The groundwater monitoring in Rammegors included EM-Slimflex measurements, FRESHEM numerical modelling and vadose zone measurements. The isolation of Rammegors from the Eastern Scheldt for a period of 43 years caused a freshening of Rammegors and small zone in the adjacent polder areas. A freshwater lens of about 10 to 20 meter thickness has developed below Rammegors, which extents for several hundreds of meters outside Rammegors. The lens has a thickness of about 3 to 6 m in the Prins Hendrikpolder and 7 to 10 m in the Haaftenpolder. The freshwater lens is not used by the farmers for irrigation. It is expected that salinization of the freshwater stock by the opening of Rammegors will take place in the same time span or even faster.
From the groundwater monitoring results, no effect of the restoration of Rammegors on the hydraulic head and phreatic groundwater level was visible. According to the groundwater model simulations, some effects of the opening of Rammegors for the surrounding Southern and Northern polders may be expected. Saline seepage and hydraulic heads may increase for a zone 100-300 m from Rammegors, with largest effects close to Rammegors. Significant increases of phreatic groundwater levels of 10-20 cm are only expected for a zone 50-100 from Rammegors. The model, however, indicates that the largest part of Rammegors will be salinized within 10 years. Yet, the model also shows that even after 50 years there will still be small freshwater patches present below areas that are never (or sporadically) inundated. Based on the monitoring and the modeling efforts, it is expected that salinization will continue for both the tidal area and the surrounding polders. It is therefore recommended to continue the hydrological monitoring for the coming 5 to 10 years (Van de Lageweg et al. 2019.
Referenties
- Rammegors tidal restauration, final report, Lageweg, W. van de et al., Centre of Expertise Delta Technology, april 2019.
Zie ook
- Rammegors tidal restauration, final report
- Perkpolder tidal restauration, one year after realisation, draft progress report
- Perkpolder Tidal Restauration
- Development of the benthic macrofauna community after tidal restoration at Rammegors
- Is there a green solution for a blue-green problem leading to clear blue water?
- The Benthic Ecosystem Quality Index (BEQI), intercalibration and assessment of Dutch coastal and transitional waters for the Water Framework Directive. Final report
- Eastern Scheldt inlet morphodynamics
- ANT Oosterschelde: Long-term trends of waders and their dependence on intertidal foraging grounds
- Aspects of sediment- and morphodynamics of subtidal deposits of the Oosterschelde (the Netherlands)
- Wadden Sea Plan 2010
