Deltas need sediment to keep up with sea-level rise (Storyline: Flood risk management) and land subsidence (Storyline: Sinking deltas). Researchers at the Water, Climate and Future Deltas hub work to understand sediment behaviour and look for sustainable strategies to manage sediment. There is already a lot of knowledge, but it is difficult to understand sediment dynamics in an integrated manner at the delta scale and beyond, which is one of the challenges the hub is committed to.
The building blocks of deltas
Sediments are important building blocks for deltas, but sediment supply to deltas worldwide is declining which raises serious concerns. The causes of this decline are dam construction, land-use change and other anthropogenic interventions in the river catchment.
Sediment is not just valuable bio-physical matter, but also a challenge for delta management
As deltas are open systems that receive water and sediment from the upstream catchment, sustainably managing deltas requires transboundary river governance. In addition, sediment problems are always coupled to issues of water safety, economic activities and nature. Maarten Kleinhans, professor of rivers and estuaries, says, "This makes sediment not just valuable bio-physical matter, but also a challenge for delta management".
Many of the deltas that receive insufficient sediment are on the verge of reaching a tipping point: at which the drowning of deltas – or parts of them – starts and cannot easily be reversed. Integrated sedimentation strategies are therefore needed, together with the institutional backing to ensure their implementation and with scientific commitment to support this.