Terpen Water System in Friesland, Netherlands.
Rafael Gridelli
2024
The northern part of the Netherlands developed into a salt marsh, as water gathered in the low, flat areas. Six thousand years ago (Vos, 2000), not only did the sea level rise, but also the amount of sedimentation. The increase in sediment resulted in the creation of salt marsh ridges. These ridges developed during high water peaks, when floods reached inland areas where water was calmer, and sediment would settle, creating layers of sediment deposit. These salt marsh ridges eventually became high enough to only flood during storm surges. The hinterland of these salt marsh ridges contained fertile soil suitable for cattle to pasture. With it, first human settlement arose. A terp was created by artificially elevating these ridges with local (waste) material like sediment, earth, wood, and manure, protecting the settlers from storm surges (Nieuwhof, 2018). These settlements proved successful, and the hills started to expand. Single terpen agglomerated to neighboring terpen, creating terpen villages. The sea level continued to rise, as the amount of sedimentation did. While villages were heightened to keep up with the rising sea level, sediment deposits continued, expanding the coastline towards the north. This provided new salt marsh ridges where settlements could evolve. Until then, terpen were the only way to live safely in a tidal area.
The terp provided safety for its inhabitants, but once the high tide covered the land, residents had to rely on their provision and the provision of others. Ditches were dug to increase seawater discharge from the surrounding landscape once the sea retired. Often, a ring ditch was built around a terp; it provided a fast discharge of salt water and reduced the impact of waves hitting the terp during storm surges. The system of ditches had pros and cons as it discharged water quicker, but simultaneously made the land more vulnerable as water could enter easier, increasing erosion.
Not everything could be grown or made on terpen, some products were only available inland, which made in inhabitants of terpen excellent traders (De Ruyter, 2016).
Circular Stories
Life on a terp was life in interaction with the sea. With human settlement and forthcoming agricultural practices, salt water threatened crops and cattle. To get rid of salt water from the landscape after storm surges, ditches were dug to accelerate saltwater discharge. Implementing ditches provided another benefit: it reduced erosion of the terp as it absorbed energy from incoming waves. With high tide, water containing sediment was brought to land. This was key to the area’s existence as the sea level rose. With sediment deposition, the coast. Summer dikes provided a way to trap more sediment. They were used to accrete fertile sediment and protect freshwater puddles from high tide. Since humans and cattle depend on freshwater, different methods were used to gather fresh water. Most of it was provided by rain, cached in dobben on top of terpen. Gutters increased fresh water supply from roofs.
