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  • 1. magazine No. 2 2009 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 Groundwater 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: Text Direct Dutch Publications, The Hague Design Teldesign, Rotterdam Layout Sirene Ontwerpers, Rotterdam PO Box 177 Print JB&A, Wateringen 2600 MH Delft Paper Printed on paper free of chlorine The Netherlands Cover photo © Ewout Staartjes, SmartSoils® Port expansion The shape of T +31 (0)88-DELTARES (335 82 73) Anna Jacoba polder, The Netherlands. changing soil in the things to come properties to 21st century order
  • 2. CONTENTS NEWS Our Common Delta • Delft-FEWS pilot in Australia > page 4 • Upgrade your knowledge • Advanced laboratory research Fehmarn Belt The fundamental • Delft hosts first importance of International Conference morphological research on Frontiers in Shallow to coastal and river Subsurface Technology management > page 24 The shape of things to come > page 6 PhDs • Trends in groundwater Integrated coastal zone quality in relation management in Suriname to groundwater age From mud bank • Bridging Boundaries: to mangrove Making scale choices in multi-actor policy analysis > page 10 on water management • Dune erosion during storm Bacteria to replace piling India: surges Dutch polders Maasvlakte 2: Delta Alliance: SmartSoils : ® bare essentials • Satellite data as in Louisiana Port expansion in a problem shared changing soil of groundwater complimentary information marshlands? the 21st century is a problem halved properties to order management for hydrological modelling > page 13 > page 14 > page 18 > page 19 > page 22 > page 26
  • 3. PREFACE 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 We are engaged in similar processes in many different countries and in relation to a host of disciplines, from economic growth, social needs, and earth sciences to water quality management and from pressures on the natural environment. 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 However, in delta areas and coastal zones around the and new morphological knowledge plays an essential world, experience shows time and again that such a role in this project. Likewise, in Singapore, hydraulic balance is difficult to achieve or maintain. How can we engineering, ecology and morphology overlap in plans ensure the future of our common delta? for the use of seagrass, coral and mangroves in coastal protection. And, closer to home, an understanding Creating a sustainable delta is a complex business. of the natural formative processes of the coast and Safety is a sine qua non. But how can we effectively dunes is a crucial element in a large-scale land creation counter the threat of hurricanes, typhoons, earth- project off the Dutch coast: economic growth is going quakes, droughts, tidal waves and other mighty natural hand in hand with nature compensation in the design Three-dimensional view of river and delta phenomena? How can we anticipate the effects of long- and construction of Maasvlakte 2. This issue contains deposits. The colours are as follows: red and yellow - fine sands, blue – clayey deposits, term processes like sea level rise or subsidence? And a major article on the project. and green - mixed deposits. Cooperative study how can we subsequently reconcile safety standards of the long-term development of linked river with economic growth and a sound approach to the Our and delta areas, involving Deltares, TU Delft and StatoilHydro. natural environment? “Morphology is just one of the Developing a delta area in a sustainable way is partly many areas of physical knowledge a question of knowledge. Morphological knowledge, for in which Deltares is in its element“ example. We need to know the shape of the coast or river Common basin and how it changes as a result of processes like erosion, sedimentation, and the interaction between Morphology is just one of the many areas of physical vegetation and benthic organisms. And, indeed, as a knowledge in which Deltares is in its element. Expertise result of human intervention. As this issue reports, of this kind is helping in the worldwide development of Deltares is working in close cooperation with vari- a balanced – i.e. sustainable – future. While it is gener- Delta ous government organisations in the United States ally used in combination with other types of knowledge to develop fundamental morphological knowledge. relating to water, soil and subsurface, morphological The aim is to guarantee the safety of the coast and knowledge is – as we see it – a fundamental prerequi- © Ewout Staartjes, Dutch Dunes. also, for example, to permit improved management of site for building the future of our common delta. the fragile Colorado River system and so preserve a unique piece of the natural world. Each partner is con- Huib de Vriend tributing its own expertise; we are learning from each Director Science other and generating new knowledge and applications which can subsequently also be used back home in The Netherlands or elsewhere in the world. 4 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 5
  • 4. Coastlines and river basins change shape all The fundamental importance of morphological the time. Sometimes the changes are sudden research to coastal and river management and dramatic, resulting from extreme events like hurricanes or tsunamis. More often, they are The shape USA and Indonesia 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. of things In 2005, Deltares researcher Deepak Vatvani travelled to Indonesia to produce a computer model capturing so much research is being conducted on coastal mor- phology in countries like the US. Deltares researcher to come the origins, development and impact of the tsunami Dano Roelvink, Professor of Coastal Engineering and that devastated the coast of Sumatra in the closing Port Development at UNESCO-IHE, talked to us about days of 2004. The model he made not only forms cooperation with the US Geological Survey (USGS). the basis of a Tsunami Early Warning System (see “We are cooperating with the USGS on modelling box on page 8), but also provides new information hydrodynamics, sediment transport and morphology about the relationship between tsunamis and coastal in various coastal areas. In general, the USGS possess- morphology. And that is extremely welcome. es the necessary data – often in impressive amounts – while Deltares can offer the modelling software and Process of change expertise. In tidal inlets along the west coast, for ex- ”We used Delft3D software to model the origins and ample, there is a problem with the migration of gullies development of the tsunami”, Vatvani explains. “We and sandbanks, which causes parts of the coastline to show how the tidal waves changed the coast and where erode. Rather than build endless hard coastal defences, the coast is now vulnerable to future inundation. This the USGS prefers to get to the root of the problem and information provides a crucial basis for the design of look for an appropriate solution. In Florida we’re busy new coastal defences and future evacuation routes.” charting hurricane impacts. Whatever the approach, >>> 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 XBeach part of a continuing process of change. “Underneath the Indian Ocean, two continental plates are sliding Dano Roelvink is putting a lot of time into the develop- over each other. The friction produces earthquakes ment of XBeach, a new model designed to calculate storm and water motions. Various studies have shown that impacts like dune erosion, overwashing and breaching a tsunami like the one in 2004 occurs once in every of sandy coasts. ;“To approximate to the complexity of five hundred to a thousand years. So the morphology a coastal system, you have to include all the relevant of the coastline, including the processes of erosion physical parameters in your model. That’s what we can do top: Colorado River, USA • bottom left: Deltares researcher Dr Kees Sloff • bottom right: Disappearing beaches and sedimentation occurring along it, likewise under- and we’re working hard on it. XBeach is one of the latest- goes dramatic change at those intervals. And that has generation models, which are able to replicate a variable knock-on effects on the development of the coast over coast, differing storm conditions and combinations of hard the next few centuries. If we want to manage the coast and soft coastal elements. It was initially developed by in a sensible, sustainable way, it’s important to get UNESCO-IHE, Delft University of Technology, the University a better understanding of such long-term processes. of Miami and Deltares, on the initiative of the US Army And that’s what we’ve started to do.” Corps of Engineers. Because it’s an open source application in the public domain, a multitude of partners are now Getting to the root of the problem working on it, including the USGS, so we should ideally end Worldwide, little is known about the influence either of up with a universally – or, at any rate, widely – applicable extreme events or of longer-term processes of erosion coastal model. The more input we get the better.” and sedimentation on coastal morphology. This is why 6 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 7
  • 5. >>> you need extensive knowledge of the coastal system to like sea level rise or, indeed, the consequences of hu- data at the invitation of the USGS. It was a memora- arrive at an appropriate solution. We’re making big ad- man interventions like major hydraulic engineering ble trip. “Imagine sailing into the Grand Canyon on vances in the modelling of morphological processes.” works or sand nourishment off-shore or in a gulley. rafts loaded with monitoring apparatus and spending a week bivouacking there with geographers, environ- Fresh air mental experts and water management experts. It was Roelvink finds the vast quantity of local data pos- “If we want to manage the coast a real adventure.” sessed by the USGS a breath of fresh air. “We have a lot to offer each other. Our modelling tools enable the in a sensible, sustainable way, But why were they there? In the mid-sixties, the Glen Canyon dam was built upstream of the Grand Canyon. USGS to get a better understanding of the US coast, it’s important to get a better The dam halted the supply of sediment from the while their research teaches us more about phenome- na we also face in The Netherlands. For example, we are understanding of such long-term Colorado River. Not just that, but the hydroelectric power plant at the foot of the dam reduced the natural keen to know what sort of damage would be inflicted processes” flow of water. Since then, the river in the Grand Canyon on our coastal dunes by a storm likely to occur on the has received sediment only from minor tributaries. Dutch coast on average once in every ten thousand Because we are only now starting to realise the range “The process by which sandbanks and beaches in the years. Well, the USGS studies the hurricanes that hit of potential impacts of sand nourishment, on every- canyon were washed away by peak discharges and the American coast every year and they have the same thing from flora and fauna right through to the safety then laid down again, was lost”, says Sloff, “and what’s sort of magnitude and impact.” of bathing water. Scientific progress benefits us all.” left of them is now disappearing.” The small sandy At the same time, USGS data and research benefit model beaches play a crucial role in the natural ecosystem: development in general. “The many different kinds of Colorado River they provide a habitat for specific species of flora and monitoring data they collect help to validate the mod- This fruitful partnership is not confined to coastal mat- offer quiet places for young fish to grow. They are also els. The better a model can replicate the natural sys- ters. In March 2008, Deltares researcher Kees Sloff vital to campers and rafters making their way through Post-Katrina aerial photograph of Dauphin Island, Alabama, USA tem, the better we can anticipate long-term processes sailed down the Colorado River collecting monitoring the Canyon. “In 1996 a controlled surge was sent down Source: USGS/NASA 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.” Tsunami Early Warning System Research The 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 At 7.01 a.m. on 26 December 2004, an earthquake occurred beneath thing occurring again? And what system will compare its strength focused on the areas genuinely at campaign was intended to answer such questions. “We the bed of the Indian Ocean. Twenty minutes later, a layer of water would be the consequences if and location with the model situ- risk. The response time is short; spent a whole week taking detailed measurements of five metres high reached the Indonesian province of Aceh, situated it did? Vatvani: “We know very ation and the expected impact people have less than twenty everything from bed topography to flow rate”, says at the western tip of the island of Sumatra. The ocean receded little about tsunamis. To help scenario will appear on the screen minutes to get out.” All the better, Sloff. “The USGS collected a huge quantity of data to temporarily and then rushed back to swamp the coast under a tidal us make better estimates of the in seconds. At the places along the then, if efforts can be concentrat- enable it to determine how the system works and what wave ten metres high. The tsunami claimed the lives of almost risks associated with them, we’ve coast where the threat is greatest, ed where they are most needed. processes are involved.” But the USGS wants more than 200,000 people in Aceh. collected together and further ex- sirens will start to sound.” Vatvani says that, not long after just monitoring data. Modelling information is an impor- panded all the model calculations the tsunami of 2004, there was an tant tool for the development of a sophisticated water Deepak Vatvani sits at his laptop BRR, the Aceh-Nias Rehabilitation we made for the reconstruction.” Panic avoidance under-sea quake with a magni- management strategy. “We are helping them model all and runs a simulation of the and Reconstruction Agency, we set An existing early warning system The new insights into the con- tude (Mw) of 8.7. The alarm was the processes that determine how sand enters and exits tsunami. The tidal wave spreads to work on a reconstruction of the shows whether an earthquake will sequences of tsunamis make it sounded throughout the entire the canyon. From the very local interaction between a out over the ocean like spilled wine tsunami.”Deltares modelled the result in a tsunami. But it doesn’t possible to conduct a proper risk region and a million people were rapid and the pool behind it right through to the entire soaking into a tablecloth. Arriving development of the wave following say how high the tidal wave will be analysis. For instance, the new evacuated. “But if you’re in a ‘wet water flow.” Once again, both sides are learning from at the coast of Aceh, it continues the earthquake and produced a and which particular areas will be TEWS shows that no evacuation feet zone’, where the water won’t the exercise. “Absolutely. Here in The Netherlands, we its unrelenting course, reaching simulation of the inundation of engulfed. That gap has been filled will be necessary in the case of get deeper than 30 cm, there’s encounter similar small-scale interactions, for example several kilometres inland. Banda Aceh, the capital of Aceh by coupling the database con- an earthquake measuring 7 on no need to flee. With the ‘Dutch’ in groyne fields along the major rivers. Greater knowl- “Following the disaster, various province. “Comparison with satel- structed by Vatvani to the early the moment magnitude scale. TEWS installed, the authorities edge of this phenomenon is extremely welcome. And government projects were lite images shows that the simula- warning system. (Seismologists believe that the could have sent out differentiated this is high-quality research: the wealth of monitoring launched in the Netherlands”, tion results approximate closely to “The crux of the new Tsunami December 2004 earthquake had warnings and avoided panic and data, the research on the best possible way of modelling Vatvani explains. Together with what actually happened.” Early Warning System (TEWS) is a magnitude of 9.1 on that scale, disruption.” morphological processes… it’s cutting edge stuff.” two partners, Deltares set up the the coupling of earthquake-related although tsunami experts think Sea Defence Consultant consor- Coupling data to a water motion model. it was 9.3.) “It means that, in a For more information:, tium (SDC). In consultation with How great is the risk of such a If another earthquake occurs, the real-life emergency, efforts can be, 8 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 9
  • 6. Integrated coastal zone management in Suriname From mud bank to mangrove 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. Suriname Human activities threaten its natural morphodynamic processes. Transport by boat in Suriname It is vital to strike a balance between economic and banks. “The Surinamese and Dutch coasts have more plan, part of the job is to conduct a stakeholder analy- at a particular section of the coast or at particular ecological interests and find a way of rhyming coast- in common than you might think”, explains Marcel sis. As Bucx explains, representatives of ministries, issues, like coastal development or the protection of al protection with coastal development. With this Marchand. “Both are low-lying, at high risk of inunda- knowledge institutions and civil society organisations mangrove swamps, taken in isolation. But it’s better to in mind, the Ministry of Planning and Development tion, and highly dynamic: in other words, both coast- have provided input during interviews and workshops. consider such issues in relation to each other. Things Cooperation has commissioned the preparation of an lines are naturally extremely mobile. Deltares has a “We are using their input to check and supplement like spatial planning and flooding, for instance. And Integrated Coastal Zone Management Plan (ICZMP). lot of in-house expertise concerning low-lying coastal that’s what we’re doing now.” zones and their problems.” [See box on page 12] Given such a broad subject area, it’s hardly a sinecure. A consortium of local and international experts is “This is the first time that As Marchand points out, “Just defining the problem is involved in the project, which is headed by Lievense Consulting Engineers. Deltares consultant Marcel Integration Under The Netherlands Climate Assistance Programme all the issues to do with difficult: for instance, where do you place the limits of the coastal zone?” And there are factors in each of the Marchand is largely responsible for the preparation of (NCAP), research was done in the late ’90s on the living and working in the various districts that complicate the preparation and a plan for the entire coastal zone, while another ICZM consultant, Tom Bucx, is focusing on a sub-plan for the vulnerability of Suriname and possible consequences of climate change for the country. Follow-up studies coastal zone are being implementation of an ICZMP. Marchand cites examples like over-fishing and the upstream gold mining that densely populated districts of Paramaribo and Wanica. were performed between 2005 and 2008. The NCAP dealt with together” leads, via the rivers, to mercury pollution on the coast. They are working hand in hand with a team of ex- recommended the development of integrated coastal A total of 25 issues are vital enough to require fur- perts in ecology, morphodynamics and morphology, zone policies and also the production of a Master Plan ther investigation. Marchand: “It isn’t easy to ensure social economics, and urban development. Colleague for the Drainage of Greater Paramaribo. This plan was our own findings and to help pinpoint priorities. At the that the plan does justice to all these aspects. But it’s Paul Erftemeijer is concerned primarily with the im- produced in 2002 with the assistance of what was then same time, involving stakeholders ensures public sup- important to mention them all, including the gaps in portance and regeneration of the mangrove swamps, Delft Hydraulics. The NCAP I and II reports are being port for the plan.” current knowledge.” while Han Winterwerp is advising on morphodynam- used as input to the present ICZMP. So what is the ics. Their participation is hardly surprising: Deltares added value of the ICZMP? Tom Bucx: “The measures Complex Master plan has been involved in coastal research in Suriname ever proposed in the earlier reports were frequently global in The unique thing about this project is its scope. The ICZMP will pay special attention to the districts of since the 1960s, when the Waterloopkundig Labora- nature; we are firming them up in order to arrive at an Marchand: “This is the first time that all the issues Paramaribo and Wanica. That is where the problems torium (later known as Delft Hydraulics and now part adaptation strategy.” Since it is extremely important to do with living and working in the coastal zone are are most pressing, particularly in relation to popula- of Deltares) conducted research on the offshore mud to involve all the stakeholders in the development of the being dealt with together. Earlier studies just looked tion. Two-thirds of the country’s population live in >>> 10 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 11
  • 7. Dutch polders >>> those areas and coastal development is sometimes too early 2010. Marchand thinks this is a step in the right close to the sea. Where mangrove forests have direction but “Integrated coastal zone management is been cleared, the risk of coastal erosion increases. not a project; it’s a process that takes years. This is just in Louisiana marshlands? Recommendations will therefore include the estab- one part of that process.” lishment of a natural buffer zone several kilometres There will soon be a framework document to provide wide. “Some people won’t like it”, Bucx admits, “but guidelines for further development. “Suriname still it’s a cheaper, more sustainable and more ecological has a lot of land available and that means that there solution than measures like dike-building, especially is scope to choose between alternative approaches. in the long term. This way we can plan for balanced Dikes are one possibility, of course, but a buffer zone Set in the Mississippi Delta, New Orleans is a vulnerable city in a sensitive economic development while preserving ecological is also an option. An even better one is making use of environment. Human interventions, including the building of flood control structures values. Which is what the government of Suriname natural processes to ‘build with nature’. Government along the river, have produced subsidence and erosion in the surrounding marsh- asked for.” Another part of the solution is further recognises the importance of this but it takes time to lands. Vegetation is disappearing and unique wildlife areas are being lost, together implementation of the Master Plan for the Drainage get round to implementing plans in practice. In twenty with an important buffer against storm surges. The tide needs to be turned, but how? of Greater Paramaribo (in particular, catch-up mainte- years’ time, Suriname may be a textbook example of nance of the drainage system). There are also plans to balanced coastal zone management.” construct new pumping stations and build a ring dam and canal. Such measures should end the frequent For more information: left: flooding that afflicts the capital. or Louisiana marshlands Long-term process right: The sub-plan for Paramaribo and Wanica is almost Field trip by the research finished and the entire ICMZP should be complete by team “Integrated coastal zone management is not a project; it’s a process that takes years” “For example, by restoring the tion are leading to a rapid diminu- swamp, peat is formed or sediment Vulnerable coast marshlands south-west of the tion of the wetland area. This is is retained so that the polder area city.” Deltares ecologist Bregje van worrying because large stretches of is naturally restored to its old level, Suriname is a South-American country wedged Wesenbeeck is involved in planning wooded swamps have the ability to equal to that of its surroundings.” between French Guiana, Guyana and Brazil. sustainable coastal flood defences absorb a lot of storm surge water. Its coast is extremely dynamic. Sediments from for New Orleans. In the wake of Besides, they are enormously valu- Buffer the Amazon form offshore mud banks that the hurricane Katrina flood disas- able wildlife areas with an impor- Once a healthy swamp has devel- stretch for tens of kilometres and migrate at ter of 2005, various Dutch water tant role in the area’s culture and oped in the subsidence-affected a speed of around 1.5 km a year. These fluid experts offered their help. “Our history.” areas, the link with the surround- mud layers damp out wave energy and produce Dutch experience with integrating ing marshland can gradually be temporary coastal accretion. Between the mud natural processes and materials Impoldering restored by removing the dikes. banks, however, there is a risk of coastal erosion into hydraulic engineering projects National government is taking A healthy wetland zone of suffi- and inundation. Accretion and erosion occur in and coastal flood defences can pro- measures to combat the subsid- cient size will eventually be able approximately 30-year cycles. House-building vide a solution in this situation. We ence. One is to re-open the swamps to sustain itself and act as a buffer close to the coast is not advisable. call it ‘building with nature’.” to sediment-rich river water. “The against storm surges. “Healthy Human activities are increasing the risk of ideal would be to restore the natu- natural surroundings make the city coastal erosion, especially in the densely Worrying ral dynamics of the marshlands. less vulnerable”, says Bregje, “and populated districts of Paramaribo and Wanica. The Mississippi flows through typi- We decided that temporarily im- the nice thing is that nature will do Mangrove swamps Mangrove swamps are a natural form of coastal cal delta landscape. From freshwa- poldering areas of open water most of the work for itself.” defence but urban development is nibbling away ter to salt. From swamp woodlands would give the swamps a chance at this buffer. Wherever the sediment-retaining full of vast trees to grassy wetlands to develop in the most natural pos- For more information: mangroves disappear, coastal erosion increases. nearer the coast. “The marshes are sible way. Sophisticated control of bregje.vanwesenbeeck In the longer term, moreover, Suriname faces the in a poor state”, says Bregje. “Innu- water levels can be used to encour- risk of inundation as a result of rising sea levels. merable little drainage canals, peat age the growth of marshland veg- compaction and lack of sedimenta- etation. Depending on the type of 12 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 13
  • 8. 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 The Netherlands 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. Testing the scale model in the Delta Flume Maasvlakte 2: The first phase of the new 2,000-hectare deep-water revetments. The cobble shore has been developed and Port expansion in port area is to be completed by 2013. The new facilities selected by PUMA because of the lowest total cost of will be built on sand extracted from the sea floor. But the ownership. Of course, cobble shores are dynamic during Maasvlakte 2 development project is about more than both year-round and design storm conditions. As such, just land reclamation. It involves questions like how to PUMA’s design and maintenance plan includes buffers the 21st century compensate for the impact of sand extraction on local to accommodate the predicted loss. For the parts that marine life, what consequences the extra port activities contain concrete blocks, these blocks are being recy- and industry will have for the environment, and how to cled from the previous Maasvlakte sea defence. “That’s protect newly reclaimed land against storm damage. environmentally friendly and also cost-effective.” Maasvlakte 2 is based on innovative know-how and a multifaceted knowledge of the Dutch Delta. Scale model Deltares has been commissioned by PUMA to test and Sea defences analyse a number of design optimisations for certain This year has seen the start of construction work by sections of the hard sea defence. Van Gent: “We are PUMA, a joint venture between Dutch hydraulic engi- conducting series of tests in scale models in facilities neering contractors Boskalis and Van Oord. PUMA has like our Scheldt flume and Delta flume, where we can been contracted by the Port of Rotterdam Authority to generate large waves. The sea defence must be able to be responsible for the design, construction and main- withstand a superstorm expected to occur on average tenance of Maasvlakte 2. once in every ten thousand years. That’s the standard Marcel van Gent, Deltares’ project manager for sea for all primary sea defences along the Holland coast. defences, says that PUMA’s design for the hard sea So we’re simulating a range of storm conditions, with defences has been extensively tested in Deltares’ wave various wave heights and lengths.” In the 230-metre- facilities and elsewhere. PUMA has used the results long Delta flume, this can even be done without major of the scale model testing to optimise and verify its scale effects: the waves are up to 1.5 metres high with design. The Design, Construct & Maintenance contract some even reaching 2.5 metres. “In addition, we are has given the consortium about three years to explore advising on certain aspects of construction and main- possible improvements and ensure maximum effec- tenance and providing an independent second opinion tiveness. The result of its efforts is a highly innovative when required.” and sophisticated design. As Van Gent explains, the sea defences are to com- Building with nature prise a number of different elements: an approximately Once in use, Maasvlakte 2 will attract more industrial 7-kilometre stretch of sandy coast (beach and dunes) activity, increased shipping and more goods traffic. © PUMA, Development Maasvlakte 2 will be succeeded in the north by several kilometres Atmospheric emissions of nitrogen oxides (NOx) are of sea defences involving the use of quarry stones expected to increase. Adverse effects are to be compen- (cobble size) and concrete blocks. “This combination sated by creating a 35-hectare area of naturally devel- is unusual”, Van Gent explains. “Cobbles have never oping dune habitats. Bert van der Valk, senior advisor before been used in The Netherlands in sea defences with Deltares, and his colleague Frank van der Meulen, on this scale. The idea was inspired by natural shin- have advised The Netherlands Ministry of Transport, gle beaches and PUMA has developed it further for Public Works and Water Management on how this new use in Maasvlakte 2. Dutch sea defences normally dune landscape can best be designed in relation to consist of concrete blocks, rock slopes or placed-block coastal geology, coastal engineering, long-term drift >>> 14 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 15
  • 9. Blaas. “To my knowledge, it’s the first time that data using a purpose-made monitoring framework. “These assimilation techniques have been used to monitor measurements are needed, for example, to calibrate sediment transport. Data assimilation means that and validate the results of the computer model.” monitoring data – at this stage mostly remote sens- The data assimilation relies on proper interpretation 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 “To my knowledge, it’s the first meteorology and oceanography.” time that data assimilation tech- Promising niques have been used to monitor Satellite images of the water surface provide up-to- date information but don’t reveal what is going on sediment transport” © PUMA, Artist’s impression of Maasvlakte 2 beneath the surface, at night and in cloudy weather. Model information can be used to bridge these gaps. of the satellite images. Blaas confirms this: “IVM is Blaas explains: “We use the satellite images to correct highly skilled at analysing the satellite signals and the sediment transport model and generate a physi- deducing the different components – sediment, algae cally consistent picture of the situation, either now or and dissolved organic material – from the colour of the in the past. Currently, we are determining the refer- water. The combination of satellite observations of sea ence conditions, from 2003 to 2008, and in the coming water colour and water quality models, supplemented years we plan to model the situation including the dis- by periodic on-the-spot monitoring is extremely prom- turbance caused by the construction works from 2009 ising, partly because it can also be used to detect and to 2013.” This reconstruction of the long-term situa- model other substances. For example, there is a great tion will make it possible to identify trends and help worldwide need both for accurate real-time information the Port of Rotterdam Authority to assess the impact on algal blooms and for ways of predicting them.” of the sand extraction on the local environment. The Port of Rotterdam Authority is also doing its own For more information:, >>> (morphology) effects and ecological development. The maritime monitoring of sediment and related factors 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 Monitoring: will ‘nature compensation’ work? the port of Rotterdam and improve the quality of life in the Rijnmond region. The construction of Maasvlakte 2 will result in activities, from studying bird numbers and behav- “The intended result – which will only be apparent in the loss of an area of shallow marine habitat. To iour to modelling and measuring physical process- ten to twenty years’ time – is to be achieved through a compensate, an area of around 25,000 hectares es and parameters like water motion, temperature combination of engineering and natural dune forma- in the Voordelta – a protected nature reserve off and salinity. But the consortium is also monitoring tion. The aim is to create a new range of dunes and a the south-west coast of the Netherlands – has human use impacts.” The plethora of data has to wet dune slack. That’s a place where groundwater can been designated as a ‘sea floor protection area’. be forged into a consistent whole that can be used come to the surface in the winter and freshwater ponds to identify trends and interrelationships. will develop between the newly engineered dune and Basically, the designation means that certain “It’s important that the work is based on a sound the old foredune.” Sand drifting up against the old fore- activities in the tourism sector and methods of monitoring strategy and that data will be integrat- dune will eventually form ‘grey’ dunes (dunes covered fishing that disturb the sea floor are restricted or ed in a scientific way. That’s where we come in.” mainly with grasses, herbaceous plants and mosses, banned. The Ministry of Transport, Public Works which provide a unique habitat and are regarded in and Water Management has commissioned Deltares has also advised on drawing up a ‘Moni- Europe as extremely valuable). Data assimilation Deltares to monitor and analyse the situation toring and Evaluation Plan’ (MEP) both for the new Like the new port area, the new Delfland dunes will be The construction of Maasvlakte 2 will require the to see whether ecological quality in the area is dune area and for the area expected to be affected the result of the hydraulic fill method of construction. extraction of 210 million m³ of sand in the North Sea. improving according to plan. by NOx emissions. Bert van der Valk: “We need to However, as Van der Valk explains, the top metre is to The question is whether this operation will cause a local know, for example, whether the dune morphology be created by natural processes. “This is a new feature temporary increase in the turbidity of sea water with “Our role in the process is primarily that of knowl- is developing in the expected way over the next few of dune design in The Netherlands. The sand is pre- consequent environmental disturbance. The Port of edge broker”, says Meinte Blaas. “We have asked years and whether the water table is high enough. selected dredge material from the sea but the seeds Rotterdam Authority has asked Deltares and the Vrije a six-party consortium headed by IMARES (the We think we’re establishing the right conditions for and spores have to find their own way to the dune. In Universiteit Amsterdam’s Institute for Environmental independent Institute for Marine Resources & Eco- nature development but if we’ve got it wrong, we’ll other words, a proportion of the construction work is Studies (VU-IVM) to contribute to the monitoring of the system Studies in Wageningen) and environmental be able to intervene without delay.” left to natural forces to get a varied and more valuable impact of sand extraction on sediment transport. “The consultants CSO to do the monitoring and help ecosystem. Using this idea in such a large and prestig- study will combine model calculations and satellite us interpret the results. The job includes a host of For more information: ious project is a revolutionary step.” observations”, says Deltares project manager Meinte 16 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 17
  • 10. The Mekong Delta. Bacteria to replace piling SmartSoils : ® changing soil focus attention on the integrated, sustainable development of delta areas. The main emphasis will be on integrated water and coastal properties to order 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- Delta Alliance: ing and supporting the application Delta soils are frequently composed of relatively of these in policy and administra- young geological materials like sand, clay and a problem shared tion. The network will therefore include not only universities and other knowledge institutions, but peat. Since these materials are soft and damp, they are far from ideal building ground. is a problem halved also government authorities, engi- neering companies, consultancies, NGOs and civil society groups. Europe Road and railway subsidence is a constant danger and dikes weakened by piping can The basis for the Delta Alliance has suddenly collapse. Over the last decade, Deltares has been working with The Mekong Delta and San Francisco Bay are around 12,000 km apart. now been established. Partners in national and international partners to develop innovative, sustainable Similarly, the distance between the Rhine estuary in The Netherlands and four key deltas in the Netherlands, the mouth of the Ciliwung on Java (Indonesia) is over 11,000 km. And yet Indonesia, Vietnam and the US techniques for modifying the properties of soil: SmartSoils. these places are closely related: wherever great rivers approach the sea, (organised in Chambers) are now they create fertile, densely populated deltas. busy formulating their views on Alliance activities and possible research projects. The partners BioSealing and BioGrout are two promising applica- remembers how the research was begun by Deltares, Landscapes, peoples and cultures priorities, encouraging research, will be expected to make an active tions in which bacteria play a leading role. ‘Fed’ the Delft University of Technology and building contractor may differ, but delta-dwellers exchanging experience and sharing contribution to the network’s right dose of nutrients, they can seal leaky dikes or Visser en Smit Bouw in 1999. “The idea came up of around the world face the same knowledge. By working together to finances and activities, possibly strengthen soil – on site, with no onerous earthmoving using naturally occurring soil bacteria to look for and problem: how to strengthen these address common problems they to be matched from international operations. The idea of getting bacteria to do the heavy repair leaks. Given the right kind and amount of nutri- vulnerable areas. There is no com- can produce solutions helpful to sources. work has not come out of the blue. In the environmental ents, they multiply and produce deposits around the mon blueprint for deltas worldwide. more deltas than just their own. geo-technology field, bacteria have long been used leak. Lab work showed that BioSealing was an effective But the consequences of climate For more information, please to clean up contaminated soils. This made Deltares system. We experimented with different materials and change, as well as demands for International network contact the Delta Alliance researchers wonder whether they could also be used rates of flow. It was a process of trial and error. With few food, safety, space and economic Following the Aquaterra Forum on Project Officers: to strengthen soils or make them less permeable. This errors, because in every case the result was to stop the viability have to be faced. The in- Delta & Coastal Development, held or would make it possible to build in places where soft leak. So we could soon start scaling up the tests.” terests of the human population in Amsterdam in 2009, a number or unpredictable subsoils currently prevent it. Or to have to be reconciled with those of of Dutch organisations have de- or visit: carry out remediation work without disturbance (for From lab to field nature. Everywhere, then, difficult cided to establish an international example, under existing buildings or infrastructure). BioSealing is now a fully tried and tested procedure. choices have to be made; every- knowledge platform and partner- In 2004 a successful pilot was run on the Maasvlakte where, a balance has to be struck ship. This Delta Alliance is due to (Netherlands) and this led to a patent application. to keep life in the delta safe and go into official operation in 2010. Biosealing: making soil watertight Lambert: “On the Maasvlakte, we buried three leak- productive. Decisions and meas- It aims eventually to expand into ing shipping containers and administered nutrients to ures need to have a firm knowl- an international network of delta- It was leaks occurring in the course of projects like the bacteria naturally present in the sand. The leaks edge basis. Delta populations can based partners able to work to- the construction of a tram tunnel in The Hague that funnel in the chemical and biological products of the help each other by formulating gether in a coordinated way to prompted Dutch research into the repair and preven- bacteria, ensuring that they accumulate around the tion of leaks in underground water-retaining structures source and slowly but surely plug it.” The first real- like sheetpile walls. Deltares researcher John Lambert life application followed soon after, when a leak in an >>> 18 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 19
  • 11. 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. top: BioSealing Pilot, with shipping containers Scaling-up and new applications on the Maasvlakte, The market is already showing interest in BioGrout 1. The Netherlands The process has been successfully scaled up for use in the field. In November 2007, 1 cubic metre of sand was bottom: BioSealing Pilot, Cemented BioGrout strengthened using BioGrout. Recently, the process project in Austria container 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- >>> aqueduct on a high-speed rail link near Amsterdam project in 2004, after staff read a scientific publication piping under dikes”, adds fellow researcher Maaike cause new techniques are expensive. Getting an innova- was successfully repaired. from Murdoch University (Australia). The research was Blauw. “We think – although this still has to be checked tive process onto the market takes years.” Meanwhile, conducted in collaboration with Murdoch University, out in practice – that BioGrout will do the job without SmartSoils research is not standing still. Alongside Bio- Dike plugged in Austria Delft University of Technology, Volker Staal & Fun- displacing the problem. It’s a more sustainable solution Grout 2, which is about to leave the lab, there is plenty There is also interest from abroad. A pilot project in deringen and French building contractor Soletanche than using a screen, for example, which is completely of experimentation with other soil materials and with Austria, directed primarily at repairing a leaking Danube Bachy. impermeable and will disrupt the hydrological regime. a range of chemical and environmental biotechnology river dike near Greifenstein, provided a welcome op- With BioGrout, you strengthen the ground just where methods. For example, Deltares is conducting research portunity to examine the environmental impact of Bio- Using urea and calcium chloride it’s needed, while the dike itself remains permeable.” on ways to strengthen peat and dredging spoil and on Sealing. The University of Vienna carried out the study, The first version of BioGrout used urea and calci- new, lightweight dike materials. examining both chemical and bacteriological effects. um chloride, injected into the ground together with New-style BioGrout Lambert: “The university took samples of ground- laboratory-bred bacteria. Deltares researcher Leon Deltares is currently trying out a new variant of Bio- For more information: 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 “The bacteria work their SMARTSOILS were positive. In other words, no increase in pathogenic bacteria was observed. As a direct result, an application magic, turning sand into BioSealing = BioGrout 1 = strengthening BioGrout 2 = strengthening has since been lodged for the certification of BioSealing sandstone” plugging/sealing for use in Germany, Austria and Switzerland.” A pilot project is now planned in Canada, where the technique Process Sealing soil using naturally Strengthening sand by Strengthening sand using is to be used to repair a leaking dam. van Paassen: “The bacteria work their magic, turning occurring soil bacteria fed turning it into sandstone bacteria present in the soil. sand into sandstone. That is, the bacteria injected into with a nutrient solution. using lab-bred bacteria The bacteria are fed with the soil convert the urea into chalk and that cements injected into the soil together calcium acetate and calcium BioGrout: soil strengthening the grains of sand together.” The disadvantage of the with urea and calcium nitrate. process is that ammonium is released and this, like chloride. BioGrouting – using bacteria to strengthen sand – is the injected chloride, has to be collected and removed. another branch of SmartSoils. The purpose of this “It’s not yet the perfect solution”, admits Van Paassen, Applications Sealing dikes and Strengthening dikes, See BioGrout 1. in-situ technique is to increase the stiffness of soil showing off one of the experimental sandstone blocks. construction pits to prevent dunes and canal walls. at a particular location. Sand is converted into sand- “The process is complicated and expensive, but for or repair leaks. Strengthening loosely packed stone with exactly the required increase in strength. certain applications – say, strengthening the ground sand under buildings, roads Unlike BioSealing, this technique was first subjected under a railway line without disrupting rail traffic – it and railway lines. to in-depth laboratory testing. Deltares launched the may already be a realistic solution.” “Or to deal with 20 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 21
  • 12. India: bare essentials of groundwater management left: Training people • right: Local water pump India’s need for water is enormous. The United Nations’ the results so that they can take action if there is any of groundwater of sufficiently good quality to irrigate danger to health.” crops”, he explains. “Salt intrusion as a result of the millennium development goal – to halve the proportion of people over-pumping of groundwater is a major problem without sustainable access to safe drinking water – will help to Capacity building and one that is expected to increase as time goes on. Data on water levels and chemical substances in the Our first priority is to produce a model of an area of meet it. But safe drinking water is not the only need; in large groundwater should lead to a better understanding Saurashtra measuring about 1,200 km2. We can use India parts of India there is also a major demand for irrigation water. of the water system as a whole. The presence of sub- this to analyse the effectiveness of the measures taken stances like nitrate, chloride, bi-carbonate, calcium to combat salinization over the last thirty years and so and magnesium is an indication of the quality of the to identify the most successful strategies. We are also water but can also provide clues about its provenance; calculating the effects of a number of future scenarios In those areas, water shortages mean loss of income Gram Vikas is active principally in the state of Orissa whether the substrate is clay or granite, for example. drawn up in partnership with Indian experts. Later on, or even famine. Water supply projects try to deal with and has already helped many rural communities to Kuijper: “All this information helps us understand the we’ll compare the area we’re looking at now with other water scarcity, often by sinking wells and exploiting create water and sanitary facilities. “But the number of water system better and explain better how it works. coastal areas in Gujarat, to see whether we can use the groundwater. However, providing a water supply is not wells and water connections is not the only thing that We are also working on a geohydrological map of the same research methods there.” in itself the same thing as managing water resources. counts”, says Marijn Kuijper, “maintenance is equally region. Gram Vikas staff will input the measurement Effective groundwater management is essential to important, if not more so. And what happens if the results into a database and actively monitor the status safeguard the long-term supply of sufficient good- well develops salinity problems or dries up? The local of the village water supply.” “We teach the people to carry out quality water for human consumption and irriga- tion. Marijn Kuijper, Deltares adviser on groundwater community won’t have the necessary knowledge to carry out water management tasks”. This realisation Together with Gram Vikas, project staff visit local research institutions, universities and government the tests and interpret the results so systems, and Frank van Weert, IGRAC groundwater has led to the development of the ‘barefoot hydrolo- bodies with the aim of strengthening the contacts be- that they can take action if there is management consultant, talk about their involvement in groundwater management projects in the Indian gists’ concept. Kuijper explains: “By ‘barefoot hy- drologists’ we mean people capable of carrying out tween them and Gram Vikas and seeing where they can cooperate. As part of the capacity building effort, Gram any danger to health” states of Orissa and Gujarat. basic water management in their own communities. Vikas staff are being trained to become trainers for the Working in partnership with Gram Vikas, we train one next generation of barefoot hydrologists. Indirectly relevant data In India, local NGOs frequently play a major role in pro- person in each village to take measurements of the However, as Van Weert admits, this research method- viding village-level water supplies. Such bodies are usu- water level and water quality and to advise on the best Successful strategies ology first has to be developed. “The data we expected ally involved not just with water and sanitation, but also location for new wells. We have developed a special Whereas the project in Orissa is primarily about prac- to use as input for the model, like water levels in rivers with livelihood development, microcredit schemes and ‘toolkit’ of elementary tests, for example to spot the tical groundwater management, in Gujarat Frank van and irrigation figures, proved to be unavailable. We women’s education. Gram Vikas is one such organisa- presence of chloride and nitrate in the groundwater. Weert’s task is to develop a groundwater model. “In had to think again. We’re used to working with sophis- tion. Its name means, literally, ‘village development’. We teach the people to carry out the tests and interpret the parched coastal zones of Gujarat, there is a lack ticated models, which are very data-dependent. How >>> 22 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 23
  • 13. NEWS >>> could we construct models for data-poor areas? We Delft-FEWS pilot Delft hosts first solved the problem by using indirectly relevant data, like what crops grow in an area and how much water in Australia International Conference is needed to cultivate them.” This input was collected on Frontiers in Shallow by partner organisation ACF, which was also respon- sible for local project coordination. “ACF stands for Deltares is working together with the Australian Bureau of Meteorology (BOM) to investigate Subsurface Technology Ambuja Cements Foundation. It’s an NGO set up by a whether Delft-FEWS could be used as an upgrade major cement company. You see that a lot in India: big to their current hydrological forecasting The first International Conference on Frontiers money-making firms re-investing a proportion of their environment. in Shallow Subsurface Technology (1st FSST) is profits in the community.” to take place on 20 – 22 January 2010 at Delft A pilot project has been set up, within which a combined University of Technology’s Aula Conference Centre. Mutual learning Deltares and BOM project team has implemented an To what extent is the project’s experience applicable experimental forecasting system for the Brisbane It will be hosted by Delft University of Technology, the elsewhere? “Gujarat is not the only part of India where basin combining Delft-FEWS with the current BOM Dutch Ministry of Housing, Spatial Planning and the coastal areas face the problem of salt intrusion”, says operational hydrological model URBS. Environment, and Deltares. The aim of the conference Van Weert. “For that reason, we’ve invited other states is to stimulate the exchange of ideas among a com- to attend a multi-day conference this autumn. We The system uses the new interactive forecast- munity of scientists and professionals with a common plan to present our research results there and hope ing paradigm added to Delft-FEWS for the National Advanced laboratory interest in understanding the impacts of subsurface in turn to learn from water management strategies in other areas. That’s what it’s all about: mutual learn- Weather Service in the USA. The first phase of the pilot has now been successfully completed and a second research Fehmarn Belt utilization. Participants will include scientists and professionals, regulators and policymakers, engineers ing. After all, I’m involved in the project on behalf of phase will be launched to look at possible implemen- and contractors, consultants, and government and IGRAC and the IGRAC motto is ‘sharing groundwater tation strategies for the whole of Australia. Deltares has been asked to perform hi-tech other stakeholders. The language of the conference information and experience’.” IGRAC, the International laboratory research for the construction of a will be English. Groundwater Resources Assessment Centre, works un- For more information: crossing - a bridge or tunnel - between Puttgarden der the auspices of WMO and UNESCO and is hosted by (Germany) and Rødbyhavn (Denmark). Topics are: Deltares. (See • Characterization, imaging, and monitoring The 20-km sea crossing between Puttgarden and techniques Rødbyhavn is currently served by busy ferry services. • Subsurface engineering “You demystify groundwater By 2018, however, there is intended to be a fixed • Subsurface heterogeneities knowledge for us” link enabling cars to drive directly to Copenhagen or Hamburg. This connection is to be called ‘The Fehmarn • (Bio)geochemical and physical processes • Ecosystem functions Belt Fixed Link’. Deltares is to perform the relevant soil • Subsurface management and organization The possibility of up-scaling is also part of the Orissa research in cooperation with the Danish Geotechnical planning project, as Kuijper confirms: “Together with our Dutch Institute (GEO). • Geo-energy partner ICCO, the Interchurch Organisation for Devel- Upgrade your • Risk management and safety opment Cooperation, we’re now looking to see whether similar projects could be run in other parts of India or knowledge The contract was awarded after a tense tender phase in which the criteria were the quality and proper deploy- For more information: elsewhere. The success of a project like this depends ment of an enthusiastic team. The main experiments on the presence of an organization like Gram Vikas, Deltares Academy is Deltares’ educational facility to be performed at our laboratory are: cyclic direct sim- big enough to adopt our approach and perpetuate it in the field of water and subsurface engineering. ple shear, constant rate of strain, cyclic triaxial experi- later.” Kuijper stresses that an essential part of that Our international courses and masterclasses focus ments and resonant column. The assignment is a great approach is the popularisation of knowledge. “We are on knowledge enhancement for professionals. opportunity for our geotechnical lab. making hydrology and groundwater management Participants may be consultants and engineers accessible to people at grassroots level. ‘You demys- who are involved in the planning, design and con- For more information: tify groundwater knowledge for us’, as the director of struction of water, soil and subsurface related Gram Vikas puts it.” projects but we also welcome risk management operators, government staff and principals. Our For more information: lecturers are highly qualified. The content of each or course is based on real-life cases. Courses are con- ducted in English. For more information on the 2010 course programme: or visit 24 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 25
  • 14. PhDs Trends in groundwater quality in relation Dune erosion during storm surges to groundwater age Large parts of The Netherlands surf zone (as close as possible to Groundwater quality has ity monitoring network in Brabant. are prevented from flooding by the dune). In addition a (stereo) improved since 1990 in Brabant, These data were combined with a narrow strip of sandy beaches camera pair was deployed to a province in the south of the estimated age of groundwater and dunes. Simple dune erosion make 3D reconstructions of the The Netherlands. Concentrations samples. The age of groundwater models are available to assess dune face from image pairs in of nitrate and other contaminants is the time that has elapsed the impact of storm surges on order to study the interaction be- related to agriculture have since it infiltrated the soil as rain sandy coasts. However, the tween the dune and the (swash) decreased in groundwater that water. The groundwater ages in applicability of these models is waves that impacted on it. has recharged since 1990. Brabant were determined by the limited (the available models radioactive decay of the hydro- presume a uniform coastline and • The modelling of near dune hy- This improvement in groundwater gen isotope tritium.This research the absence of hard structures). drodynamics. The study found quality may be attributed to leg- has also shown that nitrate reacts that it is not the highest (wind) islation implemented in the past with sediments in the subsurface The purpose of this thesis was to waves in deeper water that reach twenty years, which was actually of Brabant. The sediments act as a improve the understanding of dune the dune and erode it, but rather aimed at reducing the leaching of trap for nitrate, effectively protect- erosion physics and to develop a the much longer (infragravity) • The aggregation of new physical nitrate and phosphate to surface ing deeper groundwater against more generic dune erosion model waves resulting from interactions insights and model approaches water and groundwater. nitrate pollution. Unfortunately, threat to the quality of deeper that could be applied in more com- between the shorter wind waves. in the morphodynamic model The improvement in groundwater this reaction may release heavy groundwater in Brabant. plex coastal systems. To this end, XBeach. The model was applied quality was demonstrated by a metals, which occur naturally in the thesis discusses: • A model approach to simulate to a range of dune erosion condi- re-analysis of existing measure- these sediments. This release of For more information: the high sediment concentra- tions. ments from the groundwater qual- heavy metals may pose a hidden • A large-scale dune erosion ex- tions in the vicinity of the dune. periment conducted in the Delta In this approach, wave breaking For more information: Flume. During the experiment, induced turbulence is injected detailed measurements of waves, into the water column and reach- flows and sediment concentra- es the bed as a pulse, which stirs Bridging Boundaries: Making scale choices in tion were collected in the inner up large quantities of sand. multi-actor policy analysis on water management the agenda, the options found and empirical cases: the Long-Term the impacts addressed. This also Vision for the Scheldt Estuary and Satellite data as complimentary information affects the process, because scale choices are not politically neutral: The Netherlands Water Shortage Study. Scale choices appear to be for hydrological modelling they may benefit or disadvantage an important framing instrument certain actors by putting their that can be used by policy analysts. On 30 September, Hessel upper Zambezi. In a tributary to urgent problems and/or preferred The tool presented in this thesis to Winsemius defended his PhD the Zambezi, the Luangwa River, options on the agenda, and may make scale choices a subject of dis- thesis, resulting in a cum laude evaporation estimates, based on hide or stress the positive or nega- cussion can also serve as a means PhD degree. The thesis dealt satellite data were used in combi- tive impacts of options. They may for the policy analyst to address with the problem of hydro- nation with scarce non-overlapping also influence the actors that are other fundamental issues that are logical modelling in data scarce rainfall-runoff records to constrain involved, the possibilities for con- usually present below the surface regions. model parameters using a proba- sensus building and the political but are hardly ever out in the open, bilistic framework. Both studies sensitivity of the study. It is impor- such as differences in power, inter- Several satellite data sources have show that studies in data scarce This thesis synthesizes different tant, therefore, to pay sufficient ests and hidden agendas. been used in combination with regions can benefit from remotely perspectives on scale choices attention to scale choices in the scarce and poor quality data in case sensed observations. The thesis (spatial boundary setting, tem- design of policy analyses. For more information: studies in the Zambezi River ba- can be downloaded from http:// poral boundary setting and the sin, Southern Africa. Observations selection of the level of aggrega- Yet little is known about the from the GRACE gravity satellite tion) in policy analysis. specific effects of scale choices and mission, monitoring large-scale For more information: how they are made in practice. In terrestrial water storage changes, Scale choices influence the con- this research, the making of scale were used to construct and vali- tent of a study: the problems on choices was studied using two date a hydrological model for the 26 Deltares VIEWS Nº 2 Deltares VIEWS Nº 2 27