A new technique for tidal habitat restoration: Evaluation of its hydrological potentials

The inability to create an adequate tidal regime in embanked areas is a major problem for restoring estuarine habitats. The controlled reduced tide system (CRT) was previously hypothesized to overcome this constraint. As part of an estuarine management plan which combines flood protection and tidal habitat restoration, the first CRT system was implemented in the freshwater zone of the Schelde estuary (Belgium). Based on four years of high-frequency monitoring on the first CRT and the adjacent estuary, this study demonstrates the hydrological functionality of CRT.The tidal characteristics generated by this technique were suitable in the short and the long term, with a reproduction of the spring-neap tidal cycle. In both the CRT and the estuary, the spatial and temporal variability of several hydrological descriptors were comparatively analysed. In spite of some hydrological deviations from the estuarine pattern, nothing precluded a suitable ecosystem feature in CRT.The potential influences of CRT-specific hydrology on ecology and estuarine restoration are discussed. The restoration potential of the CRT system is shown to be particularly relevant for tidal marshes in early succession stage, habitats which are often lacking in embanked estuaries. Additionally, it offers a more robust and adaptable alternative to other systems. Conclusively, the CRT system should be more advocated in estuarine restoration.

► Tidal regime is essential for the creation of estuarine habitats.
► Controlled reduced tide system is a new restoration technique which was supposed to overcome this constraint in lowered embankments.
► CRT was constructed in a severely impacted estuary.
► After four years of continuous monitoring of hydrology, earlier model predictions were validated and empirical proof of successful tidal gradient reproduction by CRT is presented.
► The hydrological regime generated by CRT was found to be suitable for tidal marsh development.