Saltwater intrusion: A growing threat to soil health

With ongoing climate change, the global mean sea level is projected to rise and accelerate. This exposes coastal areas to hazards ranging from enhanced flooding and erosion to salinization of soils, groundwater and surface waters. In estuaries such as the Elbe estuary, the effects of climate-change-driven sea level rise can propagate several dozens of kilometres upstream. Due to its higher density in comparison to freshwater, saline water along coasts and estuaries flows landward under the less dense freshwater until reaching equilibrium. With increasing sea level, this seawater interface can shift landwards reducing the thickness of the freshwater layer on top. One of the less understood effects of such phenomenon is the transport of saline through the unsaturated zone and to the surface adversely affecting soil health. In this study, we employ numerical methods to investigate the complex coupling between sea level rise, saltwater intrusion, solute transport in soil and soil salinity under different boundary conditions.

Thereby, we aim at identifying parameters that affect soil salinity as a result of saltwater intrusion driven by the projected sea level rises. In particular, we will focus on areas along the Lower Elbe where saltwater intrusion is already a growing concern which could affect many activities including but not limited to tourisms, vegetation and agriculture. An important example for the latter is the orchard “Altes Land” which is located along the Lower Elbe. With >10 million trees and 10,500 ha, it is one of the largest contiguous orchard plantations in Europe which could be affected by the soil salinization.

In this project, we are utilizing a comprehensive series of hydrogeological and climate data to provide predictive tools capable of identifying the extent of soil salinity as a result of SLR-driven saltwater intrusion in aquifers with a particular focus on possible future salinization scenarios under different climate conditions.  

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