A Dutch climate resilience water authority: “Hoogheemraadschap Hollands Noorderkwarier”
Almost all the inhabitants of the province of North Holland live below sea level. Hoogheemraadschap Hollands Noorderkwartier (HHNK), the water authority for the northern part of the province, ensures that all 1.2 million residents can work and live in safety.
In the Netherlands the safety for pluvial flooding is set in standards. HHNK (and all water authorities) Dutch water authorities, including HHNK, constantly invest in water system design to limit pluvial flooding and to ensure that the system complies with the Dutch standards (NBW). However, this does not mean that there is no risk of flooding.
To be prepared for what could come, HHNK conceived a big masterplan. With the help of knowledge institutes, companies, and the public sector. The masterplan aimed to develop a methodology using state of the art technology to compute and map water depth and flow with unprecedented accuracy and speed. 3Di hydrodynamic simulation software made it possible to harvest the availability of high-resolution data. Thereby realizing a new level on informed decision making on flood risk management and spatial planning.
More than seven hundred models were created with 3Di, based on high resolution 2D data sets including data on elevation, infiltration, soil storage capacity and the soil roughness (hydraulic surface roughness). Five years ago, this would have been impossible to achieve on this scale. 3Di created over 4.5 TB of never seen HD flood scenarios. Large multi-disciplinary project teams analysed these results. The amount of detail left the experts wondering: “Is dit nou een plas, of wateroverlast.” Roughly translated: “Is this a puddle or flooding.”
The results of this project changed the Dutch perspective on how to define and mitigate risk of flooding, leading to a new national guideline on the assessment of pluvial flooding.
HHNK was able to match their core processes with 3Di and is now enabling their mission with the best hydrodynamic simulation data available now and in the future.