Living safely below sea level is not as simple as you may think
Safe despite living below sea level
Almost all inhabitants of the province of North Holland live below sea level. As the water authority for the northern part of the province, Hoogheemraadschap Hollands Noorderkwartier ensures that all 1.2 million regional residents can work and live in safety. We work to keep the water behind solid dykes and channel excess water in the right direction. Now, however, with sea levels rising, more frequent rainfall and the ground sinking, the difference between the level of the water behind the dykes and the street level is increasing. This means there's a lot of work ahead for us.
If we do nothing, this ‘sink' we live in will fill up with water. That's why, on top of our daily tasks of managing and controlling water levels in the region, we are going to be investing hundreds of millions of euros in dyke fortification, as part of the High Water Protection Programme, and in measurements to prevent serious water issues.
Dry feet: fortifying dykes and dunes
The inhabitants of North Holland keep their feet dry thanks to almost 350 kilometres (about 217 miles) of dunes and dykes surrounding the region. And, to an additional 1,500 kilometres (932 miles) of dykes and dams (such as secondary dykes) along inland waterways. The water authority makes sure these embankments are well-maintained and enhanced where necessary, to prevent flooding.
In recent years we have strengthened hundreds of kilometres of dykes and dunes as part of our High Water Protection Programme. Fortification entails different things depending on the situation. Sometimes a dyke needs to be higher, in other cases broader and more stable. In one location we might place basalt rocks to break the surf, in another extra sand or soil is better.
Sufficient fresh water: water level
If ditches contain too much water, we use pumping stations to transport it to higher-level ditches, waterways or drainage channels. From there, it flows out to sea, to Lake Markermeer and Lake IJsselmeer. During dry spells we do the reverse, letting in extra water from the two lakes. What the right level is, depends on the purpose of the surrounding land. Nature benefits from a high water level, whereas agriculture requires a low one. Our district has hundreds of different water levels that we manage and control.
Water storage: preventing water issues
In the future we can expect longer periods of dry spells and episodes of heavy rainfall. For the temporary storage of excess rain, we build water storage structures. During the development of new residential areas, we advise on possibilities for drainage and storage as early as in the design phase.
Clean water in ditches and small lakes is of vital importance to humans and nature. That's why we have nineteen sewage treatment plants, which filter around a hundred million cubic metres of wastewater a year. This water returns as surface water that is clean enough for people, nature, agriculture and horticulture to use.
We have the additional task of managing approximately 1,300 kilometres (790 miles) of secondary roads. We maintain the road surface, lineation, public lighting, bridges, shoulders, ditches and recreational spots along the road, all with a permanent focus on maximum traffic safety.
Hoogheemraadschap Hollands Noorderkwartier plays a central role in everything to do with water in the region of North Holland above the North Sea Canal. In these efforts, we work closely with the Directorate-General for Public Works and Water Management (Rijkswaterstaat), the local county and council, stakeholder organizations, entrepreneurs, citizens, engineers and other specialists.The water authority organizes consultation groups and information meetings to share and discuss needs, wishes and possibilities.
As a regional water authority, Hoogheemraadschap Hollands Noorderkwartier is a government organisation. Our board is democratically chosen and we have our own tax system. Our administrative organization is comparable to a city council. The general management can be likened to the council, the daily management to the aldermen, and the dyke warden to the mayor. Every four years, voters elect a new managing board.
We share the costs
The costs of being able to live safely below sea level in North Holland are shared by everyone living in the region. Residents pay two kinds of water taxes:
- Water Authority Rates, to continue maintenance of dykes and water management;
- Sewer Rates, to fund wastewater treatment.
The tasks of a water authority
A regional water authority is the same as a water management authority. It ensures that:Inhabitants have dry feet.
- There is sufficient fresh water;
- There is sufficient clean water.
- Roads are safe.
Maintenance of the road system is an additional task of Hoogheemraadschap Hollands Noorderkwartier.