From linear to circular port maintenance dredging

Abstract

Purpose
Maintenance dredging is essential for navigability but often follows linear “extract–dispose” practices that lead to material loss and offshore impacts. This study develops a structured framework to quantify circularity in maintenance dredging and evaluates how sediment reuse can contribute to regenerative port management. The central question is how circularity, through material retention, reuse, and reduced environmental impact, can be measured and compared against conventional offshore disposal strategies.

Methods
A circularity assessment framework was developed by integrating circular economy principles with process-based modeling of dredging operations. The framework combines operational, environmental, and material performance dimensions and applies the Material Re-utilization Score (MRS) and Material Circularity Indicator (MCI) to quantify sediment retention and flow quality. A discrete-event simulation using OpenCLSim was coupled with physics-based power, energy, and emission models to analyze two scenarios at the Port of Delfzijl (the Netherlands): (1) linear offshore disposal with a Trailing Suction Hopper Dredger, and (2) circular reuse through discharge into clay-ripening compartments for dike reinforcement. Event tables were used to structure activities, operational durations, energy use, emissions, and sediment state transformations.

Results
The circular scenario achieved substantial material recovery (MRS = 0.87; MCI = 0.78), whereas offshore disposal resulted in zero circularity. Despite higher establishment costs and longer total project duration due to ripening, the circular scenario required 23% less operational energy and produced fewer emissions, primarily because of shorter sailing distances. Operational dredging time was comparable between scenarios, demonstrating that circularity does not inherently reduce efficiency. The event-table approach revealed explicit trade-offs between logistics, material degradation, energy use, and utility of the final clay product. Overall, transitioning to circular dredging requires upfront investment but yields long-term value through resource retention and reduced dependence on offshore disposal.

Conclusions
This study provides a quantitative framework for assessing circularity in maintenance dredging and demonstrates its practical applicability through a real port case. Circular reuse of dredged sediment offers measurable material and environmental benefits despite increased preparation requirements. The framework enables evidence-based comparison of linear and circular strategies, supporting decision-makers seeking to advance regenerative, resource-efficient, and sustainable port maintenance practices.