BESE-elements allow vegetation to return and protect the riverbank from wave energy. At the same time plastic is eliminated in the environment and maintenance minimized. This decreases the long-term costs for riverbank maintenance. Three projects along Dutch canals and rivers have started to test this principle in different types of applications. See project descriptions and pictures of location plus design set-ups below.
Oude Rijn – Alphen aan de Rijn (set-up summer 2022)
Problem
Along the river ‘Oude Rijn’ a nature friendly riverbank design was implemented. Where riparian vegetation was able to grow behind a dam wall. Unfortunately, the design still resulted in erosion of the riverbank, due to increased flow rates behind the dam wall. Moroever, the erosion caused the plastics (geotextiles) used in construction of the riverbank to surface and pollute the waterway.
Solution
BESE-elements were placed along the riverbank, which aimed to decrease flow rate and thereby induced erosion behind the dam wall. And consequently increase vegetation growth. Moreover the bare lying plastics were removed and replaced with BESE-elements, to stabilize the riverbank.
In the spring of 2023 the BESE-elements will be planted with riparian vegetation to fasten the regrowth of plants along the riverbank, and halt further erosion.
Zeevangsdijkje – Kwadijk (set-up winter 2022, 2023)
Problem
Another project to halt erosion along a riverbank is set-up in Kwadijk, along ‘Zeevangsdijkje’.
On this site the riverbank is eroding and slowly damaging the stability of the road behind. Current protection of the road is a small strip of riparian vegetation, which is reducing in extend every single year.
Solution
The set-up is different than the Oude Rijn project as in this waterway the BESE-elements are placed as a dam wall (vertically in the watercolomn). Behind the BESE-elements soil was brought up to fill up the area behind the BESE-elements and the road. Within this soil, seeds of riparian vegetation are present, to kickstart regrowth in springtime 2023.
Borsele - Scheldestromen (2019)
Problem
Shoreline erosion at the project location limited the growth of reed and riparian vegetation. Moreover the riverbank was stabilized with bitumen enforced plastics, which the local waterboard wanted to remove.
Solution
In May 2019, a 44-meter BESE-riverbank was created by placing BESE-elements side by side along the riverbank. The riverbank was excavated to create a smooth surface for optimal placement of the BESE-elements. Soil with reed canes was applied below the BESE-elements. The BESE-elements were then placed on the excavated riverbank and fastened with rebar.
Results
During the summer and fall of 2019 and the spring of 2020 we monitored vegetation growth and riverbank stability. Already in July 2019, the BESE-riverbank started to turn green and the vegetation kept flourishing during the summer season. Next to reed, 22 different species of plants were found growing in and on the BESE-riverbank!
