Remotely-sensed spatiotemporal dynamics of the coupled Trichonida – Lysimachia lake system in Western Greece at the seasonal, annual, and decadal time scale

Understanding how the combined effects of hydroclimatic variability and anthropogenic interventions shape lake reservoirs is crucial for sustainable water resources management as well as for numerous ecosystem services. In the present study, we focus on the interplay between two lakes in Western Greece that are part of the Natura 2000 network of protected areas, namely the Trichonida – Lysimachia lake system. Lake Trichonida is the largest natural lake in Greece and is connected to the substantially smaller lake Lysimachia through an open channel. The two lakes, together with the connecting channel, constitute a couple system. The channel regulates the flow from Trichonida to Lysimachia lake based on irrigation needs (summer time) and peak flows in the main river corridor (winter-time discharge of Acheloos river). The spatial variability in the extent of the two lakes was quantified at the seasonal, annual, and decadal time scales with remote sensing spectral indices, compiling a wealth of Earth observations. Moreover, water level data from satellite altimetry and ground measurements were combined to characterize water level fluctuations in each lake and their cross-correlation. Gridded data of key meteorological variables (air temperature, precipitation, etc.) as well as drought indices were used to characterize the hydroclimatic variability in the watersheds associated with the two examined lakes. The combined used of ground measurements together with multivariate Earth observations offers new insights into the spatiotemporal dynamics of the coupled Trichonida – Lysimachia lake system that could support and guide sustainable water resource management in the area under environmental change.