IHE Delft 💧 Alumni Online Seminar: Coastal evolution and management by Prof Roelvink

Dano Roelvink, Professor of Coastal Engineering and Port Development at IHE Delft, presents this edition of the alumni online seminar on 'coastal evolution and management: a new tool to understand the past and future'.

Sandy beaches are extremely valuable natural resources, providing a first line of defense against coastal storm impacts, as well as other ecosystem services such as ecological habitats and recreation areas. They often are an important part of nations’ heritage. However, many of the world’s coastlines suffer erosion, due to interruption of sand flows from upstream and alongshore, sand mining and sea-level rise effects, especially in the vicinity of tidal inlets. As a result, the safety of ever-increasing populations against hazards such as overtopping, inundation and erosion is seriously undermined.

A lack of reliable, widely usable models makes it difficult to develop sound, science-based strategies for managing complex sandy coasts. While the physics of beaches have been studied extensively and Delft has a strong reputation in developing useful models that are used worldwide, these are often too complex and time-expensive to use for engineering application at larger scales; other models are too simple to represent interesting cases such as sandy barriers, spits, spiral beaches and migrating tidal inlets and river mouths.

At IHE Delft, in collaboration with Deltares, we have recently developed a radically new method, ShorelineS, to hindcast and forecast coastline evolution. Though it is based on a relatively simple representation of wave-driven transport, the representation of the coastline as strings of coastline points that can freely develop and move about gives is a powerful behaviour that allows us to rapidly model coastal planform evolution, for cases ranging from the development of the Sand Engine to development of spits and from a moving river mouth in Senegal to moving barrier islands in Portugal and Alaska.

Input and calibration data for such modelling are available at an unprecedented scale (e.g. satellite imagery-derived coastlines) alongside ever more detailed global models and datasets of forcing conditions (wave climate, tides). This allows you to develop and calibrate a model of your own situation based on past observations, and then to simulate the future given a range of scenarios.

Though still under development, we believe a system can be developed where engaged citizens can analyse and simulate the coastal development in their areas, can see how human impact has altered their coast and what are sensible strategies to cope with increasing population pressure and climate change.

In the webinar I will first take you on a little tour along typical coasts, where we’ll see how even before climate change is kicking in we are facing serious problems, and how this may be exacerbated by sea level rise and changes in wind and wave climate. But, being engineers, we will not rest there, but try to work with a mix of solutions, hard and soft, nature-based where possible. I’ll show how a model like ShorelineS can play an important role in the evaluation of the problem and of possible solutions and I’d like to pick your brain on how you envisage tools like this being used, and what ideas you have for directions they could develop towards.