Page tree
Skip to end of metadata
Go to start of metadata

 
Building with Nature Guideline

Home BwN Approach Building solutions Projects Toolbox

 Building with Nature Guideline > Projects > Tidal flat nourishment - Galgeplaat, NL

Log in  

 


Tidal flat nourishment - Galgeplaat, NL

Location: Oosterschelde (Eastern Scheldt), the Netherlands

Date: 2008-2012

Involved parties: Deltares, IMARES, Rijkswaterstaat, NIOZ (former NIOO-CEME), EcoShape 

Technology Readiness Level: 9

Environment: Estuaries, Sandy shores

Keywords: Benthic ecology, tidal flat restoration, estuary protection, measures against erosion, biodiversity, morphology, hydrodynamic model

 

 

 

 

Abstract

Tidal flats are valuable habitats and are important for coastal protection. The total area of tidal flats is decreasing worldwide due to various problems like sea level rise, coastal squeeze, subsidence by gas extraction and erosion initiated by man made constructions. The construction of a storm surge barrier and compartmentalization dams in the Eastern Scheldt in the 1980s is one example of a man made structure that resulted in a change in hydrodynamic conditions of the Eastern Scheldt estuary and hence the sediment equilibrium. As a result, channels are filling in and tidal flats inside the estuary are eroding. Nourishing tidal flats with sediment might be a promising solution to mitigate these effects. 

 

To test this approach, a small area of the Galgeplaat, a tidal flat in the Eastern Scheldt, was nourished in 2008 with 130.000 m3 sand dredged from adjacent channels over a total area of 150.000 m2. The processes of sediment distribution on the flats and benthic recolonization are coupled and interact with each other. Therefore the design challenge is to find an optimum to reduce the initial impact of the nourishment on the benthic fauna, while optimizing the distribution of the sand over the tidal flat by wind and waves and the subsequent recovery of benthic life.

 Read more

 

Planning and design

Primary purpose of the Galgeplaat pilot was to investigate whether nourishment can compensate the erosion of a tidal flat. Furthermore, the pilot offers the opportunity to gain a better insight into the biological and morphological development of an intertidal flat and the relationship between biotic and abiotic parameters. This will help improving the design of new measures with respect to the mitigation of the ongoing erosion of tidal flats in estuaries like the Eastern Scheldt in the future.

   Read more


Construction

From August to September 2008 130,000 m³ of sand was deposited on the Galgeplaat in a low circular mound, creating a kind of sand reservoir (figure 9).

First, a protective ring of sand was built, approximately 1 m high with a diameter of 450 m. The ring was made by bulldozers with sediment taken from the flat itself. At the south east side an opening was created for discharging excess water during the nourishment operation. At the inner side of the opening a settling-basin was excavated, in order to reduce the content of suspended matter in the effluent. The opening was oriented towards the nearby channel (Brabantsche Vaarwater).

 Read more

 

Operation and Maintenance

 The development of the nourishment and its impact on the morphological and biological processes has been and will be further monitored for several years, primarily by Rijkswaterstaat. Additionally Building with Nature has taken extra samples of the benthic macrofauna and has installed an Remote monitoring of bio -and morphological developments (ArgusBio) for morphological imaging and close-up images of birds, and other ecological features like the presence of algal mats and microphytobenthos. 

 Read more

 

Lessons Learned

Several lessons-learned have been obtained on the field of morphology, ecology dynamics and (predictive) modelling 

 Read more

 

 References


 

Back to Top

  • No labels