Water Board Hoogheemraadschap De Stichtse Rijnlanden (HDSR) uses the registrations of the water management structures in their domain (valves, (auger) pumps, weirs, fish ladders) for analyses and management of the surface water system. To be able to use these (discharge) registrations first the theoretical discharge equations must be calibrated.

Since 2011 Aqua Vision has been organizing and performing these calibrations by carrying out ADCP discharge measurements at the operational structures. In total more than 150 locations have been calibrated until now.

In most cases the calibration of the discharge equation was done by ADCP discharge measurements in the channel leading to the pump or weir. An improved relation between the pump rpm or weir height was derived this way.

In some cases, the specific situation of the waterwork called for innovative ways to determine the amount of discharge being pumped. For example, at pumping station Goyerbrug it’s impossible to measure discharge with an ADCP due to a lake at the outflow and a big channel at the inflow. In this case the water level was registered with several pressure sensors and the area of the lake was measured (with a RTK-GPS) before and after the pumping. The capacity of the pump (for three different rpm’s) was derived from the volume change in the outflow lake during an hour of pumping.  There was a good correlation between the different pump settings and an improved discharge equation could be derived from this.

With the newly derived equations errors in theoretical capacity or registration of water levels/weir height are discovered and corrected for, resulting in an improved water management system.