Introduction

Many coasts around the world are under threat of erosion due to storms and slow but progressive retreat by sea level rise. Predictions of future climate change impacts and the effective implementation of hard and soft coastal protection measures are essential to help coastal communities deal with this challenge. However, the traditional coastal models are either too slow for the evaluation of climate change scenarios (only to be used for years at km-scale regions) or they are not capable of dealing with complex coastal structures (e.g. groynes and offshore breakwaters) and dune or shoreface interactions. There is also a lack of a generic methods to make these predictions in complex areas (including near sea inlets, on gravel/muddy coasts and densely built-up coastal areas). To be able to provide a good quantitative estimate of the coastal maintenance effort that will be needed in the coming decades, this gap has to be bridged. The ShorelineS model has been developed in recent years to consider the development of sandy coasts and the effectiveness of interventions efficiently and accurately, also on long timescales. The model also offers the possibility to define boundary conditions for evaluations of nature development, groundwater management and other coastal functions. The philosophy is to make a practical tool with the following benefits:

Easy to use (saves time to set up and run);
Broad applicability, as it handles complex coastlines with spits, barrier islands and dunes;
Ability to deal with interventions (e.g. nourishments and complex coastal structures);
Computes up to decadal time scales;
Computationally efficient compared to detailed 2-dimensional models.

Scope

The TKI-ShorelineS 2.0 has the aim to allow efficient long-term simulations at decadal time scales also for complex ebb-deltas, gravel beaches, cliffs and vegetated dunes. Furthermore, the code structure and efficiency of the model will be improved to allow for much quicker simulations. Through the new physical processes the applicability of the model to cases around the globe will be solidified, creating a key tool for coastal engineering and societal questions. And through the speed-up also long-term climate related questions are becoming tangible. Therefore the project has been sub-divided in the following building blocks:

Task 1 : Technical physical development of the model
- Inclusion of transport formulations for gravel or fine-sediment transport at coasts;
- Adding cross-shore profile change besides the alongshore morphology (1D cross-shore and 1D alongshore coupling);
- Adding interaction between the coastline and the dunes using a grid based approach that is easy to apply;
- Developing functionality to deal with complex 2D foreshores (e.g. at tidal inlets);
- Improving parameterizations and validated settings for complex coastal structures;
Task 2 : Improvement of speed and robustness of the model code;
Task 3 : Development of tools to simplify the setup, calibration and post-processing of models;
Task 4 : Test and use the model in societally relevant projects with partners
Task 5 : Develop a pilot case with a framework to assess climate adaptation pathways for coastal maintenance and assessment of socio-economic impacts.

Timeline

The project has been sub-divided into five half-yearly blocks.
Meetings with the consortium are organized at each half-year to steer the developments.

2025-may Kick-off meeting
Define scope further
Partners introduce their cases.

2025-nov Half-yearly progress meeting #1
Proposed shingle/gravel formulation & mud
Improved bypassing / diffraction at structures
Introduce first tool to setup cases
Proposition for cross-shore modelling / efficient code
Discuss training / case studies

2026-may Half-yearly progress meeting #2
Evaluation of gravel/sand transport
Pilot couplings shoreface and dunes
Tools to visualize cases
Improved code for efficiency #1
1st delivery case studies (participants)

2026-nov Half-yearly progress meeting #3 :
Improved cross-shore couplings
Tools to calibrate and improve efficiency #2
Finalize case studies (participants)

2027-may End meeting
Final ShorelineS code + manual
End report + Case study reports