
Netherlands
Effects on water level Estimated costs
Project Type of measure at design discharge(- cm) (106 US$)
Nederrijn River
Bakenhof floodplain in Arnhem Dike relocation (1400 m set back ca. 200 m), creation of
side channel and floodplain lowering 7 9.6
Weir at Driel Lowering of weir isle and construction of fish passage 8 8.8
Rosande polder near Oosterbeek Modification abutment of railway bridge 10 62.5
Waal River
Hydraulic ‘bottle neck’ at Nijmegen Relocation of homes, dike relocation (1500 m set back
max. 350 m) and creation of side channel 45 281.3
Afferdensche and Deestsche Waarden Floodplain lowering and creation of side channel in
combination with ecological rehabilitation 8 15.0
Focal Points for the Future 10 percent by the year 2005 and by 25 percent by the year
1 Because high water discharges and near floods are 2020; (b) reducing extreme floods downstream caused by
1 the regulated section of the upper Rhine, aiming at a re-
20 erratic, it is crucial that the administrators make efforts to
st prevent flood awareness among the public from fading. duction by 30 cm in 2005 and by 70 cm in 2020; (c) in-
u creasing public awareness of flood risks; and (d) improving
ug Following the high-water situations in 1993, 1995, and 1998,
A the flood warning system. Until this point, it proved politi-
2 the national and international co-operation in flood defense cally impossible to coordinate the formulation of an action
2 has gained momentum. Public opinion, which was ex-
1 plan within the Commission for the Protection of the
2 tremely critical regarding dike reinforcements in the pre-
3: Meuse. Accordingly, a Flood Defense Task Force for the
1 ceding decade, changed totally into public support for a
n] at rapid dike reinforcement program. Local and regional au- Mof etuhsee I wCaPsR e. sTtahbel i“sMheedu, swe hHoisgeh f uWnactteior nA icst isoimn iPlalar nt”o wthaast
e thorities developed a renewed awareness of flood protec-
g established by the Belgian, Dutch and French ministers in
me tion issues, which had almost disappeared. The last serious Namurs (Belgium) in 1998 (Anonymous, 1998b). The
Nij high discharge situation in 1926. The government is now Meuse High Water Action plan is in all respects less am-
eit using various means to stimulate awareness and keep citi- bitious and concrete than the plan for the Rhine, quantify-
sit zens alert, providing a basis for generating sufficient pub- ing neither concrete objectives nor concrete measures. In
er lic support for the implementation of the new approach to
v addition, no estimate of the investment required is pro-
ni flood defenses, land use, and water management. In this
U vided. Nevertheless, the plan does embrace a number of
oud rpeesrpieencct,e sth ien gmoavjeorrn nmateionnt acla ann pdr ionbtearbnlyat iloeanranl pfrroomjec ptsa s(st uecxh- basic strategic principles that also form part of the plan
b for the Rhine: (a) increasing awareness and developing
d as road and railway construction projects), which also in-
a an approach to the risks, (b) employing the three-step-
R volved changes in land use. In order to keep public aware-
d by [ nine sths ea rt eaa hliizgahti loenv oelf, hthazea mrdu mniacpipsa, leimtieesr gmeunscty b see rsvuipcpeos ratnedd s(ctr)a etexgpya nadpipnrgo ascpha coef froetra tihnein Mg,e sutsoer ianngd a intds tdrribaiuntianrgie ws;a atnerd,
de (d) improving the prediction and warning systems.
a information material by superior authorities (Böhm et al.,
o The European Union supported the implementation of
nl 2001). A key role for success of event management is
w the flood action programs for the Rhine and Meuse catch-
o communication, which therefore must be very well pre-
D ment with the formulation of the abovementioned IRMA
pared and checked regularly.
program during1997 to 2001. This program has stimulated
international co-operation and building of networks between
International Cooperation
planners, managers and research groups (Hooijer et al.,
Authorities of the Rhine and Meuse riparian states
2002; Van Rooij and Van Wezel, 2003). It is recommended
have become aware that sustainable flood defense can
that these networks should be kept active, extended and
only be achieved when the entire catchment area is taken
exploited further. Certainly, international co-operation re-
into consideration. The formulation of flood action pro-
quires transboundary understanding, and this is only pos-
grams for the Rhine and Meuse catchment areas was the
sible if all parties concerned are not cooperating on an
direct result of the declarations of Arles and Strasbourg
ad-hoc basis, but within long-term international and inter-
(Anonymous, 1998a), and was accomplished for the Rhine
disciplinary networks.
through the actions of the treaty participants in the ICPR.
The “Rhine Action Program on Flood Defense” was ap-
Funding
proved at the 12th conference of Rhine Ministers, held in
It is unrealistic to assume that the governments of the
Rotterdam, the Netherlands (Noteboom, 1998). The ob-
Rhine and Meuse riparian countries will finance all the
jectives of this plan are: (a) reducing the damage risks by
required measures and activities to achieve sustainable
IWRA, Water International, Volume 30, Number 1, March 2005