Delta Life 12

The civil engineering sector has a large eco­ logical footprint world­ wide. The extraction of sand and dredging operations, for example, affect natural systems and dumped residual materials pollute eco­ systems. That is why Deltares is looking at solutions for things like the re-use of sludge (see inset). When it comes to the circular economy, companies and organisations often think in terms of individual sectors such as water, energy or agriculture. The use of biofuels (from rapeseed and algae, for example) reduces carbon emissions. But growing themalso requires a lot of water and nutrients. Deltares therefore advises focusing not just on one cycle but precisely on the interaction between different cycles. The circular economy also contributes to stability in the world. When resources become scarce, conflicts and flows of climate refugees become more likely. Better land use can prevent desertification, for example by retaining rainwater, planting new trees, temporarily stopping grazing and using groundwater sustainably. Deltares is investigating these areas in collaboration with other research institutes. The use of fresh groundwater is rising worldwide. In deltas, that can lead to land subsidence and the salinisation of groundwater stocks. Deltares is trying to raise awareness about this issue and we are looking at possible ways of using brackish groundwater for agri- cultural or industrial applications. For more information: hans.vissers@deltares.nl 19 Deltares researchers are looking at the circular economy from different angles. For example, the Clay Ripener research project is focusing on the possibilities for using wet, salt sediment dredged in the port of Delfzijl or from the Bree- baart polder to produce clay that is suitable for strengthening dikes. If they are successful, the clay will not have to be brought in over long distances, and it will be possible to prevent high costs and environmental pollution. Another example is the Hazerswoude Topsurf pilot project, which is looking at how to use a mixture of manure, sludge, dredged material and vegetable materials to combat land subsidence. This approach can also be good for the environment because these organic materials capture CO 2 and the sludge doesn't have to go to landfall or be incinerated. Another interesting development is the SURICATES project that is being conducted by an international research consortium (including Deltares) to devise solutions for environmental pollution caused by dredging. Every year, dredgers extract no less than 200 million cubic metres of sediment from European ports and waterways (source: SedNet, Venice, 2004). Just under 1% of that material (800,000 tonnes per year) is re-used: 99% of it is dumped at sea. SURICATES is in- vestigating how sediment can be used for coastal protection and restoration. The aim is to re-use 2.3 million tonnes of dredged sediment annually in the European Union within ten years. In short, about three times the current amount. Deltares also developed a circular economy scan recently. This is an objective method for determining the extent to which water and subsurface projects contribute to circularity. In collaboration with Rijkswaterstaat, this method is being developed further for applications in delta technology. Deltares and the circular economy