Coastal erosion is a widespread issue – it is estimated that approximately 70% of the world's coastlines are eroding to some extent. This phenomenon has significant economic consequences, as costs associated with property damage, infrastructure loss, and remediation projects grow annually. Let’s investigate the role of geological and geotechnical analysis in understanding coastal erosion, and bring to light any possible advantages that these analyses can provide to aid stakeholders.

Due to Finite Element Analysis (FEA)’s systematic approach to simulating complex geotechnical behaviours, it provides a powerful tool in predicting how coastal defences will behave under various conditions. Here are some of the ways in which this application can be useful:

Geometry discretisation: In FEA, the coastal topography and proposed defences are discretised into smaller elements. This allows any geometry to be created in the analysis model, even in 3D. It also allows material properties such as density, strength and stiffness to be assigned to different parts of the model representing the soil and rock of the natural ground, the water and the structural elements of the proposed coastal defences.

Soil-Structure Interaction Analysis: FEA allows us to simulate the interactions between the natural ground of the coastline and the structural elements of the proposed coastal defence schemes. The interactions can be complex due to the different engineering properties of the natural ground and stiff structural elements. FEA accounts for factors like soil-structure interface properties and relative deformations between them. It takes account of forces due to wave action and, for port structures, mooring loads. It also takes account of water flow around structures due to the tides and wave action. Furthermore, FEA helps identify potential failure modes for fortification structures. These include sliding, overturning, or bearing capacity failure. By applying various loading scenarios, the safety and stability of coastal defence structures can be determined.

Geographic Information Systems (GIS) can also be harnessed to fortify coastlines against erosion since they serve as a central repository for various geospatial datasets including topography, bathymetry, land cover, and historical erosion data. Here are some of the ways in which GIS data and analysis can serve to improve FEA models:

Topographic Modelling: One of the key aspects of coastal erosion management is managing the terrain, and this is one of the areas best suited to assistance from GIS. Geospatial analysis employs Digital Elevation Models (DEMs) to represent the topography of coastal areas. High resolution DEMs are crucial for accurate modelling.

Site Selection for Fortification: Geospatial analysis allows for site suitability assessments for coastal fortifications. By incorporating criteria such as accessibility, environmental impact, and cost considerations, GIS can help in selecting optimal locations for seawalls, breakwaters, or beach nourishment projects.

These two approaches to understand the issue of coastal erosion complement one another by improving the accuracy of models and predictions but also, crucially, by providing means of validation after construction. GIS helps to manage historical erosion data and create spatiotemporal analyses. This is invaluable for assessing erosion trends and understanding the factors contributing to coastal degradation. In addition, continuous monitoring of coastal changes is crucial. Geospatial data analysts use remote sensing data such as satellite imagery and InSAR to detect changes in shoreline position and beach profiles. GIS enables the extraction of meaningful information from these images, supporting ongoing assessment and decision making.

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