This thesis explores the relationship between income inequality and carbon emissions, focusing on how changes in income distribution influence consumption patterns, and subsequently affect GDP and emissions over time. A theory-based System Dynamics (SD) modelling approach is used to examine these macroeconomic and environmental dynamics in the Canadian context. This research builds on the LowGrow SFC model as developed by Jackson and Victor (2019), which simulates the Canadian economy from 2012 to 2073 exploring multiple post-growth scenarios. A sub-model that incorporates income inequality as an input variable is added to the original LowGrow SFC model. The results show that more equal income distributions lead to higher total consumption due to increased aggregate demand. However, counterintuitively, these same scenarios produce lower GDP and EBI values. This occurs because rising consumption leads to a decline in both government spending and business investment, ultimately reducing GDP. Because EBI is closely linked to GDP in the model, it follows a similar trajectory. These results challenge the equity-pollution dilemma and suggest that improving income equality may be compatible with achieving climate goals. This insight offers a hopeful and compelling argument for integrating social equity with environmental sustainability in future policy design.

Urban mobility systems in European cities face climate, health, and spatial challenges that call for policies to reduce private car use while increasing access by public transport and active modes. Road space reallocation shows promise, but there is limited understanding of how citywide implementation affects travel behavior over time. This research addresses this gap by conceptualizing the effects of citywide road space reallocation on travel behavior and developing a quantitative System Dynamics (SD) model. The method is combined with Scenario Discovery to evaluate the role of uncertainties on the effectiveness of the policy, and expert interviews are conducted to support the validation of the model. Applying the model to a single case study with ongoing road space reallocation indicates that the policy can trigger significant modal shift to cycling for mid-distance trips (1.5–6 km), while modal shift from the car to public transport for long-distance trips (7–10 km) is slower and more uncertain. The level of change depends on uncertainties, including the future availability of bike parking and the uptake of e-bikes. The research contributes a data-light SD model that quantifies existing conceptual models and provides strategic insights for designing robust road space reallocation policies. Next modeling steps should prioritize the inclusion of bike-and-ride, and future empirical research should examine bike adoption over time in cities with improving cycling networks. Recommendations for policy makers include accelerating bike adoption through targeted initiatives, improving monitoring and target-setting, and collaborating across municipalities to address car dependence in suburban areas.

Recent years have shown an increased level of food insecurity: a surge in the level of poverty and hunger in low-income countries caused by higher global food prices. One of the potential causes of the commodity price spikes is the process of financialization, including an increased level of financial speculation in food commodity markets. Because the literature is inconclusive on the exact effects of speculation, this research aims to provide a fresh analysis of the potential impacts of financial speculation on food commodity prices as well as to explore policies that could influence the level of financial speculation. The main question to be answered through this research is: ‘What are the likely effects of the increase in financial speculation on the behavior of commodity prices in the current soybeans market, and which policies can be used to regulate these effects?’ First, a literature review was conducted to study sources on the potential theoretical effects of speculation, as well as sources on the current regulatory measures to counter speculation. Next, the system dynamics approach was used to investigate the role of speculative activity in price-setting behavior. Lastly, expert interviews were conducted to validate the behavior of commodity prices as shown in the model, as well as to gain knowledge on policy interventions.
Guided by the literature review, three important interacting markets were identified for inclusion in the conceptual system dynamics model for the soybeans market: the market for storage, the cash market, and the futures market. The results show how interactions between these markets determine the behavior of spot prices. Furthermore, in the literature review, speculators were found to be trend-following, fast-reacting entities who contribute to strengthening of price expectations and spot prices. The quantitative system dynamics model shows how speculators are able to amplify the oscillation of spot price behavior, which can be compared to the forming and crashing of price bubbles in a commodity market. This amplification occurs because speculators react faster to changes in spot prices than other market participants. While the model is still relatively simplistic, it creates an understanding of the system structure of financial markets that determines spot price behavior.
The research describes how experts agree on the fact that some kind of policy intervention is required to limit the negative effects of speculation. Policy makers should pay attention to the level of transparency in setting position limits and focus on clarifying and explaining the classification of speculators and hedgers. Furthermore, it is recommended that only traders with an active and real interest in the commodity should be allowed to participate in the futures market.

The intellectual disability population increased from 65.545 people in 2011 to 116.200 people in 2020. In other words, the population almost doubled in less than ten years' time. Interventions are required to be able to make sure everyone receives the needed care. Therefore, the causes for the growth should be further examined before any decision on intervention can be taken. This thesis contributed to understanding the factors influencing the increase in the intellectual disability population and evaluating the behaviour of the sector. To improve the understanding, a System Dynamics model was designed analysing the influence of self-reliance on the intellectual disability population.

The question of why there is an increase in the intellectual disability population has been attempted to be answered within this study. After evaluating multiple factors as a cause for the growth in the intellectual disability population, self-reliance was selected as being an important factor. In the conceptual model, three reinforcing feedback loops were found, indicating that when there is no intervention, the self-reliance of the intellectual disability population continuously decreases, resulting in more people applying for care from the Wlz. In the qualitative model, this proposition could not be rejected, indicating the importance of the role of self-reliance on the growth of the intellectual disability population. Especially for the population with an IQ score between 70 and 85, more attention should be paid to the increase or maintaining of self-reliance. In that way, the intellectual disability sector is always able to care for the ones who cannot live without.

Substance use disorders, particularly alcohol use disorder (AUD), are a major global health challenge, significantly impacting morbidity and mortality rates. In the Netherlands, around 20% of the population is affected by excessive alcohol consumption, with a notable treatment gap and disproportionate effects on the elderly. Despite increased research into AUD treatments, patient numbers remain stable, straining healthcare systems. Moreover, the Dutch government anticipates that addressing the needs of both diagnosed and undiagnosed patients, the workforce should be increased in the general healthcare sector from the current level of 16.67% to 25% of the total Dutch workforce by 2040. Furthermore, existing regulations and policies appear inadequate in effectively managing these demands.

This study aims to explore the socio-organisational drivers and policy effects on the Dutch mental health care system, focusing on AUD, to maintain sustainable quality care. It examines organizational drivers, expert perspectives, policy influence on system dynamics, and the relationship between capacity shortages and care quality. The research employs a mixed-method approach, including a literature review, exploratory interviews, a Participatory System Dynamics Modeling (PSDM) workshop, and a comparative analysis of data from 12 mental health services (MHS).

Key findings include the significance of internal factors like patient satisfaction and therapeutic alliance, and the crucial role of over and undertreatment considerations during treatment processes. External factors like self-coping, and individualization and blurring of alcohol in shops also influence both treatment effectiveness and alcohol consumption. Current policy regulations inadvertently contribute to capacity shortages and treatment gaps. System Dynamics (SD) modelling reveals that increased regulatory pressures and quality care demands lead to capacity being consumed by administrative tasks and budget gaps. This relates to a 'fixes that fail' archetype, combined with social dynamics like an ageing population and increased alcohol consumption, exacerbates the 'growth and underinvestment' archetype in the Dutch mental healthcare system.

The study highlights the unintended consequences of current policies, such as disjointed preventive measures and reduced practitioner autonomy. It also emphasizes the complexity of healthcare systems as revealed by the challenge of identifying cause-and-effect due to multiple aggregational levels, the diverse perspectives on the system both by literature and experts, the varied healthcare contexts and the multi-disciplinary and collaborative nature of (mental) healthcare. Key limitations include not fully addressing safety in health quality and challenges in integrating quantitative methods.

This thesis underscores the importance of a holistic approach in healthcare, considering both social and organizational aspects. It suggests that current policies may lead to over-regulation or insufficient prevention awareness, impacting both society and MHS organisations. Adopting a holistic system approach can enhance further understanding of policy impacts crucial for preventing a growing treatment-capacity gap and ensuring a sustainable mental health care system for society’s vulnerable members.

Since the Brouwersdam was built as part of the Delta plan, the Grevelingen outer delta undergoes large-scale morphological changes. These changes led to the formation of a shoal adjacent to the dam, which is referred to as the Brouwersdam beach. The beach has been eroding and shifting towards the northeast ever since. The beach has no safety function, as the hinterland is protected from flooding by the Brouwersdam. However, the beach has a large recreational value, which will decrease if no human interventions are taken. Consequently, many stakeholders demand the preservation of the beach. For the Municipality of Schouwen-Duiveland, the loss of recreational value of the beach is estimated to decrease the yearly financial benefits by 0.8 to 5.4 million euro. Hence, their interest in the preservation of the beach is large and therefore they have commissioned this study. This study aims to design nature-based solutions for the ongoing erosion and coastline shift to which the Brouwersdam beach is subjected. The design approach of this research is based on the Building with Nature (BwN) design steps. A thorough analysis of the physical, ecological and social system is followed by the set-up of a Program of Requirements (PoR) for the design. Insight in the physical system is partly obtained by a modelling study in Delft3D-WAVE and UNIBEST-CL+. Based on the PoR, designs are identified, evaluated and selected iteratively. The design iterations, based on the systems’ insights and the PoR, led to the creation of three Nature-based Solutions. The alternative solutions include the creation of a shellfish habitat by making structures of layered brushwood fascine mattresses filled with shells or other hard substratum. The shellfish reef, in which mainly Japanese oysters are expected to settle, provides many ecosystem services such as enhancing biodiversity. Moreover, the structures can be constructed CO2-neutral. The different configurations of the solutions, ensuring coastal protection, are: A groyne configuration, creating multiple pocket beaches, of 1 straight groyne and 4 L-shaped groynes with an orientation slightly tilted towards the west, i.e., the dominant wave direction (Solution A) ; A straight groyne with a west-east orientation, combined with a sediment beach fill between the current coastline and the groyne (Solution C) ; A fishtail groyne, which is a structure with a slightly curved, shore-normal groyne arm and a shore-parallel breakwater arm (Solution E). These solutions were compared with frequent nourishing (solution F) and to the reference situation, i.e. taking no action. The assessment of the solutions by means of a Multi-Criteria Analysis (MCA), based on the categories functionality, costs, recreational value (water and beach recreation separately), ecological value and aesthetics, led to the conclusion that the designs are equally feasible but score differently on the categories. The results of the MCA thus illustrate that the conclusion on the most feasible solution depends on priority. The study concludes that preserving the Brouwersdam beach in a nature-based way is feasible. The MCA tool can potentially support future decision-making processes following this study by clarifying the trade-offs between the different designed solutions. Further exploring the economic benefits of recreational functions will contribute to validating the weight factors in these categories. The results of this study contribute to the discussion on the preservation of the Brouwersdam beach and to the strive for knowledge on ecosystem-based projects within the field of hydraulic engineering.