Shipping traffic in inland waterways leads to changing hydraulic loads on the banks. With the introduction of the European Water Framework Directive (WFD), the banks, which have so far been mainly secured using technical methods, are to be made more natural over the long term by using plants.
For the initial state, additional fortifications and measures are usually required to ensure the safety of the banks until sufficient roots have formed. This also includes temporary geotextile fleeces, which guarantee filter stability in the bank area for the first three years after installation. These must retain the soil and have sufficient permeability and strength while also being permeable to roots and biodegradable over the long term so as not to permanently restrict the passage of microorganisms in the bank area. Once suitable filter fleeces are available, the applicability of more natural bank protection measures on inland waterways can be increased.
Geotextile filter closes research gap
Biodegradable nonwovens tested to date for technical and biological bank protection are not sufficiently stable under the given loads and degrade too quickly. Alternatives made from plastic are stable and durable but remain permanently in the soil. A suitable solution that meets all of the requirements is still lacking.
With the development of a biodegradable geotextile filter made from renewable raw materials, the partners in the “Bioshoreline“ project are closing this gap. This is because the innovative filter enables plants to grow in technical and biological bank protection systems and it gradually breaks down completely so that the vegetation can take over the filter stability in the bank. The geotextile filter is composed of various rapidly degradable natural fibers and slowly degradable industrially-created fibers, whereby the technical requirements are met for at least three years.
Field experiment planned for prototypes
Geotextile prototypes are currently being developed for this purpose. During the next phase of the project, selected prototypes will be tested with regard to permeability to roots in special experiments on the BAW site. In addition, the prototypes will be installed on a section of waterway in a field experiment and investigated over several years as regards their technical properties and biodegradation. The geotextile filters will then be optimized based on the knowledge gained.