Coastal aquifer, shoreline and shallow marine sediment permeability on a global scale

The world's coast is an important interface of global hydrogeology. It mediates the flow of groundwater to the oceans and the supply of fresh groundwater that much of the coastal population relies on for drinking water. The coast connects also fresh groundwater and marine seawater. For a better understanding of the global water cycle, the interaction between freshwater and seawater along the more than 2 million kilometers of global coast needs to be studied more intensively. For this, knowledge of coastal permeability is paramount.

The global coastal permeability map (GCPM) aims to represent the coastal permeability of the world's coast in 1-kilometer segments. The GCPM divides coastal permeability into three distinct views: Permeability of the landward aquifer, the shoreline, and the shallow marine sediments. Extensive GIS-based work was conducted to merge several recent global datasets which represent attributes indicating permeability with the shoreline.  Using the multiple features of these datasets, the coastline was then classified into permeability configurations.

The GCPM provides an important and useful baseline data set for local to regional coastal hydrogeology and especially for global coastal hydrogeology. Possible uses include serving as an input parameter for coastal boundary conditions for global models that integrate sea-land interactions, as a parameter for submarine groundwater discharge calculations, and as an aid in identifying areas of increased saltwater intrusion hazard. Also, pooling coastal parameters from the individual datasets will increase accessibility and allow opportunities for broader analyses. Differentiating between costal aquifer, shoreline, and shallow marine permeability will make the GCPM valuable to a broader field of coastal science and applications, as well as influence the way coastal permeability is viewed in the future.