The surface water level is measured in ditches and lakes by means of gauges. The measurements are generally shown in metres or centimetres in relation to Dutch Ordnance Level (NAP). The surface water level is determined by diverse processes (natural and human-influenced) that operate at or just below the ground surface. Examples are precipitation, evaporation of the surface water, groundwater suppletion and abstraction of shallow groundwater for irrigation.

The observations of the surface water level are important not only for establishing the current levels but also for information about their fluctuations. Information about the fluctuations of surface water levels is based on the analysis of series of measurements. Measurements over the long term provide information about the influence of the seasons and any trends in the series.

Gauges on the map

Water level gauges can be found on the map under Other research.