Water levels and water level regulation plans
The water authority determines the water level in the various parts of our region. We reach agreements about this in water level regulation plans. We monitor the water levels closely.
Measuring water levels
We measure water levels automatically with so-called pressure transducers. The water level is recorded every 15 minutes in a special computer in the hydraulic-engineering structure. At the largest and most important water-level areas, this computer automatically controls the pumping station or weir. The recorded data is plotted on the map at least once a day.
Water levels are expressed in centimetres relative to Amsterdam Ordnance Datum (NAP).
When is winter or summer level?
Water levels in watercourses vary between summer and winter. This is because there is more precipitation in winter than in summer and because of the demand for water. More information Winter and summer water levels
Target levels
If you would like to know what the target levels are in our management area, please refer to our water-authority map.
- On the map on the left side of the page, click on ">" to open the map layer list.
- Here you can check the box for "Water level areas."
- You can now zoom in on the map to see all the information you need.
Amsterdam Ordnance Datum (NAP)
- To compare heights within the Netherlands, we use one zero point: the NAP.
- We measure higher (+ .. centimetres NAP) and lower levels (- .. centimetres NAP) relative to that.
- 0 metres NAP is approximately equal to average sea level.
Determining water level regulation plans
The water authority determines the required surface-water level under normal conditions in the most important canals, lakes, streams, and ditches. The Board of Directors decides on these target levels. This way, everyone knows which agreements apply. In the Noorderzijlvest region, the water level is not the same everywhere. Our area is divided into different water-level sections, each with their own water level. Within each water-level section, this water level is controlled by one or more hydraulic-engineering structures that can regulate the water level. These can be pumping stations, weirs, locks, or inlets.
- A pumping station is a pump that can raise water from a lower to a higher level. Water naturally flows from high to low. The pumping station makes sured that the water level in an area remains at a preset level.
- A weir holds back water to keep it at a certain level.
- A lock is located between two watercourses that have different water levels. So on one side of a lock, the water is higher or lower than on the other side. We can open a lock so that water can flow through.
- An inlet in a dyke or quay allows fresh water to flow into the polder.
Target level
The target level is set in a water level regulation plan. The target level is the water level in NAP at the drainage structure of a water level area, often a weir or a pumping station, when it is a surface water system at rest. Strictly speaking, the water system is never completely at rest. After all, when it rains heavily, the water level rises, and when there is a long dry spell, evaporation is high. As a result, the actual water level may deviate from the target level.
When should we adopt a new Water Level Regulation Plan?
Circumstances and insights into how we want to manage water levels in a particular area can change. That is why it may be necessary to review existing agreements carefully from time to time.
Water level regulation plans are always prepared for:
- Determining the target level in a catchwater. A catchwater is a temporary storage facility for excess water in the polders. A catchwater is the water into which polder pumping stations discharge excess water. For Noorderzijlvest, this concerns the Electra catchwater and the Fivelingo catchwater.
- Determining the target level for areas that are wholly or partly designated as 'nature'.
- Areas affected by subsidence caused by natural-gas extraction or peat oxidation.
When natural conditions cause significant fluctuations in water levels, it is not always possible to maintain a constant level. In such areas, a Water Level Regulation Plan does not always apply. This is the case in the Drenthe stream valleys in our region.
What do we look for in new water level regulation plans?
We always investigate the water system as it currently functions in the area concerned. We also engage in dialogue with the people in the region. Our study always covers the following topics:
- The use of water and land. Is there agriculture or nature? Are there boats? Is there fishing?
- The main characteristics of the water and soil. What is the current water level? What is the elevation of the plots? Does the soil consist of sand, clay, or peat?
- Water quality. What is the quality like, and can we improve it by adjusting the water level?
- Storing too much water. Are the ditches and canals large enough to store the excess? For example, if it has rained heavily?
- Is the area susceptible to drought? What can we do about it?
- How much has the ground subsided due to gas extraction? Or due to peat oxidation? Should we adjust the water level as a result?
What does a Water Level Regulation Plan cover?
A Water Level Regulation Plan is about surface water and therefore does not concern:
- Deep groundwater. The provincial executive is responsible for deep groundwater (e.g., for larger groundwater extractions).
- The 'shallow groundwater' in built-up areas. The municipality has a duty of care for the groundwater there.
- Groundwater problems on plots of land. The owners have a duty of care for their own property.
Current water levels
Current water levels throughout the country and in the region can be monitored online. No rights can be derived from this information.
Current water level regulation plans
Agreements on water levels sometimes need to be renegotiated. Circumstances and insights can change. We provide an overview of recent water level regulation plans and plans we are currently preparing.