The replacement of hydraulic structures in light of tipping points

In many delta areas hydraulic structures are key elements in water management strategies for fresh water supply and flood risk management. Adaptation of delta areas to changing climatological and societal conditions will be in pace with the renovation and replacement of these hydraulic structures. Since hydraulic structures are prone to deterioration, their performance diminishes over time. Changes in society, the economy, and the physical environment can also alter the functionality of structures, or have an impact on their performance. Although faced with deterioration and exogenous changes, timing of replacement is essential because replacing too early leads to insufficient use of invested capital, while replacing too late leads to loss of societal benefits. This article explores the timing of replacement using adaptation tipping points. We indicate three drivers deterioration, biophysical change, and socio-economic change - that determine the moment in time when replacement becomes necessary. Moreover, we conclude that for determining the moment of replacement, at the very least, the objectives, maintenance and operations of hydraulic structures need to be taken into account. This exploration is illustrated with the task of replacing seven hydraulic structures in the River Meuse.