Water levels and gauges
The water board determines the water level in the various parts of our working area. We make agreements about this in water level decisions. We monitor the water levels closely.
Measuring water levels
We measure water levels automatically using pressure transducers. The water level is recorded every 15 minutes in a special computer in the hydraulic structure. At the largest and most important water level gauges, this computer also 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 centimeters relative to Normal Amsterdam Level (NAP).
When is winter or summer level?
Water levels in waterways vary between winter and summer. 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 board map.
- On the map on the left side of the page, click on '>' to open the map layer list.
- Here you can check the 'Water level areas' layer.
- You can now zoom in on the map to see all the information you need.
Normal Amsterdam Level (NAP)
- To compare heights within the Netherlands, we use one zero point: the NAP.
- We measure higher (+ .. centimeters NAP) and lower levels (- .. centimeters NAP) relative to that.
- 0 meters NAP is approximately equal to average sea level.
Determining water level decisions
The water board determines the desired surface water level under normal conditions in the most important canals, lakes, streams, and ditches. The general board decides on these target levels. This way, everyone knows what agreements apply. In the Noorderzijlvest working area, the water level is not the same everywhere. Our area is divided into different water level zones. Each of these has its own water level. Within each water level zone, this water level is controlled by one or more hydraulic 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 ensures that the water level in an area remains at a preset level.
- A dam holds back water to keep it at a certain level.
- A lock is located between two waterways 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 dike or quay allows (fresh) water to flow into the polder.
Target level
A water level decision sets the target level. The target level is the water level in NAP at the drainage structure of a water level area, often a weir or pumping station, when the surface water system is 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 will we make a (new) benchmark decision?
Circumstances and insights into how we want to manage water levels in a particular area can change. That is why it may be necessary from time to time to carefully review existing agreements.
Water level decisions are always made for:
- Determining the target level in the reservoir. The reservoir is a temporary storage facility for excess water in the polders. The reservoir water is the water into which polder pumping stations discharge excess water. For Noorderzijlvest, this concerns the Electraboezem and the Fivelingoboezem reservoirs.
- Determining the target level for areas that are wholly or partly designated as 'nature'.
- Areas affected by land subsidence due to 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, water level regulations do not always apply. This is the case, for example, in the stream valleys of Drenthe in our working area.
What do we look for in new water level decisions?
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 research 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? Is the soil sandy, clayey, or peaty?
- 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 surplus? 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 decision not cover?
A water level decision concerns surface water and therefore does not concern:
- Deep groundwater. The province is responsible for deep groundwater (e.g., for larger groundwater extractions).
- The 'shallow groundwater' within built-up areas. The municipality has a duty of care for the groundwater there.
- Groundwater problems on plots of land. The owner has a duty of care for their own property.
Current water levels
Current water levels throughout the country and in the Noorderzijlvest working area can be monitored online. No rights can be derived from this information.
Current water level decisions
Agreements on gauging sometimes need to be renegotiated. Circumstances and insights can change. We provide an overview of recent gauging decisions and decisions that we are currently preparing.