On Tuesday 18 April you can join one of the excursions. The bus will leave in the morning from the Aula Conference Centre and will bring you back at the end of the day. Limited spots per excursion are available.
Excursion 1: The subsiding coastal plain of the western Netherlands: historic and future trends
The subsiding coastal plain of the western Netherlands is of great economic importance and is densely populated. In large parts of this area, the present surface elevation is up to a few meters below mean sea-level and subsidence is ongoing (~5-10 mm/yr), mainly due to continuous drainage of peat soils for maintaining meadows for dairy farming. This makes the Dutch coastal plain vulnerable for sea-level rise and climate change, increasing the risks of flooding and salinization, and damage to buildings and infrastructure, while emitting greenhouse gasses (GHG) by oxidation of drained peat soils. It is expected that climate change will increase subsidence rates and greenhouse gas emissions substantially.
During this field trip we will visit (1) a former peat excavation area, transformed into a nature reserve, (2) a subsidence and GHG-monitoring and experimental site at which innovative measures are developed and tested, and of which effects are monitored using various measuring techniques, to minimize peat oxidation to conserve the peat meadow area, and (3) a village in a rural area showing the consequences of land subsidence in both the built-up and agricultural part of the area.
Photos: Impression of the subsiding coastal plain of the western Netherlands. Top left: Monitoring site Zegveld (source: NOBV). Top right: Nieuwkoopse Plassen, nature reserve (source: Natuurmonumenten). Lower left: Subsiding street and sidewalk village of Kanis (copyright: Sam Rentmeester). Lower right: Dairy farming in the peat meadow area (source: Joop van Osch, WUR).
Some topics to be addressed and seen are:
- Peat growth and historic land subsidence in the western Netherlands.
- Consequences of land subsidence in the western Netherlands.
- Subsidence monitoring since 1970 of peat meadow parcels with low and high ditch water levels.
- Playground for measuring techniques to monitor subsidence. New start and continuation of the Dutch monitoring site Zegveld on subsidence.
- Research on the effect of infiltration via submerged drains to rise groundwater levels to decrease subsidence rates and GHG emissions.
- Research on paludiculture (wet agriculture) to diminish subsidence rates and GHG emissions.
- Controlled high groundwater levels (kept at 20 or 40 cm below surface) to minimize subsidence rates and GHG emissions.
- Key site for the Dutch monitoring program of GHG emissions of peat meadows: how can the CO2-emission of the Dutch peat meadow area be reduced with 1 Mton per year?
- New ways of dairy farming.
Excursion 2: Battles of a low-lying country: Delta Works and sinking cities expo
The flood of 1953 was the greatest natural disaster to occur in the Netherlands in the 20th century. The disaster claimed the lives of more than 1800 people and demonstrated more clearly than ever the importance of protecting of the country against flooding. To prevent a disaster like this one the coastline was shortened by 700 kilometers via constructing closed and permeable dams; the Delta Works.
We start our tour in the area of the ‘Watersnood’ museum (flood museum). We will explore an area flooded in 1953 and you will be confronted with the catastrophic effects of the 1953 flood. In the museum we will visit the ‘Sinking cities’ photo-exhibition. Cynthia Boll, winner of the prestigious 'Silver Camera award' 2018 will tell us more about her work; how people in cities as the Dutch city Gouda, but also Jakarta and Venice are affected by floods and subsidence.
After the 1953 flood, the Delta Plan was carried out, to safeguard this area for future generations. During the excursion we will cross several dams that were constructed for that reason and we will spend some more time to have a view and explanation on the Easter Scheldt storm barrier, the construction that forms the capstone of Delta Works in 1986. This construction is only closed by huge slides, only in case of extreme high tides. For environmental reasons, the slides are open under normal conditions.
Excursion 3: Excursion to the reclaimed province of Flevoland
The construction of the newest province in the Netherlands, Flevoland, began eighty years ago. New land was reclaimed from the former Zuiderzee and in 1968 close to 2.5 thousand square kilometres was added to the Netherlands. Two small islands of Urk and Schokland became part of the polder. Today more than 400,000 inhabitants live on average 5 metres below sea level. Cultivation of the new land meant that the soft soils of the former sea bottom had to be drained. As a result the province still has to contend with subsidence. This was of course foreseen, but initial estimates were exceeded in the following decades and the final estimates have been increased several times to up to 2 metres in the Southern part of Flevoland.
In the morning, we will visit the Oostvaardersplassen, which is a nature reserve managed by Staatsbosbeheer. Covering about 56 square kilometres in the province of Flevoland, it is an experiment in rewilding. The Oostvaardersplassen can be divided into a wet area in the northwest and a dry area in the southeast. In the wet area along the Markermeer, there are large reedbeds on clay, where moulting geese often feed. Oostvaardersplassen is a Special Protection Area for birdlife. In 2013, an award-winning natural history documentary film on the Oostvaardersplassen was published (http://www.denieuwewildernis.nl/).
In the second part of the morning, we will visit the water board of Zuiderzeeland, who are responsible for the management of ground- and surface water. We will hear how they manage the consequences of subsidence in the new land.
In the afternoon, we will go to the former island of Schokland, a UNESCO world heritage site. The area surrounding the island and the former island itself is suffering from subsidence. Besides the challenges for the water board we will experience the dramatic history of the small community that lived there.
Excursion 4: Loosing land!
We will visit several spots in a transect from the solid ice-pushed Pleistocene hills, passing the soft polder area, towards the North Sea (Hilversum-Zandvoort) and answer many questions: how the Netherlands have lost and are still losing land? Have the Dutch built or “burnt” their land? Why do they have to abandon some of their polders? What is so special about the way they extract ground water?
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