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Theme Project 9: Virtual Delta


To support medium and short term decision making for salt intrusion in the Rhine Meuse Delta the responsible water authorities (I&M/RWS) and the Water Boards urgently need an updated system to anticipate for major changes in the freshwater management in the coming years. For the short term, 1 – 10 years, support is needed for decisions on deepening of the RWW, or the extension of the sluices complex in IJmuiden. For the long term 10-100 years, they need to explore the effects of rapid sea level rise and measures to mitigate the impacts. To support this decision making this project 9 will deliver a digital twin, the virtual delta, to mimic decision making and management of salt intrusion on these time scales.

Project description

This Virtual Delta will be constructed by merging existing computational tools describing salt water intrusion with the deliveries from the other projects, i.e. the newly developed advances in data assimilation and analytics, models both 1D and 3D, that mimic mitigation measures and their impact. Step wise during the programme they are merged leading in year 6 to a full-fledged digital twin including the engine and the interface driving the Virtual Delta.

The key scientific challenges of the Virtual Delta are (a) to provide the maximum predictability of key indicators for short-, medium-, and long-term decision making for salt- and freshwater distribution in managed estuaries and delta’s and (b) provide an efficient system that eases decision making with respect to salt intrusion.

The main technical challenge of Project 9 is to develop the engine and interface of the digital twin: The Virtual Delta. The Virtual Delta will contain modules to address (a) the specific needs of operational (1 hour-seasonal lead time) decision making (WP9.1 and 9.2), and (b) medium to long term management of salt intrusion (WP9.3). The latter will cover planning for the coming decades to address consequences of engineered and nature based SALTISolutions and on the long term for predicted climate change and sea level rise.

When successful, next to utilisation in the Netherlands by the public sector we also foresee utilisation in the market sector, both nationally as well as internationally since the tested improvements are implemented in the open source software that is developed by Deltares (e.g. This software is used in many places in the world to support decision-making in coastal regions estuaries and deltas. As such the results of SALTISolutions will be transferable to other estuaries worldwide.

The Virtual Delta will initially be built from existing components that are currently used by the water management authorities. The module built in 9.1 assimilates chloride concentration data from measuring stations throughout the delta and will be used for decisions on water re-distribution for real-time control of salt intrusion. WP9.2 will explore the potential of monitoring from space using the steadily increasing wealth of satellite Remote Sensing (RS) to complement in-situ monitoring for the more data-sparse deltas around the world. In 9.2 we will build upon the advanced 3D models from Project 3. SALTISolutions will explore the potential of coupling such monitoring to improve the short-range predictive capability in WP9.1. In 9.3 we will build the module for ‘design’ purpose, assessing the vulnerability of our delta to climate change. During the program, each PI will ensure the new advances in data, models, mitigation both grey and nature-based solutions are integrated into the Virtual Delta. The climate projection results from P5 will point to interesting/critical cases which can be re-addressed in more detail by the 3D models, using the same downscaled forcing. Commitment of different stakeholders is a prerequisite for efficient decision making. For the module build in 9.3 the IAM designed in P8 will be the basis for the module for the medium to long term planning system. In WP9.3 from year 4 onward this IAM will be advanced in a stepwise manner by incorporating the results from Projects 2-4, climate data bases generated in Project 5, nature-based solutions from 6 and 7. The core of the Virtual Delta will be developed based on the high-resolution 3D model provided by Project 3. The short-term decision support system will be tested in hindcasting mode for a series of well monitored events in the RM delta. The core of the long-term planning system will also be tested on the RMD and Mississippi Delta. The systems will be used to explore the effectiveness of a series of responses for short term salt intrusion management during extreme weather events and for the robustness of long-term management options to manage salt water in the delta under changed climate conditions and sea level.

This project will address the following knowledge gaps for managing salt intrusion:

  • How much information for decision making can be obtained for both the daily as for the decadal time scale model simulations using an affordable computational demand?
  • Can we use of remote sensing images to support operational decisions for freshwater withdrawal?
  • How do grey-green mitigation measures influence the propagation of the salt wedge in estuaries with strong tidal forcing and in low dynamic parts?
  • Is applying nature-based engineering an option to sustaining freshwater availability in future deltas? Can we build in resilience to mitigate salinization?

Project deliverables

  • Advanced operational model for short-medium term forecasting of salt concentration (9.1)
  • Prototype data assimilation using radar data and RS data in next generation systems (9.2)
  • An engine and interface for the digital twin, the Virtual Delta (9.3)
  • A validated system for saltwater management decision making in deltas for long term (9.3)


Related updates

Consortium meeting: Shaping the Virtual Delta


View details

Project leader

Prof. Dr. J.C.J. Kwadijk


Prof. A.H. Weerts

Prof. dr. ir. Mascha van der voort

Prof. dr. J.D. Pietrzak

Prof. M. Verlaan

Dr. C. Katsman

PhD candidates & Postdocs

Bas Wullems

Avelon Gerritsma

Prof. Dr. J.C.J. Kwadijk

Prof. Dr. J.C.J. Kwadijk

University of Twente


Last modified: 17/06/2022