We use our groundwater for different purposes: for instance, as a resource for drinking water or as a water supply for nature conservation. The applications that groundwater may serve depend mainly on its quality. Traditionally, water production companies have monitored the quality of the groundwater that is pumped up in the Netherlands. In order to perform this control task properly, they sample the groundwater at the pumping station and nearby and send it to laboratories for analysis. In recent decades, national and provincial authorities have increasingly taken over the more regional monitoring of the quality of the groundwater. But of course, at the abstraction sites, the water producers themselves monitor the groundwater quality.
The analysis of groundwater samples focuses mainly on the substances dissolved in the water that have an indicator function. For instance, chloride (Cl) may indicate salinisation, or contamination, or microcontaminants. Other examples are metals, such as the zinc and cadmium in the groundwater in the Kempen area, and residual products from slurry or pesticides that may get into the groundwater. The quality of the groundwater also says something about the groundwater’s provenance, including the depth it comes from. The age of the groundwater can also be determined: this provides insight into its flow paths through the ground.
The quality of the groundwater data varies. Although DINO Groundwater contains many reliable measurements that give a full and clear picture of a sample, it also contains data that are much less reliable or provide an inadequate analysis of the groundwater in a filter. The reliability largely depends on two factors.
The first is the number of steps in the sampling method and the corresponding method of analysis, as errors may occur at each step when measuring the groundwater levels and subsequently inputting them into DINO. Errors may also occur during the production and processing of the “technical” data on the measuring points, such as the height of the surface.
The second factor is the quality of the sampling method, which is also linked to the analysis method. When a filter is sampled, a small volume of water is removed from the subsurface, usually by means of a pump, for laboratory analysis. During the pumping different types of groundwater become mixed. The degree of mixing depends on the duration of the pumping. How a sample is subsequently stored and processed affects the result of the analysis.
Samples on the map
The "Samples" data type can be found on the map under Groundwater research.