NUMERICAL MODELS’ APPLICATION FOR MORPHODYNAMICS ASSESSMENT OF CLIMATE CHANGE IMPACTS IN THE MINHO RIVER ESTUARY

The knowledge of physical, biological, and chemical estuarine processes and how they are affected by climate change conditions is essential for improving estuarine management. A common methodological approach for studying these complex processes is based on the implementation of numerical models supported by field data as bathymetry, sediment characteristics, flow discharges, current velocities, and sea water levels. This work is based on the implementation of a numerical model of the Minho River estuary using the Delft3D software. This model is able to simulate hydrodynamic and morphodynamic processes for different time scales. It was calibrated using the OpenDA tool, which automatically determines some of the models’ parameters, such as the tidal constituents and the roughness coefficient, aiming to minimize the error between observed data and simulated results. Different scenarios were considered to assess the effects of climate change, according to the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Results showed that the elevation in the estuary mouth can reach 77 cm, depending on the considered scenario. It was also determined that floods are the main sediment transport driver along the estuary, intensifying the accretion processes. Furthermore, the sea-level rise reduces the amount of transported sediments to the coastal platform, increasing the erosion risk in this area and increasing the accretion inside the estuary.

Assessment of Fire Effects on Surface Runoff Erosion Susceptibility: The Case of the Summer 2021 Forest Fires in Greece

The wildfires of summer 2021 in Greece were among the most severe forest fire events that have occurred in the country over the past decade. The conflagration period lasted for 20 days (i.e., from 27 July to 16 August 2021) and resulted in the devastation of an area of more than 3600 Km2. Forest fire events of similar severity also struck other Mediterranean countries during this period. Apart from their direct impacts, forest fires also render an area more susceptible to runoff erosion by massively removing its vegetation, among other factors. It is clear that immediately after a forest fire, most areas are much more susceptible to erosion. In this paper, we evaluate the erosion hazard of Attica, Northern Euboea, and the Peloponnese that were devastated by forest fires during the summer of 2021 in Greece, in comparison with their geological and geomorphological structures, as well as land cover and management. Given that a very significant part of these areas were burnt during the major conflagrations of this summer, erosion risk, as well as flood risk, are expected to be very high, especially for the coming autumn and winter. For the evaluation of erosion risk, the burnt areas were mapped, and the final erosion-risk maps were constructed through GIS software. The final maps suggest that most of the burnt areas are highly susceptible to future surface runoff erosion events.