Modelling mega-recharge schemes

Numerical computer models can be used to provide scientific evidence to help to inform decisions surrounding the design of recharge schemes.  Models can be used to assess the potential consequences, both positive and negative impacts, of different approaches to mega-recharge.  The Coastal Evolution Model (CEM) is an exploratory model which simulates alongshore sediment transport.  It allows for the exploration of shoreline change in response to management strategies. A CEM has been applied along the Dungeness shoreline, south east England, to investigate the potential evolution of a hypothetical gravel intervention over 3 shoreline management planning epochs: present day (0-20 years), medium term (20-50 years) and long term (50-100 years) (Brown et al. 2016; Phelps et al. 2015). Six hypothetical gravel interventions were shown to limit alongshore sediment drift causing increased down-drift erosion over the short term (> 25 years) with longer term impact (> 50 years) being mostly beneficial across the frontage or at least negligible.

Scenario B: No additional intervention

Scenario S1: Recurved spit positioned to the west (55 ha)

Scenario S2: Recurved spit positioned off centre towards the east (55 ha)

Scenario S3: Recurved spit positioned to the east (55 ha)

Scenario M: Multi-location recurved spits located at S1-S3 (165 ha)

Scenario L: Large recurved spit positioned off centre towards the east (270 ha)

There is the potential to apply this research worldwide, to explore where to focus beach recharge and explore the size of beach mega-recharge schemes in order to address problems of coastal erosion and/or flood risk. Implementing a similar research strategy using models such as COVE, Delft3D, X-Beach or CEM for complex, dynamic coastlines can help to identify the positive (beach widening) and negative impacts (inhibited sediment drift) of different mega-recharge designs and aggregate sizes (or combinations of aggregates).  Models, such as FV-COM, Delft3D and LISFLOOD-FP, can also be used to investigate changes in coastal hydrodynamics, to assess current flood risk, and to evaluate likely future flooding due to sea-level rise or from extreme events (storms, hurricanes, tsunamis etc.)

In addition to modelling tools, monitoring technologies such as radar, fixed and video camera, drones (UAV) and instrument deployments enable the results of beach recharge schemes to be tracked to ensure the delivery of intended goals and to reveal and address any unintended consequences.

The results of modelling and monitoring can be fed into Decision-Support Systems (DSS) or Decision-Support Tools (DST), such as those developed though the ARCoES project, to help identify where and when interventions are best made.