Developing water wise cities. A Resilience Assessment method applied to Oasen's water system

Strategic asset management and long-term infrastructure planning for urban water systems is currently increasingly challenged by a series of conflicting trends and processes. These include demand issues due to urbanization and increasing expectations of the services provided, water supply issues in terms of quantity and quality, especially in view of large- scale hydro-climatic changes and delivery issues as aging infrastructure becomes less reliable, and new investment is limited. These issues impact the reliability and climate- proofing of cities, as aging infrastructure, often designed with a single “extrapolated” future in mind, restrict the flexibility and adaptability of the entire socio-technical urban system in view of more dynamic futures. For this purpose, the idea of resilience has been gradually embraced by the water sector as the way of moving away from the ever-more elusive objective of ‘fail-safe’ infrastructure design towards a more realistic ‘safe-to-fail’ approach, and thus dominates policy discourse in future ‘proofing’ systems. The new aim is to design systems able to perform under significant long-term uncertainties, essentially being more “resilient”. However, the term itself as well as the framework to operationalize its analysis are not well defined; both are actually at their infancy.

Het Water Wise Concepts model is verder uitgewerkt en toegepast voor een stress-test in de praktijk voor een deel van het watersysteem van Oasen. Het model kwantificeert de veerkracht van verschillende watersysteemconfiguraties onder complexe toekomst scenario’s en wildcards (dijkdoorbraak, extreme droogte en verzilting, hacking en extreme immigratie). Decentrale configuraties met RO-waterbehandelingssystemen zijn veerkrachtiger dan de centrale configuratie op basis van conventionele zuivering. De mate van decentralisatie kan worden geoptimaliseerd aan de hand van veerkracht en kosten. De resultaten geven het management inzicht in de gevolgen die bepaalde infrastructurele keuzes kunnen hebben voor de veerkracht van hun (geprojecteerde) systeem. Het model is bruikbaar voor toepassing op andere waterinfrastructuursystemen.