Uncertainties of creek evolution in coastal wetlands facing sea-level rise

Adaptation of coastal areas facing climate change is a global challenge. Some of these low‐lying regions are commonly managed and engineered to reduce damage, loss of life, and environmental degradation caused by natural hazards originating from the sea. However, sea-level rise and changes in storm regimes are putting unprecedented pressure on these managed systems, forcing the adoption of “no active intervention” or “managed realignment” strategies in areas where “hold the line” options cannot be justified due to financial constraints. The aim of this research is to explore how disintegration of sea defences would affect creek topology under present day and future sea level rise scenarios, using the Hesketh marsh as a case study.  A reduced complexity numerical model is applied to produce ensemble predictions for analysis. Without the presence of vegetation, results suggest that creek geometry efficiency and density of tidal creeks are insensitive to sea level rise.

The model assumes the erodibility of the wetland is homogeneous and constant which leaves room for improvement because coastal environment is subject to changes as a result of global climate change and human activities. Changes in environmental stressors, such as sea level rise, elevated CO₂ concentration, changing storm patterns, etc. could adjust the resistance of the wetland to erosion in either way. Hence, the adequacy of current parameterizations of soil erodibility in numerical models requires further investigation.