SALTISolutions: Working package 7.1

Introduction about SALTISolutions

SALTISolutions is a research consortium in which five Dutch universities are involved in collaboration with companies in the fields related to salt intrusion. The consortium focuses on different aspects of salt intrusion and its impact on nature and society. The main goal is the development of a Virtual Delta that encompasses a digital twin and a serious game. For more information, see the website of SALTISolutions.

Working package 7.1

Working package 7.1 (WP 7.1) of SALTISolutions focuses on the development of nature-based solutions to mitigate salt intrusion. This PhD research consists of three phases:

1. Sensitivity analysis of salt intrusion;
2. In-depth physical assessment(s) of nature-based solution(s);
3. Multidisciplinary assessment of nature-based solutions.

Phase 1: Sensitivity analysis: The sensitivity analysis determines the sensitivity of the salt intrusion in an estuary to thirteen variables assessed (three boundary conditions, and ten geometric characteristics). Due to the complexity of the physical processes determining salt intrusion and the scale of the analysis, machine learning techniques are used.

Phase 2: In-depth assessment: Based on the sensitivity analysis of the first phase, some high-potential nature-based solutions are drawn and investigated in more detail.

Phase 3: Multidisciplinary assessment: The Building with Nature-approach includes three perspectives in its assessment of nature-based solutions: (1) physics, (2) ecology, and (3) socio-economy. In this last phase, the ecological and socio-economical perspectives are added to the assessment of nature-based solutions to mitigate salt intrusion.

This repository

This repository functions as a collective overview of all work performed as part of the introduced research topic. The result is a repository without any code, but cross-references to the standalone repositories containing products that resulted from the research, so-called sub-repositories.

All code is developed on a private repository, and once ready for publication, stored in (or added to) a sub-repository.

Author

Gijs G. Hendrickx (Delft University of Technology)

Contact: G.G.Hendrickx@tudelft.nl.

Sub-repositories

Every sub-repository contains its own elaborate, case-specific README-file to assist in its use. The following sub-repositories are included:

1. ANNESI: Artificial neural network for estuarine salt intrusion. (Coupled web-API at ANNESI-web.)
2. EMMA: Ecotope-map maker based on abiotics.
3. GAPool: Genetic algorithm with "best pool" functionality.
4. HybridModelling: Hybrid modelling using machine learning techniques and process-based models, i.e., implementation of work-flow as described in Hendrickx et al. (2023). (Private repository, accessible upon reasonable request.)
5. SaltFluxDecomposition: NumPy-based salt flux decomposition.

Relevant publications associated with the sub-repositories are stated in their respective README-files.

References

An overview of related publications is presented below.

Peer-reviewed articles

The following peer-reviewed articles include aspects of this PhD research:

1. Hendrickx, G.G., Antolínez, J.A.A., and Herman, P.M.J. (2023). Predicting the response of complex systems for coastal management. Coastal Engineering, 182:104289. doi:10.1016/j.coastaleng.2023.104289.

2. Hendrickx, G.G., Kranenburg, W.M., Antolínez, J.A.A., Huismans, Y., Aarninkhof, S.G.J., and Herman, P.M.J. (2023). Sensitivity of salt intrusion to estuary-scale changes: A systematic modelling study towards nature-based mitigation measures. Estuarine, Coastal and Shelf Science, 295:108564. doi:10.1016/j.ecss.2023.108564.

3. Hendrickx, G.G., Manuel, L.A., Pearson, S.G., Aarninkhof, S.G.J., and Meselhe, E.A. (2024). An earthen sill as a measure to mitigate salt intrusion in estuaries. Estuaries & Coasts, 47(5):1199-1208. doi:10.1007/s12237-024-01359-2.

4. Brunink, S., and Hendrickx, G.G.. (2024). Predicting ecotopes from hydrodynamic model data: Towards an ecological assessment of nature-based solutions. Nature-Based Solutions, 6:100145. doi:10.1016/j.nbsj.2024.100145.

5. Hendrickx, G.G., and Pearson, S.G. (2024). On the effects of intertidal area on estuarine salt intrusion. Journal of Geophysical Research: Oceans, 129(9):e2023JC020750. doi:10.1029/2023JC020750.

6. Saccon, E., Hendrickx, G.G., Hulscher, S.J.M.H., Bouma, T.J., and van de Koppel, J.. (2025). Wetland topography drives salinity resilience in freshwater tidal ecosystems. Ecological Engineering, 217:107650. doi:10.1016/j.ecoleng.2025.107650.

7. Bakker, F.P., Hendrickx, G.G., Keyzer, L.M., Iglesias, S.R., Aarninkhof, S.G.J., and van Koningsveld, M.. (2025). Trading off dissimilar stakeholders interests: Changing the bed level of the main shipping channel of the Rhine-Meuse Delta while considering freshwater availability. Environmental Changes, 21:101323. doi:10.1016/j.envc.2025.101323.

Conferences

The following presentations at conferences include aspects of this PhD research (presenter in bold):

1. Hendrickx, G.G., Aarninkhof, S.G.J., and Herman, P.M.J. (March 25, 2021). Nature-based solutions to mitigate salt intrusion. NCK Days 2021. Online.

2. Hendrickx, G.G., Antolínez, J.A.A., Aarninkhof, S.G.J., Huismans, Y., Kranenburg, W.M., and Herman, P.M.J. (March 4, 2022). Combining machine learning and process-based models to enhance the understanding of estuarine salt intrusion and development of estuary-scale nature-based solutions. Ocean Sciences Meeting 2022. Online.

3. Hendrickx, G.G., Aarninkhof, S.G.J., and Herman, P.M.J. (March 17, 2022). Estuarine sensitivity to salt intrusion mitigation measures. NCK Days 2022. Enschede, the Netherlands.

4. Hendrickx, G.G., Antolínez, J.A.A., Herman, P.M.J., and Aarninkhof, S.G.J. (December 5, 2022). Estuarine sensitivity to nature-based salt intrusion mitigation measures. 37th International Conference on Coastal Engineering 2022. Sydney, Australia. doi:10.9753/icce.v37.management.146.

5. Hendrickx, G.G., Meselhe, E.A., Herman, P.M.J., and Aarninkhof, S.G.J. (April 13, 2023). A sill as nature-based solution to mitigate salt intrusion. Coastal Sediments 2023. New Orleans, LA, the United States of America. doi:10.1142/9789811275135_0184.

6. Hendrickx, G.G., Meselhe, E.A., Aarninkhof, S.G.J., and Herman, P.M.J. (April 27, 2023). Designing a sill to mitigate salt intrusion. Lower Mississippi River Science Symposium. New Orleans, LA, the United States of America.

7. de Wilde, J., Kranenburg, W.M., Huismans, Y., Pietrzak, J.D., and Hendrickx, G.G.. (March 14, 2024). Tidal phase differences in multi-branch systems and their effect on salinity intrusion. NCK Days 2024. Amersfoort, the Netherlands.

8. Hendrickx, G.G., Manuel, L.A., Pearson, S.G., Aarninkhof, S.G.J., and Meselhe, E.A.. (March 14, 2024). When and where to construct a sill to mitigate estuarine salt intrusion. NCK Days 2024. Amersfoort, the Netherlands.

9. Hendrickx, G.G., Pearson, S.G., and Aarninkhof, S.G.J.. (September 13, 2024). Engineering guidelines for nature-based solutions to mitigate salt intrusion. International Conference on Coastal Engineering 2024. Rome, Italy.

Software and datasets

The following software and datasets have been produced as part of this PhD research:

1. Hendrickx, G.G. (2022). ANNESI: An open-source artificial neural network for estuarine salt intrusion. 4TU.ResearchData. Software. doi:10.4121/19307693.

2. Hendrickx, G.G. (2023). NEESI: Numerical experiments of estuarine salt intrusion dataset. 4TU.ResearchData. Dataset. doi:10.4121/22272247.

3. Hendrickx, G.G. (2023). NumPy-based Salt Flux Decomposition. 4TU.ResearchData. Software. doi:10.4121/bccbe767-667b-40ba-a4d1-d8fcad900772.

4. Hendrickx, G.G., and Brunink, S.. (2023). EMMA: Ecotope-Map Maker based on Abiotics. 4TU.ResearchData. Software. doi:10.4121/0100fc5a-a99c-4002-9864-3faade3899e3.

5. Hendrickx, G.G., Manuel, L.A., Pearson, S.G., Aarninkhof, S.G.J., and Meselhe, E.A. (2024). Dataset underlying the study ''An earthen sill as a measure to mitigate salt intrusion in estuaries.'' 4TU.ResearchData. Dataset. doi:10.4121/10d493df-8efb-442b-8c3d-04e92bcf4c4e.

6. Hendrickx, G.G., and Pearson, S.G. (2024). Dataset underlying the study ''On the effects of intertidal area on estuarine salt intrusion.'' 4TU.ResearchData. Dataset. doi:10.4121/c357f1c7-dea8-4971-b5a1-c54c42e4172a.

7. Saccon, E., Hendrickx, G.G., Hulscher, S.J.M.H., Bouma, T.J., and van de Koppel, J.. (2024). Dataset underlying the study ''Wetland topography drives salinity resilience in freshwater tidal ecosystems.'' 4TU.ResearchData. Dataset. doi:10.4121/93d8d223-e2ab-486e-a85b-da14789532d4.