Deltares views nr 2 2009

SmartSoils® changing soil properties to order

Port expansion in the 21st century

The shape of things to come

magazine No. 2 2009

PO Box 1772600 MH DelftThe NetherlandsT +31 (0)88-DELTARES (335 82 73)[email protected]

Colophon

VIEWS is issued free of charge to all qualified subscribers and is published by Deltares.

Deltares is an independent research insti-tute for water, soil and subsurface issues. It has been established by Delft Hydraulics, GeoDelft, the Subsurface and Ground water unit of TNO and parts of Rijkswaterstaat. Throughout the world, more and more people are settling in opportunity-rich, but vulnerable, deltas, coastal areas and river basins. That vulnerability is being spot-lighted because of rising sea levels, extreme river levels, subsiding soil, and increasing pressure on space and the environment. Deltares develops knowledge for innovative solutions that make living in delta areas safe, clean and sustainable.

For more information: [email protected]

Text Direct Dutch Publications, The HagueDesign Teldesign, RotterdamLayout Sirene Ontwerpers, RotterdamPrint JB&A, WateringenPaper Printed on paper free of chlorineCover photo © Ewout Staartjes, Anna Jacoba polder, The Netherlands.

Our Common Delta

> page 4

Bacteria to replace piling SmartSoils®: changing soil properties to order

> page 19

Integrated coastal zone management in SurinameFrom mud bank to mangrove

> page 10

Maasvlakte 2: Port expansion in the 21st century

> page 14

The fundamental importance of morphological research to coastal and river management The shape of things to come

> page 6

Delta Alliance: a problem shared is a problem halved

> page 18

India: bare essentials of groundwater management

> page 22

NEWS

Delft-FEWS pilot in •

AustraliaUpgrade your knowledge•

Advanced laboratory •

research Fehmarn BeltDelft hosts first •

International Conference on Frontiers in Shallow Subsurface Technology

> page 24

PhDs

Trends in groundwater •

quality in relation to groundwater ageBridging Boundaries: •

Making scale choices in multi-actor policy analysis on water management Dune erosion during storm •

surgesSatellite data as •

complimentary information for hydrological modelling

> page 26

Dutch polders in Louisiana marshlands?

> page 13

CONTENTS

Our Common Delta

Three-dimensional view of river and delta deposits. The colours are as follows: red and

yellow - fine sands, blue – clayey deposits, and green - mixed deposits. Cooperative study

of the long-term development of linked river and delta areas, involving Deltares, TU Delft and

StatoilHydro.

Deltares VIEWS Nº 24 Deltares VIEWS Nº 2 5

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It is now more than twenty years

since the Brundlandt Commission

report Our Common Future (1987) put

the term sustainable development on

the map. Today, everyone is familiar

with the idea that a balance needs to

be struck and maintained between

economic growth, social needs, and

pressures on the natural environment.

PREFACE

“Morphology is just one of the many areas of physical knowledge in which Deltares is in its element“

However, in delta areas and coastal zones around the world, experience shows time and again that such a balance is difficult to achieve or maintain. How can we ensure the future of our common delta?

Creating a sustainable delta is a complex business. Safety is a sine qua non. But how can we effectively counter the threat of hurricanes, typhoons, earth-quakes, droughts, tidal waves and other mighty natural phenomena? How can we anticipate the effects of long-term processes like sea level rise or subsidence? And how can we subsequently reconcile safety standards with economic growth and a sound approach to the natural environment?

Developing a delta area in a sustainable way is partly a question of knowledge. Morphological knowledge, for example. We need to know the shape of the coast or river basin and how it changes as a result of processes like erosion, sedimentation, and the inter action between vegetation and benthic organisms. And, indeed, as a result of human intervention. As this issue reports, Deltares is working in close cooperation with vari-ous government organisations in the United States to develop fundamental morphological know ledge. The aim is to guarantee the safety of the coast and also, for example, to permit improved management of the fragile Colorado River system and so preserve a unique piece of the natural world. Each partner is con-tributing its own expertise; we are learning from each other and generating new knowledge and applications which can subsequently also be used back home in The Netherlands or elsewhere in the world.

We are engaged in similar processes in many different countries and in relation to a host of disciplines, from earth sciences to water quality management and from chemistry to ICT. Where morphology is concerned, Deltares is also involved, for example, in a Chinese research programme investigating the consequences of major modifications to the Yangtze River. Existing and new morphological knowledge plays an essential role in this project. Likewise, in Singapore, hydraulic engineering, ecology and morphology overlap in plans for the use of seagrass, coral and mangroves in coastal protection. And, closer to home, an understanding of the natural formative processes of the coast and dunes is a crucial element in a large-scale land creation project off the Dutch coast: economic growth is going hand in hand with nature compensation in the design and construction of Maasvlakte 2. This issue contains a major article on the project.

Morphology is just one of the many areas of physical knowledge in which Deltares is in its element. Expertise of this kind is helping in the worldwide development of a balanced – i.e. sustainable – future. While it is gener-ally used in combination with other types of knowledge relating to water, soil and subsurface, morphological knowledge is – as we see it – a fundamental prerequi-site for building the future of our common delta.

Huib de VriendDirector Science


Coastlines and river basins change shape all

the time. Sometimes the changes are sudden

and dramatic, resulting from extreme events like

hurricanes or tsunamis. More often, they are

the gradual result of complex processes of erosion

and sedimentation. We still know relatively little

about morphological processes but advanced computer modelling is providing

new insights.

The fundamental importance of morphological research to coastal and river management

The shape of things to come

USA and Indonesia

Dano Roelvink is putting a lot of time into the develop-ment of XBeach, a new model designed to calculate storm impacts like dune erosion, overwashing and breaching of sandy coasts. ;“To approximate to the complexity of a coastal system, you have to include all the relevant physical parameters in your model. That’s what we can do and we’re working hard on it. XBeach is one of the latest-generation models, which are able to replicate a variable coast, differing storm conditions and combinations of hard and soft coastal elements. It was initially developed by UNESCO-IHE, Delft University of Technology, the University of Miami and Deltares, on the initiative of the US Army Corps of Engineers. Because it’s an open source application in the public domain, a multitude of partners are now working on it, including the USGS, so we should ideally end up with a universally – or, at any rate, widely – applicable coastal model. The more input we get the better.”

XBeach

In 2005, Deltares researcher Deepak Vatvani travelled to Indonesia to produce a computer model capturing the origins, development and impact of the tsunami that devastated the coast of Sumatra in the closing days of 2004. The model he made not only forms the basis of a Tsunami Early Warning System (see box on page 8), but also provides new information about the relationship between tsunamis and coastal morphology. And that is extremely welcome.

Process of change”We used Delft3D software to model the origins and development of the tsunami”, Vatvani explains. “We show how the tidal waves changed the coast and where the coast is now vulnerable to future inundation. This information provides a crucial basis for the design of new coastal defences and future evacuation routes.”The coastline of Aceh province was dramatically altered by the 2004 tsunami. New areas of land have emerged from the sea, while others have vanished under the waves. The tsunami may seem like a single one-off event but, as Vatvani explains, it is actually part of a continuing process of change. “Underneath the Indian Ocean, two continental plates are sliding over each other. The friction produces earthquakes and water motions. Various studies have shown that a tsunami like the one in 2004 occurs once in every five hundred to a thousand years. So the morphology of the coastline, including the processes of erosion and sedimentation occurring along it, likewise under-goes dramatic change at those intervals. And that has knock-on effects on the development of the coast over the next few centuries. If we want to manage the coast in a sensible, sustainable way, it’s important to get a better understanding of such long-term processes. And that’s what we’ve started to do.”

Getting to the root of the problemWorldwide, little is known about the influence either of extreme events or of longer-term processes of erosion and sedimentation on coastal morphology. This is why

so much research is being conducted on coastal mor-phology in countries like the US. Deltares researcher Dano Roelvink, Professor of Coastal Engineering and Port Development at UNESCO-IHE, talked to us about cooperation with the US Geological Survey (USGS).“We are cooperating with the USGS on modelling hydrodynamics, sediment transport and morphology in various coastal areas. In general, the USGS possess-es the necessary data – often in impressive amounts – while Deltares can offer the modelling software and expertise. In tidal inlets along the west coast, for ex-ample, there is a problem with the migration of gullies and sandbanks, which causes parts of the coastline to erode. Rather than build endless hard coastal defences, the USGS prefers to get to the root of the problem and look for an appropriate solution. In Florida we’re busy charting hurricane impacts. Whatever the approach, >>>

top: Colorado River, USA • bottom left: Deltares researcher Dr Kees Sloff • bottom right: Disappearing beaches


you need extensive knowledge of the coastal system to arrive at an appropriate solution. We’re making big ad-vances in the modelling of morphological processes.”

Fresh airRoelvink finds the vast quantity of local data pos-sessed by the USGS a breath of fresh air. “We have a lot to offer each other. Our modelling tools enable the USGS to get a better understanding of the US coast, while their research teaches us more about phenome-na we also face in The Netherlands. For example, we are keen to know what sort of damage would be inflicted on our coastal dunes by a storm likely to occur on the Dutch coast on average once in every ten thousand years. Well, the USGS studies the hurricanes that hit the American coast every year and they have the same sort of magnitude and impact.”At the same time, USGS data and research benefit model development in general. “The many different kinds of monitoring data they collect help to validate the mod-els. The better a model can replicate the natural sys-tem, the better we can anticipate long-term processes

data at the invitation of the USGS. It was a memora-ble trip. “Imagine sailing into the Grand Canyon on rafts loaded with monitoring apparatus and spending a week bivouacking there with geographers, environ-mental experts and water management experts. It was a real adventure.”But why were they there? In the mid-sixties, the Glen Canyon dam was built upstream of the Grand Canyon. The dam halted the supply of sediment from the Colorado River. Not just that, but the hydroelectric power plant at the foot of the dam reduced the natural flow of water. Since then, the river in the Grand Canyon has received sediment only from minor tributaries. “The process by which sandbanks and beaches in the canyon were washed away by peak discharges and then laid down again, was lost”, says Sloff, “and what’s left of them is now disappearing.” The small sandy beaches play a crucial role in the natural ecosystem: they provide a habitat for specific species of flora and offer quiet places for young fish to grow. They are also vital to campers and rafters making their way through the Canyon. “In 1996 a controlled surge was sent down this stretch of the river. The idea was to stir up the bottom sediments delivered by the tributaries at just the right moment to trigger the desired process. The measure was repeated in 2004 and 2008.”

ResearchThe key question is what strategy will produce the best results. Would it help to open the sluices? And, if so, when and for how long? The extensive monitoring campaign was intended to answer such questions. “We spent a whole week taking detailed measurements of everything from bed topography to flow rate”, says Sloff. “The USGS collected a huge quantity of data to enable it to determine how the system works and what processes are involved.” But the USGS wants more than just monitoring data. Modelling information is an impor-tant tool for the development of a sophisticated water management strategy. “We are helping them model all the processes that determine how sand enters and exits the canyon. From the very local interaction between a rapid and the pool behind it right through to the entire water flow.” Once again, both sides are learning from the exercise. “Absolutely. Here in The Netherlands, we encounter similar small-scale interactions, for example in groyne fields along the major rivers. Greater knowl-edge of this phenomenon is extremely welcome. And this is high-quality research: the wealth of monitoring data, the research on the best possible way of modelling morphological processes… it’s cutting edge stuff.”

For more information: [email protected],[email protected], [email protected]

Tsunami Early Warning System

system will compare its strength and location with the model situ-ation and the expected impact scenario will appear on the screen in seconds. At the places along the coast where the threat is greatest, sirens will start to sound.”

Panic avoidanceThe new insights into the con-sequences of tsunamis make it possible to conduct a proper risk analysis. For instance, the new TEWS shows that no evacuation will be necessary in the case of an earthquake measuring 7 on the moment magnitude scale. (Seismologists believe that the December 2004 earthquake had a magnitude of 9.1 on that scale, although tsunami experts think it was 9.3.) “It means that, in a real-life emergency, efforts can be

focused on the areas genuinely at risk. The response time is short; people have less than twenty minutes to get out.” All the better, then, if efforts can be concentrat-ed where they are most needed. Vatvani says that, not long after the tsunami of 2004, there was an under-sea quake with a magni-tude (Mw) of 8.7. The alarm was sounded throughout the entire region and a million people were evacuated. “But if you’re in a ‘wet feet zone’, where the water won’t get deeper than 30 cm, there’s no need to flee. With the ‘Dutch’ TEWS installed, the authorities could have sent out differentiated warnings and avoided panic and disruption.”

Deepak Vatvani sits at his laptop and runs a simulation of the tsunami. The tidal wave spreads out over the ocean like spilled wine soaking into a tablecloth. Arriving at the coast of Aceh, it continues its unrelenting course, reaching several kilometres inland.“Following the disaster, various government projects were launched in the Netherlands”, Vatvani explains. Together with two partners, Deltares set up the Sea Defence Consultant consor-tium (SDC). In consultation with

BRR, the Aceh-Nias Rehabilitation and Reconstruction Agency, we set to work on a reconstruction of the tsunami.”Deltares modelled the development of the wave following the earthquake and produced a simulation of the inundation of Banda Aceh, the capital of Aceh province. “Comparison with satel-lite images shows that the simula-tion results approximate closely to what actually happened.”

CouplingHow great is the risk of such a

thing occurring again? And what would be the consequences if it did? Vatvani: “We know very little about tsunamis. To help us make better estimates of the risks associated with them, we’ve collected together and further ex-panded all the model calculations we made for the reconstruction.” An existing early warning system shows whether an earthquake will result in a tsunami. But it doesn’t say how high the tidal wave will be and which particular areas will be engulfed. That gap has been filled by coupling the database con-structed by Vatvani to the early warning system. “The crux of the new Tsunami Early Warning System (TEWS) is the coupling of earthquake-related data to a water motion model. If another earthquake occurs, the

At 7.01 a.m. on 26 December 2004, an earthquake occurred beneath the bed of the Indian Ocean. Twenty minutes later, a layer of water five metres high reached the Indonesian province of Aceh, situated at the western tip of the island of Sumatra. The ocean receded temporarily and then rushed back to swamp the coast under a tidal wave ten metres high. The tsunami claimed the lives of almost 200,000 people in Aceh.

like sea level rise or, indeed, the consequences of hu-man interventions like major hydraulic engineering works or sand nourishment off-shore or in a gulley.

Because we are only now starting to realise the range of potential impacts of sand nourishment, on every-thing from flora and fauna right through to the safety of bathing water. Scientific progress benefits us all.”

Colorado RiverThis fruitful partnership is not confined to coastal mat-ters. In March 2008, Deltares researcher Kees Sloff sailed down the Colorado River collecting monitoring

“If we want to manage the coast in a sensible, sustainable way, it’s important to get a better understanding of such long-term processes”

>>>

Post-Katrina aerial photograph of Dauphin Island, Alabama, USASource: USGS/NASA


The flat coast of Suriname is a succession of mud banks,

mangrove swamps and narrow beaches that stretches from the

Corantijn River in the west to the Marowijne River in the east.

Large sections are still pristine, but the coast is under attack.

Human activities threaten its natural morphodynamic processes.

It is vital to strike a balance between economic and ecological interests and find a way of rhyming coast-al protection with coastal development. With this in mind, the Ministry of Planning and Development Cooperation has commissioned the preparation of an Integrated Coastal Zone Management Plan (ICZMP).

A consortium of local and international experts is involved in the project, which is headed by Lievense Consulting Engineers. Deltares consultant Marcel Marchand is largely responsible for the preparation of a plan for the entire coastal zone, while another ICZM consultant, Tom Bucx, is focusing on a sub-plan for the densely populated districts of Paramaribo and Wanica. They are working hand in hand with a team of ex-perts in ecology, morphodynamics and morphology, social economics, and urban development. Colleague Paul Erftemeijer is concerned primarily with the im-portance and regeneration of the mangrove swamps, while Han Winterwerp is advising on morphodynam-ics. Their participation is hardly surprising: Deltares has been involved in coastal research in Suriname ever since the 1960s, when the Waterloopkundig Labora-torium (later known as Delft Hydraulics and now part of Deltares) conducted research on the offshore mud

banks. “The Surinamese and Dutch coasts have more in common than you might think”, explains Marcel Marchand. “Both are low-lying, at high risk of inunda-tion, and highly dynamic: in other words, both coast-lines are naturally extremely mobile. Deltares has a lot of in-house expertise concerning low-lying coastal zones and their problems.” [See box on page 12]

IntegrationUnder The Netherlands Climate Assistance Programme (NCAP), research was done in the late ’90s on the vulnerability of Suriname and possible consequences of climate change for the country. Follow-up studies were performed between 2005 and 2008. The NCAP recommended the development of integrated coastal zone policies and also the production of a Master Plan for the Drainage of Greater Paramaribo. This plan was produced in 2002 with the assistance of what was then Delft Hydraulics. The NCAP I and II reports are being used as input to the present ICZMP. So what is the added value of the ICZMP? Tom Bucx: “The measures proposed in the earlier reports were frequently global in nature; we are firming them up in order to arrive at an adaptation strategy.” Since it is extremely important to involve all the stakeholders in the development of the

Integrated coastal zone management in Suriname

From mud bank to mangrove

Suriname

plan, part of the job is to conduct a stakeholder analy-sis. As Bucx explains, representatives of ministries, knowledge institutions and civil society organisations have provided input during interviews and workshops. “We are using their input to check and supplement

our own findings and to help pinpoint priorities. At the same time, involving stakeholders ensures public sup-port for the plan.”

ComplexThe unique thing about this project is its scope. Marchand: “This is the first time that all the issues to do with living and working in the coastal zone are being dealt with together. Earlier studies just looked

at a particular section of the coast or at particular issues, like coastal development or the protection of mangrove swamps, taken in isolation. But it’s better to consider such issues in relation to each other. Things like spatial planning and flooding, for instance. And that’s what we’re doing now.” Given such a broad subject area, it’s hardly a sinecure. As Marchand points out, “Just defining the problem is difficult: for instance, where do you place the limits of the coastal zone?” And there are factors in each of the various districts that complicate the preparation and implementation of an ICZMP. Marchand cites examples like over-fishing and the upstream gold mining that leads, via the rivers, to mercury pollution on the coast. A total of 25 issues are vital enough to require fur-ther investigation. Marchand: “It isn’t easy to ensure that the plan does justice to all these aspects. But it’s important to mention them all, including the gaps in current knowledge.”

Master plan The ICZMP will pay special attention to the districts of Paramaribo and Wanica. That is where the problems are most pressing, particularly in relation to popula-tion. Two-thirds of the country’s population live in

“This is the first time that all the issues to do with living and working in the coastal zone are being dealt with together”

Transport by boat in Suriname

>>>


those areas and coastal development is sometimes too close to the sea. Where mangrove forests have been cleared, the risk of coastal erosion increases. Recommendations will therefore include the estab-lishment of a natural buffer zone several kilometres wide. “Some people won’t like it”, Bucx admits, “but it’s a cheaper, more sustainable and more ecological solution than measures like dike-building, especially in the long term. This way we can plan for balanced economic development while preserving ecological values. Which is what the government of Suriname asked for.” Another part of the solution is further implementation of the Master Plan for the Drainage of Greater Paramaribo (in particular, catch-up mainte-nance of the drainage system). There are also plans to construct new pumping stations and build a ring dam and canal. Such measures should end the frequent flooding that afflicts the capital.

Long-term processThe sub-plan for Paramaribo and Wanica is almost finished and the entire ICMZP should be complete by

early 2010. Marchand thinks this is a step in the right direction but “Integrated coastal zone management is not a project; it’s a process that takes years. This is just one part of that process.”There will soon be a framework document to provide guidelines for further development. “Suriname still has a lot of land available and that means that there is scope to choose between alternative approaches. Dikes are one possibility, of course, but a buffer zone is also an option. An even better one is making use of natural processes to ‘build with nature’. Government recognises the importance of this but it takes time to get round to implementing plans in practice. In twenty years’ time, Suriname may be a textbook example of balanced coastal zone management.”

For more information: [email protected] or [email protected]

Suriname is a South-American country wedged between French Guiana, Guyana and Brazil. Its coast is extremely dynamic. Sediments from the Amazon form offshore mud banks that stretch for tens of kilometres and migrate at a speed of around 1.5 km a year. These fluid mud layers damp out wave energy and produce temporary coastal accretion. Between the mud banks, however, there is a risk of coastal erosion and inundation. Accretion and erosion occur in approximately 30-year cycles. House-building close to the coast is not advisable. Human activities are increasing the risk of coastal erosion, especially in the densely populated districts of Paramaribo and Wanica. Mangrove swamps are a natural form of coastal defence but urban development is nibbling away at this buffer. Wherever the sediment-retaining mangroves disappear, coastal erosion increases. In the longer term, moreover, Suriname faces the risk of inundation as a result of rising sea levels.

Vulnerable coast

“Integrated coastal zone management is not a project; it’s a process that takes years”

Set in the Mississippi Delta, New Orleans is a vulnerable city in a sensitive environment. Human interventions, including the building of flood control structures along the river, have produced subsidence and erosion in the surrounding marsh-lands. Vegetation is disappearing and unique wildlife areas are being lost, together with an important buffer against storm surges. The tide needs to be turned, but how?

Dutch polders in Louisiana marshlands?

“For example, by restoring the marshlands south-west of the city.” Deltares ecologist Bregje van Wesenbeeck is involved in planning sustainable coastal flood defences for New Orleans. In the wake of the hurricane Katrina flood disas-ter of 2005, various Dutch water experts offered their help. “Our Dutch experience with integrating natural processes and materials into hydraulic engineering projects and coastal flood defences can pro-vide a solution in this situation. We call it ‘building with nature’.”

Worrying The Mississippi flows through typi-cal delta landscape. From freshwa-ter to salt. From swamp woodlands full of vast trees to grassy wetlands nearer the coast. “The marshes are in a poor state”, says Bregje. “Innu-merable little drainage canals, peat compaction and lack of sedimenta-

tion are leading to a rapid diminu-tion of the wetland area. This is worrying because large stretches of wooded swamps have the ability to absorb a lot of storm surge water. Besides, they are enormously valu-able wildlife areas with an impor-tant role in the area’s culture and history.”

ImpolderingNational government is taking measures to combat the subsid-ence. One is to re-open the swamps to sediment-rich river water. “The ideal would be to restore the natu-ral dynamics of the marshlands. We decided that temporarily im-poldering areas of open water would give the swamps a chance to develop in the most natural pos-sible way. Sophisticated control of water levels can be used to encour-age the growth of marshland veg-etation. Depending on the type of

swamp, peat is formed or sediment is retained so that the polder area is naturally restored to its old level, equal to that of its surroundings.”

BufferOnce a healthy swamp has devel-oped in the subsidence-affected areas, the link with the surround-ing marshland can gradually be restored by removing the dikes. A healthy wetland zone of suffi-cient size will eventually be able to sustain itself and act as a buffer against storm surges. “Healthy natural surroundings make the city less vulnerable”, says Bregje, “and the nice thing is that nature will do most of the work for itself.”

For more information: bregje.vanwesenbeeck @deltares.nl

>>>

Mangrove swamps

left: Louisiana

marshlands

right: Field trip by the research

team


With an annual throughput of around 400 million

tonnes, the Port of Rotterdam is one of the biggest

seaports in the world. This is partly thanks to the

Maasvlakte, a major new port area created in the

1960s on land reclaimed from the sea. Even so, the

10,000-hectare port complex is now bursting at the

seams. To accommodate industry and the container traffic of the future, it is

once again being expanded seawards.

The first phase of the new 2,000-hectare deep-water port area is to be completed by 2013. The new facilities will be built on sand extracted from the sea floor. But the Maasvlakte 2 development project is about more than just land reclamation. It involves questions like how to compensate for the impact of sand extraction on local marine life, what consequences the extra port activities and industry will have for the environment, and how to protect newly reclaimed land against storm damage. Maasvlakte 2 is based on innovative know-how and a multifaceted knowledge of the Dutch Delta.

Sea defences This year has seen the start of construction work by PUMA, a joint venture between Dutch hydraulic engi-neering contractors Boskalis and Van Oord. PUMA has been contracted by the Port of Rotterdam Authority to be responsible for the design, construction and main-tenance of Maasvlakte 2.Marcel van Gent, Deltares’ project manager for sea defences, says that PUMA’s design for the hard sea defences has been extensively tested in Deltares’ wave facilities and elsewhere. PUMA has used the results of the scale model testing to optimise and verify its design. The Design, Construct & Maintenance contract has given the consortium about three years to explore possible improvements and ensure maximum effec-tiveness. The result of its efforts is a highly innovative and sophisticated design. As Van Gent explains, the sea defences are to com-prise a number of different elements: an approximately 7-kilometre stretch of sandy coast (beach and dunes) will be succeeded in the north by several kilometres of sea defences involving the use of quarry stones (cobble size) and concrete blocks. “This combination is unusual”, Van Gent explains. “Cobbles have never before been used in The Netherlands in sea defences on this scale. The idea was inspired by natural shin-gle beaches and PUMA has developed it further for use in Maasvlakte 2. Dutch sea defences normally consist of concrete blocks, rock slopes or placed-block

revetments. The cobble shore has been developed and selected by PUMA because of the lowest total cost of ownership. Of course, cobble shores are dynamic during both year-round and design storm conditions. As such, PUMA’s design and maintenance plan includes buffers to accommodate the predicted loss. For the parts that contain concrete blocks, these blocks are being recy-cled from the previous Maasvlakte sea defence. “That’s environmentally friendly and also cost-effective.”

Scale modelDeltares has been commissioned by PUMA to test and analyse a number of design optimisations for certain sections of the hard sea defence. Van Gent: “We are conducting series of tests in scale models in facilities like our Scheldt flume and Delta flume, where we can generate large waves. The sea defence must be able to withstand a superstorm expected to occur on average once in every ten thousand years. That’s the standard for all primary sea defences along the Holland coast. So we’re simulating a range of storm conditions, with various wave heights and lengths.” In the 230-metre-long Delta flume, this can even be done without major scale effects: the waves are up to 1.5 metres high with some even reaching 2.5 metres. “In addition, we are advising on certain aspects of construction and main-tenance and providing an independent second opinion when required.”

Building with nature Once in use, Maasvlakte 2 will attract more industrial activity, increased shipping and more goods traffic. Atmospheric emissions of nitrogen oxides (NOx) are expected to increase. Adverse effects are to be compen-sated by creating a 35-hectare area of naturally devel-oping dune habitats. Bert van der Valk, senior advisor with Deltares, and his colleague Frank van der Meulen, have advised The Netherlands Ministry of Transport, Public Works and Water Management on how this new dune landscape can best be designed in relation to coastal geology, coastal engineering, long-term drift

The Netherlands

>>>

Maasvlakte 2:

Port expansion in the 21st century

Testing the scale model in the Delta Flume

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(morphology) effects and ecological development. The creation of the dune area, like that of Maasvlakte 2 itself, is part of the Project Main Port Development Rotterdam (PMR), the purpose of which is to enlarge the port of Rotterdam and improve the quality of life in the Rijnmond region.“The intended result – which will only be apparent in ten to twenty years’ time – is to be achieved through a combination of engineering and natural dune forma-tion. The aim is to create a new range of dunes and a wet dune slack. That’s a place where groundwater can come to the surface in the winter and freshwater ponds will develop between the newly engineered dune and the old foredune.” Sand drifting up against the old fore-dune will eventually form ‘grey’ dunes (dunes covered mainly with grasses, herbaceous plants and mosses, which provide a unique habitat and are regarded in Europe as extremely valuable). Like the new port area, the new Delfland dunes will be the result of the hydraulic fill method of construction. However, as Van der Valk explains, the top metre is to be created by natural processes. “This is a new feature of dune design in The Netherlands. The sand is pre-selected dredge material from the sea but the seeds and spores have to find their own way to the dune. In other words, a proportion of the construction work is left to natural forces to get a varied and more valuable ecosystem. Using this idea in such a large and prestig-ious project is a revolutionary step.”

Data assimilationThe construction of Maasvlakte 2 will require the extraction of 210 million m³ of sand in the North Sea. The question is whether this operation will cause a local temporary increase in the turbidity of sea water with consequent environmental disturbance. The Port of Rotterdam Authority has asked Deltares and the Vrije Universiteit Amsterdam’s Institute for Environmental Studies (VU-IVM) to contribute to the monitoring of the impact of sand extraction on sediment transport. “The study will combine model calculations and satellite observations”, says Deltares project manager Meinte

Blaas. “To my knowledge, it’s the first time that data assimilation techniques have been used to monitor sediment transport. Data assimilation means that monitoring data – at this stage mostly remote sens-ing data – are combined with the computer model to achieve a closer approximation to reality. Similar techniques are already being used in the fields of meteorology and oceanography.”

Promising Satellite images of the water surface provide up-to-date information but don’t reveal what is going on beneath the surface, at night and in cloudy weather. Model information can be used to bridge these gaps. Blaas explains: “We use the satellite images to correct the sediment transport model and generate a physi-cally consistent picture of the situation, either now or in the past. Currently, we are determining the refer-ence conditions, from 2003 to 2008, and in the coming years we plan to model the situation including the dis-turbance caused by the construction works from 2009 to 2013.” This reconstruction of the long-term situa-tion will make it possible to identify trends and help the Port of Rotterdam Authority to assess the impact of the sand extraction on the local environment. The Port of Rotterdam Authority is also doing its own maritime monitoring of sediment and related factors

using a purpose-made monitoring framework. “These measurements are needed, for example, to calibrate and validate the results of the computer model.”The data assimilation relies on proper interpretation

of the satellite images. Blaas confirms this: “IVM is highly skilled at analysing the satellite signals and deducing the different components – sediment, algae and dissolved organic material – from the colour of the water. The combination of satellite observations of sea water colour and water quality models, supplemented by periodic on-the-spot monitoring is extremely prom-ising, partly because it can also be used to detect and model other substances. For example, there is a great worldwide need both for accurate real-time information on algal blooms and for ways of predicting them.”

For more information: [email protected], [email protected]

The construction of Maasvlakte 2 will result in the loss of an area of shallow marine habitat. To compensate, an area of around 25,000 hectares in the Voordelta – a protected nature reserve off the south-west coast of the Netherlands – has been designated as a ‘sea floor protection area’.

Basically, the designation means that certain activities in the tourism sector and methods of fishing that disturb the sea floor are restricted or banned. The Ministry of Transport, Public Works and Water Management has commissioned Deltares to monitor and analyse the situation to see whether ecological quality in the area is improving according to plan.

“Our role in the process is primarily that of knowl-edge broker”, says Meinte Blaas. “We have asked a six-party consortium headed by IMARES (the independent Institute for Marine Resources & Eco-system Studies in Wageningen) and environmental consultants CSO to do the monitoring and help us interpret the results. The job includes a host of

activities, from studying bird numbers and behav-iour to modelling and measuring physical process-es and parameters like water motion, temperature and salinity. But the consortium is also monitoring human use impacts.” The plethora of data has to be forged into a consistent whole that can be used to identify trends and interrelationships. “It’s important that the work is based on a sound monitoring strategy and that data will be integrat-ed in a scientific way. That’s where we come in.”

Deltares has also advised on drawing up a ‘Moni-toring and Evaluation Plan’ (MEP) both for the new dune area and for the area expected to be affected by NOx emissions. Bert van der Valk: “We need to know, for example, whether the dune morphology is developing in the expected way over the next few years and whether the water table is high enough. We think we’re establishing the right conditions for nature development but if we’ve got it wrong, we’ll be able to intervene without delay.”


Monitoring: will ‘nature compensation’ work?

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“To my knowledge, it’s the first time that data assimilation tech-niques have been used to monitor sediment transport”

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Bacteria to replace piling

SmartSoils®: changing soil properties to order

Delta Alliance:

a problem shared is a problem halved

Landscapes, peoples and cultures may differ, but delta-dwellers around the world face the same problem: how to strengthen these vulnerable areas. There is no com-mon blueprint for deltas worldwide. But the consequences of climate change, as well as demands for food, safety, space and economic viability have to be faced. The in-terests of the human population have to be reconciled with those of nature. Everywhere, then, difficult choices have to be made; every-where, a balance has to be struck to keep life in the delta safe and productive. Decisions and meas-ures need to have a firm knowl-edge basis. Delta populations can help each other by formulating

priorities, encouraging research, exchanging experience and sharing knowledge. By working together to address common problems they can produce solutions helpful to more deltas than just their own.

International networkFollowing the Aquaterra Forum on Delta & Coastal Development, held in Amsterdam in 2009, a number of Dutch organisations have de-cided to establish an international knowledge platform and partner-ship. This Delta Alliance is due to go into official operation in 2010. It aims eventually to expand into an international network of delta-based partners able to work to-gether in a coordinated way to

focus attention on the integrated, sustainable development of delta areas. The main emphasis will be on integrated water and coastal management, food supplies, urban development, spatial planning and climate change. The Delta Alliance intends to encourage international exchanges and the development of relevant science and technology, while at the same time stimulat-ing and supporting the application of these in policy and administra-tion. The network will therefore include not only universities and other knowledge institutions, but also government authorities, engi-neering companies, consultancies, NGOs and civil society groups.

The basis for the Delta Alliance has now been established. Partners in four key deltas in the Netherlands, Indonesia, Vietnam and the US (organised in Chambers) are now busy formulating their views on Alliance activities and possible research projects. The partners will be expected to make an active contribution to the network’s finances and activities, possibly to be matched from international sources.

For more information, please contact the Delta Alliance Project Officers:[email protected] or [email protected] or visit: www.delta-alliance.org

The Mekong Delta and San Francisco Bay are around 12,000 km apart. Similarly, the distance between the Rhine estuary in The Netherlands and the mouth of the Ciliwung on Java (Indonesia) is over 11,000 km. And yet these places are closely related: wherever great rivers approach the sea, they create fertile, densely populated deltas.

Delta soils are frequently composed of relatively

young geological materials like sand, clay and

peat. Since these materials are soft and damp,

they are far from ideal building ground.

Road and railway subsidence is a constant

danger and dikes weakened by piping can

suddenly collapse. Over the last decade, Deltares has been working with

national and international partners to develop innovative, sustainable

techniques for modifying the properties of soil: SmartSoils.

Europe

BioSealing and BioGrout are two promising applica-tions in which bacteria play a leading role. ‘Fed’ the right dose of nutrients, they can seal leaky dikes or strengthen soil – on site, with no onerous earthmoving operations. The idea of getting bacteria to do the heavy work has not come out of the blue. In the environmental geo-technology field, bacteria have long been used to clean up contaminated soils. This made Deltares researchers wonder whether they could also be used to strengthen soils or make them less permeable. This would make it possible to build in places where soft or unpredictable subsoils currently prevent it. Or to carry out remediation work without disturbance (for example, under existing buildings or infrastructure).

Biosealing: making soil watertight

It was leaks occurring in the course of projects like the construction of a tram tunnel in The Hague that prompted Dutch research into the repair and preven-tion of leaks in underground water-retaining structures like sheetpile walls. Deltares researcher John Lambert

remembers how the research was begun by Deltares, Delft University of Technology and building contractor Visser en Smit Bouw in 1999. “The idea came up of using naturally occurring soil bacteria to look for and repair leaks. Given the right kind and amount of nutri-ents, they multiply and produce deposits around the leak. Lab work showed that BioSealing was an effective system. We experimented with different materials and rates of flow. It was a process of trial and error. With few errors, because in every case the result was to stop the leak. So we could soon start scaling up the tests.”

From lab to fieldBioSealing is now a fully tried and tested procedure. In 2004 a successful pilot was run on the Maasvlakte (Netherlands) and this led to a patent application. Lambert: “On the Maasvlakte, we buried three leak-ing shipping containers and administered nutrients to the bacteria naturally present in the sand. The leaks funnel in the chemical and biological products of the bacteria, ensuring that they accumulate around the source and slowly but surely plug it.” The first real-life application followed soon after, when a leak in an

The Mekong Delta.

>>>


aqueduct on a high-speed rail link near Amsterdam was successfully repaired.

Dike plugged in Austria There is also interest from abroad. A pilot project in Austria, directed primarily at repairing a leaking Danube river dike near Greifenstein, provided a welcome op-portunity to examine the environmental impact of Bio-Sealing. The University of Vienna carried out the study, examining both chemical and bacteriological effects. Lambert: “The university took samples of ground-water before, during and after the pilot. The aim was to examine the local environmental impact of bacteria getting into the groundwater via the leak. The results were positive. In other words, no increase in pathogenic bacteria was observed. As a direct result, an application has since been lodged for the certification of BioSealing for use in Germany, Austria and Switzerland.” A pilot project is now planned in Canada, where the technique is to be used to repair a leaking dam.

BioGrout: soil strengthening

BioGrouting – using bacteria to strengthen sand – is another branch of SmartSoils. The purpose of this in-situ technique is to increase the stiffness of soil at a particular location. Sand is converted into sand-stone with exactly the required increase in strength. Unlike BioSealing, this technique was first subjected to in-depth laboratory testing. Deltares launched the

project in 2004, after staff read a scientific publication from Murdoch University (Australia). The research was conducted in collaboration with Murdoch University, Delft University of Technology, Volker Staal & Fun-deringen and French building contractor Soletanche Bachy.

Using urea and calcium chlorideThe first version of BioGrout used urea and calci-um chloride, injected into the ground together with laboratory-bred bacteria. Deltares researcher Leon

van Paassen: “The bacteria work their magic, turning sand into sandstone. That is, the bacteria injected into the soil convert the urea into chalk and that cements the grains of sand together.” The disadvantage of the process is that ammonium is released and this, like the injected chloride, has to be collected and removed. “It’s not yet the perfect solution”, admits Van Paassen, showing off one of the experimental sandstone blocks. “The process is complicated and expensive, but for certain applications – say, strengthening the ground under a railway line without disrupting rail traffic – it may already be a realistic solution.” “Or to deal with

SMARTSOILS

BioSealing = plugging/sealing

BioGrout 1 = strengthening BioGrout 2 = strengthening

Process Sealing soil using naturally

occurring soil bacteria fed

with a nutrient solution.

Strengthening sand by

turning it into sandstone

using lab-bred bacteria

injected into the soil together

with urea and calcium

chloride.

Strengthening sand using

bacteria present in the soil.

The bacteria are fed with

calcium acetate and calcium

nitrate.

Applications Sealing dikes and

construction pits to prevent

or repair leaks.

Strengthening dikes,

dunes and canal walls.

Strengthening loosely packed

sand under buildings, roads

and railway lines.

See BioGrout 1.

piping under dikes”, adds fellow researcher Maaike Blauw. “We think – although this still has to be checked out in practice – that BioGrout will do the job without displacing the problem. It’s a more sustainable solution than using a screen, for example, which is completely impermeable and will disrupt the hydrological regime. With BioGrout, you strengthen the ground just where it’s needed, while the dike itself remains permeable.”

New-style BioGrout Deltares is currently trying out a new variant of Bio-

Grout using naturally occurring rather than lab-bred bacteria. These are dosed with calcium acetate and calcium nitrate to make them grow and multiply more quickly, producing the chalk “cement” and nitrogen gas as by-products. The latter is harmless and needs not be removed. The bubbles of gas generated in the soil work their way to the surface and their production declines as soon as the administration of nutrients is halted. The process is cheaper and more sustainable, although at present more time-consuming: BioGrout 1 takes three days but BioGrout 2 as much as three months. Van Paassen: “The bacteria have to multiply in response to the extra nutrients and that takes more time than usually available.” Research is now focusing on ways to speed up the BioGrout 2 process.

Scaling-up and new applications The market is already showing interest in BioGrout 1. The process has been successfully scaled up for use in the field. In November 2007, 1 cubic metre of sand was strengthened using BioGrout. Recently, the process was successfully applied to 50 cubic metres of sand. The logical next step is to apply the process at a small pilot site. Blauw: “That may not happen for a while, be-cause new techniques are expensive. Getting an innova-tive process onto the market takes years.” Meanwhile, SmartSoils research is not standing still. Alongside Bio-Grout 2, which is about to leave the lab, there is plenty of experimentation with other soil materials and with a range of chemical and environmental biotechnology methods. For example, Deltares is conducting research on ways to strengthen peat and dredging spoil and on new, lightweight dike materials.

For more information: www.smartsoils.com

Cemented BioGrout container

top:

BioSealing Pilot, with shipping containers on the Maasvlakte,

The Netherlands

bottom:BioSealing Pilot,

project in Austria

“The bacteria work their magic, turning sand into sandstone”

>>>


In those areas, water shortages mean loss of income or even famine. Water supply projects try to deal with water scarcity, often by sinking wells and exploiting groundwater. However, providing a water supply is not in itself the same thing as managing water resources. Effective groundwater management is essential to safeguard the long-term supply of sufficient good-quality water for human consumption and irriga-tion. Marijn Kuijper, Deltares adviser on groundwater systems, and Frank van Weert, IGRAC groundwater management consultant, talk about their involvement in groundwater management projects in the Indian states of Orissa and Gujarat.

In India, local NGOs frequently play a major role in pro-viding village-level water supplies. Such bodies are usu-ally involved not just with water and sanitation, but also with livelihood development, microcredit schemes and women’s education. Gram Vikas is one such organisa-tion. Its name means, literally, ‘village development’.

Gram Vikas is active principally in the state of Orissa and has already helped many rural communities to create water and sanitary facilities. “But the number of wells and water connections is not the only thing that counts”, says Marijn Kuijper, “maintenance is equally important, if not more so. And what happens if the well develops salinity problems or dries up? The local community won’t have the necessary knowledge to carry out water management tasks”. This realisation has led to the development of the ‘barefoot hydrolo-gists’ concept. Kuijper explains: “By ‘barefoot hy-drologists’ we mean people capable of carrying out basic water management in their own communities. Working in partnership with Gram Vikas, we train one person in each village to take measurements of the water level and water quality and to advise on the best location for new wells. We have developed a special ‘toolkit’ of elementary tests, for example to spot the presence of chloride and nitrate in the groundwater. We teach the people to carry out the tests and interpret

India’s need for water is enormous. The United Nations’

millennium development goal – to halve the proportion of people

without sustainable access to safe drinking water – will help to

meet it. But safe drinking water is not the only need; in large

parts of India there is also a major demand for irrigation water.

India: bare essentials of groundwater management

the results so that they can take action if there is any danger to health.”

Capacity buildingData on water levels and chemical substances in the groundwater should lead to a better understanding of the water system as a whole. The presence of sub-stances like nitrate, chloride, bi-carbonate, calcium and magnesium is an indication of the quality of the water but can also provide clues about its provenance; whether the substrate is clay or granite, for example. Kuijper: “All this information helps us understand the water system better and explain better how it works. We are also working on a geohydrological map of the region. Gram Vikas staff will input the measurement results into a database and actively monitor the status of the village water supply.” Together with Gram Vikas, project staff visit local research institutions, universities and government bodies with the aim of strengthening the contacts be-tween them and Gram Vikas and seeing where they can cooperate. As part of the capacity building effort, Gram Vikas staff are being trained to become trainers for the next generation of barefoot hydrologists.

Successful strategiesWhereas the project in Orissa is primarily about prac-tical groundwater management, in Gujarat Frank van Weert’s task is to develop a groundwater model. “In the parched coastal zones of Gujarat, there is a lack

of groundwater of sufficiently good quality to irrigate crops”, he explains. “Salt intrusion as a result of the over-pumping of groundwater is a major problem and one that is expected to increase as time goes on. Our first priority is to produce a model of an area of Saurashtra measuring about 1,200 km2. We can use this to analyse the effectiveness of the measures taken to combat salinization over the last thirty years and so to identify the most successful strategies. We are also calculating the effects of a number of future scenarios drawn up in partnership with Indian experts. Later on, we’ll compare the area we’re looking at now with other coastal areas in Gujarat, to see whether we can use the same research methods there.”

Indirectly relevant dataHowever, as Van Weert admits, this research method-ology first has to be developed. “The data we expected to use as input for the model, like water levels in rivers and irrigation figures, proved to be unavailable. We had to think again. We’re used to working with sophis-ticated models, which are very data-dependent. How

India

“We teach the people to carry out the tests and interpret the results so that they can take action if there is any danger to health”

>>>

left: Training people • right: Local water pump


NEWS

Delft-FEWS pilot in Australia

Deltares is working together with the Australian Bureau of Meteorology (BOM) to investigate whether Delft-FEWS could be used as an upgrade to their current hydrological forecasting environment.

A pilot project has been set up, within which a combined Deltares and BOM project team has implemented an experimental forecasting system for the Brisbane basin combining Delft-FEWS with the current BOM operational hydrological model URBS.

The system uses the new interactive forecast-ing paradigm added to Delft-FEWS for the National Weather Service in the USA. The first phase of the pilot has now been successfully completed and a second phase will be launched to look at possible implemen-tation strategies for the whole of Australia.


Upgrade your knowledge

Deltares Academy is Deltares’ educational facility in the field of water and subsurface engineering. Our international courses and masterclasses focus on knowledge enhancement for professionals. Participants may be consultants and engineers who are involved in the planning, design and con-struction of water, soil and subsurface related projects but we also welcome risk management operators, government staff and principals. Our lecturers are highly qualified. The content of each course is based on real-life cases. Courses are con-ducted in English.

For more information on the 2010 course programme: [email protected] or visit www.deltaresacademy.com

Delft hosts first International Conference on Frontiers in Shallow Subsurface Technology

The first International Conference on Frontiers in Shallow Subsurface Technology (1st FSST) is to take place on 20 – 22 January 2010 at Delft University of Technology’s Aula Conference Centre.

It will be hosted by Delft University of Technology, the Dutch Ministry of Housing, Spatial Planning and the Environment, and Deltares. The aim of the conference is to stimulate the exchange of ideas among a com-munity of scientists and professionals with a common interest in understanding the impacts of subsurface utilization. Participants will include scientists and professionals, regulators and policymakers, engineers and contractors, consultants, and government and other stakeholders. The language of the conference will be English.

Topics are:Characterization, imaging, and monitoring •

techniques Subsurface engineering •

Subsurface heterogeneities •

(Bio)geochemical and physical processes •

Ecosystem functions •

Subsurface management and organization •

planningGeo-energy •

Risk management and safety •


Advanced laboratory research Fehmarn Belt

Deltares has been asked to perform hi-tech laboratory research for the construction of a crossing - a bridge or tunnel - between Puttgarden (Germany) and Rødbyhavn (Denmark).

The 20-km sea crossing between Puttgarden and Rødbyhavn is currently served by busy ferry services. By 2018, however, there is intended to be a fixed link enabling cars to drive directly to Copenhagen or Hamburg. This connection is to be called ‘The Fehmarn Belt Fixed Link’. Deltares is to perform the relevant soil research in cooperation with the Danish Geotechnical Institute (GEO).

The contract was awarded after a tense tender phase in which the criteria were the quality and proper deploy-ment of an enthusiastic team. The main experiments to be performed at our laboratory are: cyclic direct sim-ple shear, constant rate of strain, cyclic triaxial experi-ments and resonant column. The assignment is a great opportunity for our geotechnical lab.


could we construct models for data-poor areas? We solved the problem by using indirectly relevant data, like what crops grow in an area and how much water is needed to cultivate them.” This input was collected by partner organisation ACF, which was also respon-sible for local project coordination. “ACF stands for Ambuja Cements Foundation. It’s an NGO set up by a major cement company. You see that a lot in India: big money-making firms re-investing a proportion of their profits in the community.”

Mutual learning To what extent is the project’s experience applicable elsewhere? “Gujarat is not the only part of India where coastal areas face the problem of salt intrusion”, says Van Weert. “For that reason, we’ve invited other states to attend a multi-day conference this autumn. We plan to present our research results there and hope in turn to learn from water management strategies in other areas. That’s what it’s all about: mutual learn-ing. After all, I’m involved in the project on behalf of IGRAC and the IGRAC motto is ‘sharing groundwater information and experience’.” IGRAC, the International Groundwater Resources Assessment Centre, works un-der the auspices of WMO and UNESCO and is hosted by Deltares. (See www.igrac.net)

The possibility of up-scaling is also part of the Orissa project, as Kuijper confirms: “Together with our Dutch partner ICCO, the Interchurch Organisation for Devel-opment Cooperation, we’re now looking to see whether similar projects could be run in other parts of India or elsewhere. The success of a project like this depends on the presence of an organization like Gram Vikas, big enough to adopt our approach and perpetuate it later.” Kuijper stresses that an essential part of that approach is the popularisation of knowledge. “We are making hydrology and groundwater management accessible to people at grassroots level. ‘You demys-tify groundwater knowledge for us’, as the director of Gram Vikas puts it.”

For more information: [email protected] or [email protected]

>>>

“You demystify groundwater knowledge for us”


PhDs

Trends in groundwater quality in relation to groundwater age

Dune erosion during storm surges

Bridging Boundaries: Making scale choices in multi-actor policy analysis on water management

Satellite data as complimentary information for hydrological modelling

Groundwater quality has improved since 1990 in Brabant, a province in the south of The Netherlands. Concentrations of nitrate and other contaminants related to agriculture have decreased in groundwater that has recharged since 1990.

This improvement in groundwater quality may be attributed to leg-islation implemented in the past twenty years, which was actually aimed at reducing the leaching of nitrate and phosphate to surface water and groundwater.The improvement in groundwater quality was demonstrated by a re-analysis of existing measure-ments from the groundwater qual-

ity monitoring network in Brabant. These data were combined with the estimated age of groundwater samples. The age of groundwater is the time that has elapsed since it infiltrated the soil as rain water. The groundwater ages in Brabant were determined by the radioactive decay of the hydro-gen isotope tritium.This research has also shown that nitrate reacts with sediments in the subsurface of Brabant. The sediments act as a trap for nitrate, effectively protect-ing deeper ground water against nitrate pollution. Unfortunately, this reaction may release heavy metals, which occur naturally in these sediments. This release of heavy metals may pose a hidden

threat to the quality of deeper groundwater in Brabant.


Large parts of The Netherlands are prevented from flooding by a narrow strip of sandy beaches and dunes. Simple dune erosion models are available to assess the impact of storm surges on sandy coasts. However, the applicability of these models is limited (the available models presume a uniform coastline and the absence of hard structures).

The purpose of this thesis was to improve the understanding of dune erosion physics and to develop a more generic dune erosion model that could be applied in more com-plex coastal systems. To this end, the thesis discusses:

• A large-scale dune erosion ex-periment conducted in the Delta Flume. During the experiment, detailed measurements of waves, flows and sediment concentra-tion were collected in the inner

surf zone (as close as possible to the dune). In addition a (stereo) camera pair was deployed to make 3D reconstructions of the dune face from image pairs in order to study the interaction be-tween the dune and the (swash) waves that impacted on it.

• The modelling of near dune hy-drodynamics. The study found that it is not the highest (wind) waves in deeper water that reach the dune and erode it, but rather the much longer (infragravity) waves resulting from interactions between the shorter wind waves.

• A model approach to simulate the high sediment concentra-tions in the vicinity of the dune. In this approach, wave breaking induced turbulence is injected into the water column and reach-es the bed as a pulse, which stirs up large quantities of sand.

• The aggregation of new physical insights and model approaches in the morphodynamic model XBeach. The model was applied to a range of dune erosion condi-tions.


This thesis synthesizes different perspectives on scale choices (spatial boundary setting, tem-poral boundary setting and the selection of the level of aggrega-tion) in policy analysis.

Scale choices influence the con-tent of a study: the problems on

the agenda, the options found and the impacts addressed. This also affects the process, because scale choices are not politically neutral: they may benefit or disadvantage certain actors by putting their urgent problems and/or preferred options on the agenda, and may hide or stress the positive or nega-tive impacts of options. They may also influence the actors that are involved, the possibilities for con-sensus building and the political sensitivity of the study. It is impor-tant, therefore, to pay sufficient attention to scale choices in the design of policy analyses.

Yet little is known about the specific effects of scale choices and how they are made in practice. In this research, the making of scale choices was studied using two

empirical cases: the Long-Term Vision for the Scheldt Estuary and The Netherlands Water Shortage Study. Scale choices appear to be an important framing instrument that can be used by policy analysts. The tool presented in this thesis to make scale choices a subject of dis-cussion can also serve as a means for the policy analyst to address other fundamental issues that are usually present below the surface but are hardly ever out in the open, such as differences in power, inter-ests and hidden agendas.


On 30 September, Hessel Winsemius defended his PhD thesis, resulting in a cum laude PhD degree. The thesis dealt with the problem of hydro-logical modelling in data scarce regions.

Several satellite data sources have been used in combination with scarce and poor quality data in case studies in the Zambezi River ba-sin, Southern Africa. Observations from the GRACE gravity satellite mission, monitoring large-scale terrestrial water storage changes, were used to construct and vali-date a hydrological model for the

upper Zambezi. In a tributary to the Zambezi, the Luangwa River, evaporation estimates, based on satellite data were used in combi-nation with scarce non-overlapping rainfall-runoff records to constrain model parameters using a proba-bilistic framework. Both studies show that studies in data scarce regions can benefit from remotely sensed observations. The thesis can be downloaded from http://www.vssd.nl/hlf/f041.htm.


Deltares views nr 2 2009

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Transcript of Deltares views nr 2 2009