Coastal wetlands can be saved from sea level rise by recreating past tidal regimes

Abstract

Climate change driven Sea Level Rise (SLR) is creating a major global environmental crisis in coastal ecosystems, however, limited practical solutions are provided to prevent or mitigate the impacts. Here, we propose a novel eco-engineering solution to protect highly valued vegetated intertidal ecosystems. The new ‘Tidal Replicate Method’ involves the creation of a synthetic tidal regime that mimics the desired hydroperiod for intertidal wetlands. This synthetic tidal regime can then be applied via automated tidal control systems, “SmartGates”, at suitable locations. As a proof of concept study, this method was applied at an intertidal wetland with the aim of restabilising saltmarsh vegetation at a location representative of SLR. Results from aerial drone surveys and on-ground vegetation sampling indicated that the Tidal Replicate Method effectively established saltmarsh onsite over a 3-year period of post-restoration, showing the method is able to protect endangered intertidal ecosystems from submersion. If applied globally, this method can protect high value coastal wetlands with similar environmental settings, including over 1,184,000 ha of Ramsar coastal wetlands. This equates to a saving of US$230 billion in ecosystem services per year. This solution can play an important role in the global effort to conserve coastal wetlands under accelerating SLR.

A Review of Unoccupied Aerial Vehicle Use in Wetland Applications: Emerging Opportunities in Approach, Technology, and Data

“…UAVs are tools that enable restoration assessment at the whole-site levels and allow for cost-effective change analysis of restored environments [8,9,121,122] due to their flexibility in flight times and heights and lack of disturbance to sensitive restoration areas [56]. Furthermore, repeat aerial surveys facilitate adaptive management techniques [118] of iteratively examining and modifying projects, and this continual decision-making capability helps ensure long-term success of restoration projects.…”

“…UAV-based restoration monitoring involves a variety of objectives, including biomass estimates [120], hydrological mapping [8,9,11,123], morphological evaluations [43,57], and classification of plant communities in peatlands [10,56,119,122] and coastal regions [44,117,118,121]. While many researchers leverage RGB aerial imagery for restoration monitoring [8,9,120,122,123], multispectral imagery, and specifically the near-infrared wavelength, which can detect species and topography in shallow wetland environments [155].…”

“…Additionally, thermal aerial imagery can be used to locate groundwater discharge in restored peatlands, greatly reducing time spent conducting ground-based seep detection studies [11]. Vertical takeoff and landing in constricted or topographicallycomplex areas generates popularity of quadcopter UAV usage for small restoration study regions [8][9][10][11]120,122], while fixed-wing UAVs are preferred when mapping larger restoration projects [56,118,121,123]. UAVs prove to be efficient tools to track human-induced ecological modifications [9,11,44,118,122,123], and cheaper and lighter multispectral sensors for quadcopter, and fixed-wing UAVs will help advance future restoration assessments and analysis.…”

“…Positional inaccuracies may accumulate and propagate across workflows, eroding the quality and reliability of the final products [162]. Such concerns are especially problematic in studies heavily relying on 3D information, such as assessments of site elevation change in response to restoration treatments or sea level rise [28,35,43,57,88,118,130].…”

Estuarine tidal range dynamics under rising sea levels

“…Changes in the estuarine tidal range can also affect the structure of tidal currents and thereby, sediment transport dynamics [ 33 , 34 ]. The process of sediment erosion, suspension, and deposition, as well as the hydroperiod (i.e., depth, duration, and frequency of tidal inundation), influences the establishment of vegetation communities and their distribution/extent within an estuary [ 26 , 35 – 37 ]. As such, SLR-induced variations in tidal range dynamics are likely to pose a significant challenge within many estuaries, requiring further attention.…”