University of Twente Student Theses

An Eco-efficiency analysis of conventional and living dikes : Comparing the long term economic- and environmental impact of a conventional dike construction method, and a ’Living dike’ on Schiermonnikoog, the Netherlands.

Snoeijink, N. (2024) An Eco-efficiency analysis of conventional and living dikes : Comparing the long term economic- and environmental impact of a conventional dike construction method, and a ’Living dike’ on Schiermonnikoog, the Netherlands.

PDF
3MB

Abstract:	This thesis presents a comprehensive eco-efficiency analysis comparing conventional dikes and living dikes, with a specific focus on their economic and environmental impacts over a long-term period of 50 to 200 years. The research employs Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) methodologies to quantify the environmental and economic impacts, respectively. These methodologies provide a detailed evaluation of the total costs and benefits associated with each dike type over a 50-year design period. The study aims to determine if the inclusion of ecosystem services (ES) such as, carbon sequestration, biodiversity enhancement and other benefits for society significantly changes the overall cost-benefit outcome of the dike construction methods. By including a case study on the reinforcement of an existing dike at Schiermonnikoog, a Dutch island in the Wadden sea, the study evaluates the conventional dike construction method, characterized by a sand core and impermeable clay outer layer, against a nature-based alternative that integrates salt marshes in flood protection. The findings reveal that conventional dikes, although effective in providing immediate flood protection and relatively low direct costs, come with significantly more environmental disruptions due to the reliance on large quantities of construction materials. Living dikes, on the other hand, offer substantial ecological benefits, including improved water quality, habitat creation, and increased resilience to sea level rise (SLR). The presence of salt marshes in living dikes reduces wave energy, thus decreasing the hydraulic load on the dike, which can extend the dike's functional lifespan. However, ensuring stable salt marsh requires costly maintenance. An essential aspect of the analysis involved assessing the resilience of salt marshes to SLR at the case study location. Research indicates that while salt marshes can adapt to gradual SLR, rapid increases could exceed their growth capacity, leading to higher reinforcement costs or failure of the flood defence. The study also examines the impact of material use and sustainability on economic and environmental outcomes, highlighting the importance of using sustainable construction materials. The results from the LCA and LCC assessments underscore that living dikes provide significant environmental benefits and decreased long-term costs when ES are included in the comparison. Conventional dikes, despite lower direct costs, exhibit higher long-term environmental costs, especially under high SLR scenarios. This research shows that integrating salt marshes into flood defence strategies not only enhances ecological sustainability but also provide economic advantages over time. The conclusion drawn from this study is that living dikes are a viable and sustainable alternative to conventional dikes, offering a more sustainable approach to flood protection that aligns with broader ecological and economic goals in relatively high hydraulic boundary conditions. This however is a scenario that also results in the highest uncertainty of salt marsh survival. Using locally acquired materials results in higher direct costs but is the favoured approach for most hydraulic boundary conditions, as the implementation of ES result very low environmental costs compared to regular construction materials. The findings highlight the need for more comprehensive and detailed valuation techniques for ES to better reflect the true value of Nature-based solutions. Additionally, pilot projects at various locations with suitable conditions are recommended to gather more data and refine implementation strategies for living dikes. Overall, this thesis provides valuable insights for policymakers, engineers, and environmental planners seeking to implement Nature-based solutions for coastal protection in muddy coasts, emphasizing the importance of considering long-term impacts and integrating ES into flood defence planning.
Item Type:	Essay (Master)
Faculty:	ET: Engineering Technology
Subject:	56 civil engineering
Programme:	Civil Engineering and Management MSc (60026)
Link to this item:	https://purl.utwente.nl/essays/103399
Export this item as:	BibTeX EndNote HTML Citation Reference Manager

Show download statistics for this publication

Repository Staff Only: item control page