In 2014 and 2017, the Water Act was significantly amended with regard to safeguarding flood safety in the Netherlands. Commissioned by the Ministry of Infrastructure and Water Management, Decisio, consultancy firm TwynstraGudde, and architecture and engineering consultancy Sweco evaluated the effects of these legislative changes.
Strong boost for efficiency and manageability
The 2014 and 2017 amendments to the Water Act have demonstrably contributed to a more efficient and better manageable Flood Protection Programme (HWBP). In particular, the introduction of ex‑ante cost estimation and the project‑specific contribution strengthened cost awareness and professionalisation. At the same time, ex‑ante estimation led to conservative cost forecasts and excessive risk provisions, which put pressure on programme‑level efficiency. The evaluation emphasises that adjustments within the existing framework are more effective than introducing new legislative changes.
Financial safeguards under pressure due to rising costs
Although the 50%:40%:10% cost distribution for flood protection measures—between the national government, all water authorities, and the implementing water authority respectively—is laid down in law, the project‑specific contribution of the implementing water authority turns out to be not 10% in practice, but 1.1%. This distorts the financial balance and increases pressure on solidarity contributions. The costs for the HWBP up to 2050 are estimated at 24 billion euros, with a wide margin of uncertainty. New financial arrangements are needed to ensure the continuity of the programme and to distribute the burden fairly.
Assessment and supervision significantly improved
Extending the assessment cycle to 12 years, introducing the Legal Assessment Instrumentarium (WBI), and assigning a central supervisory role to the Human Environment and Transport Inspectorate (ILT) have led to better insight into the condition of flood defences. The new risk‑based approach offers managers of flood defences more room for action, but this potential is not yet fully utilised. The signalling value and minimum threshold support timely programming, although they are not always practically applicable.
Recommendations: optimise within existing frameworks
The report calls for tailored financing for exceptional projects, better safeguarding of the project‑specific contribution, and greater use of innovative and short‑cycle reinforcement options. Through targeted adjustments and collaboration within the alliance, the HWBP can be implemented more effectively and made more future‑proof.
More information
For more information about this evaluation, please contact Gerwin van der Meulen at g.vandermeulen@decisio.nl or +31 (0)20 670 05 62.
