4. Contents
Preface 5
1. Trends and issues in the development of deltas 7
1.1 Deltas: economic and environmental hot spots 7 3
1.2 Deltas: melting-pot of drivers and trends 9
1.3 Issues at stake in deltas 11
1.4 Conceptual view on planning of delta development 18
1.5 A closer look at some societal trends 19
1.6 Linking responses to drivers and trends 21
2. Management and restoration of natural systems 23
2.1 Functions and values of deltas 23
2.2 Natural coastal protection and wetland restoration 31
2.3 Integrity of ecosystems: biodiversity, environmental flows 33
2.4 Room for rivers 37
2.5 Multiple use of wetlands 39
3. Extension and revitalization of infrastructure 41
3.1 Role of infrastructure in delta development 41
3.2 Infrastructure to support economic development 43
3.3 Rehabilitation of infrastructure 48
3.4 New approaches in design of infrastructure 50
5. 4. Development and adaptation of land and water use 57
4.1 Modes in adaptation of land and water use 57
4.2 Spatial planning and zoning 58
4.3 Urban (re)development 60
4.4 Adaptation to flood risks 62
4.5 New agricultural practices to adapt to salinity problems 63
4.6 Adaptation to climate change 64
5. Governance of delta development and management 69
5.1 Role of governance in delta development 69
5.2 Co-operation between levels and sectors of government 71
5.3 Cooperation between government and private sector 77
5.4 Involvement of stakeholders and citizens 80
5.5 Approaches for dealing with risks and uncertainties 83
4
6. Way forward? 87
6.1 Two conflicting perspectives on development of deltas 87
6.2 Enabling the sustainable development of deltas 90
6.3 Delta vision: a shared view on delta development 91
6.4 Delta technology: innovations in science and technology 92
6.5 Delta governance: social and institutional innovations 93
6.6 Delta dialogue: establishing best delta practices 94
References 97
6. Preface
This research on deltas, estuaries and coastal zones is part of the preparation
of the Aquaterra 2009 Conference and the World Forum on Delta and Coastal
Development. Deltas may be defined as low-lying areas where a river flows into
a sea or lake. A delta is often considered a different type of river mouth than
an estuary, although the processes shaping deltas and estuaries are basically
the same. In line with the scope of the Aquaterra Conference we have adopted
in this research a broad interpretation of deltas which includes deltas proper,
estuaries and the adjacent coastal zone.
Deltas are areas with major economic potential as well as large environmental
values. The challenge for sustainable development of deltas is to strike a
balance between economic development and environmental stewardship. The
Aquaterra Conference will present and discuss the state and future of deltas
worldwide, with a special focus on eight selected deltas. All these selected
deltas are densely populated and/or economically developed. 5
• Yellow River Delta (China)
• Mekong River Delta (Vietnam)
• Ganges–Brahmaputra Delta (Bangladesh)
• Ciliwung River Delta (Indonesia)
• Nile River Delta (Egypt)
• Rhine River Delta (The Netherlands)
• Mississippi River Delta (USA)
• California Bay Delta (USA)
Another focus of the Aquaterra Conference is the response in deltas to a
number of drivers such as economic growth and climate change as well as to
a number of trends in society such as privatization and decentralization. Four
response themes are being considered:
• Natural systems (management and restoration)
• Infrastructure (extension and revitalization)
• Land and water use (development and adaptation)
• Governance (of delta development)
The research has explored the perspectives of and experiences with these
response themes. Some of these responses may already be classified as ‘best
7. practices’ or better ‘good ideas’ (at least in the local context), others are yet
promising approaches. Anyway, the research aims to provide an overview of
current practices in dealing with delta issues.
An effort has been made to arrange these practices into global trends. Trends
which are illustrated with examples taken from deltas all over the world, with
an emphasis on the eight selected deltas of the Aquaterra Conference and in
particular the Rhine River Delta. The examples presented are not necessarily
the best illustrations of the trends. Own experiences of the researchers as well
as easy access to information have played a role in the selection of examples.
However, taken together, the trends and examples provide a comprehensive
overview of the type of current activities and developments to enable delta
life.
The focus of the research has been on the identification of issues, trends and
responses. The outcome is still qualitative and descriptive. It may be viewed
as a first step in the description and analysis of state and future of deltas
6 worldwide. It may be worthwhile to elaborate on the current research. Such
elaboration may include a more rigorous assessment of the functioning of
deltas based on a set of indicators. Also an extension to other deltas should be
included. This might be a nice challenge for future Aquaterra Conferences.
Delft, January 2009
Prof. dr. Huib de Vriend, Director Science, Deltares
8. 1. Trends and issues in the
development of deltas
1.1 Deltas: economic and environmental hot spots
The major rivers systems of the world all have a unique delta region, with
their specific challenges and opportunities. But there are also common
characteristics. Deltas are usually areas with major economic potential
because of their strategic location close to seas and inland waterways.
Deltas provide also some of the world’s most fertile lands important for food
production. That is why navigation and port development, oil production and
refinery as well as agriculture and fisheries have always been the engines of
economic development of deltas.
Attracted by these potentials, large numbers of people live in deltas; a
development which has led to the growth of coastal (mega-)cities. Population
growth and economic development make extensive demands on the available
natural resources and trigger pollution. If not properly managed deltas may
easily turn into sinks in the frontier between continents and oceans.
9. Trends and issues in the development of deltas
The rivers that flow through the deltas are an important source of fresh water
and nutrients that are critical for sustaining life in the deltas. The mixing of
salt and fresh water in the estuarine part of the deltas creates environmental
conditions for a unique flora and fauna. Delta and estuarine ecosystems are
therefore valuable and among the most productive ecosystems on earth.
But, being low-lying areas, deltas are also vulnerable to flooding and have
to cope with stagnating drainage. That is why living in deltas has always
required human intervention. Land reclamation, irrigation, soil drainage and
embankments have made many a delta a safe place to live and work.
Box 1.1
Opportunities of deltas Challenges in deltas
• strategic location close to seas and water ways • areas vulnerable to flooding and drought
• high potential for port development and oil • human intervention needed to safely live and
industry work
• fertile soils and rich aquatic environment • filter or sink for upstream pollution
• large potential for agriculture and fisheries • areas with high pressure on available space
• valuable and most productive ecosystems
10. 1.2 Deltas: melting-pot of drivers and trends
Population growth, economic development and climate change are the main
drivers for change in deltas. These developments pose extensive demands on
the available natural resources of deltas. In addition to these drivers there
are a number of societal trends which affect the organization and outcome
of planning of delta development. The main drivers and trends are briefly
described in Box 1.2.
Of these trends decentralization and privatization may be viewed as
autonomous developments. The challenge is to utilize the advantages of
both trends, while minimizing their undeniable drawbacks. This calls for a
selective enhancement of governance structures, reflecting the regional scale,
integrated nature and long term perspective of delta development.
Nile delta
11. Trends and issues in the development of deltas
Box 1.2
Drivers for change Trends in society
population growth: the global population still decentralization: brings delta issues closer to
grows with some 2% per year, although there are the stakeholders involved. Due to lack of national
distinct regional differences. The number of people coordination there is, however, a sincere risk of
to be served and to be protected against natural uncontrolled and/or chaotic developments.
hazards will increase.
economic development: despite the current privatization: public-private partnerships
economic recession, economic growth may be are becoming the modus operandi for new
expected over larger periods of time, resulting infrastructural projects and services. Increased
in larger demands to be met, higher values to efficiency of tax payer’s money is a key motive.
protect, more energy to be generated and more The risk of privatization, however, is a focus on
goods to be transported. the short term as well as a neglect of the public
10 interest.
climate change: although the extent of climate participation: involvement of stakeholders and
change may be subject of debate, there is general citizens is important to promote societal support
consensus that rise of global temperature is of development projects as well as maintenance of
inevitable, with its associated (local) impacts on infrastructure; planning may benefit from the tacit
sea level rise and the hydrological cycle (larger and knowledge of stakeholders
more frequent droughts and floods)
technological development: innovations may environmental concerns: worldwide concern
open opportunities to enhance the functionality over a changing climate and environmental
of infrastructural solutions, to extend the life time degradation has raised the environmental
of infrastructure and/or to develop more cost- awareness; it influences the valuation of impacts
effective designs and the choice of measures
risk aversion: acceptance of risk is decreasing in
our modern societies; hence considerable efforts
are made to further reduce or control the risks of
natural hazards
12. 1.3 Issues at stake in deltas
Overview of pressing delta issues
The characteristics, which make deltas attractive areas to live and work,
are under stress. Available space is under pressure, vulnerability to flooding
is increasing, fresh water resources are threatened, etc. Population growth,
economic development and climate change will cause additional stress on
deltas, unless appropriate measures are taken. The main issues at stake in
deltas are briefly described in Box 1.3
Box 1.3
Main issues at stake in deltas
Pressure on available space: being a focal point of economic development population density is
generally high and further rising. Coastal mega-cities have developed; their size and number are
growing.
11
Vulnerability to flooding and drought: being low-lying areas, deltas are vulnerable to flooding.
Subsidence of soft soils adds to this vulnerability. Accumulation of people and wealth will further
increase the vulnerability with respect to climate change.
Shortages of freshwater resources: many deltas in the world currently face water shortages. Climate
change may result in more frequent and prolonged periods of low river discharges. This will have
profound repercussions on the delta agriculture, as well as on delta and coastal ecosystems.
Ageing or inadequacy of infrastructure: many deltas have irrigation and drainage systems which
require an upgrade or major revision to improve their effectiveness. Other deltas have inadequate
flood protection schemes or schemes that will require major upgrading.
Erosion of coastal areas: many deltas face a sediment shortage. This sediment shortage is often
caused by regulation works in the upstream river. The sediment shortage causes coastal erosion
problems. Sea level rise will aggravate these erosion problems.
Loss of environmental quality: Ecosystem functioning and biodiversity in deltas is under very high
pressure worldwide. Main causes are a high population density and concentration of industrial,
harbor and mining activities. Deltas are also receptor of pollutants from upstream.
13. Trends and issues in the development of deltas
Importance of issues in the eight selected deltas
The Aquaterra Conference will present and discuss the state and future of
deltas worldwide, with a special focus on eight selected deltas:
1. Yellow River Delta (China)
2. Mekong River Delta (Vietnam)
3. Ganges–Brahmaputra delta (Bangladesh)
4. Ciliwung River Delta (Indonesia)
5. Nile River Delta (Egypt)
6. Rhine River Delta (The Netherlands)
7. Mississippi River Delta (USA)
8. California Bay (USA)
12
14. In the research a quick assessment has been made whether the delta issues are
a minor or major problem in these deltas. Box 1.4 displays to what extent issues
play a role. The classification distinguishes four types of problems. Problems
are judged minor if they are either unimportant, small in magnitude or well
controlled (•). A minor problem can become bigger in future (e.g. due to climate
change or delta developments) in which case it is given two bullets (••). An
issue is classified as a currently big problem if the issue is requiring significant
management attention and is not (yet) controlled (•••). If the problem is likely
to increase in the near future it is given four bullets (••••).
Box 1.4
issues
deltas pressure on flood freshwater ageing or coastal loss of
space vulnerability shortage inadequate erosion environmental
infrastructure quality and
biodiversity
Yellow River Delta •• • •• • ••• ••• 13
(China)
Mekong River Delta •• •••• •••• •• • •••
(Vietnam)
Ganges– •••• •••• •• •• •••• ••••
Brahmaputra Delta
(Bangladesh)
Ciliwung River Delta •••• •••• •• •• • ••••
(Indonesia)
Nile River Delta •••• • •••• •••• •• ••
(Egypt)
Rhine River Delta ••• •• •• ••• •• •
(The Netherlands)
Mississippi River • •••• • •••• •••• ••••
Delta (USA)
California Bay •• •••• •••• ••• • •••
(USA)
Legend:
• relatively minor problem, now and in the near future
•• currently a minor problem, but is likely to increase in the near future
••• currently already a big problem, future trend uncertain
•••• currently already a big problem, likely to increase in the near future
15. Trends and issues in the development of deltas
Brief explanation of assessments
The assessments presented in Box 1.4 reflects our current understanding
of the issues at stake in the eight deltas and may need revision once more
information becomes available. A short explanation of the reasoning behind
the assessment is presented underneath. The separate delta descriptions
provide further background on the issues.
Yellow River Delta (China)
pressure on space: With a relatively low population density (210 inhabitants/km2 in the rural
area) this issue is not urgent
vulnerability to flood: Flood risk is relatively low: the river is fully embanked and there is no
storm surge hazard
freshwater shortage: Although minimum flows for the delta are guaranteed, future climate
change is likely to reduce overall water availability in the river basin
ageing infrastructure As the delta and its occupation is of recent date, ageing of infrastructure
14
does not play an important role yet
coastal erosion: Especially along the northern coast erosion is a big problem due to
sediment starvation
loss of biodiversity: Nature Protection areas along the coast are under high pressure of
limiting freshwater and economic activities (esp. from the oil industry)
Mekong River Delta (Vietnam)
pressure on space: The population density is 410 inhabitants/km2 and with a growth rate of
2.5% per year, pressure on space will increase in future
vulnerability to flood: Floods are a common feature of the delta and society has learned to live
with it.
freshwater shortage: During low flows salinity intrusion is a recurrent problem, likely to
increase with sea level rise. Groundwater use is growing.
ageing infrastructure The delta has an extensive canal and embankment system, some of which
over 100 years old
coastal erosion: The sediment balance of the Mekong river is, compared to other major
Deltas, relatively stable
16. loss of biodiversity: The Delta has an extremely rich biodiversity which is under pressure due
to the rapid economic growth
Ganges–Brahmaputra Delta (Bangladesh)
pressure on space: With some 1500 inhabitants/km2 the delta is one of the most densely
populated regions on earth.
vulnerability to flood: Most of the delta is prone to tropical cyclones with high storm
surges.
freshwater shortage: Due to upstream developments and climate change, critical low flow
conditions of rivers are likely to increase
ageing infrastructure Management of embankments and irrigation system is a recurrent
problem
coastal erosion: Annual rate of erosion is ± 10,000 ha and accretion is only 2,500 ha. 15
Erosion is a bigger problem than flooding.
loss of biodiversity: Especially the mangrove forests (Sundarbans) are highly valuable but also
under high pressure from encroachment and exploitation.
Ciliwung River Delta (Indonesia)
pressure on space: Jakarta is the fourth largest urban area in the world (23 million
inhabitants)
vulnerability to flood: Almost half of the area is below sea level and is still subsiding. The city is
prone to inundation due to excessive rainfall and flash floods
freshwater shortage: Land conversion from forest to agriculture and urban area results in
water shortages during the dry season.
ageing infrastructure Although much of the infrastructure is relatively recent, rehabilitation is
needed, esp. with respect to drainage systems
coastal erosion: Locally there is coastal erosion due to natural and man-made factors.
Islands in the Bay are disappearing as a result of coral reef destruction
loss of biodiversity: Water quality is a major issue as many upstream domestic and industrial
waste water is discharged untreated.
17. Trends and issues in the development of deltas
Nile River Delta (Egypt)
pressure on space: With half of Egypt’s population of 80 million living in the delta and a
population growth rate of nearly 2% pressure on available space is the
main issue of the Nile Delta
vulnerability to flood: River floods are minimized through the High Dam and coastal storms are
rather mild.
freshwater shortage: The entire country is dependent on Nile water inflow. As demands
continue to rise, freshwater shortage will increase in the future.
ageing infrastructure The extensive irrigation system is stretched to its limits; there is a
constant need for efficiency improvement
coastal erosion: Due to Aswan dam most of the Nile sediments are trapped in Lake Nasser.
Sediment balance at the coast is disturbed, leading to coastal erosion
loss of biodiversity: As the bird-rich coastal lagoons are at the end of the system, their water
quality is threatened by salinization and pollution.
16
Rhine River Delta (The Netherlands)
pressure on space: With a population density of around 500 inhabitants/km2 the delta is
densely populated which implies a high pressure on space
vulnerability to flood: Although the flood risk is quite small, potential consequences of a flood
are high. Future sea level rise and growing investments will increase flood
risk.
freshwater shortage: Rising sea levels will increase the problem of salt water seepage and will
cause local freshwater shortages.
ageing infrastructure The sophisticated infrastructure will require adaptation to new
conditions induced by climate change.
coastal erosion: Coastal erosion is well controlled with extensive sand nourishments. Sea
level rise will increase the maintenance nourishments needs
loss of biodiversity: The health of estuarine and coastal ecosystems is compromised by
pollution and reduced hydrodynamics. Plans are underway to improve the
situation.
18. Mississippi River Delta (USA)
pressure on space: The population is not very dense, less than 100 inhabitants/km2.
vulnerability to flood: The delta is recurrently visited by hurricanes. The flood protection system
requires upgrading.
freshwater shortage: As yet there is no serious shortage of freshwater in the Delta.
ageing infrastructure There is a high investment need to upgrade the flood protection and
navigation (the Mississippi River Gulf Outlet, MRGO) system. The MRGO
is a former federal navigation channel opened in 1968 to provide a short
route between the Port of New Orleans and the Gulf of Mexico.
coastal erosion: Soil subsidence, canal construction and wave exposure have led to huge
land loss. Likely to increase due to sea level rise.
loss of biodiversity: Wetlands are disappearing at an alarming rate since decades.
California Bay (USA)
1
pressure on space: Pressure on the available space is currently not a major issue. But
population growth rates in the Delta are projected to be higher than in the
state as a whole.
vulnerability to flood: Most of the delta is below sea level. Sea level rise, earthquake hazard and
subsidence will increase vulnerability. Large scale flooding of the Delta
with saline water could have immense consequences for the entire state.
freshwater shortage: Nearly two-thirds of the state’s population depend on the Delta for at
least some of their water supply. The delta experienced severe droughts in
the past. Limited opportunities to increase supply.
ageing infrastructure Delta infrastructure started to develop as from 1850. Because of shifting
demands it requires constant updating and maintenance.
coastal erosion: The delta itself does not have a coast. In the wider region (San Francisco
Bay) several beaches suffer from erosion
loss of biodiversity: The Delta is in an ecological tailspin. Invasive species, water pumping
facilities urban and agricultural pollution are degrading water quality and
threatening multiple fish species with extinction.
19. Trends and issues in the development of deltas
The main purpose of the overview of Box 1.4 is to show that there is quite some
variation between the eight deltas. For example vulnerability to flooding is a
major issue in most deltas but not in all. The table also shows that some deltas
have to deal with a range of major issues, whereas in other deltas most issues
are minor or at least under control. Although some individual assessments
may need further study , this will not alter the overall picture.
1.4 Conceptual view on planning of delta development
The delta issues described have something in common: they reflect
development of land and water use and development of infrastructure which
was not sustainable. In other words the developments were not in harmony
with the limitations and potentials of natural systems. To analyze the
sustainable development of deltas a framework of analysis is needed. In this
research the so-called ‘Layer modeli has been adopted (see Figure 1.1). The
Layer model divides the space in three physical planning layers, each with their
1 own dynamics. These layers are the base layer (water and soil), the network
Figure 1.1 Layer model for planning of delta development
20. layer (infrastructure) and the occupation layer (physical pattern arising from
human activities: living, working, recreating; in short: land and water use).
The essence of the Layer model is the difference in dynamics and vulnerability
between the layers, which results in a logical order in planning the various
layers. The layers enable and/or constrain activities in another layer.
The Layer model may be instrumental in for example the design of strategies
for adaptation to climate change. The key to adaptation to climate change
(climate proofing) lies in the base layer. If the structure of the base layer is
climate proof, then the other layers follow suit. This is not a matter of hierarchy
or dominance but of logical order: the base layer first.
The climate proofing of the base layer is the sole responsibility of government.
The way to act is to make maximum use of the large adaptive capacities of
natural systems. Moving to the occupation layer the role and influence of
government becomes more restricted and the influences of private parties and
citizen’s interests become more dominant. 1
1.5 A closer look at some societal trends
Privatization
In many countries governments tend to pull away from ownership and
management of infrastructure. The central government increasingly plays
a role of coordinating networks and markets and organizing supervision
(Broekhans Correljé, 2008). Public-private partnerships are becoming more
and more the modus operandi for new infrastructural projects. Utility sectors,
such as railways, electricity and drinking water have been privatized in many
countries. Increased efficiency of tax payer’s money is a key motive for this
development. But that does not mean that there is no role left for the central
government. Indeed, in order to safeguard public values in the liberalized
utility sectors, authorities are installed that oversee quality and guaranteed
delivery of goods and services.
Another form of privatization is the handover of land (and water) that was
previously owned and managed by the government. Examples can be found
in Eastern European and some Asian countries. These countries are now
under transition from a previously communist regime to a more democratic
21. Trends and issues in the development of deltas
and capitalist economy. This transition has often increased the much needed
agricultural productivity, but also created new ‘tragedies of the commons’.
For instance, in Vietnam, liberalization of market forces and privatization
of coastal resources has led to serious cases of overexploitation (Kleinen;
Adger Luttrell, 2000). A case study from the Red River Delta revealed that
privatizing water management institutions does not necessarily mean a
better management of water (Fontenelle, 2000).
Decentralization
Decentralization of planning and management is visible in many countries as
well. For example in India decentralization is taking place through the Panchayat
system (i.e. local government bodies at the village level). There can be different
reasons for downscaling management and planning at more regional and local
levels: e.g. reduction of government bureaucracy, increased empowerment
and participation of local stakeholders, state budget constraints and political
motivations. Although most people generally agree that it is better to decide
and manage at the lowest possible level (e.g. subsidiary principle: the idea that
20 a central authority should have a subsidiary function, performing only those
tasks which cannot be performed effectively at a more immediate or local level
(Wikipedia, accessed on 3 December 2008), this does not mean that this goes
without any problems. For instance, a study on the decentralized management
of fishery and wetland resources on the Kerala Coast (India), concluded that
‘fisheries is the big looser in the local self-governance system’ (Panday, 2003).
Although intentions are often good, the elaboration of clear roles and human
capacity are often the bottleneck.
Global environmental concern
Global climate change poses both risks and opportunities: worldwide concern
over a changing climate and environmental degradation has raised an
environmental awareness that was not seen before. The Intergovernmental
Panel on Climate Change, the UN Millenium Development Goals, global
conventions on biodiversity, wetlands and transboundary pollution and
the World Water Forum are but a few of the examples that exemplify this
awareness. This leads to the notion by many people that human society needs
to adapt to the (limiting) carrying capacity of the environment, i.e. the ‘base
layer’ in our conceptual model.
Dealing with these trends
These trends pose tremendous challenges to delta management. Existing
22. management approaches and tools are not always adequate as they tend to
tackle these challenges in a piecemeal and sector wise way. For example, in
many countries a full fledged Environmental Impact Assessment legislation
is operational. Although this is a great improvement over past practices
neglecting the negative consequences of development projects, it mostly does
not account for multiple and cumulative impacts. Also planning regulations
and limitations do not always serve an optimal spatial development. And
sometimes even are counter effective. For instance, hazard regulations that
could promote risk reduction in the long run, could turn into vehicles for short-
term and short-sighted economic gain. We see this in communities that rush
to issue permits before the publication of new maps that show that the area to
be built in is vulnerable to an increased or changed flood hazard (Armstrong,
2000). It has also been long standing knowledge that nature conservation by
means of protective areas or reserves has significant limitations. Endangered
species get trapped in those isolated havens as their habitat becomes unsuited
due to climate change.
These are but some examples of the difficulties delta management is confronted 21
with. As a way out, a more holistic and integrated view on delta management
is getting shape. We see this for instance in integrated water management,
coastal zone management and at the scale of entire river basins. But there
is more: ideas to reconcile human development with nature are emerging in
various fields. ‘Building with Nature’ is practiced already in the form of beach
nourishments as opposed to hard structures to control erosion. Multifunctional
use of infrastructure is being implemented in densely populated deltas, to save
space and money. Restoring the natural purification capacity of wetlands and
estuaries are being considered in highly modified deltas, as in the Netherlands.
Renewable energy from waves, tides and salinity gradients is being studied.
Decentralization and privatization may be viewed as autonomous
developments. The challenge is to utilize the advantages of both trends, while
minimizing their undeniable drawbacks. This calls for a selective enhancement
of governance structures, reflecting the regional scale, integrated nature and
long term perspective of delta development.
1.6 Linking responses to drivers and trends
To promote sustainable development of deltas a clear vision has to be developed
on how to respond to the various drivers of change as well as on how to play along
23. Trends and issues in the development of deltas
with the various trends in society. A strategy for sustainable development of
deltas cannot be limited to infrastructural measures or restoration measures
for natural systems. A sensible combination of different kind of responses is
required. This should include measures for management and restoration of
natural systems, for development and adaptation of land and water use and
for extension and revitalization of infrastructure. Furthermore enhancement
of the governance structure is required to enable implementation of these
responses. These are in fact the four major response themes distinguished
in the Aquaterra 2009 Conference (see Figure 1.2). The first three response
themes reflect the three layers of the conceptual planning model.
The research has explored the perspectives of and experiences with these
response themes. Some of these responses may already be classified as
‘best practices’, others are yet promising approaches. Anyway, the research
provides an overview of current practices in dealing with delta issues. An
effort has been made to arrange these practices into trends. These trends are
22 discussed by response theme in the next sections.
Figure 1.2 Linking response themes to drivers and trends
24. 2. Management and restoration of
natural systems
2.1 Functions and values of deltas
Delta processes: shaping the base layer
Deltas are relatively young landforms shaped by the interplay of coastal and
riverine processes. For example the entire Yellow River Delta was formed in a
period of slightly more than century. Since 1855, when the Yellow River shifted
its course from debouching in the Yellow Sea towards flowing into the Bohai
Sea, each year up to several thousands of hectares of new land was formed
(Liu Drost, 1996). This rapid expansion of the delta is thanks to the enormous
23
25. Management and restoration of natural systems
quantities of sediment transported by the Yellow River from the extensive Loss
plateaux and from which the river has received its name. Although the Yellow
River is quite exceptional in its sediment load, all other deltas have been formed
by the sediments brought in by their respective river and shaped by the interplay
of tides, waves and currents. At the seaside of a delta, these forces tend to erode
and disperse the sediments. But as long as the net input of sediments exceeds
the rate of erosion, the delta will grow. This brings us to the first important
observation: these natural processes are crucial in the long term evolution of a
delta. A net deficit in sediment supply will lead to coastal erosion and – hence –
could lead to problems in the human use of the delta base layer.
Besides sediments, the river also constantly supplies the delta with fresh water,
nutrients and organic matter. When the freshwater mixes with the seawater,
flocculation leads to rapid settling down of small particles and produces an
extremely nutrient rich aquatic environment. For this reason the delta estuaries
and its marine environs have the highest biological production of all natural
areas in the world. From this wealth, economic benefits are reaped in the form
24 of fish, shellfish and other seafood. And by the way, it also explains the highly
prized occurrence of oil and gas stocks under present day deltas: these are the
fossil remains of the organisms that once thrived in the similarly productive
coastal waters.
Table 2.1 Official Ramsar sites in deltas
Delta Site Size
Nile Delta Lake Burullus 46,200 ha
Ganges Sunderbans 601,700 ha
Rhine Delta all open and closed estuaries (10 sites) 188,475 ha
Rhone Delta Camargue La Petite Camargue 122,000 ha
Ebro Delta entire delta 7,736 ha
Danube Delta entire delta 647,000 ha
Volga Delta entire delta 800,000 ha
Senegal Delta Parc National du Diawling 15,600 ha
Red River Delta Xuan Thuy Natural Wetland Reserve 12,000 ha
26. It is not surprising that these rich deltas attract migrating birds. Lying at
strategic positions along flyways, delta nature sites are key stepping stones of
millions of birds en route from north to south and vice versa. At this moment
some 2,4 million hectares of delta wetlands have been given the official status
of Ramsar Site, indicating that these wetlands are of international importance
for the survival of many bird populations (see Table 2.1). In three instances,
even the entire delta has been designated as official Ramsar site, viz. the Ebro,
Danube and Volga delta.
Functions and values for mankind
Deltas are a gift of nature to mankind. Deltas have flat, highly fertile soils that
are easy to till. They can be travelled across on its waters, full of fish. But as the
Table 2.2: major ecosystem functions in deltas
Category Function Ecosystems and mechanisms (main
examples)
25
Regulation functions Storm and flood Mangroves, coral reefs, salt marshes, dunes,
protection etc.
CO2 sequestration Forests
Nutrient cycling Estuarine denitrification
Soil formation delta development (sediment deposition etc.)
Habitat functions Refugium function Suitable living space for wild plants and
animals
Nursery function Suitable reproduction habitat (e.g. mangroves
as nursery for fishshrimp)
Production functions Food production Fishery agriculture
Raw materials Sand and clay / wood
Energy production Tidal energy
Wind energy
Information functions Recreation tourism Beach recreation
Watersports
Eco-tourism
27. Management and restoration of natural systems
sea gives, it can also take. Their low lying topography make deltas vulnerable
to storm surges and river floodings. And if not from aside, the seawater enters
from below: seepage of saline groundwater poses a constant threat to the crops.
Hence, man has to dig and develop. Land reclamation, irrigation, soil drainage
and embankments have made many a delta hospitable: a place to safely live in
and to live off the fruits of the land and sea. Several of the deltas have developed
into the major granary or rice bowls of an entire country, such as the Red River
Delta in Vietnam and the Godavari and Krishna deltas in India.
A generic classification of functions and values of nature and natural processes
is given by (de Groot et al., 2002) and distinguishes regulation-, habitat-,
production- and information functions. Nature provides these functions, free
of cost, to mankind. In deltas, ecosystems provide the following major
functions (Table 2.2):
Table 2.2 shows that for instance ‘Storm and flood protection’ is provided by
delta ecosystems that include mangroves, coral reefs, dune systems and salt
26 marshes, but can also include coastal forests, seagrass beds, intertidal flats,
and lagoons, depending on the delta in question. Mechanisms for regulating
storm and flood impacts in coastal areas include: wave dissipation, barrier
to flood surge, wind breaking, coastal accretion and stabilization (long-term)
and regulation of sediment transport linked with coastal geomorphology.
Obviously, coastal ecosystems can perform several of these functions
simultaneously: a mangrove forest protects land from a storm surge, it
provides a nursery area for fish and shrimp, it yields useful timber and serves
as a habitat for many species including migrating birds. Section 2.5 presents
several examples of multifunctional uses.
How much are these functions worth? One well known study has estimated
‘Estuaries have the the monetary value of the world ecosystems. In this study, (Costanza et al.,
1997) calculated that estuaries have the highest economic value of 22,832
highest economic US $ ha-1 year-1 of all ecosystems. Nutrient recycling and food production are
the major functions that contribute to their high economic value. Off shore
value of all seagrass and algae beds closely follow with 19,004 US $ and tidal marsh/
mangroves contribute a respectable 9,990 US $. These figures become all the
ecosystems’ more significant when compared with, for instance, tropical forests (2007
US $) and open oceans (252 US $). These figures signify the enormous relative
importance coastal and delta ecosystems have for humankind.
28. Status and trends in delta values and functions
The most important direct drivers of change in ecosystems worldwide – and
probably also for delta ecosystems – are habitat change, overexploitation,
invasive alien species, pollution and climate change. Habitats are converted to
agricultural land or shrimp ponds and especially fish stocks are overexploited.
Alien species and disease organisms continue to increase because of both
deliberate introductions and accidental translocations through commercial
shipping related to growing trade and travel, with significant harmful
consequences to native species and many ecosystem services. With respect
to pollution, particularly the nutrient loading to regional seas is disturbing:
Excessive flows of nitrogen contribute to eutrophication of freshwater and
coastal marine ecosystems. For instance, there has been an 10 fold increase in
nitrogen flux of the Yellow river to the sea since the industrial and agricultural
revolutions and for the North Sea watersheds this is even a 15-fold increase.
Table 2.3 Drivers of coastal change (source: (Agardy Alder, 2005)
2
Habitat Loss or Conversion Habitat Degradation Overexploitation
Coastal development (ports, Eutrophication from land- Directed take of low-value
urbanization, tourism-related based sources (agricultural species at high volumes
development, industrial sites) waste, sewage, fertilizers) exceeding sustainable levels
Destructive fisheries (dynamite, Pollution: toxics and Directed take for luxury
cyanide, bottom trawling) pathogens from land based markets (high value, low
sources volume) exceeding sustainable
Coastal deforestation (especially levels
mangrove deforestation) Pollution: dumping and dredge
spoils Incidental take or bycatch
Mining (coral, sand, minerals,
dredging) Pollution: shipping-related Directed take at commercial
scales decreasing availability of
Civil engineering works Salinization of estuaries due resources for subsistence and
to decreased freshwater inflow artisanal use
Environmental change brought
about by war and conflict Alien species invasions
Aquaculture-related habitat Climate change and sea level
conversion rise
29. Management and restoration of natural systems
Indeed, compared to other types (such as forests, drylands and mountains),
worldwide coastal ecosystems have been most impacted over the last century
by all of these drivers and current trends are increasing (MEA, 2005). In Table
2.3 a description of the major drivers of change on the delta ecosystems have
been indicated.
Loss of habitat can occur through a variety of causes, but the majority of
habitat loss in delta environments is the conversion of freshwater- and salt
marshes into agricultural land (for instance through land reclamation) and – in
the tropics – the conversion of mangroves into aquaculture. Worldwide decline
in mangrove forest is estimated to be around 2% per year between 1980 and
1990 and 1% per year between 1990 and 2000 (Lewis III, 2005). In the 18th
century the Sundarbans of Bangladesh (the largest single mangrove forest in
the world) was twice its present size, which was lost to agricultural lands of the
adjoining landlords (Chowdhury and Ahmed, 1994).
But also a more complex set of factors can lead to reductions in original delta
2 habitats. For instance, the combination of subsidence, incidental hurricanes
and the construction of levees and canals (for the oil exploration and navigation)
has led to massive reduction in Louisiana’s coastal wetlands. An area the size
of a football field disappears every 35 minutes (National Geographic News,
2005). Louisiana had already lost 1,900 square miles of coastal lands, primarily
marshes, from 1932 to 2000. 217 square miles of Louisiana’s coastal lands
were transformed to water after Hurricanes Katrina and Rita (USGS, 2006;
USGS reports on latest land change estimates for Louisiana coast; USGS News
Release, October 3, 2006).
Estuarine systems are among the most invaded ecosystems in the world. Often
introduced organisms change the structure of coastal habitat by physically
‘sea level rise is displacing native vegetation. For example, San Francisco Bay in California has
over 210 invasive species, with one new species established every 14 weeks
probably the most between 1961 and 1995. Most of these bio-invaders were brought in by ballast
water of large ships or occur as a result of fishing activities. (Agardy Alder,
important climate 2005)
change induced Of all potential impacts of a rising global temperature, sea level rise is probably
the most important for deltas. Combined with subsidence of the delta soils, sea
factor for deltas’ level rise can lead to a series of changes in the delta environment. It increases
coastal erosion, thereby threatening human settlements and enlarging the
30. risk of coastal flooding. But sea level rise also leads to landward movement
of the tidal influence and salt wedge in rivers, which jeopardizes freshwater
intakes for agricultural, industrial and domestic water supply systems.
That coastal erosion can also occur without a change of climate, is a well known
fact. It has everything to do with the sediment balance within a coastal cell,
which can be disrupted by natural and human-induced causes. A good example
of the latter is the increased erosion along the Nile Delta after the completion
of the Aswan High Dam (see Figure 2.1).
Compared with the past five decades, both river discharge and sediment
load will probably decrease for some large river systems with 30-40% in the
next 50 years and decrease up to 50% in the next 100 years as a result of
2
Figure 2.1: Coastal erosion Nile Delta: coastline changes in Egypt between 1935 and 1985
(from West Damietta to West Port Said)
31. Management and restoration of natural systems
human activities and dam construction. Thus general erosion in the coastal
zone, including estuaries, deltas and associated beach systems seems to be
inevitable (Agardy Alder, 2005).
What can we do about it?
The good news is that delta ecosystems can be relatively easily restored.
Because the delta environment is highly dynamic, delta nature has a
‘the good news remarkable adaptive and resilient capacity. In contrast to for instance tropical
rainforests which require centuries to reach a climax succession stage, delta
is that delta ecosystems such as salt marshes, mangroves and dunes develop quickly into
rich habitats once the environmental conditions are favourable.
ecosystems can be
All over the world we see restoration ideas turning into reality. Of course not
relatively easily every initiative is an immediate success. There is much trial and error. But the
most important thing is that people see the need to protect their environment
restored’ and to work with nature instead of against it. In this chapter a number of these
initiatives will be presented, some of them still in its early conceptual stage,
30 but others already worked out in practice. These best practices show the
importance of:
• Good knowledge of the basic physical and ecological processes;
• Early involvement of local stakeholders leading to a participatory planning
process;
• An integrated approach
We have selected experiences that illustrate different ways of combining
ecosystem functions for the benefit of society. In the next section we will show
how nature can help in protecting the coast, by soft and ecological engineering.
Then we present examples that demonstrate the benefit of safeguarding
the integrity of coastal ecosystems by restoring estuarine dynamics and
guaranteeing a minimum river flow. We proceed by presenting a showcase
in the ‘Room for Rivers’ philosophy and we conclude with examples of the
multiple use of wetlands.
32. 2.2 Natural coastal protection and wetland restoration
There is ample evidence that coastal protection can greatly benefit from a
resilience based approach. Many of the world’s coastlines are highly dynamic
by nature through the forces of winds, waves and currents. Hard engineering
structures have more often than not led to increased erosion, either on the
location itself, or at nearby, unprotected beaches. Instead, coastal practitioners
are increasingly applying soft engineering measures, such as beach and
foreshore sand nourishments. Modern modelling and surveying techniques
are used to optimise these nourishments, whereby the question is how to best
make use of the prevailing local physical conditions. A new approach of ‘super-
nourishments’ is currently being under study in the Netherlands (see Box 2.1).
Box 2.1
Rhine case: sand nourishment through pilot of Sand engine, suppletion strategy from
new Delta committee
31
Sand nourishment is the mechanical placement of sand in the nearshore zone to advance the shoreline
or to maintain the volume of sand in the littoral system. It is a soft protective and remedial measure
that leaves the coast in a more natural state than hard structures and preserves its recreational
value. The method is relatively cheap if the borrow area is not too far away (10 km) and the sediment
is placed at the seaward flank of the outer bar where the navigational depth is sufficient for hopper
dredgers. Three types of nourishments are distinguished: beach-, shoreface- and dune nourishments
(Van Rijn, 2008).
It should be noted that these kinds of measures need to be repeated every few years, because due to
wave and current forces, these nourishments will be gradually spread out to the onshore and offshore
direction. Typical lifetime of a normal shoreface nourishment is in the order of 5 years (Van Rijn,
2005). Therefore, also other alternative techniques of nourishments are being studied.
At this moment the potentials and risks of a ‘super-nourishment’ called ‘The Sand Engine’ in front
of the Dutch coast (shoreface) are being investigated. Although the current beach nourishments are
successful and effective for local coastline maintenance, such a super-nourishment could turn out to
be more efficient in serving more functions than safety alone. The idea is to apply an extra amount
of sand that would be redistributed by nature itself, thus stimulating natural dynamics of the coast,
increasing a bufferzone for future sea level rise and enlarging the coastal intertidal zone which is
beneficial for natural and recreational values alike.
33. Management and restoration of natural systems
Besides and in addition to these sand nourishments, also ecological
Ecological engineering is being practiced. From the notion that mangroves can provide
effective storm protection (see Box 2.2), there is increased attention to restore
engineering these coastal forests. Great potential exist to reverse the loss of mangrove
forests worldwide through the application of basic principles of ecological
approaches offer restoration using ecological engineering approaches. Mangrove restoration
can be successful, provided that the hydrological requirements be taken into
great potential account, which means that the best results are often gained at locations where
mangroves previously existed, such as abandoned) aquaculture ponds (Lewis
III, 2005; Stevenson et al., 1999; Samson Rollon, 2008).
32
Figure 2.2: Mangrove seedlings waiting for transplantation (Banda Aceh, Indonesia)
34. Box 2.2
Example of storm protection by mangroves
Since 1822, a total of 69 extreme cyclones landed on the Bangladesh coast of which 10 hit the
Sundarbans mangrove forest. However, a cyclone that lands on the Sundarbans causes less damage
compared to the likely damage caused the cyclone of equal magnitude lands on the central and
eastern part of the coast. Most of the cyclone damage is caused by the surge. For example, a cyclone
that landed on the Cox’s Bazar coast generated 4.3 m surge caused deaths of 11,069 people in 1985.
On the other hand, when a similar cyclone landed on the Sundarbans in 1988, the number of fatalities
was just half of the 1985 cyclone (MEA, 2005).
2.3 Integrity of ecosystems: biodiversity,
environmental flows
In our relentless effort to reshape our coastal environment for our own benefit, 33
we sometimes forget that everything has its price. Besides the profits we
gain, there are also losses to sustain. But instead of accepting these losses in
biodiversity and ecological functions, there are ways to restore the integrity
of ecosystems. This does not necessarily require a complete restructuring of
the original situation, but can also lead to a rejuvenation or improvement of
already modified ecosystems. A good example is the restoration of estuaries
by reconnecting them with rivers and sea without compromising the attained
high safety against flooding in the Rhine Delta of the Netherlands (Box 2.3).
Setting and
Ensuring the integrity of the linkages between delta and river often also requires
measures upstream. Developments in the river basin, such as deforestation, maintaining
irrigation and hydro-power generation dams all exert an influence on the
well-being of delta ecosystems. Sediment loads change, freshwater inflows environmental
often reduce and persistent pollutants accumulate. Recently new insight has
been gained with respect to the importance of freshwater inputs in coastal flow requirements
ecosystems. Seasonal changes in river flow can temporarily change the
‘normal’ condition of an estuary. Usually the estuarine ecosystems and their promotes the
species are adapted to this highly dynamic environment as long as these
seasonal variations remain within the average natural dynamics. Upstream integrity of
water diversions can permanently change this pattern with significant
consequences for the estuarine ecosystem. Establishing an environmental ecosystems
35. Management and restoration of natural systems
flow requirement is being considered as an important management measure
to guarantee the integrity of downstream ecosystems. An example of how this
is done is presented for the Yellow River Delta (see Box 2.4)
Box 2.3
Restoration of estuarine dynamics in the Rhine Delta, The Netherlands
The Southwestern delta has a long history of embankments. Embankments have a twofold effect.
Inside dike rings, active sedimentation is excluded and thus dike rings must be considered to be
completely sediment starved. Moreover, soil compaction, peat oxidation and drainage lead to self
perpetuating land subsidence. Increasing saline seepage is one of the side effects. Outside the dike
ring, in the estuaries, storm flood levels increase due to the decreased basin storage. The cumulative
effect of sediment starvation, land subsidence, sediment export and sea level rise is an enormous
historical sediment deficit, defined as the negative difference between land surface and Dutch
ordnance datum (NAP). The total deficit for the Dutch lowlands is estimated at 13.3 km3 (vd Meulen
et al., 2006). The sediment deficit for the delta area is illustrated in figure 2.3, comparing the land
34 surface in the delta anno 1000 and the land surface above sea level in the delta at present.
Figure 2.3: Comparison land surface above sea level delta anno 1000 and 2000
The reshaping of the formerly morphologically dynamic delta into a completely petrified landscape,
eliminating adaptiveness and resilience, indeed has its price! And the bad message is that there is
no way back. Morphodynamics cannot be reintroduced without jeopardizing safety against flooding.
History commits to continued and even increasing dependency on flood defenses.
36. As a consequence of the last great flood in 1953 the Dutch government decided to close off most
of the Delta estuaries, turning them into stagnant salt or freshwater lakes. Although safety from
flooding was greatly enhanced, it turned out that these new ecosystems did not develop satisfactory.
In the closed estuaries, shoreline erosion forms a threat for the remaining terrestrial and transitional
zones between the dike and water. In the remaining open estuaries, the Eastern and Western Scheldt,
the vulnerability of salt marshes to erosion also increased: in the Eastern Scheldt because of the
diminished tidal influence, and in the Western Scheldt because of dredging operations to maintain a
deep channel as shipping route to Antwerp.
ROTTERDAM
NIEUWE WATERWEG
HARINGVLIET
GREVELINGEN
HOLLANDSCH 35
DIEP
KRAMMER-VOLKERAK
OOSTERSCHELDE
ZOOMMEER
MIDDELBURG VEERSE MEER
BERGEN OP ZOOM
MARKIEZAATSMEER
VLISSINGEN
WESTERSCHELDE
TERNEUZEN
ANTWERPEN
BRUGGE
Figure 2.4: Summary of measures to restre estuarine dynamics
37. Management and restoration of natural systems
Besides these morphologically induced problems most waters also suffer from an impoverished
water quality. Many of the closed-off water bodies, like for instance brackish Lake Veere and saline
Lake Grevelingen, experience stratification and anoxia in deeper layers, mainly because of reduced
refreshment and long water residence times. The worst situation exists in the freshwater Lake
Krammer-Volkerak, where eutrophication processes caused by agricultural run-off lead to a very bad
water quality with extensive scums of blue green algae.
Some years ago, the provincial managing authorities have drafted a vision for the future, in which
the restoration of estuarine dynamics has a prominent place. Central to this vision is to partially
restore the tidal dynamics and/or to restore the link with the rivers, while maintaining the same level
of safety. This will start the water flowing again, which improves the natural turnover of nutrients
and production of shellfish, fish and birds without the nuisance of algal blooms. Each water body in
the Delta requires its own approach. Although the first sluice between Lake Veere and the Eastern
Scheldt has opened already back in 2004, it will take many years to complete the implementation of
this new vision.
36 Box 2.4
Yellow River Delta: environmental flow requirements to protect downstream water uses
Fresh water is of key importance for many economic activities in the Yellow River Delta. It is used as
drinking water, for growing crops, for industrial activities and for maintaining healthy ecosystems.
Of all consumers, the irrigated agriculture has the highest demand, which is not surprising because
of the high evaporation rate during most of the year. This evaporation surplus causes capillary rise of
the saline groundwater into the top soils, which has to be flushed with fresh water. Currently around
two third of the Delta area has moderate to serious salinity problems.
The most important source of freshwater is the Yellow River. But unfortunately, the Yellow River basin
is very deficient in water resources. The conflict between supply and demand is prominent. Especially
since 1992 annual discharges of the lower Yellow River reached dangerously low levels, leading to
frequent periods of zero discharges of more than 100 days per year. From 1995 to 1998, the river
was dry during more than 120 days every year, up to as much as 226 days at Lijin in 1997. This
regular drying up of the lower Yellow River had serious impacts on the downstream socio-economic
functions and caused large ecological damages in the delta. Therefore, the Yellow River Conservation
Commission (the basin wide administrative agency) has implemented a regulated discharge regime
of the river since 1999, in order to recover the river stretches downstream of Lijin (Liu Xiaoyan et al.,
2006). This relieved the risk of drying up and the water deficiency in the lower delta to some extent.
38. However, there is still a long way to go to the optimal allocation of water resources required by all
economic sectors and the ecosystems of the delta (Liu Gaohuan Drost, 1997; Liu Gaohuan, 2006).
Until recently, for the Yellow River, little was known about the exact water demand for ecological
system development of the delta and about the ecological effect and influences of allocation of
water. Especially, proper identification of the habitats demanding water in the delta was lacking,
as well as the amount of water needed to restore damaged wetland ecosystems and to maintain
sustainability of the delta ecology (see e.g. Guan Yuanxiu Liu Gaohuan, 2003). A recent study on
the water allocation for the two Nature Reserves in the lower Yellow River Delta revealed that the
total future water requirement that includes domestic, industrial, agricultural and restored wetland
demands is less than 10% of the annual average river discharge at Lijin. Although this suggests that
there is ample water, the situation could be different in the months of March, April and May. During
this low flow period the water demand is typically at its highest and critical situations (e.g. in dry
years) are not ruled out. This exemplifies the need for an optimization of water requirements through
daily water management (Lian Yu et al., 2007).
3
2.4 Room for rivers
For centuries rivers have been harnessed to make better use of them.
Normalisation and canalisation have straightened and narrowed naturally
meandering and braided river systems into a single channel system, benefiting
navigation for increasingly bigger ships. Embankments were raised to reduce
flooding frequencies of the adjacent lands, which became more and more
populated. Over the past decades the adverse consequences of these river ‘Room for rivers’:
engineering measures became apparent. Natural values have greatly declined
and river beds eroded, leading to undermining of sluices and bridges. Groynes a more resilient
and the narrowing of the floodplain impeded a rapid discharge of water and
ice, increasing the risk of flooding. As climate change could result in higher strategy for flood
peak discharges, river managers were confronted with the question to further
heighten the sea defenses or exploring other possibilities. The ‘Room for risk management
Rivers’ concept, giving back the areas of natural horizontal expansion during
floods through wideing of floodplains and creation of retention areas, was
born out of a belief that it is better to opt for a more resilient strategy than
to go for resistance against the forces of nature. The Rhine programme in the
Netherlands is a showcase for this new philosophy and supports the paradigm
shift from ‘fighting the floods’ to ‘living with water’.
39. Management and restoration of natural systems
Box 2.5
Rhine programme ‘Room for Rivers’
High discharges of the Rhine and Meuse Rivers in 1994 and 1995 have led to a significant shift
in dealing with safety against river floods in the Netherlands. The age old practice of raising and
strengthening of embankments along the rivers is replaced with a new approach, giving more room
to high waters. This so-called room for rivers policy contains a wide range of measures, such as
lowering of floodplains, creation of side channels, lowering of groynes, river dredging and realignment
of dikes. Dike strengthening has become a last option, if other interventions prove to be technically
or financially impossible. Most of these measures will have significant consequences on regional and
local spatial planning. This makes public participation in planning of flood management strategies
crucially important. It also calls for a more integrated planning, thereby combining safety objectives
with other policy goals, such as nature development, landscape quality improvement and economic
prosperity. The new management policy is now being implemented over the entire stretches of the
Dutch parts of Rhine and Meuse in a multi-billion Euro programme. Besides practical innovations
in river management, the programme is also innovative with respect to its planning approach of
3 ‘central direction and decentralised implementation’. This creates opportunities for innovative public
private partnerships, such as Design Construct agreements, in which planning and implementation
is dealt with through one contractor. This requires great adaptation skills from both contractor and
government agencies, and a path of trial and learning. The programme has to be finished in 2015.
Figure 2.5: River improvement measures in Room for Rivers concept
40. 2.5 Multiple use of wetlands
As coastal wetlands can perform different functions, this means that they do
not necessarily need to be protected by denying access. Local people often
have used these ecosystems for centuries and are eager to continue doing
so. But how can this use be allowed without compromising the integrity of
wetlands, without leading to overexploitation of the natural resource? This
problem can be tackled by using the ‘ecosystem approach’. This approach is
advocated by the Convention on Biological Diversity and denotes a strategy
for the integrated management of land, water and living resources that
promotes conservation and sustainable use in an equitable way. It is based
on the application of appropriate scientific methodologies focused on levels of
biological organization which encompass the essential processes, functions
and interactions among organisms and their environment. It recognizes that
humans, with their cultural diversity, are an integral component of ecosystems
(website Convention on Biological Diversity).
Below three examples are given of multiple use of wetlands. Box 2.6 illustrates Ecosystem
the values of Xuan Thuy Ramsar reserve in the Red River Delta, Vietnam. 3
Because of weak management these values are presently under great pressure. approach for a wise
The second example (Box 2.7) is considered as a world-renowned model for
multiple use of wetlands: the East Calcutta Wetlands. And the last example multiple use of
(Box 2.8) is the restoration of infertile, acid sulphate soils (a widespread
problem in several tropical deltas and coasts) by the replanting of the original wetlands
vegetation, such as the Melaleuca trees in the Mekong delta.
Box 2.6
Example of a multifunctional value Ramsar site
Xuan Thuy Natural Wetland Reserve. 20/09/88; Nam Ha; 12,000 ha; 20º10’N 106º20’E. Strict Nature
Reserve. Delta and estuary islands supporting the last significant remnants of coastal mangrove
and mudflat ecosystems in the Red River Delta; includes land enclosed by sea dikes, with fringing
marshes. A critically important area for migratory waterbirds and shorebirds, regularly supporting
several globally threatened species. Human uses include fishing and aquaculture yielding up to
10,300 tonnes per year, rice production yielding 40,000 tonnes per year, duck rearing, bird hunting,
and reed harvesting. The mangrove forest is of considerable importance in maintaining the fishery,
as a source of timber and fuelwood, and in protecting coastal settlements from the full impact of
typhoons. Ramsar site no. 409. Most recent RIS information: 1992.
41. Management and restoration of natural systems
Box 2.7
Example of a multiple use wetland: East Calcutta Wetlands. West Bengal (12,500 ha).
World-renowned as a model of a multiple use wetland, the site’s resource recovery systems, developed
by local people through the ages, have saved the city of Calcutta from the costs of constructing and
maintaining waste water treatment plants. The wetland forms an urban facility for treating the city’s
waste water and utilizing the treated water for pisciculture and agriculture, through the recovery of
nutrients in an efficient manner - the water flows through fish ponds covering about 4,000 ha, and the
ponds act as solar reactors and complete most of their bio-chemical reactions with the help of solar
energy. Thus the system is described as “one of the rare examples of environmental protection and
development management where a complex ecological process has been adopted by the local farmers
for mastering the resource recovery activities” (RIS). The wetland provides about 150 tons of fresh
vegetables daily, as well as some 10,500 tons of table fish per year, the latter providing livelihoods
for about 50,000 people directly and as many again indirectly. The fish ponds are mostly operated by
worker cooperatives, in some cases in legal associations and in others in cooperative groups whose
tenurial rights are under legal challenge. A potential threat is seen in recent unauthorized use of the
40 waste water outfall channels by industries which add metals to the canal sludge and threaten the
edible quality of the fish and vegetables. Ramsar site no. 1208. Most recent RIS information: 2002.
Box 2.8
Melaleuca wetlands for provision of ecosystem services in the Mekong delta
Currently about half of the Mekong Delta has acid sulphate soils, as a result of drainage of wetlands and
the expansion of aquaculture and canals. This severely limits the agricultural potential of the delta.
Recent research on ecosystem functioning has helped build understanding of how environmental
and economic benefits can be simultaneously achieved. In particular, research has demonstrated the
role of Melaleuca trees (Melaleuca cajuputi) in improving water quality, thereby lowering the acidity
of soil in surrounding fields. The relationship between depth of water in the Melaleuca wetland forest
reservoir and days of irrigation needed for good soil quality has been established. This discovery
makes it possible to use Melaleuca to lessen the acidity of affected soils and increase agricultural
production.
42. 3. Extension and revitalization of
infrastructure
3.1 Role of infrastructure in delta development
Living in deltas has always required human intervention. Infrastructure was
developed to adapt the natural systems to create more favourable conditions
for living and working in deltas. Traditionally the development and maintenance
of infrastructure has been the task or responsibility of governments. A
responsibility which is more and more shared with other parties through
public-private partnership.
41
43. Extension and revitalization of infrastructure
Demographic and economic development lead to a growth in the number of people and economic
activities to be served and protected. As a consequence demands on the infrastructure will grow. There
are also trends in society and governance to reckon with in the development of infrastructure, such as
environmental; concerns, privatization and decentralization. At the same time, the vulnerability of deltas
is increasing because of rising sea levels, subsiding soft soils, and increasing pressure on space and
environment. Dealing with all these developments together is a complex and challenging task. There are
basically two options to respond to the increase in vulnerability: (i) adapting land and water use or (ii)
adapting the infrastructure.
Box 3.1
Development of infrastructure in The Netherlands: a short history
The Dutch history of human intervention in deltas is a history of land reclamation and flood protection.
Huge areas of land were already reclaimed in the 17th and the 18th centuries, thanks to technological
and economic developments. At the end of this period, large water bodies had been transformed
into productive agricultural land, partly by reclaiming broad meres and lakes, partly by reclaiming
42 silted up land outside the dikes. Improvements in drainage techniques enhanced the quality of the
reclaimed ‘polder’ land (a polder is a low-lying tract of land enclosed by embankments known as
dikes, that forms an artificial hydrological entity).
The process of land reclamation was continued in the 19th and 20th century on an even larger
scale. The largest lake reclamation scheme of the 19th century was that of the Haarlemmermeer
(nowadays host to Schiphol international airport) in 1852, with a size of well over 18,000 hectares.
Land reclamation in the 20th century was concentrated in the Lake IJssel area (with four polders with
sizes of 20,000, 43,000, 48,000 and 54,000 hectares) . This lake was formed in the 1930’s after the
construction of the Closure dam (Afsluitdijk). The dam was build in response to a major flood in 1916
in the area of the former Zuiderzee.
Another serious storm surge in 1953 triggered the construction of the Delta works. The project included
the closure of all sea inlets, except for the Rotterdam Waterway (entrance to the Port of Rotterdam)
and the Western Scheldt (entrance to the Port of Antwerp). The Delta works together considerably
shortened the total length of the coastline and thus the length of the potentially vulnerable coastal
defenses. The plan for closure of the Eastern Scheldt, the largest sea inlet of all, was finally abandoned.
In stead, after a societal debate, a storm surge barrier was build to maintain the Eastern Scheldt’s
abundant marine flora and fauna, its rich tidal salt marshes and shellfish fisheries. The debate on the
Eastern Scheldt was a landmark in the Dutch history of delta development. For the first time the need
for safety against flooding was reconciled with environmental concerns.
44. This chapter will focus on extension and revitalization of infrastructure. It
will discuss how infrastructure is being developed to enable delta life. It will
be discussed how development of infrastructure may help to deal with the
ever increasing pressure on available space in deltas and how it may help to
secure future water supplies. Other important drivers for the development of
infrastructure are the sea-ward extension of ports and the growing interest for
the generation of renewable (hydro) energy.
Environmental concerns play an important role in the design and construction
of infrastructure. In fact these concerns have given rise to a shift in paradigm
from building against nature to ‘Building with Nature’. There is also a trend
towards more robust infrastructure in response to a growing risk aversion
in societies. Another observation is that a lot of infrastructure in deltas is
already present for decades or centuries. Rehabilitation of this infrastructure
will be a tall order for the (near) future. Technological development may
open new opportunities to enhance the functionality of infrastructural
solutions. Technological development may also help to extend the life time of
infrastructure and/or to develop more cost-effective designs and construction 43
methods of infrastructure. The perspectives of technological development are
discussed at the end of this chapter.
3.2 Infrastructure to support economic development
Dealing with pressure on available space
Population growth and economic development lead to an ever increasing
pressure on the available space in deltas. Basically there are two options
to deal with this pressure: enlarge the available space or combine different
functions of the available space. The first option: land reclamation was and
is a proven way to deal with this pressure: However, the increasing pressure
on the available space also drives a growing interest in the second option: the
multifunctional use of infrastructure.
Land reclamation
The Netherlands has a century old tradition in land reclamation. Several 1000
km2 of land have been reclaimed from the 17th till the middle of the 20th
century. The final polder that was reclaimed was Zuidelijk Flevoland in 1968
in the Lake IJssel area. The plans to reclaim one more polder in the Lake IJssel
area (the so-called Markerwaard) were abandoned because of budgetary and
45. Extension and revitalization of infrastructure
environmental reasons. Although the actual land reclamation came to a halt,
the concept of land reclamation kept its attraction. In the last few decades
various plans for land reclamation were developed, including an extension of
the coast in between Hoek van Holland and The Hague (Plan Waterman) and
an island in the North Sea to host a new airport, etc. None of these ideas,
however, have yet been implemented. Most recently the new Delta Committee
proposed a seaward extension of the coastline with about 1 km to promote
coastal development more or less as a ‘by-product’ of improving the protection
against coastal flooding.
While land reclamation ideas in the Netherlands did not go beyond the drawing-
board, land reclamation worldwide was a thriving business. The last decade
Land reclamation shows a number of prestigious land reclamation projects being completed.
These include the airport development in Hong Kong and the island resorts
is a well-proven developments along the coast of Dubai.
way to deal with Land reclamation has grown into a popular strategy in cases where the
44 pressure on the available space is high. The land reclamation examples of
increasing pressure Hong Kong and Dubai are large scale and technologically advanced. Their
implementation required large investments too. There are, however, also
on space other ways of reclaiming land. In the delta of the Ganges / Brahmaputra in
Bangladesh natural processes of river morphology are used to reclaim land on
a local scale. The high dynamics of the rivers support a relatively cheap way
of land reclamation. It compensates, however, only partly of the loss of land
due to erosion.
Multifunctional use of infrastructure.
A promising way to respond to the increasing pressure on space is through
Revitalization of multifunctional use of infrastructure. Revitalization of infrastructure opens
new opportunities for multifunctional use. Examples to be discussed later in this
infrastructure chapter include the transition of conventional embankments into super levees
in Japan and the rehabilitation of the Closure dam of Lake in The Netherlands.
opens opportunities
Multifunctional use of infrastructure may be especially promising for flood
for multifunctional protection works. Linking flood protection to other development issues such
as urban (re)development or nature development may be an attractive way
use to combine more immediate benefits of e.g. urban development with the long
term benefits of flood protection. As such it may contribute to secure the
necessary funds for improvement or maintenance of flood protection works.
46. Securing future water supplies
Due to climate change prolonged and more frequent periods of drought are
expected. At the same time water demands in deltas are increasing because of
population growth and economic development. As a consequence water shortages
will grow in magnitude and frequency, unless land and water use will be adapted
or future water supplies will be improved either by storage or transfer.
In many countries shortage of fresh water is viewed as one of the most serious
challenges in water resources management. Even in a country such as the Shortages of fresh
Netherlands, with generally an abundance of water, droughts occasionally
occur. Due to climate change water shortages are expected to become more water are a major
likely and counter measures are being considered. In fact the Delta committee
has proposed to raise the target water level of Lake IJssel with some 1.5 m to concern in delta
increase the amount of water being stored. The water from this lake provides a
source of water supply to other parts of the country in periods of drought. development
The expected increase in water shortages is a major trigger for adaptation worldwide
to climate change. However in some countries such as Spain, the drought 45
problems are so acute that emergency measures are taken.
Projects for improving the water supply may offer opportunities to realize
other objectives as well. An example of such multipurpose development is the
development of Marina Bay in Singapore, addressing flood protection, water
supply and recreation.
Box 3.2
Water shortages and adaptation to climate change (example from Spain)
The drought problem in Spain is treated rather separately from the adaptation to climate change,
despite the obvious and recognized link between the two. In general, drought is regarded as an
emergency issue and many ad-hoc actions are taken. This happens often on a short time scale, which
does not necessarily fit with the long-term adaptation to climate change. Many activities aim at
solving particular bottlenecks caused by drought, especially in the irrigated agriculture. Examples of
such measures are the implementation of interbasin transfers, a much disputed issue in Spain, as well
as the continuous inauguration of desalination plants, especially close to the major coastal cities such
as Barcelona. These kind of drought-driven activities are sometimes included in plans for adaptation
to climate change, but tend to be implemented independent as a kind of ‘no-regret’ measures.
