EngD defense Mishel Reyes | Development of a Dashboard for Management of Saltwater Intrusion in a Semi-closed Estuary

EngD defense Mishel Reyes, 2 October 2026, 10:30-12:00h, Waaier 4

Development of a Dashboard for Management of Saltwater Intrusion in a Semi-Closed Estuary

The Haringvliet estuary is managed to balance flood safety, freshwater availability, and ecological connectivity. Under the Kierbesluit, the Haringvliet sluices are partially opened during flood tide to support fish migration. However, saltwater entering the estuary can become trapped in bathymetric depressions and, under unfavourable conditions, may spread inland towards freshwater-intake areas. Managing this trade-off requires operational guidance that accounts for uncertainty in both environmental conditions and model-based predictions.

This EngD project developed a dashboard for saltwater management in the Haringvliet Estuary. The work builds on the existing operational protocol and analytical model, combining them with sensitivity and uncertainty analyses, an assessment of the model’s representation of mixing, and an iterative stakeholder-centred design process.

The analyses identified Outer-delta salinity, Inlet volume and Ebb volume as the main factors influencing predicted saltwater behaviour. Outer-delta salinity most strongly affected the predicted equilibrium location of saltwater, whereas Inlet and Ebb volumes strongly influenced the total salt mass retained in the system. We tested a modification of the analytical model to represent spatial differences in vertical mixing between bathymetric depressions. Although this made the physical interpretation of mixing more explicit, it did not improve the overall prediction of Equilibrium Location, demonstrating that changes to one process should be accompanied by recalibration of the broader model framework.

The resulting executable dashboard translates model results into transparent, uncertainty-aware information. It provides a recommended Inlet volume, an estimated probability of keeping saltwater within a selected target location, confidence information, operational warnings and a conservative safe inlet recommendation. It also enables users to compare up to four scenarios and explore the effects of changing discharge, salinity, protocol settings and uncertainty assumptions.

Stakeholder feedback shaped the dashboard’s terminology, input workflow and layered interface. The final product is intended primarily for technical and strategic users to support scenario evaluation, discussion and learning. It is a working research tool, but it has not yet been tested for real-time operational use. It is meant to help experts make decisions about saltwater management in the Haringvliet, not to replace their judgement.