PRELIMINARY ACTIVITIES AND OBJECTIVE

4.1.1. PREFACE

In the introduction (paragraph 1.1), the problem has been stated for the whole Netherlands and in particular the IJsselmeergebied. Climate is changing differently than the expected long term climate circles; most probably bringing higher temperatures, sea level rise, dryer summers and wetter winters, consequently influencing discharges from the incoming rivers, possibility for discharging to the sea by free flow and water availability. Combination of those events will lead to significant problems for the Netherlands, and specifically for the IJsselmeergebied, in terms of safety (flooding, stability of dikes) and freshwater supply. In order to cope with those threats, there is need to define a climate-proof IJsselmeergebied. From the point of view of the decision maker, measures have to be implemented which are able to guarantee the present functions of the system under climate change, while gaining the broadest consensus among the stakes which might directly or indirectly be influenced.

4.1.2. NORMATIVE FRAMEWORK, DECISION MAKER

As stated in paragraph 2.2.1 the Dienst IJsselmeergebied is responsible for maintenance, management and construction of the main infrastructures in the region, as well as for the practical implementation of water policies.

Being the manager of the area, the only authority (under the supervision of Rijkswaterstaat and Ministry of Infrastructure and Environment) which has the duty and the power to approve and implement water policies and infrastructures in order to assure a good functioning of the IJsselmeergebied for the Dutch society, the Dienst IJsselmeergebied is only decision maker of the tests case.

This has important consequences for its definition:

− The objective of the test case is inherited directly from the definition of the

objective of the decision maker;

− The evaluation of the measures towards the definition of the optimal alternative is

performed according to the judgments and prioritizing criteria expressed by the decision maker.

4.1.3. TOWARDS THE DEFINITION OF THE OBJECTIVE OF THE TEST CASE: STAKES

AND PRIORITIES

Taken from paragraph 2.2.1, the objective of the decision maker (DIJ), and consequently of the Test Case is:

THE DEFINITION OF A CLIMATE-PROOF IJSSELMEERGEBIED, WHILE GAINING THE BROADEST CONSENSUS WITHIN THE STAKEHOLDERS ON THE SELECTED MEASURES A climate proof IJsselmeer would guarantee that the functions related to all the stakes in the area are preserved under the future scenarios, so that the DIJ would need to analyze all the stakes in the area and inherit their objectives into its goal.

However, in the present research, it is not possible to consider all the stakes of the system in the optimization procedure, therefore different stakes have to be taken into consideration on different levels.

This is mainly because, from a computational point of view, it is impossible to deal with the complexity of the problem when the objectives of all the stakes are included in the optimization algorithm. This is especially true in the present research where, as stated at constraint 1 (see box 1.3), the objective function has to be unique.

Only some stakes, with their objectives, will be taken into consideration in computing the optimum and selecting the efficient alternatives; for others, the selected solutions will be only tested after the optimization in order to understand the impacts.

This is also the strategy used in the PIP in the definition of the Project Problem (paragraph 3.1.1.), which corresponds to the Test Case of the present research: the system is simplified and only some relevant stakes will be considered in the optimization process used to select efficient alternatives for the next phases of the consultation, for the others effects are evaluated a posteriori (Soncini-Sessa 2007).

According to the above considerations, the stakes can be divided in two different groups:

− Project Stakes (P): which have fundamental stakes in the system which the decision

maker has to take into account and inherit in its goals for a climate proof-IJsselmeer. Their objectives will concur in the definition of the test case objective and they will be taken into account in the optimization problem.

− Impact Stakes (I): whose objectives are not part of the optimization process, and

therefore not considered in the test case objective. However, those stakes are relevant enough to need an evaluation of the consequences of the efficient actions selected trough optimization.

As stated by the constraint 2 (see box 1.3), the stakes which will subject of the optimization in the present research are safety of the dikes and fresh water demand. They have

been chosen for the

optimization, because they represent the main concern of the policy makers regarding

BOX 4.1

CONSTRAINT 6, safety of the dikes (P1) has higher priority than satisfaction of fresh water demand (P2); all the other stakes have lower priority (P3). Such hierarchy between the two project stakes has been assumed due to the single objective of the optimization and has been suggested by the conclusions of the Delta commission. Discussed at 4.1.3.

future scenarios, as is confirmed by the high number of reports and studies on the subject, and especially by the Delta Commission, which states in its document: “[cit] Water safety is the center of this report, and includes both flood protection and securing fresh water supplies. Achieving water safety prevents causalities and social disruption, while avoiding damage to our economy, landscape, nature, culture and reputation.” (Deltacommissie 2008).

Furthermore, given the single objective formulation of the optimization problem

(constraint 1 Box 1.3) it is necessary to define a priority between the two stakes

subjected to optimization. The Delta commission states that safety is the highest priority, so that in the present research safety of the dikes is considered a more important stake than fresh water demand. In this way, satisfaction of the second comes only after the satisfaction of dike safety standards.

All the other stakes discussed in chapter 2.2 will be addressed as impact stakes, and therefore not included directly in the definition of the test case objective and the optimization. When possible, according to the information available on the operational desires of the stakes, evaluation of the impacts of the selected alternatives will be given with the help of indicators developed for the stakes. Otherwise the discussion will be based on comparison between the high level objectives defined in chapter 2.2 and the water level regime produced by the selected alternatives.

However, important issue for the decision maker is to gain the broadest consensus between the stakes left out of the optimization. Impact stakeholders can indirectly be represented by this aspect of the objective, which however has the lowest priority. Table 4.1 shows how the stakes have been divided into the two categories:

Project Stakes (P) Impact Stakes (I)

Safety of the dikes (both in winter and summer) (P1)

Water demand (P2)

Ecology Commercial Shipping

Recreation

Inland water management (Safety) Water management outside the dikes (safety) Table 4.1 – Project and impact stakeholders

For a detailed description of the stakes and definition of their objectives see chapter 2.2.

4.1.4. OBJECTIVE OF THE TEST CASE

The formulation of the objective of the Test Case given at the beginning of the previous paragraph is too general, in the sense that it is vague what actually “climate-proof” means in the framework of the test case.

However different degree of involvement and prioritization has been specified for the Test Case in the previous section, so that, given the choice of the project stakes (P), the impact stakes (I), and their prioritization, a climate-proof IJsselmeer is such when it satisfies first the objectives of safety of the dikes and secondly the water demand under the threats of climate change. Furthermore, under the hypothesis of satisfaction of the project stakes, it is important to gain the broadest consensus on the measures among the stakes which have not been included in the objective of the test case (impact stakes). Given this definition, the objective of the decision maker and the Test Case can be further specified with the use of the goals of the selected project stakes (P), together with the need of gaining consensus.

Box 4.2 summarized the redefined objective of the test case:

The order of the numbering represents also the priority of the three objectives.

4.1.5. BOUNDARIES OF THE TEST CASE

− Time, the research strives to find a solution, within the possible measures, for the

management of the IJsselmeer in the future. In many of the cited reports, time horizon selected is 2050 and 2100. This will be also the case for the present research.

However important understanding on the potential of the methodology can be obtained by optimizing on the past series and confront what historically happened, with what could have happened if a similar approach would have been used before.

For this reasons, the test case will look into optimized measures both for the past

and long time future horizon 2050 and 2100.

As it will become clear with the explanation of the model, the available data series cover the years from 1951 till 1998 (48 years); the data series regarding the future BOX 4.2

OBJECTIVE OF THE TEST CASE:

A climate-proof IJsselmeer under the climate scenarios selected.

1. Satisfaction of the safety standards location per location (both for summer and

winter), in the present and under the climate scenario selected (see box 2.3);

2. Satisfaction of the water demand in the present and under the climate scenarios

selected (see box 2.4);

3. Acquisition of the broadest consensus among the impact stakes.

scenarios will be derived from the available historical series modified according to the prescriptions of the KNMI’06 and updates.

− Space, as stated by constraint 5 (see box 1.5), the IJsselmeer alone defines the

spatial boundaries of the test case. Other components of the IJsselmeergebied (Markermeer, Randmeren, neighbor polders etc…) will not be part of the analysis and will not be modeled.

This is because, if more state variables are defined in the model of the system (other

water bodies, polders etc…), the computational time increases by 10n with respect to

the case of only one state variable, when n is the number or state variables (Soncini- Sessa 2007). Given the need of keeping the computational time of the model of the system low, the use of only one state variable has been defined as a limit.

4.1.6. SCENARIOS

Different scenarios have been selected for the test case, Table 4.2 shows the overview:

Horizon Climate Water demand

sea level rise Rhine and minor rivers

discharge, precipitation, evaporation, pumping form neighboring polders

wind

2050 W+2050 W+2050 none W+2050

2100 W+2100

Delta commission

W+2100 none W+2050

Table 4.2 – Scenarios used in the test case

Many of the studies and reports on the future of the IJsselmeergebied consider the most extreme scenario as the reference on which to define the measures. In the present research, the same choice has been made in order to be in line with the past studies. The analysis of the worst case has the advantage of investigating which would be the worst option.

Furthermore, a review of the KNMI ’06 produced in 2009 (Klein Tank 2009) cit. observed that “in recent years the average temperature in the Netherlands is rising faster than the global average and extreme high temperatures are occurring more frequently”. This gives room for justification for using the warmer scenarios (W, W+), which describe the current situation best.

Also the scenarios adopted by the Delta commission for sea level rise with horizon 2100 have been included in the research, in order to be in line with the past studies. This scenario predicts a higher sea level rise.

Regarding wind, North-Western wind is dominant on the IJsselmeer. As mentioned, it is responsible to storm surges in the North Sea and low water levels in the IJsselmeer at the Afsluitdijk, reducing possibilities for gravitational discharge and rising risk within the

lake. Past measurements and KNMI ’06 predictions for wind do not give reason to expect changes in North-Western wind and risks of North Sea surges. For this reason no wind scenarios are taken into account in the present research.

On the other hand more intense South-Western wind might even have positive influence on gravity discharge of the system at the Afsluitdijk. However, such scenario is too poorly defined to be taken into account in the present research (van den Hurk 2006).

For water demand, the only available information is the scenarios provided by Deltares and calculated by the PAWN tool (see paragraph 3.3.2)

under climate change

conditions KNMI ’06(W+2050).

In the present research the same scenarios have been used for the time horizon 2100, assuming that water demand does not change considerably from 2050 to 2100, also considering that agricultural development of the Netherlands will be limited in the next centuries (as argued in chapter 3.3).

This might be, in general, not true, because even if the agricultural extension of the country remains the same, a dryer climate would result in a higher water demand and more important, other demands concur in the definition of the total water demand (see paragraph 3.3.2.).