Midterm review Report

Hotspot Major Rivers

KfC 68/2012

Author: Harold van Waveren, coordinator Hotspot Major Rivers

Rijkswaterstaat Waterdienst

August 2012

Copyright © 2012

National Research Programme Knowledge for Climate/Nationaal Onderszoekprogramma Kennis voor Klimaat (KvK) All rights reserved. Nothing in this publication may be copied, stored in automated databases or published without prior written consent of the National Research Programme Knowledge for Climate / Nationaal Onderzoeksprogramma Kennis voor Klimaat. Pursuant to Article 15a of the Dutch Law on authorship, sections of this publication may be quoted on the understanding that a clear reference is made to this publication. Liability

The National Research Programme Knowledge for Climate and the authors of this publication have exercised due caution in preparing this publication. However, it cannot be excluded that this publication may contain errors or is incomplete. Any use of the content of this publication is for the own responsibility of the user. The Foundation Knowledge for Climate (Stichting Kennis voor Klimaat), its organisation members, the authors of this publication and their organisations may not be held liable for any damages resulting from the use of this publication.

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Contents

1 Introduction ...... 4 1.1 Hotspot Major Rivers ...... 4 1.2 Organisation ...... 5 1.3 Adaptation strategies ...... 6 2 Problem analysis ...... 7 2.1 Starting points and problem analysis ...... 7 2.2 Neder Rhine-Lek ...... 7 2.3 Waal ...... 8 2.4 IJssel ...... 8 2.5 Meuse ...... 9 2.6 Problem analysis conclusions ...... 9 3 Potential adaptation strategies Rivers Area ...... 10 3.1 Guiding principles strategy development ...... 10 3.2 Neder Rhine and Lek ...... 11 3.3 Waal ...... 11 3.4 IJssel ...... 11 3.5 Meuse ...... 12 3.6 Assessment of potential strategies ...... 12 3.7 Multi-layer safety ...... 15 3.8 Delta decisions and the Rivers Area ...... 16 3.8.1 Delta decision on Fresh Water ...... 16 3.8.2 Delta decisions Rhine-Meuse delta ...... 17 3.8.3 Delta decision IJsselmeer area ...... 18 3.9 Adaptive Delta management: connecting long-term with short-term area development ...... 20 4 Contribution to strategy development per KfC project and theme ...... 22 4.1 Introduction ...... 22 4.2 Contribution from 1st tranche projects ...... 22 4.3 Contribution per KfC theme ...... 26 4.3.1 Theme 1: Climate Proof Flood Risk Management ...... 26 4.3.2 Theme 7: Governance ...... 27 4.3.3 Theme 6: Climate projections ...... 28 4.3.4 Theme 8: Decision support tools ...... 28 4.4 Outlook ...... 28 5 Conclusions and outlook ...... 29 References ...... 31 Appendix 1: Delta decisions ...... 32

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1 Introduction

1.1 Hotspot Major Rivers Within Knowledge for Climate (KfC), the area of the major rivers is designated as one of the eight hotspots; one of the specific locations in the Netherlands where knowledge about climate adaption is both developed and put into practice. It is an area where especially the altered level of river discharge may have important consequences for the local inhabitants and the spatial planning of the rivers area. Reason enough to develop adaptation strategies in order to deal with a changing climate.

Two large rivers flow in the hotspot area: the Meuse and the Rhine. The latter consists of the branches Waal, Neder Rhine and IJssel. Both rivers are located at the end of large, international river basins. The basin of the Meuse is located mainly in Belgium, France and Luxembourg. The Rhine basin spans an area which includes Germany, France and Switzerland. Downstream, the border of the Hotspot Major Rivers is the point where the river changes to the Hotspot Rotterdam Region, which is near Gorinchem. For the IJssel, the border is located at the IJssel delta, near Kampen. The following map shows the area of the Hotspot Major Rivers.

Fig. 1: Basins of Rhine and Meuse. The area of the Hotspot Major Rivers runs to Kampen (IJssel) and Gorinchem (Rhine).

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1.2 Organisation Within Knowledge for Climate, Hotspot Major Rivers constitutes a special hotspot. It is a relatively small hotspot, where no administrative support has been established. This resulted in a lack of clear question- led management of the research programme. It was also difficult to source co-financing, because there were no 'natural' supporters who were willing to provide financial support to the research. In addition to this, the area of the hotspot almost completely overlaps with the Delta Programme’s Rivers sub-programme1, in which adaptation strategies are also developed to cope with the changing river discharges. There is therefore a major risk of overlap in research. In order to solve the above problems, it was decided that the hotspot and the Delta Programme’s Rivers sub-programme would work together very closely. This way, a certain degree of question-led research is developed, we are close to the administrative supporters of the Delta Programme (central government, provincial authorities, municipalities and water boards) and it creates good opportunities for co- financing. The advantage of this cooperation for the Delta Programme is that the research of Knowledge for Climate is released to them, and wherever possible, tailored work is delivered in relation to the research questions of the sub-programme. This creates maximum synergy between Knowledge for Climate and the Delta Programme in the rivers area. In terms of organisation, it means that the knowledge manager of the Delta Programme’s Rivers sub- programme is the co-hotspotleader at Hotspot Major Rivers. From his overview of the knowledge agenda of the Delta Programme he is able to provide optimal leadership in research carried out by Knowledge for Climate in the rivers area. In addition to this, a number of people from various KfC themes are joining the Delta Programme’s Rivers sub-programme. This particularly concerns researchers from theme 1 (Climate Proof Flood Risk Management) and theme 7 (Governance). Finally, a number of projects were completed in the first phase of the KfC, which offered added value to the Delta Programme. This concerned 4 projects:  HSGR02 (Aline te Linde, Deltares): Assessment of upstream flood risk in the Rhine Basin2  HSGR06 (Philip Ward, VU-IVM): Adaptation to Meuse flood risk3  HSGR07 (Jan de Goei, Movares): Delta dykes: Area-specific research into new dyke improvement alternatives4  HSRR07/HSGR08 (Joop de Boer, VU-IVM): Risk perception: Relationship between perceived flood risks, problem ownership and household and business adaptation choices5

The Delta Programme only pays limited attention to the international aspects of water management, which meant the first two studies provided added value. Delta dykes are high on the agenda since the 2nd Delta commission (commission Veerman), which meant that the third study from the first tranche

1 http://www.rijksoverheid.nl/onderwerpen/deltaprogramma/deelprogramma-s/deelprogramma-rivieren 2 http://knowledgeforclimate.climateresearchnetherlands.nl/hotspots/major-rivers/hsgr02 3 http://knowledgeforclimate.climateresearchnetherlands.nl/hotspots/major-rivers/hsgr06 4 http://knowledgeforclimate.climateresearchnetherlands.nl/hotspots/major-rivers/hsgr07 5 http://knowledgeforclimate.climateresearchnetherlands.nl/hotspots/major-rivers/HSRR07-HSGR08

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also offered added value to the Delta Programme. In consideration of the importance of involving the local residents in the Delta Programme’s area processes, the latter project is also important. Chapter 4 will go into more detail regarding the content and results of these projects.

1.3 Adaptation strategies Given the close cooperation between Knowledge for Climate and the Delta Programme, within the Hotspot Major Rivers of KfC it was decided not to develop separate adaptation strategies, but to move forward together with the Delta Programme. In practice, this means that Knowledge for Climate contributes towards the strategy development of the Delta Programme. The Delta Programme works towards decision making in late 2014 regarding so-called Delta Decisions (also see Appendix 1). This happens in 3 steps: 1. Potential strategies (report: September 2012). 2. Promising strategies (report: September 2013). 3. Preferred strategies (report: September 2014).

The knowledge developed by KfC will prove useful in this. The KfC researchers working in the Delta Programme therefore also contribute to the strategy development. In this midterm report, the potential adaptation strategies as they have been developed thus far are described in Chapter 3. Prior to this, a problem analysis is first given in Chapter 2. At the end of this report, a short explanation about the contribution to the potential adaptation strategies from the various KfC projects and themes is given in Chapter 4. There will also be an indication of what opportunities there are in the next two years to utilise the results from KfC in the further development of adaptation strategies in the rivers area.

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2 Problem analysis

2.1 Starting points and problem analysis The original task for the Delta Programme’s Rivers sub-programme was aimed at securing water safety and a supply of fresh water in the long term in the light of climate change (higher river discharges and rising sea levels), to be worked out in a preferred strategy in relation to spatial ambitions. The guiding principle was the currently established standard (overtopping probability). These tasks must be considered in connection with the short term tasks: the new Flood Protection Programme (Dutch abbreviation: nHWBP), dealing with piping and the tasks in the medium term: updating protection levels, searching for changes for implementing multi-layer safety and synergy advantages which can be achieved by intelligent linking with the replacement task for water related civil engineering works. In the problem analysis, it is taken as given that the on-going implementation programmes (Room for the River6, Maaswerken, NURG and HWBP2) have been completed and 2015 is used as the reference year. The following is used to calculate the rise in water levels: a. discharge of 18,000 m3/s at Lobith and 4,600 m3/s at Eijsden in the target year 2100; b. delta scenario’s Steam and Warm (Source: Deltascenario’s); c. the discharge distribution in accordance with policy, i.e. no discharge increase through Neder Rhine and Lek in case of discharges above 16,000 m3/s at Lobith.

Sensitivity analyses are also used to investigate autonomous developments which lie outside the bandwidth of the above scenarios. One of the scenarios considered is what happens if large scale dyke constructions are carried out in Germany along the Rhine this century. In that case, far more water may reach the Netherlands than the abovementioned 18,000 m3/s.

2.2 Neder Rhine-Lek Taking the current policy as a guiding principle (National Water Plan) not to discharge extra water via the Neder Rhine-Lek in the event of discharges above 16,000 m3/s, the long-term water task resulting from climate change for the Neder Rhine-Lek only consists of the consequences of rises in sea levels (25 cm at Schoonhoven to 60 cm at Krimpen aan de Lek). There are serious spatial frictions on the Culemborg-Vianen and Beneden-Lek routes. The short-term tasks consist of dyke sections on the south side of the Lek which do not meet the standard. The piping approach plays a role along the entire Neder Rhine-Lek. The economically optimal protection levels along the entire Neder Rhine-Lek are higher than the current standards (source: Water Safety 21st Century, WV21). Particularly on the north side the current protection levels are many factors lower (dyke rings 44 and 45, Crooked Rhine (44-1) and Gelderse Vallei (45-1, including Grebbedijk). At dyke rings 14, 15 and 44 system functioning also plays a role: the water can flow through dyke rings 15 and 44 to dyke ring 14 (Central Holland) here. The safety of the Randstad is thus threatened from the river and is currently not as it should be. On the south side

6 http://www.ruimtevoorderivier.nl/meta-navigatie/english/

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there is a major safety issue for the Alblasserwaard and Vijfheerenlanden (dyke ring 16) from the point of view of managing the risk of casualties.

The fresh water supply for Western Netherlands, including the Groene Hart (Green Heart), is dependent on the inlet of water from the river Lek. In this respect, climate change may lead to insecurity regarding the availability of sufficient water of good quality. Water shortage may cause damage to sectors such as agriculture, shipping, nature, energy provision (cooling water), but the shortage also has an effect on water safety in this area (accelerated subsidence, drying of peat dykes).

2.3 Waal In the long term, the task relates to a water level increase of 55 to 85 cm. This rise is caused both by a higher river discharge and a greater sea level rise. Especially along the section of the Waal between Tiel and Gorinchem, it will be hard to accommodate this. Choices in Rijnmond-Drechtsteden may lead to an increase in the tasks upstream. In the area of the Waal and the Merwede, an accumulation of water tasks with spatial ambitions is to be expected. The short-term task consists of dyke sections on the north side of the Waal which do not meet the standard and a major task to get to grips with piping both on the north and south side of the Waal. In the third test, about 50 km was declared unfit on the north side and on the south side 56 km in dyke ring 43. On the grounds of SCBA (MKBA) and casualty analysis (Slachtofferanalyse, SLA) of Water Safety 21st Century (WV21), there is reason to improve the protection level in the following areas: Alblasserwaard and Vijfheerenlanden (dyke ring 16-1), Heerewaarden (40- 1), Land van Maas en Waal (41) and the Betuwe (43). The Waal is not only an important historical transport axis; there is still river-related trade activity in development along the Waal. The low water task shows a significant bottleneck for shipping on the Waal and limitations for water intake from the Waal.

2.4 IJssel A rise in water levels of 25 cm to 35 cm is expected in the IJssel, due to climate change. Accumulation of the water tasks with spatial ambitions is predicted in particular in cities with historical city fronts on the river (i.e. Zwolle, Deventer and Zutphen). The results of the third test show that approximately 70 km of the dykes along the IJssel are currently not fit for the purpose. The greatest stretches of dyke which do not meet the current standards are located on the east bank between Zwolle and Deventer. Part of these dykes will meet the standard again once the Room for the River Programme is implemented. Along the IJssel, new insights regarding piping also play a role. The task on the IJssel may become weightier due to choices in the IJsselmeer level and/or choices in the Rhine-Meuse delta (less load on the Lek). On the basis of the economic analysis, the protection levels of part of the dyke rings in the region demand attention (dyke rings 47, 48, 50 and 53). The greater part of the IJssel has a casualty risk of less than 10-5 and greater than 10-6. Areas of attention are the sections along the Pannerdens canal (Rijnstrangen) and small sections on the west side of the IJssel which have a casualty risk of greater than 10-5. An area of attention for this region is the great planning variations in the most economically optimal flooding risk on the western IJssel bank.

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The water safety task is highly complex in the IJssel-Vecht delta, the area around and between Zwolle- Kampen-Zwartsluis. This is partly due to the socio-economic context (growth region) and high cultural historic and landscape values (National Landscape). This area is confronted with the possible rising of the IJsselmeer level, unsuitable dykes in the context of the third test and an increasing river discharge, whilst the protection level in parts of the area also deserve attention. A lower river level due to climate change on the Arnhem-Zwolle route may cause disruption to shipping. In addition to this, there is drought damage for agriculture along the entire area along the IJssel.

2.5 Meuse The rise in the water level of the Meuse due to climate change varies between 25 and 90 cm. Accumulation of the water task with meaningful spatial ambitions is foreseen at Maastricht, Venlo and Ravenstein. The short term task consists of virtually all the embanked sections of the Limburg Meuse, they either fail to meet the standards, or further investigation is required. This will be resolved in the on- going Maaswerken programmes or programmes derived from it, for 2015/2020. Almost the entire embanked section of the upstream Meuse does meet the current standards. Piping plays a role along the Meuse dykes and is partially still under investigation. The SCBA and casualty analysis were only investigated for sections of the Limburg Meuse in WV21. The investigation suggests that on economic grounds, the protection level in densely populated quay areas demands attention. At the same time, a complication is that for safety it is presumed that the 1/250 dyke rings along the Limburg Meuse flood at a discharge above the 1/250. A full area analysis was carried out for the embanked Meuse, which shows that from an economic viewpoint it would be desirable to improve the protection level. The low water discharge as a consequence of climate change leads to bottlenecks in the water distribution for shipping, regional water supply and energy supply.

2.6 Problem analysis conclusions On the grounds of SCBA and casualty risks from WV21, it is clear that the protection levels in the rivers area require updating in many places. This will be worked out in further detail in the following year. A number of important gaps in knowledge have also been found. For example, it is desirable to determine the water task (now available for the year 2100) for the target year 2050, the task should be based on the chance/risk of flooding, and for the Limburg Meuse only a limited number of dyke rings and SCBA and casualty analyses (Slachtofferanalyse, SLA) are available. Finally, the Flood Risk in the Netherlands (Veiligheid Nederland in Kaart, VNK) has not yet been carried out for all dyke rings. In this project, an investigation is carried out into the failing mechanisms per dyke ring. In recent years this has led to many new insights including insights on piping. There appears to be a much greater risk than had hitherto been assumed.

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3 Potential adaptation strategies Rivers Area

3.1 Guiding principles strategy development The potential adaptation strategies for the rivers area are based on the water task for the long term as a consequence of climate change, working on the basis of the current standard (overtopping probability). The work has also been carried out on the basis of the on-going implementation programmes Room for the River, Maaswerken and HWBP-2 have been completed and that spatial reservations remain. The reference year is therefore 2015-2020. The current approach consists of a mix of different types of measures per river branch (reinforcing dykes and river widening). The potential strategies are formed of equivalent types of measures, to map out the corners of the playing field. Two of these form an optimisation of the current strategy. The third features larger alterations to the system. These considerations lead to the following potential strategies for Climate Proof Flood Risk Management: 1. Room for the River Plus: Use of planning measures by using areas which have already been reserved (Barro), flood plain measures and adding new areas to the rivers area by dyke relocation. For the water defences, the traditional process of testing and reinforcing dykes also continues. One possible ‘remaining’ task which cannot be realised by means of spatial measures can be absorbed by means of heightening dykes. 2. Do more with dykes: Using different methods to reinforce dykes, including innovative prevention measures such as delta dykes with the aim of making the testing and reinforcing the dykes and the fulfilment of the task for the long term achievable in one go (target year 2050). 3. System interventions: Implement measures for water management planning of the area, usually with a supra-regional effect, for example a new river. For the water defences, the traditional process of testing and reinforcing of dykes also continues.

In order to gain insight into the effectiveness of these strategies, a reference strategy has also been investigated. The same guiding principles mentioned above apply to this strategy and the measures consist exclusively of the traditional improvement of the water defences to meet the standard, ensuing from the cyclical testing of the water defences (HWBP). The promising strategies, to be worked out in the next phase, will in turn consist of a mix of measures per river branch. In addition to the abovementioned potential strategies, it will be researched per river branch indicatively which measures might be taken in the second and third layer (of the multi-layer safety). On the basis of the inventory of these measures, which measures offer the best prospects will be assessed in future years on the way towards the preferred strategy. In addition, where relevant, per potential strategy, a consideration will be made of what the potential consequences are of a change in the discharge distribution, following from the changes on the scale of Rhine-Meuse Delta and/or the choices in the IJsselmeer area. It has already become clear that fully guiding the extra Rhine discharge of 2,000 m3/s into the IJssel is not realistic. In the following paragraphs we will set out the potential strategies per river branch in further detail.

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3.2 Neder Rhine and Lek The potential strategies have limitations in the facilitating of the long-term water task for the Neder Rhine and Lek. From the PKB Room for the River, it has already become clear that the possibilities for river widening are limited in this river branch. At the same time, particularly in the downstream part of the Lek, dyke reinforcements are complex and extremely costly as a consequence of weak subsoil and planning limitations. Further upstream, there are more options for the dyke strategy, and the strategy 'Do more with dykes' offers opportunities, such as the utilisation of delta dykes at a few strategic locations (e.g. Grebbedijk). The necessity to weigh up large gestures arises. Be it creating new systems or to come to a distribution change at the IJssel head so the Neder Rhine and Lek are further spared and extra discharge takes place via the Waal and/or IJssel. The long-term options can be linked in good cohesion to the short-term tasks for this river branch. Thus the possible strategies in cohesion with the updating of the protection levels may for example offer a solution for the safety problems of Central Holland.

3.3 Waal The potential strategies which facilitate the long-term water task for the Waal may consist of both an approach related to dykes as well as an approach related to Room for the River Plus (use of reserved areas and flood plain measures). Both the strategy ‘Do more with Dykes’ and the strategy ‘Room for the River Plus’ has a synergy with the short-term tasks (HWBP3, dealing with piping and improving protection levels). For dykes, tasks may be linked and in case of river widening, the released soil can be used. A different water distribution, whereby approximately 800 m3/s extra is discharged via the Waal in order to spare the Neder Rhine and Lek more, can be realised with a dyke strategy and a strategy with system intervention (expansion of river system/large gestures).

3.4 IJssel The potential strategies which facilitate the long-term water task for the IJssel may consist of both an approach according to 'Do more with dykes' as well as an approach with ‘Room for the River Plus’ (use of reserved areas and flood plain measures). Both a strategy focusing on dykes has synergy advantages with the short-term tasks (HWBP3, dealing with piping and improving protection levels) and the ‘Room for the River Plus’ approach. In case of a choice for a changed discharge distribution or to spare the Lek more (400 m3/s extra into the IJssel) and depending on the choice for 'rising and setting up' the IJsselmeer level (max 85 cm extra task in downstream IJssel) the abovementioned strategies do not offer a solution. This will require far- reaching actions which are detrimental to the existing value, such as the river fronts of Hanse towns and landscape value such as tree dykes. Then, strategies come into view where multi-layer safety has a place, or system interventions can be used. The Pannerdensch Canal furthermore has limited capacity and it requires far-reaching additional measures around the separation points in order to enable extra discharge towards the IJssel. The decision between sparing the Lek and discharging more via the IJssel is a question of allocating the benefits and burdens.

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3.5 Meuse The possible strategies which facilitate the long-term water task for the Meuse can be realised either with a strategy of river widening or ‘Do more with Dykes’. The decision of whether to make the 1/250 dyke rings around the Limburg Meuse floodable forms a special aspect which will be investigated in further detail in the follow-up phase. Another point of attention for the Meuse is that the measures taken upstream that could lead to downstream peaks in water flows (regional waters and the Meuse) may further coincide ('s-Hertogenbosch region).

3.6 Assessment of potential strategies The following gives an overall impression of the potential strategies. This assessment is partly based on the application of the national comparison methodology (source: vergelijkingssystematiek Deltaprogramma; version spring 2012). At the main criterion 'Target range Safety' the appropriate subcriteria have also been applied and at the main criterion 'Functions and values', a relevant selection of subcriteria has been used. The strategies have been qualitatively assessed per criterion on the basis of expert knowledge. The set-up of potential strategies determines the target range of safety to a large extent. After all, the strategies were developed from an approach involving flooding chances and the target range is assessed on the basis of risk estimation (in accordance with comparison methodology). The potential strategies have therefore not been developed in order to arrive at an optimal risk reduction. In the following assessment of the strategies for target range safety, this restriction must be taken into consideration. The following pages show the maps with the associated potential strategies.

 Map 1 - Strategy Room for the River Plus, whole of the Netherlands  Map 2 - Strategy Do more with Dykes, whole of the Netherlands  Map 3 - Strategy System interventions, whole of the Netherlands  Map 4 - Reference strategy, whole of the Netherlands

Room for the River Plus (= making use of reserved areas and flood plain measures). The river expansion outside the dykes and the use of long-term spatial reserves (from AMvB Ruimte en Infrastructuur) offer an adequate solution for the increased river water levels in most sections of rivers. For the Waal between Tiel and Gorinchem, further measures have to be taken in addition to the reserved areas. In this strategy, the chance of flooding, and in an unaltered spatial usage also damage and number of casualties, will in due course remain the same as in the current situation. The potential increase in river water levels is after all fully compensated by the river expansion. This strategy offers many chances for additional spatial quality and nature along the rivers. Due to area loss, the effect on agriculture is negative. Considering the planning impact (process risk), the feasibility of the strategy, except for along the Waal (Waalweelde), has been assessed as negative. The costs have been assessed as negative in comparison to the reference strategy due to the combination of measures (HW and river expansion). See map 1 - Strategy Room for the River Plus, whole of Netherlands.

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Do more with Dykes (= optimising current strategy: addition to HWBP-cycle with innovative preventative measures such as delta dykes, climate dykes etc.), whereby one intervention fulfils the task for the long term. This strategy is able to solve the increased river water levels everywhere; with technical innovations, many bottlenecks in traditional dyke strategy can be overcome. This strategy also leads to a reduction of both the chance of flooding and number of casualties, and therefore the risk of casualties. This is mainly realised by dykes that don't break through. The damage is reduced, but water can flow over the dyke and lead to damage. This strategy scores slightly more positively than the reference strategy for the quality of life and spatial quality. There is less recurring inconvenience due to dyke reinforcement and the possibility to make a better local connection with delta dykes to regional requirements for co-usage. The necessary extraction of clay offers some opportunities for the environment. Feasibility is scored as neutral due to the far-reaching measures (process risk) versus advantages of linking with the testing and reinforcing of dykes (HWBP). Considering the combination options with the regular reinforcement of the dykes (linking with HWBP) the cost for this strategy is between the reference strategy and the ‘Room for the River Plus’ strategy. See Map 2 - Strategy Do more with Dykes, whole of the Netherlands.

System interventions (=interventions in water management planning with supra-regional effect). This strategy can contribute to a full or partial solution to the increased river levels per river branch or for the whole river system (Rhine). This strategy therefore scores the same neutral target range for the effectiveness in the river branch concerned as the strategy ‘Room for the River Plus’. If the choice is for another discharge distribution it leads to a negative effect on the target range in the other river branch. The strategies mostly score neutrally for fresh water supply. In the ‘System interventions’ strategy, it is possible to link in with measures for storing water (retention). The possibilities and consequences of the use of system interventions at system level (upstream retention for Rhine branches) will be explored in the follow-up process. The ‘System interventions’ strategy scores mostly negative for the aspect of liveability (cutting through areas and village connections). Due to area loss, the effect on agriculture is negative. Other discharge distributions may have an effect on shipping (change in morphology: increased dredging). Due to the far-reaching spatial impact of the measures, the feasibility of the strategy has been assessed as strongly negative (process risk). The strategy has been assessed as the highest with regards to investment costs (HWBP + far-reaching or costly measures). See Map 3 - Strategy System interventions, whole of the Netherlands.

Reference strategy (= continuing the HWBP-cycle with the traditional dyke approach, reservations remain intact). This strategy solves part of the safety problems, but also has its limitations. The flooding chance for this approach remains the same in due course as in the current situation. Damage and number of casualties increase slightly in the event of flooding due to the increase in river water level (greater flooding depth). It is not self-evident that by means of this working method, the required water safety will be realised in a timely and cost effective manner in the long term (2050-2100). This strategy has been assessed as negative for the aspect of liveability (regularly recurring dyke reinforcement) and planning quality (quality of landscape). For example in a few towns and areas with high value nature,

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landscape and culture. Due to the mainstream character of this approach, the feasibility and costs have been scored as neutral (basic investment). See - Map 4 - Reference strategy, whole of the Netherlands.

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3.7 Multi-layer safety Multi-layer safety (Meerlaagse veiligheid, MLV) means that three layers of water safety can be distinguished:  Layer 1: measures that prevent floods  Layer 2: measures for climate-proof planning for the area, which can limit subsequent damage  Layer 3: crisis management (including reporting, crisis advice, operational management, evacuations in case of high water levels)

Almost all strategies which make an effort with layer 1 (prevention) produce a major reduction in the number of casualties and the amount of damage expected annually; the measures are often also very cost effective. Layer 1 is therefore the most important cornerstone for risk reduction in the rivers area. The construction of a delta dyke may be worthwhile in specific locations. For example, where an urban area borders directly onto a river (Arnhem) or where relative short dyke stretches may lead to collapse with major economic damage/high numbers of casualties (Grebbedijk). In order to prevent a cascade, a floodable dyke may be considered at a number of locations: along the north side of the Upper Rhine, at the southern Waal dyke downstream of Nijmegen and at the eastern part of the dyke of dyke ring 15. A floodable dyke can be constructed raised or lowered. When constructing a raised dyke, an implicit transfer is made onto the adjacent dykes (downstream or on the opposite side of the river). The effectiveness and particularly the efficiency of contributions of layer 2 measures differ. From the area pilots, and on the basis of earlier studies and expert judgement, a number of locations can be appointed where compartmentalisation or flow steering may be sensible, such as the dyke rings in Limburg for example (closer investigation is required here) and along the west side of the Amsterdam-Rijnkanaal (dyke ring 43). Further downstream, a compartmentalisation may be considered to protect the eastern part of Gorinchem for example.

In the other dyke rings in the downstream rivers area, compartmentalisation would not appear to be a useful measure. The dyke rings are very low, which means a high dyke is required to defend against the water. Furthermore, the dyke needs to be constructed on weak soil, and **coupling options are limited. Along the IJssel, a compartmentalising dyke may be considered at three locations: at Zwolle, Zutphen and Deventer. A compartmentalising dyke in the Land van Maas en Waal prevents water from the Waal flowing to the Meuse (system functioning). Almost all compartmentalising dykes must be combined with an outlet. Consequence reduction in the context of location choices and planning is extremely effective, in the case of restructuring this approach appears to be less cost effective. The embedding of risk- conscious planning in long term planning policy and the linking of such measures to other developments deserves closer attention. In urban regions, these measures may in the long term also prove attractive. Adjusted construction is especially useful in areas which do not flood deeply (max. 1.5 m) and with a low frequency of flooding. Adjusted construction works in the existing built-up area will only contribute to the reduction of the consequences of flooding in the very long term, as the refurbishment of existing

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buildings is too expensive and redevelopment and large-scale renovation often take place over many decades. Adjusted building works can especially be considered at locations where a lot will be invested in infrastructure and construction in coming years. In areas which will experience deep flooding, adjusted construction work is very difficult. 'Building elsewhere' due to limitations in public planning seems to be a more useful option. Such a limitation in public planning may be considered in the most downstream areas of sloping dyke rings in the rivers area or in the deep dyke rings in the transition area. Another consideration for building elsewhere may be the presence of high grounds. Making vital objects less vulnerable or protecting them can be very attractive and must be worked out in further detail and perhaps a wider line of approach must be followed. Measures in layer 3 that improve the organisation of disaster management and self-reliance may be (cost) effective. In the phase of promising strategies, the processing of multi-layered safety must be picked up in close partnership with provincial authorities and municipalities.

3.8 Delta decisions and the Rivers Area (also see appendix 1)

3.8.1 Delta decision on Fresh Water The strategies from the sub-programme Fresh Water have a mutual relationship with the task of the sub-programme Rivers on aspects of discharge distribution (relationship high-low water discharge distribution) and on spatial and economic aspects of river and river-related functions (shipping and spatial planning). The strategies 1 and 3 of Fresh Water (Water follows large scale, potentially with utilisation of market) have the objective of meeting the full water demand in drought. In the case of fast climate change (W+) this will demand large-scale measures: e.g. adjustment of the discharge at the branching point at Pannerden, up to 200 m3/s extra discharge into the IJssel in combination with closing off the Nieuwe Waterweg, or extra discharge into the Waal, minimal discharge into the IJssel, in combination with maximum buffering on the IJsselmeer. This will involve extremely high costs and far- reaching consequences for the functions in/on and around the Waal and/or IJssel. New large-scale measures may also be considered for these strategies, such as the construction of new canals and transporting water from the Waal to the Meuse. The other strategies 2, 4 and 5 (Water follows limited, Water directs spatial planning and user) lead to no, or much more limited consequences for the discharge water distribution and river(-related) functions. In 4 and 5, no measures are taken in the main water system in order to continue to facilitate the water demand, and the self-sufficiency of users and/or another spatial planning is relied upon. The discharge distribution over the various river branches forms the pivotal point between the area-based delta decisions and the generic sub-programme Fresh Water. The sub-programme Fresh Water carried out an analysis during this phase, with the most extreme positions of the control buttons. During the upcoming phase, an exploratory study will be carried out of unambiguous more realistic combination positions of the control buttons in order to augment insight into the correlation between the sub-programmes at low water and in order to arrive at promising strategies.

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3.8.2 Delta decisions Rhine-Meuse delta Due to the interdependence in the main water system of Eysden and Lobith up to the sea, a problem analysis has also been carried out on the level of the Rhine-Meuse delta. A number of elements and controllable civil engineering works (locks, weirs, storm surge barriers) determine in their mutual connection, how this system functions at a national level, or how it can be changed. These are the “control buttons” in our main water system. The combination of the possible settings of these control buttons determines how the water is distributed across the Netherlands under extreme high and low water levels, but also how to respond to future tasks. Three strategic choices (control button positions) at this level are relevant to work out the area-specific strategies: a) What do we do with the discharge distribution of the Rhine branches? b) What do we do with the Nieuwe Waterweg, maintain the opened/closed current situation? c) What do we do with the level and buffer of the IJsselmeer?

The settings of the other buttons are a derivative of the positions of these three buttons. It should, by the way, be noted that the actual changing of the position of a button will in many cases lead to considerable technical consequences, at high costs.

Figure 2: Control buttons in the Main water system

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When working out the solutions on the scale of the Rhine-Meuse estuary, the playing field was initially determined by variants whereby the entire increase of the river discharge for 2100 (from 16,000 to 18,000 m3/s, i.e. 2,000 m3/s) is led into the Waal or the IJssel. Maintaining the current policy would lead to a distribution over the Waal and IJssel of 1600 m3/s and 400 m3/s respectively, and no increase in the discharge into the Neder Rhine and Lek. Concentrating the discharge into the IJssel (2000 m3/s extra) would lead to an increased water level of approximately 2 m in the IJssel. This task on the IJssel cannot reasonably be dealt with by widening the river and/or heightening the dyke.

A solution where the entire IJssel valley is seen as a flood plain is then the only, though not very realistic, option. It is of no use to work out this option in further detail, the rise in water level is five times the rise determined in the distribution policy (approximately 40 cm). Concentrating the discharge into the Waal (2000 m3/s) leads to an increase of the water level by an average of 80 cm, whilst for the discharge distribution policy, the rise in water level would amount to approximately 64 cm. The accommodation of a rise in water level of 80 cm is difficult to realise with a strategy of river widening. This task can be realised by pursuing a strategy of dyke heightening. Nevertheless, this is not an easy solution, partly due to the expense and technical difficulty involved in realising control devices at the branching points and the risks of instability of the river morphology at these points. In addition to the options for concentrating the discharge into the IJssel and the Waal, an option for extra sparing of the Neder Rhine and Lek has been formulated in the second instance. By sparing this river branch at discharges over 7,000 m3/s (at Lobith) by approximately 1,000 m3/s, the water level rise as a consequence of sea level rises/storm at sea can largely be prevented on this river branch. In the follow-up phase, processing will be limited to this task, which leads to the examination of two variants a) entirely into the Waal; and b) approximately 800 m3/s into the Waal and approximately 400 m3/s into the IJssel. In the latter case this could lead to an increase in the frequency of normative high water situations on the IJssel.

3.8.3 Delta decision IJsselmeer area The delta decision on the IJsselmeer area is about the development of the level management in the IJsselmeer with the associated discharge distribution over the branches of the Rhine. The decision surrounding the IJsselmeer area therefore reaches further than the choice regarding the IJsselmeer level, but also affects the choices of discharge distribution. The preparation of the delta decision on the IJsselmeer area is therefore the joint responsibility of the Delta Programme Rivers and IJsselmeer area. For the relationship between the Delta Programmes IJsselmeer area and Rivers, a set-up is followed which is derived from the process that was completed for the Rhine-Meuse delta. In the first instance, the relevant control button positions are identified in the relation between IJssel discharge and IJsselmeer in order to then further process them and obtain an insight into the dependencies and choices regarding the IJsselmeer area buttons. This process was recently started by means of a first expert session in March 2012. On the basis of this meeting, first so-called 'button settings' can now be detailed for both IJssel and IJsselmeer. For the scale level of the delta decision on the IJsselmeer area, the future distribution of the increase in the Rhine discharge into the Lek, Waal and IJssel is important (from 16,000 to 18,000 m3/s), in particular how much water is led into the IJssel in the future. Then,

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what is relevant is how the increase in the IJssel discharge relates to the (im)possibilities for peak storage in the IJsselmeer and the (im)possibilities of discharging excess water (sluicing) via sluices in the Afsluitdijk.

IJssel Buttons There are (thus far) two situations which are of importance to investigate in further detail for the entire main water system, based on the analysis by the collaborating Delta Programmes in the Rhine-Meuse delta. These are: 1. distribution of the extra discharge flow-through (increase from 16,000 m3/s to 18,000 m3/s) according to the current policy (spare Neder Rhine-Lek, 1/3 IJssel - 2/3 Waal). For the IJssel this means an increase from 2,460 m3/s to 2,860 m3/s. On the scale of the Rhine-Meuse delta, the option was introduced to spare the Lek more, motivated by the situation in the lower course of the Lek where more extensive dyke reinforcement is practically impossible. The discharge via the Lek is then further decreased by extra discharge via the Waal or IJssel. At the scale level of the delta decision on the IJsselmeer it is relevant to explore the 2. extra sparing of the Neder Rhine-Lek, even in lower than normative conditions (range 7,000- 13,000 m3/s at Lobith), whereby the additional discharge was to be led via the IJssel. For the IJssel, this means an increase of the discharge up to a maximum of 3,260m3/s. Additionally, the frequency of high waters will increase.

IJsselmeer Buttons Excess water from the IJsselmeer is discharged via sluices in the Afsluitdijk into the Waddenzee. The sluices in the Afsluitdijk form a button that can be used to control the level management in the IJsselmeer. In case of high volumes of discharge via the rivers, the sluice capacity is insufficient to discharge it all directly. The water is temporarily stored in the IJsselmeer and the average water level will increase. This peak storage is also a button. Two relevant buttons can therefore be defined as: 1. Peak storage in IJsselmeer in case of high discharges, peak storage is related to the difference between the average water level on the IJsselmeer and the target level; 2. Sluice capacity (discharge of water) via sluices in the Afsluitdijk

Relationships and dependencies between the IJssel and IJsselmeer An increase in the high water discharge of the IJssel leads to amended design requirements for the discharge/sluice capacity in the Afsluitdijk (sluice complexes, potential pumping station or a combination of the two), or to an adjustment in dyke heights, which will lead to an increase in the peak storage of the IJsselmeer. There is a relationship between the sluice capacity in the Afsluitdijk and the peak storage in the IJsselmeer. The greater the sluice capacity, the less the water level on the IJsselmeer will temporarily increase at high river discharges. An increase in the peak discharge in the IJssel also leads to higher normative water levels along the river. There is a transition area between Zwolle and Kampen, the IJssel-Vecht delta, where the river and IJsselmeer levels together determine the normative circumstances. Choices with regards to the buttons have an influence on the location of this transition

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area. Normative high water situations in the mouth of the IJssel also occur in case of a serious (but not extreme) discharge in combination with a strong wind from the North West. It is relevant to gain more insight into the combination of storm from the IJsselmeer (North West) and medium high river discharges and the chances of this occurring. There is a relationship with the West of the Netherlands in this respect where a comparable problem applies. In the so-called transition areas, even medium discharges in combination with a storm can lead to normative circumstances.

3.9 Adaptive Delta management: connecting long-term with short-term area development In order to gain insight and support when connecting the short term spatial developments with the water safety task for the longer term, a partnership was initiated by DP Rivers with a limited number of projects. The state of affairs is explained below.

IJsselsprong Zutphen In December 2011 the State Secretary decided to retain construction of the Tichelbeekse Waard for the long term. Support is provided to the process of drawing up the master plan with information about the long-term task and potential long-term solutions. From carrying out river calculations, insight has been gained into the requirements to cover the water safety task. Support has also been offered for the mapping out of chances and bottlenecks in the choice for the implementation of plan sections in the short or long term.

Ooijen-Wanssum In 2011, an administrative agreement was made between the provincial authorities, water boards and municipalities for the implementation of the area plan. Among other things this area plan sets out the safety plan in the long term. The financial cover for the area plan (total 210 million Euros) was sourced from regional governments (50), the Meuse works (10) and Central Government (125). The rest is earned back via house-building, extraction of minerals and port development.

Maasplassen A master plan has been completed for the Maasplassen area with commitments between public and private parties. A plan with a structure vision for various sub-areas is being prepared.

WaalWeelde In 2011 promising and feasible projects were selected. The provincial authorities and central government reserved 30 million each for this. The schedules of the decision-making of the structural vision WaalWeelde West and the strategising within the sub-programme Rivers and the delta decision Rhine and Meuse delta have been attuned to each other.

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Ravenstein By means of the ‘Delta-atelier’, support has been given for the connection of the Ravenstein area tasks with the forming of the preferred strategy for water safety in the long term.

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4 Contribution to strategy development per KfC project and theme

4.1 Introduction As stated above, a contribution was made from a number of KfC projects towards the development of potential adaptation strategies in the rivers area. In paragraphs 4.2 and 4.3, a short description is given of contributions from first tranche projects and from the second tranche studies per theme. Paragraph 4.4 will then go into further detail on the follow up of the research within Hotspot Major Rivers. In the next two years, work will be carried out within the Delta Programme’s Rivers sub-programme on promising adaptations strategies and preferred strategies. KfC can make an important contribution here again.

4.2 Contribution from 1st tranche projects

Evaluation of flooding risk in the Rhine basin (HSGR02) From an economic perspective, the Rhine is the most important river of Western Europe, and the river basin is densely populated. Over 10 million people currently live in areas with a risk of flooding. The flooding risk is expected to increase as a consequence of both climate change and socio-economic developments in flood-sensitive regions. This is why more insight is needed into how the risks of flooding are developing and the effect of adaptation and mitigation strategies to reduce those risks. This information is crucial for the drawing up of a water safety policy, in the context of the Delta Programme for example. Key questions in this project included: 1. What is the flooding risk in the Rhine basin and how will this change in the future? 2. What is the relative effect of climate change and changes in land usage upon that risk? 3. What measures can be taken to reduce the risk? 4. What are the uncertainties in the estimations of the risk? (Scenarios are uncertain, damage is uncertain.)

A land use model was developed in this project for the entire Rhine basin (‘the Land Use Scanner’). Land use maps were developed for 2030 on the basis of story lines of different socio-economic scenarios. The risks were then estimated by using inundation maps and damage functions per land use class. Climate and hydraulic models were used to calculate anticipated changes in the chance of flooding for various routes along the Rhine. The result was a uniform method for estimating the flood risks along the Rhine. Maps with land use scenarios, potential damage and flooding risk have also been produced. Finally, a prototype for Decision Support System for flooding risks in the Rhine basin has been developed. The study shows that the potential damage is very high. So many people live in areas that are sensitive to flooding, that the damage can run up to an extremely high level. The damage maps are confronting for users. These maps immediately show the vulnerable areas, and where a great deal of damage can

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occur in the event of high water. The increase in risk in 30 years’ time is 50 to 230%, depending on what scenario is followed (little or great climate change, little or great economic development). Of this increase, 50% can be attributed to climate change and the other 50% is caused by socio-economic developments. This study again shows that the creation of storage areas in Germany does not have an effect in the Netherlands. The Netherlands does not benefit from these measures, as has long been presumed. However, if the dykes are raised in Germany, this does have a significant effect in the Netherlands. In that case, the chance of flooding will increase in the Netherlands. The most important societal result of this project is that policy makers and administrators have become more aware of the flooding risks. This project thereby contributes to the transition in thinking, from protection against high waters, towards multi-layer safety. Damage limitation measures are therefore also taken more seriously. These types of measures are now being thought about, and how you might achieve them administratively. All in all, this project has contributed an important ingredient again in the development of potential adaptation strategies in the rivers area.

Adaptation to the flooding risk of the Meuse (HSGR06) The most important research question in this project was: how will the flooding risk in the Meuse develop in the 21st century, and what measures in the domain of the planning of the space and buildings can be taken to reduce the risk? In addition to gaining insight themselves, they also wanted to share insights with the stakeholders. On the basis of this project new knowledge has been obtained about multi-layer safety, an important part of the development of potential adaptation strategies in the rivers area.

A method has been developed to allow flooding maps to be created quickly within projects. Maps have also been developed of the future flooding risk (taking into consideration climate change and changing land use) from France to Cuijk. An important insight here is that the flooding risk, in terms of average annual damage, is more sensitive to damage incurred by high frequency occurrences (i.e. 10 to 100 year repeat time) than to low frequency occurrences (1,000 to 2,000 year repeat time). This is an important insight because in current policy risk is usually calculated on only three frequencies, and that is now shown to be inadequate. A study has also been carried out into what the measures already contained in the Line of policy on major rivers actually do with the current flooding risk. These measures already have a great deal of influence – if they are carried out – the flooding risk will drop by 40%. Nonetheless, the flooding risk with these measures is still higher than the current flooding risk without measures being taken when taking climate change and spatial developments into consideration. The dry en wet proofing of buildings has also been considered. Depending on a few presumptions and scenarios, these types of measures can reduce future flooding risk by 21 to 40%.

Despite the scientific approach of the project, it also has the potential for major societal impact. Workshops were held with the provincial authority, the Roer and Overmaas water board and Rijkswaterstaat (Ministry of Infrastructure and the Environment, Dutch abbreviation RWS). The water

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board was particularly interested in what the possibilities are with spatial planning and dry and wet proofing. Measures taken in the area of dry and wet proofing have shown to be effective. Unfortunately, and to the frustration of workshop participants, there are currently not yet any instruments to implement these types of measures. Legislation and regulation could offer possibilities, but that will need to be investigated from a legal perspective. Possibilities by means of insurance policies for the implementation of dry and wet proofing measures are also conceivable. It is known of many of the wet and dry proofing measures that they are effective, based on previous applications; people who have been living for 60 years in areas that flooded now and again used to take those measures. At the moment they are no longer applied, possibly due to the fact that the damage will be covered by the government anyway.

This project has offered greater insight into what measures work to reduce the risk of flooding, besides dykes and embankments. That is an important part of the development of potential adaptation strategies in the rivers area, particularly if it concerns Multi-layer safety (see Chapter 3). The new knowledge the project has provided includes the following:  analysis of repeat times. Nothing had been published about it, and a follow-up will be carried out  knowledge at a higher level of scale on the influence of spatial planning and wet and dry proofing on the reduction of flooding risks  quantification of the relative influence of climate change and land usage on flooding risks of the Meuse. The method is not new, but its application on the Meuse is.

Delta dykes in practice (HSGR07) Among other things the Delta dykes (see Chapter 3) are considered in the development of strategy for the rivers area. On one hand because they are almost breakthrough-proof, on the other because they can also be used as part of Multi-layer safety. In the light of climate change and other possible changes in framework conditions for water defences, climate-proof alternatives for dyke reinforcement were examined in varying levels of detail for three locations along the Neder Rhine-Lek. These alternatives are so robust that they do not require reinforcement after realisation in the medium term, and offer extra safety. In the built-up area of Streefkerk this could be realised by making the dyke extra wide on the outer side, which in fact would make the current dyke into a high inner slope. Existing buildings can therefore remain in place. The character of the dyke can be retained and the connection between the village and the river can be reinforced. Despite the fact that such a 'climate dyke' is a little more expensive in terms of investment costs, over a period of 100 years it is cheaper than a conventional reinforcement. In addition to the wide climate dyke at Streefkerk, a climate-proof system with double flood defence was considered at Lienden, analogue to the seepage-reducing secondary dykes of times gone by. In the event of extreme conditions, water is allowed between two flood defences in order to prevent piping. This (partially) prevents the need for reinforcement and allows the system to be adjusted flexibly when framework conditions change.

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Particularly the location in Arnhem shows that to realise unconventional alternatives, it is necessary to have the involvement and cooperation of all stakeholders from the start, and that the timing of the launch of such an integral project is of crucial importance.

Inhabitants’ perceptions of living behind and outside the dyke (HSRR07/HSGR08) When making living and working locations climate proof, government institutions will communicate more about the risk of flooding both behind and outside the dyked areas. This is already happening in the Delta Programme. Regional processes have been set into motion per river branch, in which there is intensive communication with local residents. In order to organise communication effectively, government institutions want to know what to look out for when communicating about these subjects with inhabitants. What factors have an influence on the perception and sense of responsibility of the inhabitants? This is why it has been investigated how inhabitants respond to a number of strategically chosen storylines about these subjects. Insurances and adaptively-constructed homes were also considered. The perceptions were investigated by comparing the answers to different questionnaires. The questionnaires were answered in June 2011 by 2302 inhabitants (aged 25 to 75, head of a family or his/her partner). This was a sample of the house market area in the Rotterdam and Drechtsteden region.

On the basis of the most important results of the research, we have listed the following points which are interesting for government authorities who communicate with civilians on the risks of flooding.  In communication with inhabitants, it is important that they know what the terms binnendijks and buitendijks mean (behind and outside of the dyke) and whether they themselves live in an area that is behind or outside the dyke. Research shows that the terms can be effectively explained to inhabitants. But about half of the respondents was still not aware whether they themselves lived behind or outside the dyke after the explanation.  Government authorities can influence the level of concern among inhabitants, depending in what they choose to emphasise in the communication. Extra emphasis in the research on aspects such as climate change or the appealing aspects of water, influence whether the inhabitants showed themselves to be more or less worried.  Inhabitants who are aware of the risks of flooding behind or outside the dyke, are slightly more concerned but at the same time were more aware of having to do something to prevent unwanted events. These inhabitants showed a greater demand for insurance against flooding and they had the intention of taking measures appropriate to the risk and which could increase their ability to cope. There was also interest in water-proof homes outside the dykes, but only at a height of over 3 metres above NAP (Amsterdam Ordnance Datum).  When communicating the risk of flooding, it is important that inhabitants know what they can expect from the government. The respondents often expected government institutions to have water safety risks under control. After they became aware of the risks they displayed slightly less confidence in the effectiveness of government institutions to control the risks.

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Work will continue over the next 2 years on promising adaptation strategies in the regional processes of the Delta Programme. These present a good opportunity to put these recommendations into practice.

4.3 Contribution per KfC theme

4.3.1 Theme 1: Climate Proof Flood Risk Management Theme 1 is an important theme for the rivers area. The rivers area demands constant adjustment to changed circumstances. Theme 1 therefore intends to contribute to a good joint plan for water safety and the planning of public space in the 21st century and thereafter. This plan is being developed within the context of the Delta Programme. Research is carried out into measures and policy instruments for water safety in the area of effectiveness, attractiveness and feasibility. This contributes to more knowledge and a better understanding of water safety.

In one of the projects, the robustness of the IJssel system is investigated for high discharges (Mens, 2012). Various measures to control risks of flooding in the IJssel valley are compared in the report on the basis of flooding risk and system robustness. Considering the stage of the Delta Programme, the report came at a perfect time. The programme director has indicated that the method provides interesting insights into the functioning of the flooding risk system at high water. She also suggested following the same approach in the other river branches. Various system configurations of the IJssel valley were compared in the IJssel study on the basis of how good they are at dealing with extreme discharges on the river IJssel. 'Dealing with' is in this case translated into economic damage as a consequence of a flooding. The robustness of the entire IJssel valley is analysed by calculating the flooding damage at different discharge undulations. The first system configuration worked from the current situation as a starting point, with slightly raised dykes, the second had widened rivers (by means of flood plain lowering), and the third and fourth had breakthrough-free dykes. In the fourth configuration the breakthrough-free dykes were also differentiated by height, meaning they were higher in urban areas than in the third configuration. The results show that increasing the height of dykes and 'Room for the River' achieve an equivalent reduction in the risk of flooding, but that the damage that occurs in extreme discharges is lower in 'Room for the River'. That is because this measure lowers the water levels that occur at extreme discharges. This means that if a dyke bursts, less water will flow into the area and less damage will occur. Room for the River is therefore seen as a measure that has a positive effect on the system robustness of the IJssel valley. The configurations with breakthrough-free dykes scored highest on the robustness criteria. Because the dykes no longer burst, but only overflow, the damage is much less than in other configurations. It is furthermore much more predictable where the water will run over the dyke, in contrast to traditional dykes where it is unsure where and when they will collapse. Whether breakthrough-free dykes are a good idea in all places and at all times also depends on the costs and other effects (such as casualty risk). No attention is paid to this in this report.

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The most important conclusion from the report is that a robustness perspective, in addition to a risk approach, provides insight into the sensitivity of the system. This is extremely relevant considering the uncertainties concerning the level of discharge, the shape of the discharge wave, the discharge distribution into the IJssel and the Neder Rhine, and the uncertain location of a dyke breakthrough. Finally, the robustness analysis has considerably increased the insight into the flooding process at different configurations and flooding occurrences, and that in turn offers concrete leads for measures that will restrict effects (layer 2 of multi-layer safety). This study has particularly increased attention for the risk approach and has provided an insight into the potential of restricting effects. Thereby, an important contribution has been made to the development of adaptation strategies for the rivers area.

4.3.2 Theme 7: Governance Theme 7 has the aim of integrating existing knowledge from the fields of public administration, economics, political science, spatial planning, legislation, environmental studies and psychology. This interdisciplinary programme develops and tests government measures and thereby makes a contribution to: 1. the development and implementation of potential adaptation measures to climate change 2. increasing the adaptability of society in order to be able to cope with future climate change.

The Delta Programme sub-programme Rivers (and therefore the Hotspot Major Rivers) is used as the testing area for developing and testing new technologies. One significant subject in this respect is Multi- level Governance. The study will deliver important points to be given attention, especially for organising both area and decision-making processes. These will be tested in practice over the next two years.

Participant action research on the subject of the Delta Decision Rhine-Meuse Delta has been in progress since August 2011. This research is looking into how the sub-programmes Rivers, Rijnmond- Drechtsteden, South-West Delta and the national Delta Programme are working together on the delta decision, and how this complex multi-level cooperation can best be shaped. This will be formed in the action research, in which researchers actively help to think about the shaping of the cooperative decision-making on the Rhine-Meuse Delta decision. A study was recently started into multi-level governance in the sub-programme Rivers, particularly on the interaction between the (long-term) sub-programme Rivers and (short-term) projects in the Rivers Area. This study looks into the various relations between programme and project, and what results they will lead to. This will provide an insight into how programme management can help to achieve the (often long-term) goals of the programme and the goals of the projects, as well as those of the governments and NGOs involved. This issue is being studied in both the Rivers and South-West Netherlands Delta and will make comparative research possible.

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The first insights from the comparative study into the Rivers and the South-West Netherlands Delta will become available at the end of 2012. They will then be actively brought into and discussed in both programmes.

4.3.3 Theme 6: Climate projections Climate scenarios are crucial for the Delta Programme. The KNMI’06 scenarios are currently being used. In order to make sound analyses of those consequences researchers need detailed information on the regional climate, both now and in the future. In this theme, regional information for the Netherlands is developed further, but access is also provided to existing climate information. One important theme is the uncertainty about the speed and scale of climate change. How can we calculate, communicate and minimise these uncertainties? Each of these is a relevant research question for the Delta Programme. Products which are of specific interest to the rivers area include: 1) Future Weather. The consortium has succeeded in pushing climate models into a certain direction. This means that a serious weather situation (e.g. a lengthy periods of rain or long drought) can be simulated, and then according to the conditions of 2030. This can then be used to design adaptation strategies for such situations, and/or they can be tested as to robustness. 2) Coincidence. This is about the coinciding of medium-high river discharge and wind set-up at sea. This combination creates normative conditions in the IJssel delta and the Rhine-Meuse delta. Up to now, little has been known about how these combinations will develop in the future. For the adaptation strategies it is important to know whether these types of normative conditions will occur more frequently in the future. More work will be carried out on this in the coming years.

4.3.4 Theme 8: Decision support tools In this theme, instruments are developed to integrate climate change in national policy. This follows on from the results of previous research programmes (incl. Climate changes Spatial Planning, KvR). It contributes to processes within spatial planning such as the Delta Programme and the current Structure Visions. In the Delta Programme, work is carried out with SCBA’s and map tables among other things. These are subjects which are further developed within the theme and tested in practice in the regional processes.

4.4 Outlook During the next two years, more work will be carried out in the Delta Programme on strategy development in partnership with Hotspot Major Rivers. Paragraph 3 provides a description of the potential adaptation strategies in the rivers area. Work will be carried out next year on promising strategies, and the year after on preferred strategies. The account given in the previous paragraphs suggests that themes 1, 6, 7 and 8 are expected to make a major contribution to strategy development. More work will be carried out on the system robustness per river branch in theme 1. In theme 6, the subjects Future Weather and Coincidence will be worked out in further detail. Theme 7 continues with the research into multi-level governance, and offers support in planning the regional and decision- making processes. And theme 8 will undoubtedly provide new instruments to facilitate the decision- making process towards the preferred adaptation strategies.

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5 Conclusions and outlook

The potential adaptation strategies for the rivers area are set out in this midterm report. These strategies were developed by the Delta Programme to which Knowledge for Climate made a contribution in Tthe form of new knowledge and practical recommendations on:  Flood risk and adaptation in the international basins of the Rhine and Meuse.  Delta dykes.  The perception of risk.  Multi-level governance and organisation of the area and decision-making processes.  Multi-layer safety.  The system robustness of the IJssel.  Climate projections.  Policy instruments.

Thanks to the productive collaboration between the Delta Programme and Knowledge for Climate it was possible to develop a wide range of potential adaptation strategies for the Rivers Area. This collaboration is important for both the Delta Programme and Knowledge for Climate. For the Delta Programme because it could use the most up-to-date scientific knowledge (see the above list), and because it knows for certain that the most recent knowledge has been applied. It is valuable for Knowledge for Climate because the knowledge generated not only finds its way to the scientific world but also directly creates added value for society. The knowledge lands up in the Delta Programme, the programme that must ensure that the Netherlands is prepared for the climate changes facing us all over the coming decades. It is expected that more than one billion Euros will be spent annually over the next century on this. The new insights obtained through Knowledge for Climate will contribute to this being done in an efficient and socially effective manner.

Outlook Developing adaptation strategies will continue for the next two years. Next year the focus will be on promising strategies, and the year after on preferential strategies. The potential strategies at hand focus mainly on the domain of water in the rivers area itself. This is somewhat limited. Therefore at least two widening activities will be carried through: 1. The current potential adaptation strategies focus completely on the domain of water. By way of area processes, a link will be made with regional development over the next two years so that integral, spatial strategies will evolve. Work on these area processes is being carried out by the regional and local governments (municipal and provincial authorities and water boards), stakeholders such as agriculture, nature and shipping, as well as the inhabitants of the rivers area and many others. In addition to water safety and fresh water an important role is also played by e.g. spatial quality, both in rural and urban areas. There is close cooperation with theme 7 (Governance) for designing the area process and the associated decision-making.

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2. The current adaptation strategies are targeted on the rivers area only. It goes without saying that the rivers area is closely allied to the downstream rivers area, the South-West Netherlands Delta and the IJsselmeer. Over the next two years strategy development will therefore be taken up in association with these areas so that integral strategies will evolve for the Netherlands’ part of the Rhine and Meuse river basins. The international part of these strategies will be included in the Delta scenarios.

From the description given in the above paragraphs it can be deduced that a substantial contribution can be expected from the KfC themes 1, 6, 7 and 8 to the further development of adaptation strategies for the rivers area. Themes 1 and 6 also provide new knowledge about water safety and the climate respectively. The results from themes 7 and 8 can especially contribute to successful area processes, including the associated decision-making paths (theme 7). The tools being developed – now and in the future - by theme 8, at any rate those being developed for SCBAs and map tables, can be an enormous help.

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References

Boer, Joop de, Botzen, Wouter, Terpstra, Teun (2012). Percepties van burgers over binnen- en buitendijks wonen. Rotterdam: Gemeente Rotterdam (RCP), rapport KvK/045/2012, ISBN/EAN: 978-94- 90070-52-6.

Bruggeman et al (Deltares, PBL), Deltascenario's, Verkenning van mogelijke fysieke en sociaaleconomische ontwikkelingen in de 21ste eeuw op basis van KNMI’06 en WLO-scenario’s, voor gebruik in het Deltaprogramma 2011 – 2012, juni 2011

Deltaprogramma Rivieren, bijlage DP 2013, Samenvatting probleemanalyse en mogelijke strategieën, september 2012.

Deltares, Maatschappelijke kosten-batenanalyse Waterveiligheid 21e eeuw, maart 2011

Deltares, Analyse van slachtofferrisico’s Waterveiligheid 21e eeuw, april 2011

Linde, A. H. te, Bubeck, P., Dekkers, J. E. C., De Moel, H. and Aerts, J. C. J. H. (2011). Future flood risk estimates along the river Rhine, Nat. Hazards Earth Syst. Sci. 11(2): 459-473, doi: 10.5194/nhess-11-459- 2011.

Mens, M., F. Klein (Kennis voor Klimaat); Analyse van systeemrobuustheid: Een toepassing op de IJssel, februari 2012

Ministerie van Infrastructuur en Milieu, ONTWERP STRUCTUURVISIE en AMvB INFRASTRUCTUUR EN RUIMTE, juni 2011.

Moel, H. de, Beijersbergen, J., Berg, F. van den, Goei, J. de, Koch, R.C. de, Koelewijn, A.R., Loon- Steensma, J.M., Molenaar, I.M., Steenbergen-Kajabová, J., Schelfhout, H., Versluis, S. en A.M. Zantinge (2010). Klimaatdijk in de praktijk. Gebiedsspecifiek onderzoek naar nieuwe klimaatbestendige dijkverbeteringsalternatieven langs de Nederrijn en Lek. KvK rapportnummer KvK019/2010, ISBN/EAN 9789490070182.

Oranjewoud, HKV-Lijn in water, Syntheserapport gebiedspilots Meerlaagsveiligheid, november 2011

Rijkswaterstaat, Veiligheid Nederland in Kaart, Hoofdrapport onderzoek overstromingsrisico’s, november 2005

Royal Haskoning, Deltares, staf Deltacommissaris, Vergelijkingssystematiek Deltaprogramma, Structuur, inrichting en gebruik, Versie 1.0, januari 2012

Ward, P.J., De Moel, H. and Aerts, J.C.J.H. (2011). How are flood risk estimates affected by the choice of return-periods? Natural Hazards and Earth System Sciences, 11, 3181-3195, doi:10.5194/nhess-11-3181- 2011.

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Appendix 1: Delta decisions

Preparations for the decisions to be made for the future of our delta are central in the Delta Programme. These guiding 'delta decisions' concerning safety and the provision of water in this century will be presented to the Netherlands Cabinet in 2014 by the delta commissioner, so they can then be anchored in the next National Water Plan (2015). It concerns five decisions: 1. The updating of safety standards for primary water defences; 2. The fresh water strategy that is to provide an adequate water supply in the Netherlands in the long term; 3. Long-term water level management of the IJsselmeer aimed at the water supply in the Netherlands and the safety task in this area; 4. The protection of the Rhine–Meuse delta; 5. A national policy framework for the (re)development of built-up areas.

1. Safety standards for primary water defences In 2011 the minister of Infrastructure and the Environment makes a proposal for the actualisation of the safety standards for primary water defences. The standards determine the safety level in the Netherlands and set the framework for the measures in the sub-programmes. It is therefore important to make a decision in principle in 2011 so the plans for measures in various sub-programmes can be partly based on that decision. After 2011, principle standards are translated into their regional effects.

2. Preferred strategy for water supply In 2014, a proposal will be made for a decision regarding a preferred strategy for the supply of water in the Netherlands for the long term including infrastructural measures. Potential questions include: whether and to what extent self-sufficiency per region can be relied upon, or whether more resistance will be offered against the rising salt water, or whether a different land use will be found, or another form of pricing water, introduced to regulate the fresh water supply. The water level management of the IJsselmeer is relevant in this respect.

3. Long-term water level management IJsselmeer In 2014 a proposal will be made for the IJsselmeer for a decision regarding water level management in the long term, focusing on the water supply in the Netherlands and the safety task in the area. Water level management is linked to rivers (Black Water and IJssel) and the Wadden, and to a large area that is dependent on the IJsselmeer for its fresh water. It is therefore also directly related to the sub- programme Fresh Water Supply.

4. Protection of the Rhine – Meuse delta In 2014 a proposal will be made for a decision on protecting the Rhine-Meuse delta in the long term. This area is characterised by a high level of population and major invested capital. Due to the expectation of a higher sea level and an increase in extreme river discharges, long term solution

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directions are being developed for water safety and fresh water supplies in synergy with a sustainable and thriving spatial development of the area. The interaction with other sub-programmes is great, particularly the South West Netherlands Delta, Rivers, Safety and Fresh water supply. There is also a need for clarity in relation to the spatial development and investments in the area itself.

5. Guidance Instruments New Constructions and Restructuring By means of a national policy framework, concrete proposals will be made in late 2013 for generic and area-specific framework conditions and instruments for the (re)development of built-up areas. The proposals are related to managing the risks of water safety, flooding, drought and salinisation in new construction work and restructuring of the built-up area. In addition to this, the following subjects will also be addressed: dealing with the effects of subsidence, the special characteristics of peat and clay areas and the prevention of heat stress. The connection to other sub-programmes particularly emerges in the subjects safe and 'damage-free' building behind or outside the dykes and building in and around the water defences and within spatial reserves for river widening or (fresh) water storage for example.

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