Modelling restoration of natural flow regimes in dam impaired systems: Biomorphodynamic effects and recovery times

Dams affect the natural flow regime by altering magnitude, timing and frequency of high low flows. Many river ecosystems impaired dams are currently being restored. Restoration success is difficult to quantify often assessed comparing restored system an unimpaired static ‘reference’ system. However, restoring a past environmental conditions assessing restoration it situation neglects dynamics non-linear, adaptive responses. With this modelling study we evaluate long-term changes in morphology, morphodynamics, riparian vegetation cover habitat suitability two fish species types wetland meandering gravel bed after removal upstream dam complete regime. We ecological hydromorphodynamic recovery systems different operating regimes three time periods was present these dynamic undisturbed situation. Modelling results show that potential depends on how much has been changed state at start restoration, rather than duration pressure. Even if shortly comparable pre-disturbance conditions, there can still be time-lag response where future continues deviate from When happens, develop into alternative equilibrium becomes increasingly difficult. These stress importance considering variability as well reference systems, requiring detailed spatio-temporal monitoring assess effects.