Self-maintaining dune blowout systems
Beaches along high-energy delta coasts such as the Dutch coast, are generally fringed by high and spatially extensive dune fields. These dunes act as a vital natural safety barrier against marine flooding, host valuable natural environments, serve for the production of drinking water and offer various recreational opportunities. Christian Schwarz uses his Future Deltas seed-money project to investigate how abiotic and biotic factors shape the morphologic development of blowouts.
The safety function has dominated dune management for decades and consequently has turned the most seaward dune into a sand dike leading to static species-poor plant communities in the back dunes. Trough- or bowl shaped depressions in the seaward dune, so called blowouts, are common features in natural dunes and are essential to maintain dynamic species rich dune ecosystems (see picture above). Blowout development is governed by the hitherto unknown interaction between abiotic (e.g. aeolian sand transport and precipitation) and biotic factors (e.g. vegetation colonization).
This Future Deltas seed-money project developed a conceptual understanding of how abiotic and biotic factors shape the morphologic development of blowouts. Through literature research we could identify feedback loops between vegetation and abiotic factors (e.g. precipitation, moisture, plant species and magnitude of sand transport) which potentially facilitate blowouts to stay open (i.e. self-maintaining) or close over time. This conceptual understanding will act as a foundation for further field and model exercises able to predict blowout development and thereby answering practice-inspired questions for sustainable management of coasts and deltas.